Department of Microbiology, Parasitology and Immunology

Permanent URI for this communityhttp://10.10.97.169:4000/handle/123456789/97

Browse

Filter results by year or month

Now showing 1 - 20 of 157

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
Taenia saginata cysticercosis in cattle in Tanzania
(Sokoine University of Agriculture, 1993) Maeda Godfrey Elikalia
A review on the epidemiology and diagnosis of human taeniasis and bovine cysticercosis with special reference to East Africa is given. All humans are susceptible to the adult tapeworm, T. saginata. Cattle, is the predominant intermediate host, young animals being more susceptible than older ones. Susceptibility of a few wild ruminants makes them potential reservoirs of infection. Characteristics of T. saginata, including a long life span, a high reproductive potential, spontaneous shedding of proglottids from human carriers, occult nature of the cysticerci in cattle, etc, contribute to maintenance of infections. Dispersion and survival of T. saginata eggs are determined by sanitation, personal hygiene, coprophagous animals and weather conditions. Prevalence rates of cysticercosis in cattle reported from various countries depend on local meat hygiene legislations, efficiency of meat inspection, and record keeping in the abattoirs. In this thesis, factors promoting the spread of T. saginata infections in Tanzania were investigated, by interview information from 105 cattle owners, belonging to Masai, Arusha, Iraqw, Gogo and Rangi ethnic groups, from 52 villages in Tanzania. Taeniasis and cysticercosis were reported as common problems among members of the ethnic groups interviewed. Lack of awareness of the source of human tapeworms, scarcity of medicines against taeniasis, habits of consuming raw beef, consumption of uninspected meat, defaecation in the bush, were some of the outstanding factors elucidated. The details of this investigation are discussed and it is concluded that some of the observations need confirmation through further studies in the villages of the ethnic groups concerned. Prevalence rates of taeniasis recorded at Mbulu Hospital were 10% in 1990 and 21% in 1991. In a separate investigation, cysticercosis was detected in 52 (10.5%) out of 496 cattle X xi slaughtered in municipal abattoirs of Arusha, Dodoma, Iringa, Morogoro and Mpwapwa districts in Tanzania during the period between June 1991 and November 1991. The prevalence rates in the individual abattoirs were 16.7% (Arusha), 8% (Dodoma), 9.6% (Iringa), 6.5% (Morogoro) and 7.6% (Mpwapwa). The overall annual prevalence rates of cysticercosis in the Dodoma and Iringa regions were lower than the rates officially recorded in these abattoirs. The results are discussed in relation to sources of infection, endemicity of cysticercosis, efficiency of meat inspection, and records keeping in the abattoirs in the country. In a detailed examination, anatomical distribution of cysticerci of T. saginara (864) was analyzed in zebu cattle at Morogoro abattoir in Tanzania. The cysticerci were found located in the examined tissues preferentially in the following order: heart, M. triceps brachii, tongue, M. psoas and masseter muscles. The liver had relatively high numbers of cysts and is thus considered an important predilection site. Examination of the predilection sites for detecting carcasses positively infected with cysticerci of T. saginara revealed the following efficiency: 80% (heart), 80% (M. triceps brachii), 60% (masseter muscles), 60% (tongue) and 53% (liver). However examination of the heart, M. triceps brachii and the liver together detected all infected carcasses. Most (60%) of the infected carcasses had viable cysticerci. In conclusion, T. saginara taeniasis and cysticercosis are major, but underestimated problems in Tanzania. The diagnostic methods of cysticercosis in cattle and taeniasis in humans all have inherent limitations. But nevertheless, their sensitivity may be significantly be improved and the usual control may be more efficient. The various chapters of the thesis include discussions on ways to improve public control measures and educate consumers and herdsmen.
Urinary tract infection: The role of canine transmissible venereal tumour
(Wiley Online Library, 1996) Batamuzi, E. K.; Kristensen, F.
