Theses and Dissertations Collection

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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.
Assessment of the epidemiological status,seroprevalence and molecular detection of Peste des Petits Ruminants in goats and sheep along Tanzania-Malawi Border
(Sokoine University of Agriculture, 2016) Kamwendo, Gladson Chikaiko
Peste des petits ruminants (PPR) is a highly contagious viral animal disease that impact negatively on food security of livestock keepers in Africa due to its fast spread and death of small ruminants. The disease was first reported in West Africa and afterwards Asia, rest of Africa including East Africa and Southern African Development Community (SADC) region. Lack of vaccination and effective application of diagnostic technologies to identify carriers has led to fast spread of the disease. Malawi, Zambia and Mozambique have been warned to be at high risk of infection of PPR due to their proximity to Tanzania and Democratic Republic of Congo (DRC), where the disease has been confirmed (FAO/OIE, 2015). Quantification of the disease status in these high risk countries will ensure effective surveillance and control to keep the disease from spreading. The aim of the present study was to provide epidemiological and molecular status of Peste des PetitsRuminants Virus (PPRV) in small ruminants along Tanzania-Malawi border. Whole blood (n=350), serum (n=350) and nasal swabs (n=100)were collected from goats and sheep in Kyela and Ileje (Tanzania) and Karonga and Chitipa(Malawi). A questionnaire was administered to 113 household heads to depict factors leading to spread of the disease. Molecular diagnosis was done by partial amplification of PPRVgenome using reverse transcription polymerase chain reaction (RT-PCR). Data analysis using chi square test for seroprevalenceand partial logistic regression to check for factors associated with seropositivity were carried out using Epi info statistical package. Based on the results, overall seroprevalencewas 11.1% and analysis showed that 31 out of 83small ruminants (37.3%) in Kyelawas significantly higher (p=0.000) than 8 out of 84 (9.5%) in Ileje. A total of 2 out 95 (2.1%) animals inChitipa had PPRV detected by RT-PCR. However, the PCR products did not yield any nucleotide sequence because the viral load was low. Communal grazing and free roaming husbandry practices were shown to be risk factors for the spread of PPR in these border districts. The interviewed farmers had limited knowledge of the disease although they are helped by Veterinary and field officers for other diseases. It is concluded that there is no active infection of PPR along the border districts of Tanzania and Malawi, however low virus load may be present in Chitipa. It is recommendedthatappropriate strategies should be applied to prevent contact with infected animals through vaccination against PPRVon both sides of border districts.
Bacterial contaminants of African indigenous leafy vegetables and their antibiotics sensitivity characteristics: A case study of Morogoro Municipality, Tanzania
(Sokoine University of Agriculture, 2017) Kimaro, E. N.
A study was conducted in Morogoro Municipality, Tanzania to investigate the bacterial load found on African indigenous leafy vegetables, their sources and their sensitivity to commonly used antibiotics. A total of 126 samples of fresh African indigenous leafy vegetables (amaranth, nightshade and sweet potato leaves), water used for irrigation from rivers and shallow wells and manure fertilised soils were collected at farm sites and market outlets for bacteriological analysis. Bacterial counts were calculated as colony forming units (CFU) per millilitre (CFU/ml) of vegetable washing. The isolates sensitivity or resistances to antibiotics were determined on Muller – Hinton agar plates by the disk diffusion technique. Data was subjected to Analysis of Variance (ANOVA) using SAS Statistical software. Results showed that microorganisms were abundant on the surfaces of the African indigenous leafy vegetables, with nightshade having 1.8 × 105 CFU/ml while amaranth and sweet potato leaves having 1.7 × 105 CFU/ml and 1.5 × 105 CFU/ml respectively. The water used for irrigation from the lower section of the river had significantly (P = 0.03) higher bacterial loads 1.8 × 105 CFU/ml than water from the higher sections. Biochemical tests indicated bacterial isolates from the studied vegetables to be Escherichia coli, Enterobacter aerogenes, Proteus spp, Staphylococcus albus and Bacillus spp. The results show that Escherichia coli, Enterobacter aerogenes and Proteus spp (coliforms) were highly sensitive (>75 %) to enrofloxacin, sulphamethoxazole and ofloxacin antibiotics but resistant to rifampicin. The observed bacterial loads, and sensitivity patterns to commonly used antibiotics reveal the potential adverse health impact of the vegetables on consumers. Proper handling and preparation of vegetables before consumption is highly recommended. Further research covering different African indigenous leafy vegetables in wider agro-ecological areas and sensitivity patterns to commonly used antibiotics is also strongly recommended.
