Theses and Dissertations Collection

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Molecular characterization and antigenic prediction of foot-and- mouth disease virus in relation to vaccine improvement in endemic settings in Africa
(Sokoine University of Agriculture, 2024-05) Mathias, Mkama
Foot-and-mouth disease (FMD) affects all cloven-hoofed livestock and wildlife, and it is caused by FMD virus (FMDV) that belongs to the genus Aphthorvirus and family Picornaviridae. The disease threatens food security and livelihoods across different parts of the world. There are seven FMDV serotypes (O, A, C, Asia1, SAT1-3), and studies in southern Africa describe buffalos to be persistently infected reservoirs of SATs and transmit the viruses to cattle. The FMD control is challenging and antigenic heterogeneity among field-circulating strains represents the most significant factor. The field's infinite variants pose a challenge to the effectiveness of vaccines and suggests for quick, reliable, and cost-effective methods for obtaining vaccine improvements relevant information timely. FMD is endemic in Africa; impacting the livelihoods of pastoral communities, and hinders the livestock sector by denying access of regional and global lucrative markets. Currently, the strategies deployed to control FMD in Africa, especially tropical Africa, are typically fragmented national-level focused activities with relatively poor outcomes, rather than regionally coordinated initiatives that have been used on other continents (South America, Europe) to reduce and even eliminate virus circulation. Studies have not demonstrated whether the buffalo can also act as carrier of the EurAsian serotypes O and A occurring in parts of East Africa. Also the current epidemiological status of the field circulating strains and their genetic-antigenic characteristics need to be understood. Also, it was unclear on the main challenges to FMD control under pastoral dominated and endemic settings in Africa that has hindered FMD control for decades. This study investigated field reported outbreaks and clinically health buffalo of Tanzania to determine the molecular epidemiology of the circulating field strains between 2018 and 2021, their genetic- antigenic characteristics, and their evolutionary relationships using molecular techniques for FMDV detection, typing, and characterization. The seroprevalence of FMDV serotypes O and A in Tanzania were studied using NSP ELISA for natural infection screening and typed by Solid phase competitive ELISA (SPCE) assay. Additionally; the B-cell antigenic epitopes of SAT1 types were mapped by combined publicly available immuno-informatics tools ranging from those employing propensity scales to the most recent machine learning and artificial intelligence models, to maximize the prediction authenticity, on the FMDV type SAT1 VP1 polypeptides from this study and those sourced from global rich databases. The study identified three FMDV serotypes (A, O and, SAT1) circulating in the field as Africa Topotype G-I lineage, EA-2 Topotype, and Topotype I (NWZ) respectively. This study nucleotide sequences for serotypes O and SAT1 field strains were analysed categorically, and the shared percent identities of 92.0-100.0% and 96.9-98.8% were revealed respectively. The analysed 247 buffalo (37.6%, n =93) and cattle (58.3%, n =154) NSP ELISA positive serum samples from livestock-wildlife interface areas of Katavi, Mikumi, Mkomazi, and Ruaha ecosystems in Tanzania were further analyzed for FMDV serotype O and A by SPCE. A highest percentage seropositivity (PS) was revealed (67%, n= 103) and (55%, n= 51) in cattle and buffalo, whereas FMDV serotype A tested highest (54%, n= 83) and O (25%, n= 23) for cattle and buffalo sera, respectively. Also, some of the cattle (36%, n= 56) and buffalo (25%, n= 23) sera tested, showed evidence of multiple infection with FMDV serotypes O and A. Results showed that out of the 93 analyzed NSPE positive buffalo samples, 30.1% (28) of CI (19 – 39) had antibodies specific to FMDV Type A. Also 54.8% (51) of CI (39 – 64) and 24.7% (23) of CI (15 – 33) had antibodies specific to FMDV type O and those of mixed sero reaction respectively. Similarly, out of 154 NSPE positive cattle samples analyzed 53.9% (83) of CI (69 – 98), 66.9% (103) of CI (88 – 118) and 36.4% (56) of CI (44 – 70) had FMDV antibodies specific to type A, O, and mixed (O&A) seroreactions respectively. The results of compared serotype-specific seroreactions statuses revealed higher percentage for type O across all species, next type A, and the lowest score for mixed seroreactions. Similarly; at 95% CI, the analyzed cattle and buffalo NSPE positives expressed higher scores of (41.7%; 20.65%) by (33.6%; 11.34%) and (22.67%; 9.31%) on type O, type A and mixed seroreactions respectively. Results on Chi-square test of independence were significant, X2 (df = 4, N = 330) = 31.0876, p =.00001 at p<.05 criteria, indicating a relation between spp difference and variation in state of FMDV infection rates. The analyzed probang buffalo samples (n=89) from Serengeti national park using FMDV serotype O and A specific primers (one-step RT-PCR), 1.2% was revealed to be FMDV type O. Also, five consensus linear epitopes (PLE I – V) at positions 3-30, 44-59, 95-112, 134-149, 199-219 with 75%, 88%, 94%, 44 % and 24% of their aa reads conserved were observed respectively. Additionally; conformational epitopes (PCE I – VI) at positions 1-26, 82-87, 93-114, 131-149, 175-179, and 201-221 with 53 – 100% conserved were also identified. As the vaccines are challenged by the rapidly evolving FMDV in the field, the unveiling of conserved epitope domains is vital for enhancing future FMDV vaccines long-term effectiveness in the field. This study has demonstrated FMDV type O infections in buffalo being the first molecular and serosurvey combined study to be undertaken on Eurasian FMDV types O and A in cattle and buffalos in Tanzania. The information generated from this study strengthens knowledge on FMDV epidemiology in Tanzania and Africa, and thereby contributing to the progressive control pathway-FMD program through tailored control initiatives. The unveiled challenges of FMD control amongst Africa’s diverse pastoral communities’ landscape for triggering strategical discussions on national and transboundary regional-based FMD control approaches in Africa.
Epidemiological study of newcastle disease virus in a live bird market in Morogoro Municipality, Tanzania
(Sokoine University of Agriculture, 2024-05) Tsaxra, John Benjamin
Village poultry plays a vital role in providing essential nutrition and income for rural communities in Africa. In this context, poultry are typically traded through live bird markets, which serve as central trading hubs where producers connect with traders and consumers, facilitating the flow of poultry products along the value chain. While they serve as important trading hubs, these markets create an environment where pathogens, like Newcastle disease virus (NDV) and avian influenza, can easily emerge and spread. To date, half of NDV class II genotypes have been reported in Africa (I, IV, V, VI, VII, XI, XIII, XIV, XVII, XVIII, and XXI). The information on the circulating NDV genotypes is still scarce despite the endemic nature of ND in most countries on the African continent. Improving our understanding of the epidemiology of NDV in live bird markets is important for assessing the circulating genotypes, disease risks and identifying factors that contribute to its persistence. A one-year repeated cross-sectional study was employed to survey local chickens at the Mawenzi live bird market in Morogoro municipality for NDV presence, its temporal and spatial distribution, and risk factors for NDV infection. The oro-cloacal and blood samples were collected from 659 local chickens between June 2020 and May 2021. The sampling was conducted once every week and questionnaires administered to the middlemen and traders at the same time. The questionnaire targeted the information on the source of the chickens, vaccination status, whether homes from where chickens were bought keep mixed poultry species, transit time from the villages to the market, time taken from collection of chickens from the villages to arrival to the market. Newcastle disease virus was detected by using reverse transcription real-time polymerase chain reaction (RT-qPCR) and conventional PCR followed by sequencing of PCR products. Twenty-three percent of 659 local chickens sampled were positive for NDV based on PCR. Increased odds of NDV infection were identified in chickens that had been in the market for two or more days prior to sampling. Four significant spatiotemporal clusters of NDV-positive chickens encompassing 13 villages were detected between August and October 2020, illustrating geographic hotspots of infection when NDV was most prevalent. Furthermore, Sequencing and phylogenetic analysis revealed the presence of sub-genotype VII.2. Similar to other live bird markets, this market had enclosures with high densities of birds of mixed species, limited biosecurity, and the presence of birds with observable illness. Bird traders who source the chickens from the villages, described long transit times in mixed enclosures with limited sanitation practices without consideration of sick birds or vaccination status prior to arriving at the live bird market. The detected sub- genotype VII.2 has phylogenetic links to Zambian NDV strains implying a Southeast dissemination of the virus, considering that it was first detected in Mozambique. This study highlights the need to invest in infrastructure and biosecurity for live bird markets as well as training opportunities for increasing traders‘ knowledge on hygiene, sanitation, animal welfare, and poultry biosecurity measures. Moreover, the study underscores the need of active NDV surveillance to determine the distribution of this NDV genotype in the country and monitor its spread and contribution to the emergence of new ND virus strains.