The role of transmissible ‘venereal tumours in the pathogenesis of urinary tract infection in dogs was investigated in 86 dogs. Fifty-five had transmissible venereal tumours, and the remaining 31 animals were used as controls. A thorough clinical examination of the external genitalia was carried out in each case. In the dogs with transmissible venereal tumours, the sites of attachment were recorded. Urine samples were taken by cystocentesis and the external genitalia swabbed; the samples were cultured for bacteria using standard methods. Tumours were found on the prepuce and other parts of the penis in male dogs; in bitches they were found in the vagina, vestibule or the vestibulovaginal junction. Dogs with transmissible venereal tumours were found to be at a high risk of having bacteriuria (odds ratio [OR] = 7.04). Obliteration of the urethral orifice by the tumour, possibly leading to urine retention, was thought to be the main reason for the high incidence of urinary tract infection among dogs with transmissible venereal tumours. Long-standing cases of transmissible venereal neoplasia had a higher chance of becoming bacteriuric compared with recent cases (OR=29.60). This study indicates that transmissible venereal tumour may he a predisposing factor for the development of urinary tract infection.
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.
Identification and typing of Pasteurella multocida: a review
(Taylor and Francis, 2000-03) Blackall, P. J; Miflin, J. K
Fowl cholera is an important disease of both domesticated and wild birds ( Rimler & Glisson, 1997 ). As noted by Rimler & Glisson ( 1997 ), the disease is often classified into two forms, acute and chronic, despite the fact that field outbreaks often present clinical signs and lesions that are inter- mediate between these two forms. In the classic acute form, death may be the only indication of disease noted ( Rimler & Glisson, 1997). Astute observation of birds in the hours before death can reveal signs such as fever, anorexia, ruffled feath- ers, mouth discharge, diarrhoea and increased respiratory rate. In the chronic form, signs are typically limited to localized infections – swellingtaxa have been described. Table 1 shows the formally recognized species as well as the various un-named taxa that have been recorded as being present in birds. Hence, the identification of a Pasteurella-like isolate from an avian host is a challenging task – the complexity of which is not often appreciated by those who think of the genus Pasteurella as consisting of two to three species.
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.
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
Productivity of local chickens under village management Conditions
(Kluwer Academic, 2002) Mwalusanya N. A; Katule A. M; Mutayoba S. K; Mtambo, M. M. A; Olsen J. E; Minga U. M
The productivity of local chickens under village management conditions was studied in six villages situated in three climatic zones within Morogoro District in Tanzania. Two villages were picked in each climatic zone (warm and wet, warm and dry, cool and wet) for the study. The data were obtained by actual measurement, qualitative observations and interview of members of the households directly responsible for the care of chickens. In addition, data sheets were given to selected farmers to record the performance of their chickens. The mean £ock size for the three zones was 16.2, with a range of 2 to 58. The overall mean clutch size, egg weight and hatchability were 11.8, 44.1 g and 83.6%, respectively. The overall mean chick survival rate to 10 weeks of age was 59.7%. The mean live weights for cocks and hens were 1948 g and 1348 g, respectively. The mean growth rates to the age of 10 weeks were 4.6 g/day and 5.4 g/day, while those from 10 to 14 weeks of age were 8.4 g/day and 10.2 g/day for female and male birds, respectively. The age at ¢rst lay ranged between 6 and 8 months, and the average hen had three laying cycles per year. Most of the chickens were left to scavenge during the day and were provided with simple housing at night (95.2% of the owners). Only small amounts of supplementary feeds were occasionally given and minimal health care was provided. It was concluded that the low productivity of chickens was partly due to the prevailing poor management practices, in particular the lack of proper health care, poor nutrition and housing.
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.
Replication kinetics of different porcine circovirus 2 strains in PK-15 cells, fetal cardiomyocytes and macrophages
(2005) Meerts, P.; Misinzo, G.; McNeilly, F.; Nauwynck, H. J.
In this in vitro study, the replication kinetics of porcine circovirus type 2 (PCV2) in porcine alveolar macrophages (PAM) and fetal cardiomyocytes (FCM), two target cells in vivo, was compared with that in PK-15 cells. Cultures were inoculated with either the postweaning multisystemic wasting syndrome (PMWS)-associated strain Stoon-1010 or the abortion-associated strain 1121. Viral proteins were visualized and virus production was determined. In PK-15 cells, the capsid protein was expressed between 6 and 12 hours post inoculation (hpi), it relocated to the nucleus between 12 and 24 hpi. At that time, Rep protein was also detected in the nucleus. This sequence of events also occurred in FCM and PAM but nuclear localized antigens appeared later (48 hpi) and in a lower percentage of cells. In PAM, clear differences in susceptibility were seen between pigs. In PAM from two out of five tested pigs, nuclear localized antigens were not detected, whereas in PAM from three other pigs they were seen in up to 20% of the antigen-positive cells. Virus production was observed in PK-15 but not in PAM or FCM cultures. In a second study, the replication kinetics of seven different PCV2 strains were compared in PK- 15 cells. It was shown that the two abortion-associated strains had a different replication kinetics in comparison with PMWS or porcine dermatitis and nephropathy syndrome associated strains. With the abortion-associated strains, a higher number of infected cells was observed at 24 hpi and the percentage of infected cells with nuclear localised antigens was lower compared to that of other strains.