Biological activity of extracts from commiphora swynnertonii against microbes of veterinary importance in chickens
(Sokoine University of Agriculture, 2013) Bakari, Gaymary George
Studies were carried out to establish ethno-botanical information and biological activities of crude extracts from Commiphora swynnertonii against selected microbes of veterinary importance in chickens. Initially, a questionnaire survey was conducted to gather information on practices and knowledge on ethno-botanical uses of C. swynnertonii in the study area. Then extracts from different morphological parts of the study plant were tested against selected bacteria and fungi in vitro using agar well diffusion assay. Resin and root bark extracts showed significant activities (P < 0.001) against S. pyogenes, E. coli and B. subtilis compared to other extracts. The fungi, C. albicans and A. niger, were moderately inhibited. Antiviral activity of the resin and root bark extract was tested in ovo using embryonated chicken eggs inoculated with Newcastle disease virus (NDV). Both extracts significantly (P < 0.001) and effectively reduced virus titres. An animal trial was carried out using the resin and chickens experimentally infected with NDV. Results revealed significant reduction (P < 0.05) in clinical signs and mortality rates following administration of the resin before and after the infection. Prophylactic administration of the extract was found to be more effective than the therapeutic approach. HI titres decreased significantly (P < 0.001) in resin and root bark treated groups and in all chickens treated with resin irrespective of dose given and on whether the extract was administered before or after infection suggesting that the plant materials were capable of destroying the NDV before stimulating the developing chick‘s immunity. Another animal trial investigated the effect of the resin against experimental coccidiosis in chickens. Results showed that oral administration of the resin significantly (P < 0.001) reduced mortality rate. Safety margin of the resin was also investigated by determining its effects on selected physiological and biochemical parameters in chickens. The results revealed a good margin of safety provided that the dosage ranges between 200 to 800 mg resin/kg body weights. A phytochemical study was also carried to determine major bioactive compounds in the resin and root bark extracts. With these studies, it is concluded that extracts from C. swynnertonii especially resin, has significant antibacterial, antifungal, antiviral and anticoccidial effect against the selected microbes. Further research is required to test and validate the extract against other pathogens of medical and veterinary importance.
Characterization and thermostabilization of avibacterium paragallinarum candidate strains with potential use as candidate vaccine strains in Tanzania
(Sokoine University Of Agriculture, 2013) Chota, Andrew Claud
This study was conducted to isolate, characterize, thermostabilize and develop an easier and cheap technique for preparation of inactivated and live vaccines against Infectious coryza (IC). Fifty six (56) samples were collected from chicken. Fourty eight percent (27) isolates had phenotypic characteristics suggestive of both pathogenic and non-pathogenic Avibacterium species. Fifty nine percent (16) of 27 isolates were catalase negative, oxidase positive and NAD dependent. Moreover, they were positive to fructose, maltose, and sucrose, but negative to lactose and urease suggesting that they were Avibacterium paragallinarum. Identification and serotyping by polymerase chain reaction (PCR) confirmed that they were Av. paragallinarum serovar B. Chocolate broth (CB), a novel medium was used to propagate Av. paragallinarum. The broth’s ability to support growth of Av. paragallinarum was compared to other three routine media and analysed using t- test. Results showed that null hypothesis was accepted between allantoic fluid (AF) and CB and between CB and modified brain heart infusion (MBHI) and was rejected between CB and brain heart infusion (BHI). The cost of production of 1 mL of CB was twenty six (26) times lower than the cost of producing AF and four (4) times lower than MBHI and BHI, therefore, CB is preferred as it is an easy to prepare and cheap medium. Av. paragallinarum isolates were thermostable at room temperature (RT) at the temperature range of 27-290C. The bacteria were recovered after storage for three months at RT in 2.5% gelatin. The findings from the present study have shown that Av. paragallinarum serotype B and other members of the genus Avibacterium exist in Tanzania. Propagation of Av. paragallinarum CB will possibly result in production of vaccines that are cheap and affordable to farmers. Furthermore, preservation of Av. paragallinarum in 2.5% gelatin for 3 months is a significant finding for development of live vaccines against IC.