Characterization of Aeromonads and development of Vaccine candidate from Aeromonas Hydrophila Isolated from Tilapia fish farms in Tanzania
(Sokoine University of Agriculture, 2020) Mzula, Alexanda
Tanzania produces less than half of the country annual demand in fish. Therefore, there is an urgent need to produce more fish, particularly through fish farming. However, aeromonads infections cause major lose in aquaculture worldwide and especially in developing countries, including Tanzania, lacking advanced capacity for fish disease control and prevention. Poor fish farming management practices, lack of data on prevalence, emergence of resistances to commonly used drugs, drug residues and limited capacity to control aeromonads bacterial infections emerged as major health problems in fish farming in Tanzania. This study aimed to characterise the aeromonads species circulating in fish farms and then develop a monovalent vaccine candidate from selected prevalent aeromonads specie for supporting tilapia fish farming improvement in Tanzania. A cross sectional study was conducted in Ruvuma, Mbeya, Iringa and Kilimanjaro regions between February 2017 and October 2018. A questionnaire was administered to 32 selected fish farmers to explore their knowledge on pond, fish health and diseases management practices. The results showed that the selected farmers had limited knowledge on pond, fish health and disease management practices. On- farm training on the same to these farmers would improve their knowledge. A total of 816 whole fish samples were aseptically collected from these 32 fish farms to detect and identify aeromonads using molecular methods in order to establish the prevalence and characterise their virulence properties. The overall prevalence of 24.6% was recorded. Seventy five percent of the isolates had virulence genes of varying combinations and the in-vivo study showed high mortality (98.3%) to isolates with more virulence genes indicating their capacity to establish disease in a favourable environment. The Aeromonas hydrophila strain TZR7- 2018 was selected and attenuated using a novel thermo-continuous sub-culturing method to develop a vaccine candidate. The experimental study was carried out to assess its protective efficacy. The results showed that the vaccine candidate had acceptable protective efficacy of 82.3% and 71.4% when given through intraperitoneal injection (IP) and immersion (IM); respectively. To the best of my knowledge this study reports the development of thermo attenuated and stabilized A. hydrophila vaccine candidate for the first time in Tanzania or elsewhere
Prevalence and economic effects of non typhoidal salmonella infection in wild and domestic animals around Ruaha National Park Ecosystem, Tanzania
(Sokoine University of Agriculture, 2023) Mdindikasi Zamu
Non-typhoidal Salmonella infection is one of the zoonotic conditions caused by Gram negative bacteria of the genus Salmonella, which belong to the family Enterobacteriaceae. Non-typhoidal Salmonella infection is an important foodborne infection particularly in immunocompromised humans. This study assessed the prevalence and economic impact of non-typhoidal Salmonella infections in wild and domestic animals around the Ruaha National Park Ecosystem and the study was conducted in 2021. A laboratory analysis of 215 fecal samples from wild animals (108 samples) and domestic animals (107 samples) was carried out to determine the prevalence of non-typhoidal Salmonella infection after the samples were enriched in Selenite F broth and incubated for 24 hours. The samples were primarily cultured on the Salmonella Shigella agar (SSA) and subsequently on MacConkey and blood agar to observe any swarming. Gram staining was conducted to check whether the suspected colonies were Gram negative since Salmonellae belong to this group. Confirmatory biochemical tests were conducted using the Triple Sugar Iron (TSI) test, IMViC tests, oxidase and catalase tests and molecular confirmation was done by extracting the DNA followed by a conventional multiplex PCR. Laboratory analysis revealed that non- typhoidal Salmonella infection was absent in the wild and domestic animals. A structured questionnaire was administered to assess the awareness and economic impact of non- typhoidal Salmonella infection. Analysis of Variance (ANOVA) test was done to assess the awareness, estimated costs of resources lost as well as the costs used for treatment of animals with non-typhoidal Salmonella infections at P-value 0.05. Findings from this study revealed that for the past five years until year 2020, 20% of the livestock keepers were aware of non-typhoidal Salmonella infection. The study showed that for the past five years until year 2020 the infection had negative economic impact since 102,140 Tsh. was estimated to be spent per year in controlling non-typhoidal Salmonella infection while 680,100 Tsh. was the estimated amount of lost resources because of non-typhoidal Salmonella infection. Therefore, from the findings, we recommend that the responsible government sectors should invest in more research on non-typhoidal Salmonella infection on other national park ecosystems as well as other zoonoses but also add effort in increasing awareness of zoonoses to the communities. This will help livestock keepers improve the animal rearing methods hence reducing the incidences of zoonotic diseases particularly non-typhoidal Salmonella infection.
Genetic determination of immune responses to Newcastle disease virus vaccine in chickens
(Sokoine University of Agriculture, 2002) Lwelamira, James
A study was conducted at Sokoine University of Agriculture to investigate the genetic control of immune response of chickens against Newcastle disease virus (NOV) vaccine. The study involved local chickens from Tanzania (LL), Rhode Island Red derivative hybrids (EE), and their reciprocal crosses (LE and EL). The local ecotype had the highest mean antibody titres following primary vaccination, as well as before (residual) and after secondary vaccination, while the exotic breed had the lowest titres in all three measurements. The crossbred chicks were found to be intermediate between the two parental genotypes, but the differences between the local ecotype and the crosses were not significant except for the primary vaccination antibody titre. Furthermore, there were no significant differences between the reciprocal crosses. Differences between sexes were not significant. Despite the observed superiority of the local ecotype for antibody titre, there were no significant differences among genotypes with respect to mortality rate. Heritability estimates for antibody titre ranged from 0.27 ± 0.06 to 0.39 ± 0.09, 0.17 ± 0.03 to 0.32 ± 0.11, and 0.18 ± 0.08 to 0.28 ± 0.08 for antibody titre following primary vaccination, before, and after secondary vaccination, respectively. While the contribution of additive breed merit and heterosis effects in antibody titre before and after secondary vaccination were both significant, only the contribution of additive breed merits were significant for primary immune response. There were no significant correlation coefficients between antibody titres at different periods of measurement, nor between antibody titres and body weights. It was concluded that substantial improvement in immunological status of a stock against Newcastle disease could be achieved through both selection and crossbreeding
Factors associated with diseases and mortality of calves in Morogoro, Tanzania
(Sokoine University of Agriculture, 1997) Mellau, Lesakit Sipira Bernard
This study was aimed at elucidating the influence of management and other factors associated with diseases and mortality of calves managed under intensive, semi intensive and free range systems practised by stale farms, parastatal farms and small scale dairy producers in the region. Management factors include bucket feeding versus suckling of colostrum, administration of post colostra! feeds, housing and disease control schemes. Other factors were breeds of cattle and season of the year. A total of 368 calves were involved in the study over a period covering one rain season and one dry season. 138 calves were from Kingolwira Prisons farm (KPF), 127 from Mlali, 57 from Azam Estate, 22 from Magadu dairy Unit and 24 from SUA farm. All these farms are within a radius of 50 kilometers from Morogoro town and were selected on the basis of differing management systems, herd size and access to the farm by road. The study was conducted through questionnaires, clinical examination and laboratory analysis for hematological, parasitological and pathological parameters. Prevalence of diarrhoea was significantly high in bucket fed calves than suckeld calves “(Pc0.001). Bovine coronavirus, rotavirus and Escherichia coli K 99 antigens were detected in 61% of faecal samples collected, and mixed infection of 2 or all of these organisms was frequent. Helminthosis was observed in both weaned and unweaned calves but calves less than 1 month old were relatively less affected as compared to older calves "(P <0.001). Haemonchus spp, Trichostnmgylus spp, Strongyloides papillosus, Oesophagostonium spp and Cooperia oncophora were the most frequently isolated worms, where they accounted for 35.5%, 15.5%, 15.5%, 31.1% and 2.2% respectively. Toxocara vindorum infestation was detected in only 4 calves of less than 28 days at Mlali farm where water buffaloes graze with cattle. Other diseases were, pneumonia, cutaneous mycosis which subsided with increasing age, bovine parasitic otitis, cases of Beta hemolytic E. coll otitis and alopecia of unknown cause. Mortality rate among calves was 25%, 17.4%, 13.6%, 8.7% and 7.8% for SUA farm, KPF, Magadu dairy unit, Azam Estate and Mlali farms respectively. Weaned and unweaned calf mortality contributed equally to total calf mortality. Helminthosis was the cause of mortality in weaned calves, whereas, pneumonia and diarrhoea were the main causes of death in unweaned calves. Coccidiosis was not a serious disease in calves managed under semi intensive and free range systems as it was in intensively managed calves.