Binding and entry characteristics of porcine circovirus 2 in cells of the porcine monocytic line 3D4/31
(2005) Misinzo, G.; Meerts, P.; Bublot, M.; Mast, J.; Weingartl, H. M.; Nauwynck, H. J.
Porcine circovirus 2 (PCV2) is associated with post-weaning multisystemic wasting syndrome and reproductive problems in pigs. Cells of the monocyte/macrophage lineage are important target cells in PCV2-infected pigs, but the method of binding and entry of PCV2 into these cells is unknown. Therefore, binding and entry of PCV2 to the porcine monocytic cell line 3D4/31 were studied by visualization of binding and internalization of PCV2 virus-like particles (VLPs) by confocal microscopy and chemical inhibition of endocytic pathways (clathrin- and caveolae-mediated endocytosis and macropinocytosis), followed by evaluation of the level of PCV2 infection. It was shown that PCV2 VLPs bound to all cells, with maximal binding starting from 30 min post-incubation. Bound PCV2 VLPs were internalized in 47±5?0% of cells. Internalization was continuous, with 70?5±9?7% of bound PCV2 VLPs internalized at 360 min post-incubation. Internalizing PCV2 VLPs co-localized with clathrin. PCV2 infection was decreased significantly by chemical inhibitors that specifically blocked (i) actin-dependent processes, including cytochalasin D (75?5±7?0% reduction) and latrunculin B (71?0±3?0% reduction), and (ii) clathrin-mediated endocytosis, including potassium depletion combined with hypotonic shock (50?2±6?3% reduction), hypertonic medium (56?4±5?7% reduction), cytosol acidification (59?1±7?1% reduction) and amantadine (52?6±6?7% reduction). Inhibiting macropinocytosis with amiloride and caveolae-dependent endocytosis with nystatin did not decrease PCV2 infection significantly. PCV2 infection was reduced by the lysosomotropic weak bases ammonium chloride (47?0±7?9% reduction) and chloroquine diphosphate (49?0±5?6% reduction). Together, these data demonstrate that PCV2 enters 3D4/31 cells predominantly via clathrin-mediated endocytosis and requires an acidic environment for infection.
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.
Porcine circovirus 2 uses heparan sulfate and chondroitin sulfate B glycosaminoglycans as receptors for its attachment to host cells
(Journal of virology, 2006) Misinzo, Gerald; Delputte, Peter L; Meerts, Peter; Lefebvre, David J; Nauwynck, Hans J
Monocyte/macrophage lineage cells are target cells in vivo for porcine circovirus 2 (PCV2) replication. The porcine monocytic cell line 3D4/31 supports PCV2 replication in vitro, and attachment and internalization kinetics of PCV2 have been established in these cells. However, PCV2 receptors remain unknown. Glycosami- noglycans (GAG) are used by several viruses as receptors. The present study examined the role of GAG in attachment and infection of PCV2. Heparin, heparan sulfate (HS), chondroitin sulfate B (CS-B), but not CS-A, and keratan sulfate reduced PCV2 infection when these GAG were incubated with PCV2 prior to and during inoculation of 3D4/31 cells. Enzymatic removal of HS and CS-B prior to PCV2 inoculation of 3D4/31 cells significantly reduced PCV2 infection. Similarly, when PCV2 virus-like particles (VLP) were allowed to bind onto 3D4/31 cells in the presence of heparin and CS-B, attachment was strongly reduced. Titration of field isolates and low- and high-passage laboratory strains of PCV2 in the presence of heparin significantly reduced PCV2 titers, showing that the capacity of PCV2 to bind GAG was not acquired during in vitro cultivation but is an intrinsic feature of wild-type virus. When Chinese hamster ovary (CHO) cells were inoculated with PCV2, relative percentages of PCV2-infected cells were 27% ⴞ 8% for HS-deficient and 12% ⴞ 10% for GAG-deficient cells compared to wild-type cells (100%). Furthermore, it was shown using heparin-Sepharose chromatography that both PCV2 and PCV2 VLP directly interacted with heparin. Together, these results show that HS and CS-B are attachment receptors for PCV2
Correlation between the presence of neutralizing antibodies against porcine circovirus 2 (PCV2) and protection against replication of the virus and development of PCV2-associated disease
(2006-01-30) Meerts, P.; Misinzo, G.; Lefebvre, D.; Nielsen, J.; Bøtner, A.; Kristensen, C. S.; Nauwynck, H. J.
