Articles, Conference and Workshop Papers Collection

Permanent URI for this collectionhttp://10.10.97.169:4000/handle/123456789/105

Browse

Now showing 1 - 20 of 287

Dose-response relationships in a microneutralization test for foot-and-mouth disease viruses
(1977-05) Booth, J. C; Rweyemamu, M. M; Pay, T. W. F
Two-dimensional quantal microneutralization tests on foot-and-mouth disease viruses, in which neutralizing antibody activity was titrated against a serial range of virus doses, demonstrated a variety of dose-response curves some of which were rectilinear, others clearly curvilinear. Moreover, in the case of the non-linear responses obtained with some antisera, the shape of the curve was such that antibody titres recorded with doses of virus ranging from lCP-lO 5 TCD50 were closely similar. Studies were carried out on the effect of varying the con- ditions of the test on the shape of the dose-response curve: significant differences were obtained after treatment of the antiserum-virus mixtures with anti-species globulin, and when the test was assayed in cells of differing susceptibility to infection.
Microneutralization tests for serological typing and subtyping of foot-and-mouth disease virus strains
(1977-12) Rweyemamu, M. M; Booth, J. C; Head, Morwen; Pay, T. W. F
A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90 % of samples a positive typing was obtained in contrast with about 50 % for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination. For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing FMD virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.
The role of management systems in the epidemiology of thermophilic campylobacters among poultry in eastern zone of Tanzania
(Epidemiology and infection, 1993) Kazwala, R. R.; Jiwa, S. F. H.; Nkya, A. E.
A total of 255 samnples of droppings collected from a total of 22 different poultry units were exainined for the presence of thermophilic campylobacters and the isolates biotyped using Skirrow's protocol. The organismTs were isolated from 90 (35*3 %) of all samples. Among the 22 units investigated, 13 (59 %) were found to have unsatisfactory management svstems, while 7 (32 %) and 2 (9 %) were found to have unsatisfactory and good systems respectively. Significantly large numbers of isolations, 68 of 147 (46 2 %), were made from samples collected from poultry units with poor management (P < 0 005). compared with 19 out of 84 (22 6%) samples which were collected from satisfactory units and 3 out of 24 (125%) samples collected from units exercising particularly good management. Nineteen of 72 (26-4%) samples collected from broilers, 32 out of 132 (24-2%) samples collected from layers and 39 out of 51 (76 49 %) samples collected from indigenous free range poultry were positive for campylobacters. Among the 90 strains isolated from various units, 64 (704 0 ) were Cnampylobacterjejuni, 25 (27-7 %) were C. coli, and only 1 (2 2 %) was C. laridis.
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 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. saginata (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. saginata 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. saginata 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. SAMMENDRAG (Summary in Danish) Taenia saginata cysticercose hos kvaeg i Tanzania Afhandlingen indledes med en litteraturoversigt over epidemiologi og diagnostik af human taeniiasis og bovin cysticercose med saerlig omtale af forholdene i 0stafrika. Alle mennesker er modtagelige for infektion med baendelormen T. saginata. Kvaeget er den almindeligste mellemvaert, og yngre dyr er mere modtagelige end aeldre. Nogle f
Manual on the preparation of national animal disease emergency preparedness plans
(FAO, 1996-11) Geering, William A; Roeder, Peter L; Obi, Timothy U; Rweyemamu, Mark M
The control and eradication of livestock diseases are primarily the responsibility of national governments whose executive for this purpose is the national veterinary service. Since its inception FAO has been actively involved in the control of livestock diseases and its Animal Health Service (AGAH) is dedicated to this purpose. Over the years AGAH, with the help of expert panels and technical assistance schemes, has played a key normative role in developing standards and policies for dealing with major diseases. The result has been progressive reorientation of veterinary services, education and research so as to ensure an integrated approach to major diseases, to the improvement of animal health and productivity and in the preparation of animal products. In this regard AGAH collaborates with other international and regional organizations, particularly the International Office of Epizootics (OIE), the World Health Organization (WHO), the International Atomic Energy Agency with which FAO has a Joint Division (FAO/IAEA), regional organizations such as the Pan-American Health Organization (PAHO) and the Inter-African Bureau for Animal Resources of the