Trypanosome non-specific antibody responses during trypanosoma congolense infection of cattle
(Sokoine University of Agriculture, 1998) Buza, Joram Josephat
Trypanosome infections of cattle are characterized by concomitant increase in serum IgM, development of antibodies reacting with non-trypanosome antigens and an increase in the proportion of CD5+ B cells in peripheral blood and spleen. It is not known whether the three events are related. In mice and humans, CD5+ B cells have been shown to predominantly produce IgM antibodies that are polyreactive in nature. This experiment was initiated first to confirm whether trypanosome non-specific antibodies develop during the course of Trypanosoma congolense infections of susceptible Boran or resistant N’Dama cattle. In addition, to investigate whether a different trypanosome species, Trypanosoma vivax, can also induce these antibodies. Secondly, to investigate whether the CD5+ B cells, which increase during trypanosome infections of cattle, are the source of the trypanosome non-specific antibodies observed. Experimental infections were initiated Trypanosoma congolense by tsetsefly bite in 13 susceptible Boran and 6 resistant N’Dama cattle. A separate group of 4 Boran cattle was also infected with a different trypanosome species T. vivax. Serum samples were collected from infected cattle at different time points and tested in ELISA for trypanosome-specific and trypanosome non-specific antibodies. Seven Boran cattle from the T. congolense-vai&ci&d group were killed between 31-51 after infection and mononuclear cells prepared from spleen tissue. The cells were immunoglobulins using monoclonal antibody IL-A58. Separate populations of CD5+ and CD5' B cells were obtained by sorting using a flow-cytometer. Equal numbers of CD5+ and CD5' B cells were tested in the Silver Immunogold (SIG) blot assay for enumeration of number of cells secreting IgM, IgG and antibodies reacting with non-trypanosome antigens B-galactosidase, ovalbumin and lysozyme. ELISA tests on sera from both Boran and N’Dama cattle infected with Trypanosoma congolense revealed an increase in antibodies which react with a cytochrome, but less or no reactivity was found for antigens such as ssDNA and TNP. A similar development of trypanosome non-specific antibodies reacting with B-galactosidase was found in T. vivax infections of Boran cattle. The trypanosome non-specific antibodies were exclusively IgM, while the trypanosome-specific antibodies were both IgM and IgG. Results from the SIG blot assay revealed that numbers of IgM- and IgG-secreting cells were not different between CD5+ and CD5’ populations (P>0.05). However, significantly more cells in the CD5+ population secreted antibodies reacting with non-trypanosome antigens than in the CD5’ population (p<0.05). number of non-trypanosome antigens such as B-galactosidase, ferritin and double-stained for CD5 using monoclonal antibody IL-A67 and surface It is concluded from these studies that trypanosome non-specific antibodies develop during trypanosome infections of both in Boran and N’Dama cattle, they can be induced by different trypanosome species, are exclusively IgM and mainly secreted by the CD5+ B cells. In the first experiment, IgM antibodies reacting with a number of unrelated nontrypanosome antigens were detected in serum of trypanosome infected cattle. These antibodies were mainly secreted by the CD5+ B cells. However, the specificity of these antibodies is not known. Two alternative hypotheses have been put forward to explain the reactivity to unrelated antigens observed in serum of trypanosome infected cattle. The first one ascribes reactivity to unrelated antigens due to presence of different antibody clones, each one possessing different specifity to unrelated antigens due to presence of antibody molecules, each one capable of binding more than one unrelated antigens, such as the poly reactive antibodies secreted by murine and human CD5+ B cells. This experiment was initiated to investigate whether the trypanosome non-specific antibodies are polyclonal or poly reactive. A pool of serum was made from samples of 6 Boran cattle on 30 days after infection, when trypanosome non-specific antibody levels were highest. The serum as observed in cases of polyclonal activation. The second one attribute reactivity pool was passed through immunoaffinity colums conjugated with either trypanosome antigens or non-trypanosome antigen B-galactosidase. Antibody fractions that bound to the column and those which did not bind were collected and tested in ELISA for their reactivity to trypanosome and non-trypanosome antigens. The IgM fraction purified on B-galactosidase reacted with B-galactosidase, cytochrome, ferritin and the trypanosome lysate. Similar results were obtained for IgM fraction purified on a trypanosome lysate column. The IgM fraction that exhibited reactivity to different antigens was present in both pre-and post-infection only with trypanosome lysate but not with the non-trypanosome antigens. The trypanosome-specific IgG fraction was only found in post-infection sera. polyreactive. Their presence in pre-infection sera indicates that the infection does trypanosome-specific IgG antibodies are monoreactive and specifically induced by trypanosome infection. EXPERIMENT THREE Trypanosome infections in cattle induce production of both trypanosome-specific and the trypanosome non-specific antibodies. It is known that specific antibodies sera. In contrast, the IgG fraction purified on trypanosome lysate column reacted These results conclude that trypanosome non-specific IgM antibodies are polyreactive. Their presence in pre-infection sera indicates that the infection does trypanosome-specific IgG antibodies are monoreactive and specifically induced by trypanosome infection. EXPERIMENT THREE Trypanosome infections in cattle induce production of both trypanosome-specific and the trypanosome non-specific antibodies. It is known that specific antibodies sera. In contrast, the IgG fraction purified on trypanosome lysate column reacted These results conclude that trypanosome non-specific IgM antibodies are not specifically induce them, but helps to amplify their production. In contrast that are directed at the exposed determinants of the variable surface glycoprotein coat play a role of destruction of trypanosomes and eventual elimination of infection. However, the significance of specific antibodies, which recognize trypanosome non-specific antibodies are not known. Some workers suggested that antibodies recognizing products of lysed trypanosomes contribute to immunopathological processes such as development of anaemia. However, others suggested that some of these antibodies, such as those binding to trypanosome enzyme cystein protease may play a protective role to the host by neutralizing the enzymatic function of the enzyme. The polyreactive trypanosome non-specific antibodies may potentially bind to host or trypanosome antigens; and both pathogenic and protective consequences are possible. It is therefore, important to study regulation of antibody responses which takes place during trypanosome infections in cattle. Information obtained may help in designing means by which protective antibody responses can be selectively upregulated at the expense of pathogenetic responses. T lymphocytes play an important regulatory role on antibody responses. CD4+ T cells provide helper function to antibody production by B cells during T-cell dependent antibody responses. CD8+ T cells sometimes antibody responses during trypanosome infections of cattle is not known. The aim antibody response during T. congolense infection of Boran cattle. of this experiment was to investigate the role played by CD4+ or CD8+ on various antigens released after the destruction of trypanosomes, and the Cattle were depleted of CD4+ or CD8+-T cells subpopulations by intravenous injection of specific monoclonal antibodies IL-A11 or IL-A105 respectively, before infection. The levels of the two cell subsets in peripheral blood were monitored by flow-cytometric analyses. Serum samples collected at various time points were tested in ELISA for determination of levels of trypanosome-specific and trypanosome non-specific antibodies. Flow-cytometric analyses of peripheral blood mononuclear cells revealed a complete depletion of these T cells subpopulations over a period of two weeks. Serum samples collected at various time points were tested in ELISA assay for specific antibodies reacting with whole lysate of trypanosomes, non-specific antibodies reacting with a non-trypanosome antigen fl-galactosidase, and total IgM. Trypanosome-specific antibodies were detected in both IgM and IgG isotypes. In contrast, non-specific antibodies reacting with B-galactosidase were exclusively IgM. Depletion of CD4+-T cells significantly reduced levels of specific, nonspecific and total IgM (p<0.05) while depletion of CD8+-T cells no effect on these antibody types (p>0.05). These results show that CD4+-T cells play a crucial role in production of trypanosome-specific as well as the trypanosome non-specific antibody responses to T. congolense infection in susceptible Boran cattle. CD8 T cells have no effect onantibody responses to trypanosome infections in cattle.