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
Characterization of Tanzania shorthorn zebu cattle for tolerance to ticks and East Coast Fever
(Sokoine University of Agriculture, 2017) Laisser, E. L. K.
In Tanzania, livestock diseases, especially tick bone diseases (TBDs), impose loses to livestock in terms of mortality, decrease in production and increased costs of control measures. Among the TBDs, East Coast fever (ECF) is the most prevalent and fatal disease. The main control measure for TBDs is use of acaricides to control the vector ticks, chemotherapy of sick animals as well as immunization of cattle by the infection and treatment method (ITM). The applications of these are control measures are often limited by high costs of acaricides and veterinary drugs, development of resistance by vector ticks and the parasites as well as negative environmental impacts. This necessitated the search for alternative ways to control TBDs with minimum use of acaricides. Indigenous breeds of cattle are said to be tolerant to TBDs and adapted to harsh conditions prevailing in rural areas. Among the Tanzania Shorthorn Zebu (TSHZ) cattle, Tarime cattle are believed by livestock keepers to be tolerant to ticks and ECF. However, there are no scientific investigations which have been conducted to verify the farmers’ beliefs. Therefore, studies were conducted to validate the farmers’ belief that Tarime cattle are tolerant to ECF. In the first study, a cross-sectional survey was conducted in four selected districts of Mara (Serengeti and Tarime) and Simiyu (Maswa and Meatu) regions to determine the perception of livestock farmers on ticks, tick-borne diseases and tolerance of their cattle to TBDs. In the second study, tick burden and prevalence of Theileria parva (T. parva) infection in Tarime cattle found in Serengeti and Tarime districts were assessed. In the third study, an on-station experiment was conducted to compare tick burden and induced immunity due to T. parva infection in Tarime and Sukuma zebu cattle under different tick control regimes. The fourth study was a review on tolerance of TSHZ cattle to ticks and ECF. In the first study, a well structured questionnaire and personal observation were used to collect information. The aim of the study was to assess farmers’ knowledge and perceptions on tick species, tick-borne diseases, tick control measures, production constraints and tolerance of Tarime and Sukuma zebu cattle to TBDs. The study involved 60 agro-pastoralists from each of the districts of Serengeti, Tarime, Maswa and Meatu in Tanzania, making a total sample size of 240 livestock farmers. Data were collected through individual interview using a structured questionnaire. The results show that, livestock diseases were ranked as the first important problem affecting cattle production in Serengeti and Tarime districts while in Maswa and Meatu districts lack of livestock feeds during the dry season was ranked as the most important constraint, followed by livestock diseases. Among the diseases affecting cattle, the TBDs ranked first in Serengeti and Tarime districts while in Maswa and Meatu districts the TBDs ranked fourth and sixth, respectively. Most (74%) of the livestock farmers interviewed knew well the signs of the different TBDs. The majority of the respondents in all districts knew that ECF is caused by ticks, but did not associate the other TBDs with ticks. Most of the farmers interviewed were using acaricide to control ticks, and the most common method of application was hand spraying. All farmers used Oxytetracycline to treat TBDs, however, some farmers used local herbs. Although most farmers knew the signs of TBDs, they were not spraying/dipping their animals on regular basis due to economic reasons and the belief that their animals always carry ticks without being sick or dying and ECF affects only calves. About half of the farmers considered their breeds to be tolerant to ticks and ECF. It is concluded that, the livestock farmers in the Lake zone have substantial knowledge on tick species and TBDs symptoms and they consider ECF as less important disease compared to the other TBDs. The second study was carried out to assess the distribution, abundance of different tick species and the prevalence of T. parva infection in Tarime zebu cattle kept in selected wards of Serengeti and Tarime districts