Background: In a previous study, it was demonstrated that high replication of Porcine circovirus 2 (PCV2) in a gnotobiotic pig was correlated with the absence of PCV2-neutralizing antibodies. The aim of the present study was to investigate if this correlation could also be found in SPF pigs in which PMWS was experimentally reproduced and in naturally PMWS-affected pigs. Results: When looking at the total anti-PCV2 antibody titres, PMWS-affected and healthy animals seroconverted at the same time point, and titres in PMWS-affected animals were only slightly lower compared to those in healthy animals. In healthy animals, the evolution of PCV2-neutralizing antibodies coincided with that of total antibodies. In PMWS-affected animals, neutralizing antibodies could either not be found (sera from field studies) or were detected in low titres between 7 and 14 DPI only (sera from experimentally inoculated SPF pigs). Differences were also found in the evolution of specific antibody isotypes titres against PCV2. In healthy pigs, IgM antibodies persisted until the end of the study, whereas in PMWS-affected pigs they quickly decreased or remained present at low titres. The mean titres of other antibody isotypes (IgG1, IgG2 and IgA), were slightly lower in PMWS-affected pigs compared to their healthy group mates at the end of each study. Conclusion: This study describes important differences in the development of the humoral immune response between pigs that get subclinically infected with PCV2 and pigs that experience a high level of PCV2-replication which in 3 of 4 experiments led to the development of PMWS. These observations may contribute to a better understanding of the pathogenesis of a PCV2- infection.
New Leptospira serovar Sokoine of serogroup Icterohaemorrhagiae from cattle in Tanzania
(Microbiology Society, 2006-04) Mgode, Georgies; Machang'u, Robert S; Goris, Marga; Engelberts, Mirjam F M
The prevalence of leptospirosis is generally high in domestic animals and rodents in Tanzania. Identification of Leptospira isolates from cattle was carried out to establish prevalent Leptospira serovars. Serological typing was done based on monoclonal antibodies and the standard cross-agglutination absorption test. Molecular typing involved pathogenic- and saprophytic-specific PCRs and a PCR specifically amplifying DNA from the species Leptospira kirschneri. DNA fingerprinting with primers derived from sequences of insertion elements IS1500 and IS1533 was carried out. Both serological and molecular characterization indicated that one of the Leptospira isolates, coded RM1, represents a new serovar of the species L. kirschneri of serogroup Icterohaemorrhagiae. The serovar name Sokoine is proposed for this new Leptospira isolate.
Demographic and spatio-temporal variation in human plague at a persistent focus in Tanzania
(Elsevier, 2006-10) Makundi, R.H; Davis, S; Machan"gu, R.S; Leirs, H
Human plague in the Western Usambara Mountains in Tanzania has been a public health problem since the first outbreak in 1980. The wildlife reservoir is unknown and eradication measures that have proved effective elsewhere in Tanzania appear to fail in this region. We use census data from 2002 and hospital records kept since 1986 to describe the temporal, spatial and demographic variation in human plague. A seasonal peak in cases occurs from December to February with the numbers of cases during this peak varying between 0 and 1150. Variation in incidence, calculated for each village as the mean number of cases per thousand inhabitants per year, indicates that human plague is concentrated around a group of three neighbouring, relatively isolated, high-altitude villages; Nywelo, Madala and Gologolo. However, there was no evidence that these villages were acting as a source of infection for the remainder of the focus. The likelihood of becoming infected with plague is highest between the ages of 5 and 19 and lowest for adult men. This was most clear in the ward encompassing the three high-incidence villages where the risk of plague among children aged 10–14 was 2.2 times higher than for adults aged 30–34, and among adults aged 30–34, the risk was 2.4 times higher for women than men.