Epidemiology and control of bovine fasciolosis and schistosomosis in the Southern highlands of Tanzania
(Sokoine University of Agriculture., 201) Makundi, Asanteli Eliangikundi
The main purpose of this study was to determine if anthelmintic treatment of early patent primary fasciolosis and schistosomosis would prevent development of acute disease and would improve productivity of calves which continue grazing high potential natural transmission areas, without causing unwanted side effects or interfering with the development of immunity. Aspects of transmission biology and host parasite relationship were also investigated. Field studies, including cattle and snails, were performed at Lulanzi dairy farm where the trematode infections were highly prevalent. In addition experimental Schistosoma bovis infections were carried out in confined calves. The results from snail studies showed that Bulinus natalensis was the most abundant freshwater snail, which was responsible for the transmission of Schistosoma bovis mainly towards the end ofthe rainy season. Results ofthe field study, where cattle were naturally exposed, showed that acquisition of trematode infections was gradual. It took five months for the peak egg excretion to be reached, followed by a gradual decline to a very low level. Both triclabendazole and praziquantel drugs were highly efficacious and reduced Fasciola and Schistosoma worms by 100% and 95.6% respectively; while for S. bovis faecal and tissue eggs the reduction was 98.9% and 79-96%, respectively. Treatment kept the faecal egg excretion of both parasites species at a very low level for more than seven months and did not affect the development of immunity. Deterioration of the body weights pathological lesions, mainly fibrosis of the liver, were observed in the treated experimentally infected animals than in the untreated ones. However, no clinical and haematological parameters were only seen during the dry season and it was more severe in the untreated compared to the treated, challenged calves. More severe iii signs were associated with such changes and there was a gradual resolution of the pathological lesions. In the experimental S. bovis infections it was shown that, along the small intestine, eggs were mainly deposited in the anterior part at week seven, in the central part at week 18 and evenly distributed at week 32 post infection. The key findings from the present study are that B. natalensis for the first time was proved to transmit S. bovis and that such an infection occurred in the snails that had an existing amphistome infection. The animal studies have demonstrated that natural Fasciola and Schistososma infections in cattle are mainly sub-clinical and their impact is seen mainly during the dry season when feed supply is limited. Although treatment of early infections transiently causes additional liver fibrosis, treatment prevents development of acute disease and does not interfere with the development of immunity. Furthermore, treatment prevents further deterioration of the health of the cattle during the dry period. In addition, the observed reduction in faecal egg excretion has an epidemiological impact of reducing the transmission of these infections. In general, the present findings raise the possibility of strategic use of anthelmintics for preventing the development of acute trematode disease in young ruminants, improving their productivity and reducing the transmission intensity in endemic areas
Epidemiology and control of porcine cysticercosis in Tanzania
(Sokoine University of Agriculture, 2005) Boa, Mathias Emmanuel
In Study 1 predilection sites for cysticerci of Taenia solium were determined by calculating relative cyst density for different carcass sites. The psoas muscle was found to be an important site for localization of cysliccrci in pig carcasses followed by muscles of Triceps brachii. tongue, internal masseters, external masseters, diaphragm and heart as important sites for localisation of cystcerci in pigs. Based on these findings, all of these muscle groups/organs are proposed as predilection sites of T. solium in Tanzanian pigs and thus their examination should be mandatory for efficient routine inspection of pig carcasses. Tongue examination survey results from Chunya and Iringa Rural Districts, (Study II), showed that the two districts are endemic for porcine cysticercosis with prevalences of 7.6% and 8.4%, respectively. Structured questionnaire interviews identified factors associated with the disease prevalence in both Chunya and Iringa Rural Districts were free- ranging of pigs, home slaughtering of pigs and pork not being inspected. While in Chunya and Iringa Rural Districts lack of latrine and barbecuing were found a risk factor, respectively. In Study III, conducted in Mgeta Division, ante mortem tongue examination of 609 pigs and post mortem pork inspection of 124 carcasses found that they were all negative. These results instigated the interview study of relevant local parties, the findings of which were, none of the respondents reported having ever seen any cysts in pork or pigs. Availability, maintenance and use of latrines was found to be very high throughout Mgeta Division (97.6%) and in every village pigs are required to be kept totally confined. Health Centre data indicated that there were no cases of taeniosis, cholera or shigellosis reported during the last five years (1998 - 2002). There is an urgent need to transfer the important lessons from Mgeta districts such as Chunya and Iringa Rural. In Study IV sensitivity and specificity of the tongue examination and antigen ELISA [Ag-ELISA] tests were compared in local Tanzanian pigs and it was observed that Ag-ELISA was more sensitive [3.6 times] than tongue examination and therefore would be more appropriate for surveillance in Tanzanian pigs.
Epidemiology and control of worm infections in cattle on traditional, small-scale and large-scale dairy farms in Iringa district, Tanzania
(Sokoine University of Agriculture, 2004) Keyyu, Julius Dotto
This study aimed to determine worm control practices, anthelmintic usage and the epidemiology of gastrointestinal (GI) nematodes and flukes (Fasciola and amphistomes) in cattle on traditional, large-scale and small-scale dairy farms in Iringa District, Tanzania. A combination of qualitative data collection methods was used to obtain information on worm control practices and anthelmintic usage on the cattle farms. Strategic treatments, efficacy trials, an abattoir survey based on examination of GI tracts, cross sectional and longitudinal studies based on monthly coprological examination of cohorts for nematode and fluke eggs, worm counts in tracer calves and pasture larval counts were used to obtain quantitative data on helminth infections. Results indicated that worm control was based entirely on routine use of anthelmintics in 87.7%, 1 00% and 97.8% of traditional, large-scale and small scale-dairy farms respectively. Dairy farmers (55.5%) treated at least four times a year while traditional farmers (45.8%) treated twice a year. The treatment period on most farms depended on availability of money and not on the epidemiology of parasites. Absence of policy on worm control, lack of quality assurance of anthelmintics, inadequate extension workers and low education among farmers contributed significantly to irrational worm control and anthelmintic usage. The type of management especially the grazing practice had significant influence on the prevalence and intensity of GI nematodes and flukes. The prevalence of GI nematodes in traditional, large-scale and small-scale dairy cattle was 67%, 44.4% and 37% respectively. Worm burdens in tracers were mainly composed of Cooperia spp (51.6%), Oesophagostoinum radlatum (35.7%) and Haemonchus placet (10.2%). Faecal egg counts (EEC) and tracer worm counts were generally low and peaked only in calves and weaners. Pasture larval counts, FEC and tracer worm counts peaked toward the end of the rainy season (May). The overall prevalence of Fasciola gigantica in traditional, large-scale and small-scale dairy cattle was 63.8%, 46.2% and 28.4% respectively. The prevalence of amphistomes was 81.9%, 55.5% and 41.1% in traditional, large-scale and small-scale dairy cattle respectively. Adult animals had the highest prevalence of both Fasciola and amphistomes. The prevalence of flukes was high in all age groups on traditional cattle, only in adults arid yearlings in large-scale dairy cattle and low in all age groups in small-scale dairy cattle. The proportion of animals excreting fluke eggs in faeces was highest at the end of the dry season (November) and the early part of the rainy season. Triclabendazole (Fasinex®), nitroxynil (Trodax®) and ivermectin-clorsulon (Ivomec- Super®) were highly effective against Fasciola', a reduced efficacy of levamisole- oxyclozanide formulations was suspected. Strategic treatment with triclabendazole at the end of the rainy/early dry season significantly reduced the proportion of animals excreting Fasciola eggs while albendazole treatment maintained low nematode FEC until the next rainy season. It was concluded that helminths infection in the district has a seasonal pattern and farmers could save substantial amounts of money through strategic treatment programmes. Strategic treatments at the end of the rainy/early dry season (May/June) and at the end of the dry/early rainy season (November/December) are recommended for sustainable and cost-effective helminth control in the district. An additional treatment against GI nematodes in the middle of the rainy season (February/March) is recommended especially in calves and weaners. Treatment against GI nematodes and flukes in all age groups in small-scale dairy cattle might not be necessary if animals will be given pasture from clean areas.