Organization of African Unity (OAU/IBAR), as well as with bilateral and multilateral donor agencies. A characteristic of transboundary animal diseases (TADs) is that they themselves can be the cause of national emergencies and, as this manual demonstrates, their significance often transcends national boundaries. They are of particular importance to food security and sustained economic development and trade for many countries. It is imperative therefore, wherever possible, to limit the socio-economic disruptions resulting from outbreaks of TADs. The role of FAO in the fight against epidemic diseases of livestock has recently been strengthened with the establishment of the special programme, Emergency Prevention System for Transboundary Animal and Plant Pests and Diseases (EMPRES). Furthermore, the World Food Summit, through Objective 3.1 of Commitment Three of the Rome Declaration on World Food Security and the Plan of Action, November 1996, commits governments, in partnership with all actors of civil society, and with the support of international institutions to “seek to secure effective prevention and progressive control of plant and animal pests and diseases, including especially those which are of transboundary nature, such as rinderpest, cattle tick, foot and mouth disease and desert locust, where outbreaks can cause major food shortages, destabilize markets and trigger trade measures; and promote concurrently, regional collaboration in plant pests and animal disease control and the widespread development and use of integrated pest management practices”. It should also be noted that the need for effective preparedness for and response to emergencies, including those caused by pests and diseases, is enshrined in Commitment Five of the World Food Summit Plan of Action, where Objective 5.2 states inter alia that international organizations will “maintain, promote and establish, as quickly as possible, in collaboration with non-governmental organizations and other organizations, as appropriate, the preparedness strategies and mechanisms agreed upon at the ICN, including development and application of climate forecast information for surveillance and early warning, drought, flood, other natural disasters, pest and disease alertness”. The Manual on the preparation of national animal disease emergency preparedness plans is thus both a book of reference for national veterinary services and a contribution of the EMPRES programme towards the fulfilment of a component of the World Food Summit Commitments.
Bovine tuberculosis in the lake Victoria zone of Tanzania and its possible consequences for human health in the HIV/AIDS era
(Veterinary Research Communications, 1997) Jiwa, S. F. H.; Kazwala, R. R.; Aboud, A. A. O.; Kalaye, A. J.
A total of 8190 cattle from 42 well-managed herds in the Lake Victoria zone of Tanzania were tested for bovine tuberculosis by a single comparative intradermal test (SCITT) using avian and bovine puri¢ed protein derivative (PPD) antigens. The prevalence of bovine tuberculosis in this area was found to be 0.2%. There was signi¢cant variation (p50.001) among the herds tested in the four regions in this zone (Kagera, Mara, Mwanza and Shinyanga). The highest prevalence (2.12%) was in a herd of 566 cattle which had recently arrived in Kagera region from Dar-es-Salaam. None of the 915 cattle tested in Shinyanga or of the 254 resident cattle in the Kagera region were positive by SCITT. This area, and particularly the Kagera region, has the highest human morbidity and mortality due to the acquired immunode¢ciency syndrome in Tanzania. Therefore, the presence of bovine tuberculosis in cattle necessitates further investigations on the role of animal-derived tuberculosis in human health.
Isolation of mycobacterium species from raw milk of pastoral cattle of the southern highlands of Tanzania
(Tropical Animal Health and Production, 1998) Kazwala, R. R.; Daborn, C. J.; Kusiluka, C. J.; Jiwa, S. F. H.; Sharp, J. M.; Kambarage, D. M.
A study to determine the secretion of Mycobacterium spp. in milk from indigenous cattle was carried out in pastoral cattle reared in the Southern Highlands of Tanzania. The study was aimed at elucidating the dangers associated with milk-borne zoonoses in a society where milk is normally consumed raw. Out of 805 milk samples, 31 (3.9%) were positive for mycobacteria. There was a preponderance of atypical mycobacteria (87%) whereas only two isolates (6.5%) were con¢rmed as M. bovis. Atypical mycobacteria included: M. terrae (n=7), M. fortuitum (n=2), M. £avescens (n = 13), M. gordonae (n=1) and M. smegmatis (n = 4). Although the number of M. bovis positive samples was low, the habit of pooling milk may still pose great public health dangers to milk consumers in this part of the world. Moreover, isolation of atypical mycobacteria should also be considered to be a danger to human health in countries such as Tanzania, where the number of people with lowered immunity due to HIV infection is on the increase.