in Mara region. Adult ticks were sampled, identified and counted from 360 animals which were extensively managed in communal rangelands. Concurrently, blood samples were collected and thereafter DNA extracted and nested polymerase chain reaction (nPCR) carried out to determine the prevalence of T. parva. Two primers specific for p104 gene were used in PCR amplification to detect the presence of T. parva DNA. Four genera of ticks, namely, Rhipicephalus, Amblyomma, Boophilus and Hyalomma were identified. Rhipicephalus spp accounted for 71.8% of the total ticks whereas Amblyomma, Boophilus and Hyalomma constituted 14.1%, 14.0% and 0.1% of the ticks, respectively. There was significantly (p < 0.05) more animals infested with ticks in Tarime district (96.1%) than in Serengeti (61.7%). The average counts of ticks were higher in adult animals (p < 0.05) than in young animals. The overall prevalence of T. parva was 27.7% and was significantly (p < 0.05) higher in Serengeti (38.3%) than in Tarime district (16.7%). Interestingly, it was observed that, all animals which tested positive for T. parva did not show any clinical signs of ECF, suggesting existence of subclinical infection in Tarime zebu. These results suggest that Tarime cattle can tolerate ECF infection and are likely to save as potential carriers of T. parva to other less tolerant cattle breeds in mixed herds. Since Tarime cattle are preferred by most farmers with mixed herds, routine screening for T. parva is highly recommended to minimize introduction of infected cattle into an immunologically naive population. The third study was conducted to determine tick burden and immunological parameters of resistance to ECF in Tarime and Sukuma zebu strains exposed to natural tick infestation. Tick load, Packed Cell Volume (PCV), T. parva specific antibody percent positivity (PP) and prevalence of T. parva parasites were studied in relation to dipping regime, breed, and season of the year. A total of 25 animals per strain were used in this experiment. Animals of each strain were divided into three groups. Animals in group I were dipped every two weeks while those in group II were dipped every three weeks. Animals in group III were not dipped at all. Comparison of effect of dipping frequency on tick burden showed no significant (p > 0.05) differences when cattle which were dipped in each strain either once every 2 or 3 weeks in the two seasons. However, Tarime cattle had significantly higher (p < 0.05) tick count than Sukuma cattle and non dipped groups maintained high tick infestation throughout the experimental period. The PCV values in all cattle were within the normal physiological range; although this parameter was significantly lower (p < 0.05) in Tarime cattle. All cattle regardless of breed were sero positive (had antibody levels above ELISA cut-off point), but Tarime cattle maintained higher antibody percent positivity compared to Sukuma cattle by 15%. Conversely, the prevalence of T. parva parasites was lower in Tarime (36%) compared to Sukuma cattle (38%), although the difference was not significant. During the study period 20% (5/25) of Sukuma cattle contracted ECF, but none of the Tarime cattle showed any clinical signs for the disease. The differences between the two zebu strains shown in terms of antibody percent positivity and T. parva parasite prevalence indicate different ability of the two cattle strains to resist tick infestation and ECF infection under natural challenge. Thus, the higher antibody levels but lower parasite prevalence under high tick challenge observed in Tarime cattle, suggests a high proportion of individual animals in this strain, which are carriers of T. parva. Thus, these findings confirm the farmers’ perceptions on suitability of Tarime cattle under prevailing ecological conditions in the Lake zone of Tanzania. The fourth study was a review on the prevalence and tolerance of Tanzania Shorthorn Zebu cattle to East Coast fever in Tanzania. A search of peer-reviewed publications on ECF, ticks and ECF tolerant cattle in Tanzania was conducted from comprehensive databases including PubMed, Science Direct, Swetswise and CAB direct. The search was extended to available theses, conference proceedings and project reports. The findings show that ECF is not seen by most livestock keepers as the most serious disease compared to