Enhancement of smallholder dairy production under tropical conditions through supplementation to optimise roughage intake, digestibility and microbial protein synthesis
(The Royal Veterinary and Agricultural University, 2001) Mlay, Paul N. S.
This thesis addresses the nutritional related constraints facing the smallholder diary sector in Tanzania in general and Morogoro in particular. Smallholder dairy production practices and feeds were assessed though a structured survey carried out between January and March 1999 (Paper I). Monthly collection of forages used by farmers was done over a one-year period. The forage samples were analysed for chemical composition and in vitro organic matter digestibility to determine the annual variations in the nutritional quality. It was found that smallholder producers were playing a key role in the provision of dairy products that are in high demand in urban areas like Morogoro, in Tanzania. One of the limiting factors to enhanced productivity was the fall in milk yield (more than 40%) during die dry season. Forage analyses revealed that there was a fall in nitrogen and Metabolizable energy contents and organic matter digestibility with advancing dry season. The impact of low nitrogen in the basal feeds on animal performance was further investigated in an on station experiment set to determine the effects of nitrogen supplementation on feed intake, digestibility and rumen fermentation in animals fed poor quality forage (Paper II). In a 5x5 Latin square design, five ruminally fistulated heifers were assigned to either low quality hay only or supplemented with either low or high level of true protein (soyabean cake) or non-protein nitrogen (urea) (Paper II). At each level of supplementation, both urea and soyabean cake were iso-nitrogenous. Both soyabean cake and urea supplementation of poor quality forages led to significant improvement in the dry matter (DM), organic matter (OM) and plant fibre digestibility and microbial protein synthesis. Soyabean cake showed marginally higher (not significant) responses in most parameters at all levels compared to urea except for digestible NDF digestibility where the high level of urea supplementation showed a higher (not significant) value compared to soyabean cake. The superiority of soyabean cake may have been due to the extra DM, energy, pre-formed amino acids, minerals and extra amino acids arising from by-pass protein invariably associated with this supplement. Calculated price of supplemental protein from soyabean cake was about 3.3 Tsh compared to 0.1 Tshs per gram CP urea (see Table 1). Therefore, as far as fermentation of plant fibre was concerned, urea was equally good and a better option given the high prices of true protein sources like soyabean cake. One other interesting observation during the survey (Paper I) was the attempts by farmers to offer supplements to their cows especially the lactating ones. Surprisingly, most of the supplements used were energy rich (maize bran, molasses and cassava flour)ii while protein rich supplements were rarely used. A second on station experiment was set to investigate the effects of the commonly used supplements and a feed additive called “Magadi” on the intake and utilisation of poor quality roughage (Paper III). The experimental set up was a 5x5 Latin square design involving 5 ruminally fistulated heifers, 5 treatments and 5 periods of 28 days each. The treatments were poor quality hay plus maize bran (2.7kg DM) (control), or the control plus starch (0.9 kg DM cassava flour), sugars (1.3kg DM molasses) or “Magadi” (0.3kg). The fifth treatment was the poor quality hay supplemented with concentrate mixture (2.8kg DM) containing energy (68% maize bran) and protein (31% sunflower cake) and 1% mineral commercial mineral powder instead of the maize bran used in the control. Inclusion of “Magadi” or molasses or cassava flour in animals receiving equal amounts of maize bran produced variable results. Sugars increased OM intake and digestibility with little change in NDF digestibility compared to the control. Starch increased DM and OM intake and digestibility but reduced NDF digestibility due to high passage rate of NDF. “Magadi” did not improve DM intake but NDF digestibility and microbial protein synthesis were higher compared to supplementation with maize bran alone. There was also a higher in situ degradation of hay DM from dacron bags soaked in “Magadi” for 24 hours prior incubation in the rumen of standard cows compared to those soaked in tap water. This suggested that better response might be obtained through treatment of poor quality hay with “Magadi” than direct feeding. The supplement that contained a mixture of maize bran and sunflower cake fed to about 35% of total DM intake improved intake and digestibility of poor quality roughage compared to supplementing with plain maize bran as is the common practice with smallholder farmers in Morogoro. It was interesting to investigate whether the energy-protein concentrate mixture could be used by smallholder farmers in Morogoro as dry season supplement in order to arrest or reduce the fall in productivity during this season when the basal feeds are deficient in nitrogen and to some degree, energy. The major ingredients for making such a mixture (maize bran and sunflower cake) are easily available and reasonably cheap in Morogoro. Farmers were trained on how to compound such supplement on their own at farm level. The effect of feeding the concentrate mixture or maize bran alone as commonly done by most farmers was assessed through an on farm trial involving a total of 18 farms and 47 milking cows (Paper IV) in urban and peri-urban areas of Morogoro.
Prevalence and genotyping of human adenovirus among under-five children with acute febrile illnesses in Kasulu district, Kigoma, Tanzania
(Sokoine University of Agriculture, 2022) Masala, Mwinyi Benjamin
Respiratory tract infections are the most frequent presenting complaint accounting for up to 60% of children with acute febrile illnesses (AFI) seeking health care in Tanzania. The emergence of COVID-19 has increased the threats of respiratory viruses causing the rise of incident cases of upper respiratory tract infections (URTI) to 42.82% of cases from all the diseases and injuries in 2020. Human adenoviruses account for about 2% to 5% of all respiratory infections worldwide and are a common cause of respiratory tract infections in children, accounting for 5% to 10% of all lower respiratory tract infections in children. Viral etiologies of febrile illness cause major disease burden in tropical and subtropical countries. Despite the burden of acute respiratory infection on morbidity and mortality in children under the age of five in the world, there is a scarcity of data to evaluate the contribution and the epidemiological features of viral etiologies of acute febrile illnesses in Tanzania. The objective of this study was to determine the prevalence and genetic characteristics of human adenovirus (HAdV) circulating in Kasulu District, Kigoma, Tanzania. A total of 110 nasopharyngeal swabs were collected from under-five children with acute febrile illnesses from three health facilities. The collected samples were tested for HAdV using nested polymerase chain reaction (nPCR). Of the 110 patients, 6 patients were HAdV-positive and the detection rate was 5.45%. The prevalence of HAdV infection was higher among females 7.41% (4/56) than males 3.57% (2/54). The analysis of the nucleotide sequences showed that all six positive samples belonged to HAdV C type 2 (HAdV C2). Phylogenetic analysis showed that all nucleotide sequences from this study clustered with HAdV C2 strains from Germany (MH121114.1 and EU867472.1), China (MH322262.1), Kuwait (MF085403.1 and MF085391.1) and Argentina (JX173079.1). The findings from this study suggest that active HAdV type 2 circulate among children in Kasulu district in Tanzania. The results confirm the presence of HAdV among under-five children with acute febrile illnesses. Further studies are required to investigate the molecular epidemiology of HAdV in the country for appropriate control of the HAdV-associated diseases in the region.