Trypanosome non-specific antibody responses during trypanosoma congolense infection of cattle
(Sokoine University of Agriculture, 1998) Buza Joram Josephat
EXPERIMENT ONE 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-infected group were killed between 31-51 after iii infection and mononuclear cells prepared from spleen tissue. The cells were double-stained for CD5 using monoclonal antibody IL-A67 and surface 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 number of non-trypanosome antigens such as B-galactosidase, ferritin and 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). iv 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. EXPERIMENT TWO In the first experiment, IgM antibodies reacting with a number of unrelated non trypanosome 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 as observed in cases of polyclonal activation. The second one attribute reactivity to unrelated antigens due to presence of antibody molecules, each one capable of binding more than one unrelated antigens, such as the polyreactive antibodies secreted by murine and human CD5+ B cells. This experiment was initiated to investigate whether the trypanosome non-specific antibodies are polyclonal or polyreactive. 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 V pool was passed through immunoaffmity 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 sera. In contrast, the IgG fraction purified on trypanosome lysate column reacted only with trypanosome lysate but not with the non-trypanosome antigens. The trypanosome-specific IgG fraction was only found in post-infection sera. These results conclude that trypanosome non-specific IgM antibodies are polyreactive. Their presence in pre-infection sera indicates that the infection does not specifically induce them, but helps to amplify their production. In contrast, 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 vi 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 various antigens released after the destruction of trypanosomes, and the 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 suppress antibody production. The role played by these two T cell subsets on antibody responses during trypanosome infections of cattle is not known. The aim of this experiment was to investigate the role played by CD4+ or CD8+ on antibody response during T. congolense infection of Boran cattle. vii 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 B-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, non specific 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 viii T. congolense infection in susceptible Boran cattle. CD8 T cells have no effect on antibody responses to trypanosome infections in cattle.
Assessment of Possible Sources of Endocrine Disruptors and Microbial Pathogens and their Impacts in the Lake Victoria Basin in the East African Region
(2000) Mdegela, R.H; Mbuthia, P.G; Byarugaba, D.K; Mtenga, K; Kamundia, P.W.
This study was conducted from August 2008 to May 2009 in Mwanza (Tanzania), Jinja (Uganda) and Kisumu, Homabay and Suba (Kenya) to establish the sources of pollutants in particular endocrine disruptors and microbial pathogens in water and fish. A sociological study was undertaken using qualitative and quantitative methods. Microbial contamination of water and fish in the lake was assessed in 14 water and 60 fish samples in Mwanza. In Jinja, assessment of microbial contamination was carried out in 100 water and 26 fish samples. A total of 80 Nile tilapia were collected from Kisumu, Homabay and Suba and examined for gross pathological lesions using standard necropsy techniques. Findings from the sociological studies indicated that, the knowledge and awareness on endocrine disruptors in the region is low. Pollutants that find access into the lake and have potential for disrupting the endocrine systems exist in all cities and originate from point and non-point sources. Human, industrial, agricultural, hospital and domestic wastes are the main sources of pollutants likely to contain endocrine disruptors. These pollutants are handled poorly and most of them are disposed off into the lake without treatment. In Mwanza, contamination of water with faecal material at various landing sites was observed in 85.7%, 78.6% and 35.7% of the samples determined using Total Viable Counts, Total Coliform Counts and Total Faecal Coliform Count. All water samples were negative for Salmonella spp, Vibrio spp, Cryptosporidia spp and Giardia spp. In Jinja, microbial contamination was observed in all sampling sites as determined by aerobic plate count (APC), Total Coliform Count (TCC) and Escherichia coli count. There was no significant difference in microbial load between sampling sites (P > 0.05). The gross pathological lesions were generalized hyperemia, liver changes (paleness, grey spots and hemorrhages), cystic urinary bladder, atrophied testis and kidneys, eye opacity, degenerated ovaries, grey patches on the stomach, clear cysts in the testis, deformed dorsal fin and ulcers on the lateral side of the body. Further studies are underway to confirm the likely causes of the observed lesions and the impact of the observed pollutants and microbial pathogens.