Multilocus sequence typing method for identification and genotypic classification of pathogenic Leptospira species
(2006-11-23) Ahmed, N.; Devi, S. M.; Valverde, M.; Vijayachari, P.; Machang'u, R. S.; Ellis, W. A.; Hartskeerl, R. A.
Leptospira are the parasitic bacterial organisms associated with a broad range of mammalian hosts and are responsible for severe cases of human Leptospirosis. The epidemiology of leptospirosis is complex and dynamic. Multiple serovars have been identified, each adapted to one or more animal hosts. Adaptation is a dynamic process that changes the spatial and temporal distribution of serovars and clinical manifestations in different hosts. Serotyping based on repertoire of surface antigens is an ambiguous and artificial system of classification of leptospiral agents. Molecular typing methods for the identification of pathogenic leptospires up to individual genome species level have been highly sought after since the decipherment of whole genome sequences. Only a few resources exist for microbial genotypic data based on individual techniques such as Multiple Locus Sequence Typing (MLST), but unfortunately no such databases are existent for leptospires. We for the first time report development of a robust MLST method for genotyping of Leptospira. Genotyping based on DNA sequence identity of 4 housekeeping genes and 2 candidate genes was analyzed in a set of 120 strains including 41 reference strains representing different geographical areas and from different sources. Of the six selected genes, adk, icdA and secY were significantly more variable whereas the LipL32 and LipL41 coding genes and the rrs2 gene were moderately variable. The phylogenetic tree clustered the isolates according to the genome-based species. The main advantages of MLST over other typing methods for leptospires include reproducibility, robustness, consistency and portability. The genetic relatedness of the leptospires can be better studied by the MLST approach and can be used for molecular epidemiological and evolutionary studies and population genetics.
Survival of avirulent thermostable Newcastle disease virus (strain I-2) in raw, baked, oiled, and cooked white rice at ambient temperatures
(2007) Wambura, Philemon Nyangi; Meers, Joanne; Spradbrow, Peter
Raw white rice has not been considered a good carrier for oral vaccination, probably because of its antiviral activity. Methods are required to overcome antiviral activity in raw white rice. This study was carried out to determine the effects of various treatments of raw white rice on the survival of strain I-2 of Newcastle disease virus. These included cooking and baking the rice or mixing the rice with vegetable oil prior to coating with vaccine virus. The vaccine-coated rice was then stored for 30 min and 24 h, followed by quantitative recovery of the virus. Thirty min after mixing, uncooked, cooked, and baked rice, and rice mixed with vegetable oil showed titers of 10(6.2), 10(7.2), 10(6.6), and 10(7.0) EID(50)/0.1 ml, respectively. After storage for 24 h at 22-25oC, the titers dropped to 10(5.0), 10(6.5), 10(5.0), and 10(6.0) EID(50)/0.1 ml for uncooked, cooked, baked, and oiled rice, respectively.
Increased yield of porcine circovirus-2 by a combined treatment of PK-15 cells with interferon-gamma and inhibitors of endosomallysosomal system acidification
(2007-12-17) Misinzo, G.; Delputte, P. L.; Lefebvre, D. J.; Nauwynck, H. J.
Treatment of porcine kidney (PK-15) cells with either interferon-gamma (IFN-g) or endosomallysosomal system acidification inhibitors increases replication of porcine circovirus type 2 (PCV2). In the present study, the effect of a combination of these treatments on the number of infected cells and virus yield was tested. The number of PCV2 (Stoon-1010)-infected PK-15 cells increased in cells treated with ammonium chloride (445 39% increase), IFN-g (446 8%), ammonium chlorideþ IFN-g (1721 283%), chloroquine diphosphate (1037 121%), chloroquine diphosphateþIFN-g (2199 255%), monensin (950 178%) and monensinþIFN-g (1948 60%). Combined IFNg and endosomal-lysosomal system acidification inhibitors increased PCV2 yield by up to 50 times compared to untreated PK-15. This augmented virus replication in PK-15 cells may be helpful in the production of PCV2 vaccines.

Browse

Browsing Department of Microbiology, Parasitology and Immunology by Issue Date