Molecular investigation of foot-and-mouth disease during the 2021 outbreak in Mvomero District, Morogoro.
(Sokoine University of Agriculture, 2021) Acsa, Igizeneza
Foot-and-mouth disease is a highly contagious infection of cloven hoofed animals. The disease is caused by an RNA virus from the genus Aphthovirus in the Picornaviridae family. Foot and mouth disease virus (FMDV) affect mostly cattle at all stage of age and cause severe economic loss. In Tanzania FMDV has become endemic despite the efforts in its control. Outbreaks are still occurring and cause economic losses due to different reasons including vaccine failure. To avoid this crisis, vaccine matching can be done to ascertain a proper vaccine candidate that can create immunity in cattle against the circulating strains. To accomplish this, updated knowledge of the circulating FMDV strains in the country is required through regular epidemiological surveys and vaccine matching exercise. The aim of this study was to investigate FMDV serotype(s) responsible for the recent outbreak that occurred in Mvomero district, Tanzania. Seventeen (n=17) epithelial tissues were taken from feet and mouth of diseased cattle and transported aseptically to the Laboratory at Sokoine University of Agriculture for analysis. Detection, molecular typing and identification were done using One-step reverse transcription polymerase chain reaction (RT-PCR) followed by Sanger sequencing and phylogenetic analysis to establish the relationship to the existing FMDV sequences in GenBank. The findings indicated the morbidity and detection rates to be 27.5 % and 17.6% respectively. Further analysis revealed that the FMDV strain responsible for the outbreak was Serotype O, genotype EA-2 which clustered in the same clades with the isolates from Uganda (OUGA2009) and Kenya (O/KEN/150/2010) with accession numbers JN974311.1 and KF1352286.1 respectively. It is recommended that vaccines formulated using the characterised genotype need to be administered in cattle from that region. Continuous epidemiological studies and close follow up of the circulating strains is important so that the proper prophylactic doses can be administered before the outbreak occurs
Investigation on community awareness and level of contamination with gastrointestinal parasites on fruits and vegetables sold at selected markets in Zanzibar
(Sokoine University of Agriculture., 2022) Kakoma, Sadiki,Suleiman.
Consumption of contaminated fruits and vegetables could be one of the ways that community can be infected with gastrointestinal parasites. A cross-sectional study was conducted between March and April 2021 (i) to assess the community awareness on the knowledge of aetiology, clinical signs, transmission and control practices towards gastrointestinal parasites in fruits and vegetables (ii) to determine the prevalence of gastrointestinal parasites contaminating fruits and vegetables sold at five central public markets in Zanzibar. A random sampling method was adopted for the selection of respondents. Semi-structured questionnaires were administered to 400 respondents to assess their awareness on gastrointestinal parasites. Similarly, a random sampling method was adopted for the collection of 300 samples of fruits and vegetables from the markets, then samples were processed and microscopically examined for detection of gastrointestinal parasite contamination on fruits and vegetables. The results indicated that, 75.5% of the respondents higher awareness on gastrointestinal parasites. Specifically, the respondents had good knowledge on control practices (85.3%), followed by transmission (80.5%), clinical signs (69.5%) and aetiology (56.4%). Out of 300 samples of fruits and vegetables, 24 samples were identified to be contaminated with gastrointestinal parasites at the prevalence rate of 8%. The detected gastrointestinal parasites included; larvae and eggs of Strongyloides stercoralis (5.7%), larvae of hookworm spp (1.0%), eggs of Ascaris lumbricoides (0.7%), larvae of Bunostomum spp (0.7%), cyst of Entamoeba spp (0.33%) and larva of Haemonchus spp (0.33%).The findings of this study have indicated that community in Zanzibar were aware on transmission and control practices for fruits and vegetables contamination with gastrointestinal parasites. Moreover, the study has indicated that fruits and vegetables sold at the markets were contaminated with gastrointestinal parasites.
Epidemiology of peste des petits ruminants in relation to small ruminants movements and interactions with wildlife in Tanzania
(Sokoine University of Agriculture, 2021) Mdetele, Daniel Pius
Peste des petits ruminants (PPR) is a highly contagious transboundary animal disease of domestic small ruminants, camels and some wild artiodactyls. It is caused by Small ruminant morbillivirus (PPRV) of the family Paramyxoviridae classified into four genetically distinct lineages I, II, III and IV; and shares genetic and antigenic characteristics with rinderpest (RP) virus. The disease has significant socio-economic impact on communities which largely depend on livestock for livelihood, and is a threat to endangered susceptible wild species. This study aimed at investigating the spread and maintenance of PPR in the pastoral and agropastoral communities characterized by extensive mobility, in some areas interacting with wildlife, in order to generate necessary information for proper planning of control and eradication strategies for PPR. A Cross sectional studies, complimented with review of previous studies were carried out during the present study. Data collected from livestock and wildlife populations, samples collected from different agro ecological zones and wildlife from different habitats were involved in the study. In ecological studies, purposive sampling was performed in sheep and goats from 32 districts where PPR surveillance had never been carried out after the confirmation of PPR in Tanzania. The 32 districts involved in the study, included 3 (9.4%), 12 (37.5%) and 17 (53.1%) districts from the coast, semi-arid and plateau ecological zones, respectively. For epidemiological characterization of PPR, a total of 78 flocks of sheep and goats were investigated from Karatu (n=10), Longido (n=9), Meatu (n=7), Monduli (n=11), Ngorongoro Conservation Area Authority (NCAA) (n=13), Ngorongoro (n=18) and Serengeti (n=10).iii For the investigation of PPR seroprevalence in wildlife from different habitats, four species of wildlife; buffalos (Syncerus caffer), impalas (Aepyceros melampus), Grant’s gazelles (Nanger granti) and Thomson’s gazelles (Eudorcas thomsonii) were sampled. Sample sizes were calculated based on wildlife population obtained from TAWIRI aerial census of 2009 and 2010. PROMESA software (http://www.promesa.co .nz/ProMESA.htm) was used to estimate sample size per location in three types of wildlife habitats. Habitats were selected based on the level of contacts with wildlife. The habitats included Serengeti National Park (SNP) - designated only for wildlife, Loliondo Game Controlled Area (LGCA) - designated for wildlife livestock and other human activities and Ngorongoro Conservation Area Authority (NCAA) - designated for wildlife and livestock only. Chemical immobilization technique was used to capture buffalos and impalas, whereas gazelles were captured by using a modified netting technique, with trap made using locally available materials. With this technique three vehicles were used to head the animals towards the trap. All collected samples from livestock and wildlife were analysed at the SACIDS laboratory of Sokoine University of Agriculture. On ecological studies, the overall seropositivity across all agro ecological zones based on c-ELISA was 20.1%, of which 18.8%, 9.4%, 37.5% and 34.4% districts had very high, high, low and zero PPR seroprevalence respectively. Very high and high seroprevalence were frequently recorded in the semi-arid districts. Zero and low seroprevalence were mostly observed in districts from plateaux ecological zone. Statistically there were significant differences in PPR seroprevalences among districts of different ecological zones. On PPR outbreak characterization in the Serengeti ecosystem, a total of 160 samples were collected from clinically diagnosed cases, out of which 12 and 11 cases were confirmed using a lateral flow device (LFD) and real time reverse transcription polymerase chain reaction (qRT-PCR) tests, respectively. Of the confirmed cases aboutiv 60% of the animals were aged below six months of age with body temperature ranging from 38.5 to 41.3 o C, about 70% had lacrimation and only 45.5% had diarrhoea. Lineage III of PPRV was found to be circulating in the area. Semi structured interviews indicated pastoral communities were aware of PPR syndromes and had traditional names and remedies unlike in the agropastoral communities who mostly used Swahili terminologies. There was no clinical case of PPR observed in the 3 different wildlife habitats. However, a cross sectional survey was conducted to determine the seroprevalence of PPR in wildlife species. A total of 270 wildlife were captured, 26 (9.6%) from LGCA, 75 (27.8%) from NCAA and 169 (62.6%) from SNP, out of which two (7.7%), seven (9.3%) and 30 (17.8%) were seropositive, respectively. Results for one (3.8%), six (8%) and 42 (24.8%) animals from LGCA, NCAA and SNP, respectively, were doubtful. There were no statistically significant differences in seropositivity between habitats, species, age and sex. A modified netting technique developed and used during the present study, showed high animal and operator safety levels with minimal injuries compared to previous techniques. With this technique it was possible to capture even flighty animals that behave nervously because of hunting and other human activities, including Thomson’s gazelles (Eudorcas thomsonii), a species previously found to be difficult to capture by netting. Peste des petits ruminants was introduced in Tanzania before its confirmation in 2008 in northern Tanzania and has been spreading into different areas of the country through live animal trade and pastoralist migration. Seroprevalence of the disease in sheep and goats has been found to be higher in semi-arid agro-ecological zone. Peste des petits ruminants outbreak characterization in areas where livestock coexist with wildlife indicated age, temperature and lacrimation to be important components of the case definition for PPR syndromic diagnosis. Lineage III was found to be the lineage circulating at the moment in the area.v Although no clinical cases of PPR were observed in wildlife, PPR antibodies have been recovered in wildlife coexisting with livestock confirmed to have PPR cases which indicates that at one point wild animals contracted the virus. There was no statistically significant difference in the PPR seroprevalence between wildlife coexisting with livestock and those with no contact with livestock. Therefore, surveillance, prevention, control and eradication strategies for PPR should consider the agroecological zones favouring survival and perpetuation of the virus among reservoir hosts and the susceptible populations in these areas. Pastoral and live animal traders’ movements need to be considered in planning and implementation of PPR control strategies. Veterinary services and conservation authorities are encouraged to work together on planning PPR surveillance and control at different levels. On syndromic diagnosis of PPR in endemic settings need to consider age, body temperature and lacrimation on case definition. For species other than sheep and goats the c-ELISA test kits need to be validated as there were higher levels of doubtful results on laboratory analysis in wildlife samples.