Effect of brining on the drying rate of tilapia (Oreochromis niloticus) in a solar tunnel dryer
(2000) Kituu, G. M.; Shitanda, D.; Silayo, D.; Odote, P.; Bongyereire, J.
This study determined effect of on the drying rate of tilapia in a solar tunnel dryer. Tilapia fish was split into pieces of 4cm by 3cm by 9mm and soaked into four brine concentrations varying between 0-15%. Moisture content was evaluated by oven drying method, while air temperatures were with an automated data logger. The moisture content of fish reduced as brine concentration increased. The effective diffusion coefficient varied between 5.061 *10-11 and 3.323*10-11 m2/s as brine concentration increased, and it decreased with increase in brine concentration.
Occurrence of Rice Yellow Mottle Virus in Tanzania
(Tanzania Journal of Agricultural science, 2000) Luzi-Kihupi, A; Mlozi, Malongo R.S; Mabagala, R.B; Mushobozy, D.M.K; Nchimbi-Msolla, S
Rice yellow mottle, virus-(RYMV)-which was first recorded in Kenya in 1966 is now considered one of the most important disease in tropical Africa. Surveys were conducted in rice growing areas in Tanzania to determine the influence, severity and distribution of RYMV in the country. The incidence and severity of RYMV varied depending on the cultivar grown.
Emerging diseases of Africa and the Middle East
(FAO, 2000-02) RWEYEMAMU, MARK; PASKIN, ROGER; BENKIRANE, ABDELAL; MARTIN, VINCENT; ROEDER, PETER; WOJCIECHOWSKI, KRIS
The term “emerging diseases” has been used recently to refer to different scenarios, all of which indicate changes in the dynamics of disease in the population. Of the OIE List A diseases, major changes have been experi- enced with rinderpest, peste des petit ruminants (PPR), contagious bovine pleuropneumonia (CBPP), foot-and-mouth disease, African swine fever, lumpy skin disease, and Rift Valley fever. Rinderpest represents a success sto- ry of the 1990s, thanks to the programs of the Pan African Rinderpest Cam- paign (PARC). The situation has changed from that of the 1980s when rinderpest was widespread throughout most of Tropical Africa and the Middle East. PPR is a disease that has become of increasing importance throughout Tropical Africa and the Middle East. CBPP, which had previously been reduced to sporadic incidence within endemic areas, invaded new areas, caus- ing heavy mortality. African swine fever has extended to West Africa and to Madagascar, in both regions resulting in heavy losses. Climatic changes in both East and West Africa were associated with an upsurge of Rift Valley fever. Deficiencies in national veterinary services have contributed to failures in ear- ly detection and response; in many regions investigation and diagnosis services have deteriorated. The continuing structural adjustment program for national veterinary services will need to take into account their transformation from providers of services (e.g., vaccinations, medicines) to inspection and quality assurance services. Surveillance, early warning, and disease emergency pre- paredness will need to be pursued more vigorously in Africa and the Middle East as vital components of national veterinary services.
Risk Factors Associated with the Occurrence of Bovine Tuberculosis in Cattle in the Southern Highlands of Tanzania
(Kluwer Academic Publishers, 2001) Kazwala, Rudovick; Kambarage, D.M.; Daborn, C.J.; Nyange, J.; Jiwa, S.F.H.; Sharp, J.M.