other TBDs. This is because the zebu cattle which are predominantly kept all over the country are thought to be tolerant to ticks and ECF. Some of the zebu strains which are thought to tolerate ECF are Sukuma, Tarime, Maasai and Fipa cattle. In all agro ecological zones the most prevalent tick species is R. appendiculatus, this implies that the TSHZ cattle are at risk of being infected with ECF if the animals are not resistant and proper tick control regimes are not observed. In Tanzania, ECF control has mainly relied predominantly on tick control using acaricides and chemotherapy while ECF immunization has been recently introduced. Some research results also showed that, immunization can boost immune status of indigenous cattle and, if ECF immunization can be sustained, large areas are expected to be endemically stable. However, the adoption of immunization on wider scale is questionable due to its cost and change in farmers’ attitudes, socio-demographic and environmental concerns. The study recommends interdisciplinary collaboration between veterinary epidemiologists, socio and agricultural economists and ecologists not only to find a single most suitable method of ticks and ECF control but to integrate the available methods with tolerant strains of cattle available to create endemic stability condition for the disease which can reduce the complexity of the whole process. Generally, the findings of this study confirm farmers’ perception on the ability of Tarime cattle to tolerate ECF infection under prevailing ecological conditions in the Lake zone of Tanzania. The use of this strain, therefore, can be an alternative way of minimizing acaricide usage, whereby application can be done on monthly basis. However, when Tarime and other breeds are kept together, screening of the animals for presence of T. parva parasites is recommended. From these findings it is concluded that using Tarime cattle could be effective and economical in rural areas as it minimizes the use of synthetic acaricide to control ticks and TBDs. Further research studies to determine the gene responsible for tolerance of Tarime cattle to ECF are recommended.
Chikungunya knowledge, attitude, and practices and its Transmission indices in Tanga city, north-eastern Tanzania
(Sokoine University of Agriculture, 2020) Msolla, M.J
Chikungunya is among the important re-emerging arboviral disease caused by Chikungunya virus (CHIKV), an alphavirus belonging to Togaviridae family. Since the first outbreak in Tanganyika (now Tanzania) in 1952/53, several outbreaks are constantly being reported in different parts of the world. So far, there is no commercially available vaccine or drug effective for Chikungunya management. Vector control is the main option. This study aimed to determine the Chikungunya knowledge, attitudes and practices and its transmission indices in Tanga City, north-eastern Tanzania. This crosssectional study was conducted in Tanga city, involving Nguvumali, Mzingani and Central wards. In this study, mosquitoes were collected by a Mosquito Magnet Liberty Plus trap in six selected sites (two sites per ward). Larvae surveys were conducted to randomly selected households. A questionnaire on knowledge, attitude and practices regarding Chikungunya was administered to heads/members of households where larval surveys were conducted. Mosquitoes were identified morphologically. Detection of CHIKV in Aedes aegypti was done using one step reverse transcription polymerase chain reaction (RT-PCR). Majority of the respondents (88%) were unaware of Chikungunya fever and its associated information. A total of 1469 adult mosquitoes were collected and identified into four species. Aedes aegypti was the most abundant (73.52%). Larvae survey involved 101 households and out of them 88 water holding containers were surveyed. The House Index (HI), Container Index (CI) and Breteaux Index (BI) were 40.59%, 60.2% and 52.5% respectively. Female Ae. aegypti were pooled into 44 pools (20 mosquito/pool) for detection of CHIKV and 7 pools were positive for CHIKV. In conclusion, Aedes aegypti mosquitoes are abundant and local transmission of CHIKV is taking place in Tanga city. The community knowledge and practices as regards to Chikungunya is low. Further research should be carried out to assess the status of Chikungunya transmission in human population in Tanga.