Prevalence and risk factors associated with tuberculosis and drug resistance-tuberculosis among illicit drug users in Temeke, Dar es Salaam, Tanzania
(Sokoine University of Agriculture, 2021) Said, Aziza Ahmed
Tuberculosis (TB) is among ancient diseases which for over 4000 years has been affecting mankind. Tanzania is among the 22 TB high burden countries despite government’s efforts to fight the disease. Illicit drug users (IDU) constitute the population at high risk of harboring TB infection in the community. A cross sectional study was conducted between April and August 2020 to investigate the prevalence and risk factors associated with TB and drug-resistant TB amongst illicit drug users in Temeke district, Dar es Salaam. A total of 384 IDUs were recruited, each consenting participant providing spot sputum sample which was analyzed using GeneXpert, smear microscopy and LJ culture at Central TB reference laboratory (CTRL) in Dar es Salaam. Information on IDUs was obtained through structured Questionnaires and analyzed using univariate analysis in General Linear Model, variables with p-value < 0.2 were further analyzed using Binary Logistic Regression using IBM SPSS Version 20, variables with p-values < 0.05 were considered statistically significant. Overall, TB prevalence among IDUs was 9.89% which was significantly high compared to the reported TB prevalence of 0.25% in Tanzanian general population in 2018. Prevalence of TB among active IDUs was 16.15% and IDUs under methadone was 3.6%. Prevalence of Drug Resistance TB was found to be 2.43% for overall IDUs, among active IDUs was 3.23% and 0% for IDUs under methadone treatment. Previous TB treatment interference, HIV positivity and active illicit drug use were the risk factors significantly associated with TB infection, with (p=0.001, OR=140. 6, 95% CI=17.4-1129.9), (p=0.024; OR=2.2, 95% CI=1.4-3.3) and (p=0.004, OR=5.1, 95% CI=2.2-11.9) respectively. These findings call for immediate intervention strategies specifically focusing amongst population at high risk of acquiring and spreading TB, through ensuring early diagnosis and proper treatment to avoid long transmission time of the disease in communities.
Abundance and pyrethroid resistance of aedes aegypti mosquitoes collected in selected wards of Muheza district, Tanzania
(Sokoine University of Agriculture, 2022) Bendera, Neema Ally
Aedes aegypti mosquitoes are primary vectors that carry mosquito-borne diseases such as dengue fever, Zika and Yellow fever. Despite mosquito control measures employed in Tanzania such as indoor residual spraying and larvae source management systems, several studies have reported the presence of insecticide resistance. The present study aimed at investigating the abundance of Ae. aegypti and their susceptibility to pyrethroids in Muheza district in Tanga region. A total of 7200 mosquito larvae were collected from selected wards in Muheza district using standard dipping method and reared into adults. Some of the reared larvae died and others escaped during the rearing process leaving 2572 of the collected larvae that emerged into adults. Adult mosquitoes were identified using standard taxonomic keys. Female Ae. aegypti mosquitoes aged three to five days old were tested for susceptibility to pyrethroids using WHO guidelines and the insecticides used were permethrin (0.75%), alphacypermethrin (0.05%) and deltamethrin (0.05%). Mosquito DNA was then extracted and voltage-gated sodium channel genes were amplified targeting Domain II and Domain III yielding expected amplicons size of 640 and 740 bp, respectively. Abundant Ae. Aegypti species were from Mbaramo ward representing 21% (n=267), followed by Zeneti representing 19% (n=240), Kwafungo 19% (n=236), Genge 13% (n=161), Ngomeni 12% (n=153), Misozwe 10% (n=131) and Magila 6% (n=78). Tested Ae. aegypti mosquitoes were susceptible to alphacypermethrin and permethrin with a percentage mortality of 100 and 98.75%, respectively, and resisted to deltamethrin with a percentage mortality of 68%. S989P and V1016I point mutations were identified. Increase in Ae. aegypti resistance to deltamethrin is attributed to prolonged use of insecticides as residual sprays and on pyrethroids impregnated bed nets. Ae. aegypti resistance to deltamethrin and high abundance of this specie in some wards pose a high risk for mosquito-borne diseases and this calls for rational vector control measures.