A study was conducted in the Southern Highlands of Tanzania to determine the prevalence of bovine tuberculosis and the risk factors associated with the occurrence of the disease in cattle of di¡erent categories and in di¡erent climatic zones. The overall prevalence of the disease was 13.2%, and 51% of the herds tested contained reactor cattle. Assessment of risk factors was based on comparisons of the reactivity of the cattle in the single comparative intradermal tuberculin test (SCITT). Older cattle were more a¡ected by the disease than yearlings and calves (p50.0001). There were signi¢cant di¡erences between male and female cattle (p50.05) and between cattle with exotic blood compared to indigenous Short Horn Zebu (SHZ) cattle (p50.05). The castrated bulls, often used for draught power, were more frequently (p50.01) a¡ected than the entire bulls, mainly used for breeding. Reactivity to tuberculin did not appear to be in£uenced by the reproductive status of the animal. The reactivity to tuberculin of pregnant cattle was not signi¢cantly di¡erent from that of the rest of the cows (p40.05). However, signi¢cantly more (14.6%) lactating cattle reacted in the SCITT than did non-lactating cows (12.0%) (p50.05). There was a highly signi¢cant di¡erence (p50.001) between reactivity in the SCITT among cattle grazing in the hot and dry lower lands (14.0%) and that in those grazing in the cool and wet highlands (8.7%).
Isolation of Mycobacterium bovis from human cases of cervical adenitis in Tanzania: A cause for concern?
(The International Journal of Tuberculosis and Lung Disease, 2001-09-28) Kazwala, R. R.; Daborn, C. J.; Sharp, J. M.; Kambarage, D. M.; Jiwa, S. F. H.; Mbembati, N. A.
Pastoralist communities in the Northern and Southern zones of Tanzania. DESIGN: Observational study. OBJECTIVES: To determine the involvement of Mycobacterium bovis in tuberculosis cases presenting at tuberculosis (TB) clinics in rural areas in these zones. METHODS: A total of 149 tuberculosis cases identified on the bases of clinical manifestation were sampled. Appropriate specimens were cultured on two Löweinstein Jensen slants with respectively glycerol and pyruvate added. Forty-one isolates were cultured and subjected to biochemical typing. RESULTS: Overall, 31 (70.5%) of the mycobacterialisolates recovered from all forms of tuberculosis were identified as M. tuberculosis, seven (16.0%) were identified as M. bovis, and six (13.6%) were other mycobacterial species. There was a significantly higher isolation rate (P 0.05) of M. bovis among strains recovered from extra-pulmonary (26.8%) than pulmonary tuberculosis samples (4.3%). CONCLUSION: Based on these findings, it is imperative that M. bovis be considered as a pathogen of concern to people living in rural areas of Tanzania. Further work is required to establish a zoonotic link between cattle and the people in these communities who rear them.
Effects of nutrition and draught on reproductive and adrenal functions of female donkeys
(2003) Mollel, E.L.; Mutayoba, B.M.; Aboud, A.A.O.
Cyclic ovarian activity and plasma progesterone (P4) concentrations were assessed for 179 days in 5 (free grazing) and 6 (free grazing + high energy and protein-supplemented) normocyclic donkeys. In addition, plasma p4 and cortisol were measured in blood samples collected at 15·min intervals in the same donkeys on days 82-84 and 113-114 when made to carry a cartload weighing about three times their bodyweight for a period of 3h. Cyclic P4 concentrations were measured in samples collected three times weekly. Oestrous cycle lengths and duration of estrous were not influenced by plane of nutrition in both groups of donkey's. Plasma cortisollevets increased significantly (P<0.05) in non-supplemented donkeys during the draught period. Changes in plasma P4 levels during draught were influenced by the stage of oestrous cycle; a significant increase (p <0.01) being observed in donkeys in luteal phase and a decrease (P<0.01) in non-luteal phase. Plasma P4 levels associated with subsequent post-draught oestrous cycles were depressed (P<0.05) in both groups, decline being more prominent in donkeys stressed during non-luteal phase than those stressed during the luteal phase. These results demonstrate that draught does interfere with ovarian cyclic and endocrine functions of working female donkeys and this situation might be exacerbated by poor nutrition.
Tribal differences in perception of tuberculosis: A possible role in tuberculosis control in Arusha, Tanzania
(International Journal of Tuberculosis and Lung Disease., 2003) Mfinanga, S. G.; Mørkve, O.; Kazwala, R. R.; Cleaveland, S.; Sharp, J. M.; Shirima, G.; Nilsen, R.