Coenurosis in slab-slaughtered sheep and goats in Ngorongoro district: prevalence and predisposing factors of the disease
(Sokoine University of Agriculture, 2013) Miran, Miran Bushelegi
Taenia multiceps is a worldwide in distribution which inhabits the small intestine of dogs, foxes, coyotes and jackals. However, until recently, there were no reports of the occurrence of Taenia multiceps associated ill health in Tanzania in livestock. In this study, the prevalence of Taenia multiceps metacestode (Coenurus cerebralis) as well as other Taenia and Echinococcus metacestodes particularly Cysticercus tenuicollis and hydatid cysts in slab-slaughtered sheep and goats, community knowledge and predisposing factors of coenurosis in Ngorongoro district were determined. The study reports for the first time the occurrence on the one hand and the prevalence on the other hand of coenurosis in slaughtered sheep and goats due to Taenia multiceps metacestode (Coenurus cerebralis) in Ngorongoro district. Of 180 examined carcasses of sheep and goats, 80 (44.4%), 93 (51.7%) and 35 (19.4%) were found to be infected with C. cerebralis, C. tenuicollis and Hydatid cysts respectively whereas some had concurrent infections. Widespread dog keeping for herding purposes, large dog population, close contact between small ruminants (sheep and goats) and dogs, lack of knowledge in the community on how coenurosis occurs, free access of dogs to carcases/offal including brains of small ruminants sometimes containing viable C. cerebralis cysts and inadequate animal health services for dogs especially worm control are major factors which contribute to persisting coenurosis. Thus, knowledge of epidemiology of the disease is critical for the effective disease management and control (health protection and disease prevention). To address these, the development of a control strategy (programme) is required. Therefore, much remains to be done in research to pave the way for coenurosis control and the findings of this study can be used to guide future research programmes.
Control of haemonchosis using barbevax® vaccine in indigenous sheep and goats in Melela Ward, Morogoro Tanzania
(Sokoine University of Agriculture, 2017) Ngu'mbi, N. H.
A cross sectional study was carried out during the dry season (between June and August 2014) to establish the status of helminth infestation in nine traditionally managed small ruminant flocks in Mlandizi village of Melela ward in Mvomero district of the Morgoro region. A longitudinal study was thereafter implemented from August 2014 to January 2015 to determine the influence of Haemonchus spp. target Barbevax® vaccine on gastrointestinal parasite burdens in traditional sheep and goats using Barbevax® vaccine. Animals were visited after every 14 days for up to the 19th week. During each visit blood and faecal samples were collected. Vaccination was done four times on days 0, 28, 56 and 98. The vaccine was administered subcutaneously using 1 ml for each animal to be vaccinated. All the study flocks, which were communally grazed and purposively selected, had varying numbers of sheep and goats. The study involved 131 goats and 118 sheep, which were screened for helminth eggs and then the faecal samples, were cultured to recover helminth larvae (L3) which were identified using morphological features. Out of the animals screened, 54.2% and 67.8% of the goats and sheep examined respectively were positive for helminth infestation. The most prevalent helminth species detected was Haemonchus spp. (50.7%). Others were Trichostrongylus spp. (29%), Oesophagostomum spp. (16.4%), Cooperia spp. (5.9%) and Strongyloides spp. (3.4%). Results indicated that female sheep and goats had greater packed cell volume (PCV) than males with a significant difference (P< 0.05) and with ages 3, 6, 7 and 12 months (P< 0.05). At day 56 significant difference was observed between vaccinates and control animals (P< 0.05). The observation was that males had their EPGs going down gradually with a significant difference among males (P< 0.05). There was a significant difference in EPGs (P<0.05), for days 14 and 42. The mean EPG of males were relatively higher than those of females with a significant difference for both sexes (p<0.05). It was observed further that young animals (age 2-5 months) had relatively higher EPGs than older animals 6+ months. The mean number of larvae of Haemonchus between vaccinates and controls goats was statistically significant (p<0.05) for ages 3 and 9 months. No differences in either total or Haemonchus specific egg counts were observed between vaccinates and controls after third vaccination in either sheep or goats. Helminth infestation was shown to be a problem and haemochosis being the most prevalent. The potential of the vaccine efficacy in above associated risk factors is to be further studied in different environments under different infection rates of H.contortus. Futhermore, the studies to analyse plasma antibodies should be done to ascertain immune response after vaccination.
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.
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.
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.