Epidemiological investigation and antigenic characterization of dengue virus for the development of nanobodies
(Sokoine University of Agriculture, 2022) Mwanyika, Gaspary
Dengue is an important mosquito-borne viral disease of global health concerns. Vector control and early diagnosis remain the main interventions. Lack of vaccines against Dengue viruses (DENV) complicates the control of the disease hence increasing risk of DENV transmission. In this thesis, a systematic review was undertaken to analyse the prevalence of DENV infection and associated risk factors in Africa. A literature search was done using PubMed/MEDLINE, Scopus and Embase databases to identify articles published between 1960 and 2020. Meta-analysis was performed using a random-effect model at a 95% confidence interval. A study on seroprevalence and risk factors of dengue was carried out in Buhigwe, Kalambo, Kilindi, Kinondoni, Kondoa, Kyela, Mvomero, and Ukerewe districts representing five ecological zones in Tanzania. A total of 1,818 blood samples were collected from humans recruited from households and healthcare facilities and tested using an enzyme-linked immunosorbent assay specific for DENV immunoglobulin G (IgG) antibodies. During the 2019 outbreak in Tanzania, serum samples were collected from the outpatients seeking care from health facilities in Kinondoni and Ilala districts and tested to confirm the presence of DENV. DENV genome sequences were generated using Nanopore MinION and analysed using NanoGalaxy tool. The phylogenies and spatial distributions were reconstructed using maximum likelihood method and Bayesian Evolutionary Analysis. Multi immunoinformatics tools were used to predict B-cell epitopes on envelope protein domain III (EDIII) of DENV and the final construct was cloned into pET-22b (+) vector and expressed in Escherichia coli. The findings of the systematic review showed that between 1960 and 2020, 45 outbreaks were reported in Africa, of which 17 and 16 occurred in East and West Africa, respectively. Overall, the prevalence of DENV was 29% (95% CI: 20–39%) and 3% (95% CI: 1–5%) during the outbreak and non-outbreak periods, respectively. Old age (6/21 studies), lack of mosquito control interventions (6/21), urban residence (4/21), climate change (3/21), and recent history of travel (3/21) were the leading risks factors. Serological evidence from this study showed that the overall prevalence of DENV IgG antibodies was 16.1% (n= 292) in Tanzania. The prevalence was highest in Kinondoni district (43.8%, n= 103). Increasing age (> 28 years, p < 0.001), stagnant water bodies around homes (p < 0.01), and piped water at home (p < 0.01) were significantly associated with DENV seropositivity. This study reports for the first time DENV serotype 1 (DENV- 1) genotype V in Tanzania that was responsible for the 2019 outbreak in Dar es Salaam. Spatial analysis suggests that the genotype was possibly introduced into Tanzania from a single source in Asia. Furthermore, epitope prediction analysis revealed five continuous epitopes at 305─320, 334─348, 320─335, 378─392, 389─400 and three conformational epitopes at 310─312, 336─337 and 341─342 residues of envelope protein domain III (EDIII) that can be potential targets for development of diagnostic nanobodies targeting DENV. In conclusion, the results from a systematic review highlights and increased risk of DENV serotype circulation in Africa during the past decade (2010─2020). The national-wide seroprevalence study conducted in Tanzania reveals a wide circulation of DENV in diverse ecological zones with the highest prevalence in the north-eastern zone. This study reports for the first time DENV-1 serotype in Tanzania during the 2019 outbreak in Dar es Salaam that was likely imported from Asia. The possibility of future introduction of new serotypesof the virus from multiple geographic origins due to globalization is still inevitable. It is important that surveillance and diagnostic systems of DENV strengthened nationwide to improve early detection, clinical management and outcomes. In addition, novel biomarkers on envelop protein domains should be explored for development of vaccines that could possibly be used for the control of emerging variants of DENV-1 and DENV-2 strains.
Detection and antibiotic susceptibility of vibrio cholerae In oreochromis tanganicae (Tilapia) and water in Lake Tanganyika, Kigoma-Tanzania
(Sokoine University of Agriculture, 2019) Michael, Martin
Toxigenic Vibrio cholerae O1 and O139 are responsible for the production of cholera toxin and subsequently cause cholera. Although cholera has been very rampant around African great lakes, little is known about the status of V. cholerae in aquatic reservoirs like fish. This study aimed to determine the occurrence of toxigenic and drug resistant V. cholerae in Tanganyika Tilapia (Oreochromis tanganicae) and water from Lake Tanganyika in Tanzania. Repeated cross-sectional study design that involved 140 Tilapia fish samples and 60 water samples was carried out in Lake Tanganyika during dry and rain seasons. Bacterial analyses culture and biochemical tests were used for identification of V. cholera. Positive isolates were confirmed by PCR of the ompW and ctxA genes then serotyped with polyvalent O1 antiserum. Antimicrobial susceptibility patterns of V. cholerae O1 (n = 65) were performed using disk diffusion method. Results of the study revealed a prevalence of V. cholerae at 27.9% (n = 39/140) in Tanganyika tilapia and 33.3% (n = 20/60) in water samples. The proportions of toxigenic V.cholerae in Tanganyika Tilapia and water were 11.4% (n = 16/140) and 20% (n = 20/60) respectively. Prevalence of toxigenic V. cholerae in fish gills and intestines were 5.7% (n = 16/280) and 0.4% (n = 1/280) respectively. Vibrio cholerae were susceptible to Gentamicin (100%), Ciprofloxacin (100%), Cefotaxime (100%), Ceftazidime (73.8%), Chloramphenicol (63.1%), Tetracycline (53.8%) and Naliadixic acid (47.7%). Resistance in V. cholerae was observed for Streptomycin (100%), Amoxicillin (95.4%), Ampicillin (81.5%), Sulphamethaxole (80%) and Trimethoprim (72.3%). This study revealed that Tanganyika Tilapia and water in Lake Tanganyika harbor toxigenic, antibiotic resistant V. cholerae of the epidemic potentials, with high incidences in wet season. Raising awareness on public health practices (hygiene/sanitation) and rational use of antimicrobial agents to safeguard public health from cholera outbreaks are recommended.
The prevalence of leptospira species in fresh water fish in selected areas of Morogoro Municipality, Tanzania
(Sokoine University of Agriculture, 2018) Alexander, M. N.
Leptospirosis is a neglected zoonotic disease of world wide public health importance. Rodents are major reservoirs of leptospira although wetland and aquatic migratory birds also carry and transmit leptospira. Studies on leptospirosis in fish are few in African countries, including Tanzania, despite favourable environment and abundant reservoirs, which can spread leptospires into aquatic habitats and infect fish. The objective of this study was to determine the presence of Leptospira spp in fish; the prevalent Leptospira serovars and whether they are related to serovars reported in animals; and their potential public health risk. A Multistage sampling technique was performed in Morogoro municipality, Tanzania, between November- 2016 and February -2017. Before the sampling, knowledge, attitude and practices (KAP) questionnaire was administered to assess the awareness of people (fishermen, fish mongers) on risk factors that might lead to the diversity of Leptospira species and water quality for pH , Dissolved Oxygen and Temperature was measured using Meter Sensor at Sample sites in Morogoro Municipality.Live catfish (n=193) were caught from five different locations, namely Sokoine University of Agriculture Magadu farm, Mzumbe University waste water pond, Morogoro Urban Water Supply and Sanitation Authority (MORUWASA)- Mafisa waste water ponds , Kingolwira Centre for Fish Farming and Fingering Production and Mkindo Fish Farmers in Morogoro Urban and mvomero districts Tanzania where blood and biopsy samples were collected. Microscopic agglutination test (MAT) was used to detect antibody against four leptospiral antigens, including local serovars Sokoine (serogroup Icterohaemorrhagiae); Hebdomadis (serogroup Hebdomadis); Kenya (serogroup Ballum) and Pomona (serogroup Pomona). Samples with MAT titers ≥ 1:160 were scored as higher values while samples with MAT titers ranging from 1:20 to1:80 were scored as lower values for seropositivity. Absence of agglutination titers was scored as negative. All MAT samples, including the low titre samples were subjected to PCR using Lepat and Sapro primers for the pathogenic and non-pathogenic species (saprophytic) respectively. Tissue samples were prepared by grinding freshly obtained kidneys of sharptooth catfish (Clarias gariepinus) for culturing in Fletchers medium. Dark-field microscopy readings of each of the tubes were performed at first,second, fourth, and sixth week after culturing at 20 X magnification to assess bacterial growth, of the total 193 samples tested, 29 (15 %) were positive with MAT. The major circulating leptospiral serovars were Pomona (11.4 %,), Kenya (1.55%), Hebdomadis (1.55%) and Sokoine (0.52%). By using PCR methods and of the 193 samples screened, 4 (2%) were positive for pathogenic leptospira. No isolation of leptospira was achieved from the kidney cultures. This study has shown a relatively high seroprevalence 15% of leptospirosis in common fresh water fish type, compared to warm blooded animals hence indicate an extended public health risk, of leptospirosis to fish handlers and consumers .To minmize leptospirosis transmission in Morogoro region, and Tanzania at large, where the disease is little known and thus neglected, it is recommended, to increase public awareness of leptospirosis in the general public, and particularly those groups at risk such as farmers, livestock keepers, fishermen, sewerage and abbatoir workers. Routine screening for leptospirosis should be considered in people engaged with occupational activities that increase contact with environments likely to contain leptospires. This is especially important in situation where malaria, typhoid and other common febrile diseases are ruled out; Isolation of leptospires from different hosts and sources should be emphasized in order to understand the sources of infections, infecting serovars and developing a protocol for the diagnosis of this infectious disease appropriate for different areas. Rapid serological tests not involving live microorganisms for routine diagnosis is highly recommended.

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