SETTING: Arusha, Tanzania. OBJECTIVE: To determine tribal differences in knowledge and practices that might influence tuberculosis control. METHOD: Twenty-seven villages were selected randomly out of 242 villages in four districts. In each village, a general and a livestock keeping group were selected at random. The households were home-visited and 426 family members were interviewed. RESULTS: On average, 40% of respondents practiced habits that might expose them to both bovine and human tuberculosis. The Barabaig tribe had a significantly higher number of respondents (50%, X2(2) = 5.1, P = 0.024) who did not boil milk. Eating uncooked meat or meat products was practised by 17.9% of all respondents. The habit was practised more by Iraqw (21.1%, X2(2) = 6.9, P = 0.008) and Barabaig (31.6%, X2(2) = 5.6, P = 0.016) than other tribes. About 75% of the respondents had a poor knowledge of tuberculosis. CONCLUSION: All tribes had habits and beliefs that might expose them to both bovine and human tuberculosis. The Iraqw and Barabaig tribes practised such habits more than other tribes. Knowledge of tuberculosis was limited in all tribes.
The role of rodents in the maintenance of the east African tick-borne relapsing fever aetiological agent, Borrelia duttonii
(Sokoine University of Agriculture, 2003) JESSEY,PAX
A total of 250 rodents, 251 adult and nymph ticks and seven human blood samples were collected from Mvumi township in Dodoma region, Tanzania, between November, 2001 and February, 2002, and analysed for the presence of the tick-borne relapsing fever agent (TBRF), Borrelia duttonii. Cultures of the spirochetes were made in Barbour-Stoenner-Kellys (BSK-II) medium, and molecular characterization of the spirochetes was done by polymerase chain reaction (PCR). Spirochete cultures were successfully grown from two out of the seven human blood samples. No spirochetes grew in either of the cultures of the rodent blood or the tick haemolymph and crushed tick samples. These samples were negative for spirochetes by staining and direct microscopy. PCR detected Borrelia DNA from two of the seven human blood samples, and from one of either rodent (Rat t us rattus), and tick samples. This is the first study on the possibility of rodents playing a role in the transmission of Borrelia spp in Tanzania. The detection of Borrelia DNA in rodents originating from this TBRF endemic area suggests the possibility of rodents playing a role in the maintenance of the TBRF agent, B. duttonii. Since it is generally accepted that only humans are the reservoirs of B. duttonii, this study calls for further investigation to determine the importance of commensal rodents and other mammals in the epidemiology of relapsing fever in Tanzania.
The role of livestock keeping in tuberculosis trends in Arusha, Tanzania
(The International Journal of Tuberculosis and Lung Disease, 2003-01-15) Mfinanga, S. G.; Mørkve, O.; Kazwala, R. R.; Cleaveland, S.; Sharp, J. M.; Shirima, G.; Nilsen, R.
OBJECTIVE: To assess risk factors that might influence TB control in the general population and in livestockkeepers. METHODS: Of 242 villages in four districts, 27 were selected randomly. In each village, a general and a livestock- keeping group were selected at random. The households were home-visited and 426 family members were interviewed. RESULTS: On average, three-quarters of households practised at least one risk activity for transmission of zoonotic tuberculosis, and respondents had poor knowledge about tuberculosis. In the livestock-keeping group, the risks of having a tuberculosis patient in the family were determined by poor ventilation (OR 2.6, 95%CI 1.1–6.5), confining livestock indoors with people (OR 2.3, 95%CI 1.1–5.0) and multiple determinants including poor ventilation (OR 13.5, 95%CI 2.5–71.7). Risk activities and the risks of having a tuberculosis patient in a family were significantly higher in the livestock-keeping group. CONCLUSIONS: The respondents had limited knowledge about tuberculosis, and the households had practices that posed potential risks for both human and bovine tuberculosis infection. Poor ventilation and confining livestock indoors were associated with tuberculosis spread in the households. These risks were observed more in the livestock-keeping group than in the general population group.