Epidemiological study of infectious bursal disease virus in selected districts of the Copperbelt province in Zambia
(Sokoine University of Agriculture, 2016) Chawinga, Kenneth
Infectious bursal disease (IBD) is a highly contagious disease of young chickens between 3 and 6 weeks of age. It is caused by infectious bursal disease virus(IBDV) which occursworldwide affecting livelihoods of resource - compromised poor communities. In Zambia, there is scantily documented information on the epidemiology of IBD. In-depth knowledge on the epidemiology of IBD is needed for effective control measures. This study aimed at molecular detection of circulating IBDV strains, andknowledge assessment of farmers about the disease in Ndola, Kitwe, Kalulushi, Luanshya and Mufulira districts of the Copperbelt province. A cross-sectional purposive study was carried out in the Copperbelt province from February to March, 2015 to determine the occurrence of IBD. The identification of IBDV was done by reverse transcription polymerase chain reaction (RT-PCR) targeting the hypervariable domain (VP2-HVR). A semi-structured questionnaire was administered to 77 respondents who presented poultry related cases to clinics in the selected districts and the information collected was analyzed by statistical package for social scientists (SPSS). A total of 30 bursa of Fabricius samples from young chickens that presented with clinical signs suggestive of IBD were examined. The RTPCR results revealed two positive samples for IBDV VP2-HVR domain. Questionnaire study revealed that 70.0% (n=10) of the respondents did not know what disinfectant to use; 75.0% (n=57) felt assigning more than one individual to a flock of chickens did not compromise biosecurity whereas 20.3% (n=15) knew the important clinical signs of IBD, compared to 60.1% (n=46) and 70.7% (n=54) that knew clinical signs related to chronicrespiratory disease and ND respectively. Ninety six percent (n= 73) adhered to vaccine cold chain practices. These findings indicate that IBD viruses circulated in the Copperbelt province and chicken farmers had low awareness of IBD and respective disease control measures. Further studies to characterize the circulating IBD viruses to unravel more information for the rational IBD control strategy in Zambia are required.
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.
Epidemiological study of rift valley fever virus in Kigoma, Tanzania
(Sokoine University of Agriculture, 2013) Kifaro, Emmanuel George
Rift Valley fever (RVF) is an acute, zoonotic viral disease, caused by a Phlebovirus belonging to the Bunyaviridae family. RVF virus (RVFV) historically has been responsible for large explosive outbreaks of severe human and animal disease throughout Africa and recently in the Arabian Peninsula. In animals, it mainly affects domestic ruminants such as sheep, goats and cattle. RVFV outbreaks among livestock are economically devastating and often characterized by large sweeping abortion storms and significant mortality in adult livestock. This study was conducted to investigate RVF infection in Kigoma region. Regional wide serosurvey and conventional gel based single tube RT-PCR were conducted in Kigoma region on non- vaccinated small ruminants (sheep and goats). The study included 411 animals (32 sheep and 379 goats) sampled in 3 districts namely; Kigoma rural, Kasulu and Kibondo. Sera of animals were tested for the detection of immunoglobulins G (IgG) against RVFV using commercial enzyme-linked immunosorbent assays (ELISA) kit. Past infections were detected in 22 of 411 animals (5.4% at 95% CI 3.5 % to 8.1%) from all three districts. Kigoma rural recorded higher seroprevalence of 12.0% (CI 7.3% to 18.3%; P<0.0001) followed by Kibondo (2.3% [0.5% to 6.5%]; P>0.05) and Kasulu districts (0.8% [0.0% to 4.2%]; P>0.05). The prevalence was 12.5% and 4.7% for sheep and goats respectively. RT-PCR results indicated that only 8 samples were found positive (n=63) including 22 positive samples for IgG ELISA, where none was RT-PCR positive. This study has confirmed, for the first time, the presence of RVFV in Kigoma region, 4 years after the 2007 epizootic in Tanzania, and suggests further that the virus activity exists during the interepizootic period (IEP) even in regions with no history of RVF. In-depth studies should be conducted to clarify the complex epidemiology of RVF in the country.
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.
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.

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