Molecular investigation of multiplicity of infections and drug resistance to sulphadoxine-pyrimethamine (sp) in plasmodium falciparum malaria in Mlimba, Tanzania
(Sokoine University of Agriculture, 2004) MBUGI,ERASTO
The study was aimed at molecular investigation of multiplicity of infections and drug resistance to sulphadoxine-pyrimethamine (SP) in Plasmodium falciparum malaria. This molecular epidemiological study involved 141 blood samples from patients aged less than five years from malaria-endemic Mlimba division of Kilombero District, Morogoro, south eastern Tanzania. Blood samples were collected on filter papers (3MM Whatmann) and parasite DNA was extracted by Chelex technique. Molecular analysis on the merozoite surface protein 2 (MSP2), dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) was based on polymerase chain reaction (PCR) followed by restriction fragment length polymorphism (RFLP) of PCR products (PCR-RFLP). These techniques made it possible to determine the multiplicity of infections and SP resistance-associated point mutations anticipated at sorting out recrudescence from new infections. The commonly reported point mutations occurring at codons 51, 59, 108 and 164 in the DHFR and codons 437, 540 and 581 in the DHPS domains were investigated. The results showed the multiplicity of infection array of single to six infections per patient with an average multiplicity of 2.58 infections per patient. Fifty-one patients possessed single alleles of either allelic families of the MSP2 gene in PCR-RFLP successful samples. Double, triple and multiple infections were detected in 37.7%, 11.9% and 5.9% of patients, respectively. Regarding drug resistance molecular markers, 66.9% carried mutations at codon 108, 62.7% at codon 51 and 48.8% at codon 59 of DHFR domain. Fifty-six (43.7%) of samples carried mutations at codon 437, 39.2% at codon 540 and 0.8% at codon 581 on the DHPS domain. Proportions of mixed variants in the DHFR domain ranged from 0 - 21.5% and 0.8 - 6.3% in the DHPS domain. About 44 (36.4%) of isolatesiii harboured triple mutant DHFR genotypes, whereas quintuple mutation was observed in 24 (19.8%) of isolates. Ten (8.3%) isolates possessed at least double DHFR and double DHPS mutants. This study found a high proportion of SP resistance- associated point mutations in Mlimba two years after deployment of SP as a first-line antimalarial drug in Tanzania. However, the adequate clinical response (81.1%) observed clinically reflects the role of semi-immunity component in the study population. This implies that used molecular markers for monitoring drug resistance, be done simultaneously with studies on confounding factors pertaining to development of resistance against SP in falciparum malaria. The extensive use of antifolates other than SP for treatment of infections other than malaria is a probable candidate for potentiating selection of mutations ascribed to SP resistance. The SP resistance potential detected in this study, caution on its useful therapeutic life as an interim first-line drug against malaria in Tanzania
Contagious bovine pleuropneumonia vaccines: the need for improvements
(2004-01) Rweyemamu, M.M; Litamoi, J; Palya, V; Sylla, D
Contagious bovine pleuropneumonia (CBPP) vaccines are routinely used only in Africa. The vaccines are usually produced from one of two strains (T1/44 and KH3J), each of which has a streptomycin-resistant variant. The necessity for a 'master seed strain' is evident. At least one manufacturer in Africa produces a broth culture vaccine, while others produce a freeze-dried product. A standardised manufacturing protocol needs to be developed, together with in-process and final product quality control procedures. Some CBPP vaccine manufacturing procedures do not allow sufficient leeway for the execution of typical quality control practices. For example, it is difficult to perform batch testing on broth culture vaccine, as the vaccine is produced in its final container. Quality control test results from the Pan African Veterinary Vaccine Centre (PANVAC) are analysed in terms of causes of batch failure and indicators for process development. Taking potency as an example, most vaccine batches tested by PANVAC pass only at the limit of the OIE minimum requirement of 107 colony-forming units per dose. To improve the titre of the vaccine, it will be necessary to modify the manufacturing process, either by increasing mycoplasma yield during the culture phase or by minimising losses during downstream processes, especially freeze-drying. Data on inactivated vaccines are scarce. Duration of the immunity achieved with live CBPP vaccines is relatively short, in comparison with other live vaccines. Data may be required on the molecular basis of virulence and immunogenicity, as well as on the molecular immunology of CBPP, to enable the development of improved vaccines.

Browse

Browsing Articles, Conference and Workshop Papers Collection by Issue Date