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At least 19 recordsLinked to original sources
PubMed1983

Tsetse and trypanosomiasis survey of Southern Darfur Province, Sudan. I. Bovine trypanosomiasis.

During a survey of Southern Darfur Province, Sudan blood samples from over 4,000 migratory cattle were analysed to determine levels of anaemia and trypanosome parasitaemia by buffy coat examination of microhaematocrit centrifuged samples. Levels of trypanosomal infections in the herds correlated well with their risk of exposure to tsetse being significantly lower at increasing distance from tsetse foci. Trypansoma vivax infections predominated in all herds, increasingly so with increasing distance from tsetse foci. Packed cell volume values could not be used to assist in trypanosome diagnosis at either individual or herd levels and the lack of correlation between anaemia and parasitaemia is suggested as evidence of a degree of trypanosomal tolerance in the Western Baggara cattle. Drug use and problems of drug resistance are discussed. Bovine trypanosomiasis is largely under control at present but requires continued surveillance (particularly of drug use) to prevent future problems as tsetse/cattle interactions increase.

Animals↗
PubMed2002

Participatory investigations of bovine trypanosomiasis in Tana River District, Kenya.

Participatory research on bovine trypanosomiasis was conducted with Orma pastoralists in Tana River District, Kenya. The use of participatory methods to understand local perceptions of disease signs, disease causes, disease incidence by cattle age group, seasonal patterns of disease and preferences for indigenous and modern control methods are described. Results indicated that local characterization of diseases called gandi and buku by Orma pastoralists was similar to modern veterinary knowledge on chronic trypanosomiasis and haemorrhagic trypanosomiasis (due to Trypanosoma vivax), respectively. The mean incidence of gandi varied from 10.2% in calves to 28.6% in adult cattle. The mean incidence of buku varied from 3.1% in calves to 9.6% in adults. Pearson correlation coefficients for disease incidence by age group were 0.498 (P < 0.01) and 0.396 (P < 0.05) for gandi and buku, respectively. Informants observed cases of trypanosomiasis in 24.1% of cattle (all age groups); these cases accounted for 41.8% of all sick cattle during the preceding 12-month period. Eight indigenous and three modern trypanosomiasis control methods were identified. Results indicated that an integrated approach to trypanosomiasis control based on private, individual action was well established in the assessment area. When presented with four different trypanosomiasis control methods, community representatives selected 'better use of trypanocides' as the most preferred intervention and 'community-based tsetse control' as the least preferred intervention. This finding prompted researchers to modify the original project activities. Constraints facing the sustainability of community-based tsetse control are discussed.

Age Factors↗
PubMed1986

Haematological observations on bovine trypanosomiasis of Holstein-Friesian breed.

Haematological investigation was conducted on 20 cases of bovine trypanosomiasis caused by Trypanosoma congolense and T. vivax in imported Holstein-Friesian cattle using standard techniques. Comparison of the results with the values obtained for clinically normal animals whose blood samples were consistently negative for trypanosomes indicated that natural bovine trypanosomiasis was associated with a significant (P less than 0.001) fall in haemoglobin concentration, packed cell volume and numbers of erythrocytes. Slight reduction in the number of leucocytes, eosinophils, monocytes and basophils was recorded. No significant change (P greater than 0.001) was observed in the number of lymphocytes and neutrophils between naturally infected and control Holstein-Friesian animals.

Animals↗
PubMed1987

Bovine trypanosomiasis in southern Tanzania: parasitological and serological survey of prevalence.

In a survey for bovine trypanosomiasis blood smears from 1,617 cattle at 72 sites were examined. Trypanosomes were found in 93 cattle, representing 16% of the cattle in herds in which trypanosomiasis was confirmed. Of the positive cattle 56% had infections with T. congolense, 17% T. vivax and 2.2% T. brucei. Five cattle had mixed infections and in 18 cattle the species was not identified. Sera from 1,352 cattle were tested using microelisa. Ten out of 16 sites, at which no trypanosomes were found in blood smears and at which trypanocides were in use, had over 15% seropositive cattle compared with five of 19 sites at which trypanocides were not in use. It was concluded that the microelisa was a useful aid to the diagnosis of bovine trypanosomiasis and that there is a need for accurate records of drug use and livestock movements to be kept. The serious risk of drug resistant strains of trypanosomes emerging due to the uncontrolled use of trypanocides is emphasised.

Animals↗
PubMed1980

Use of antigens of cultured Trypanosoma brucei in tests for bovine trypanosomiasis.

MicroELISA tests for the detection of trypanosomal antibodies in cattle infected with Trypanosoma brucei, T. vivax and T. congolense were carried out using antigens prepared from culture forms and bloodstream forms of T. brucei. Antigens prepared from culture forms gave similar microELISA values to those obtained with bloodstream form antigens and statistical analysis of the results obtained with both antigen preparations and sera from the infected animals showed significant high positive correlation. It would thus be possible to use culture from antigens as an alternative to bloodstream form antigens in diagnostic tests for trypanosomiasis, with the advantage that culture form antigens are more easily prepared free from extraneous protein.

Animals↗
PubMed1992

Failure of chemoprophylaxis against bovine trypanosomiasis on Galana Ranch in Kenya.

The duration of prophylaxis provided by 1 mg kg-1 bodyweight of homidium bromide was compared with that provided by 1 mg kg-1 bodyweight of isometamidium chloride in a 12 month field trial involving 90 Boran cattle exposed to trypanosome challenge on Galana Ranch in Kenya. Weekly trypanosome prevalences of over 30% were observed during 4 of the 12 months. During these periods of heavy challenge, parasites were detected 2-3 weeks after administration of both homidium bromide and isometamidium chloride. Both prophylactic drugs were administered, on a group basis, eight times over the 12 month trial and in addition individual infections were also treated with diminazene aceturate. Isometamidium chloride provided slightly longer periods of prophylaxis than homidium bromide, 28.4 days compared with 25.4 days. There was a highly significant difference in the productivity of the two groups during a period of poor grazing. 27% of the isometamidium chloride herd died from a severe wasting condition with substantial liver damage evident on post mortem. The condition was not observed in the homidium bromide herd. The surviving animals in the isometamidium chloride herd had a mean annual weight gain of 24 kg less than that recorded in the homidium bromide herd.

Animals↗
PubMed1993

Epidemiology of bovine trypanosomiasis in the Ghibe valley, southwest Ethiopia. 2. Factors associated with variations in trypanosome prevalence, incidence of new infections and prevalence of recurrent infections.

An average of 840 East African Zebu cattle from nine herds in the Ghibe valley, southwest Ethiopia were monitored from January 1986 to April 1990. Each month blood samples were collected for analysis of packed red cell volume (PCV) and detection of trypanosomes. Animals found to be parasitaemic and with a PCV less than 26% were treated with diminazene aceturate at a dose of 3.5 mg/kg body weight. The majority of infections were associated with Trypanosoma congolense (84% of infections in adult cattle and 71% in cattle less than 24 months of age), and the mean percentage of adult animals detected parasitaemic 1 month after treatment of an infection with T. congolense was 27%. In order to assess possible existence of drug resistance, a model was applied which allowed monthly incidences of new infections to be distinguished from recurrent infections. This model showed that the monthly incidence of new infections of T. congolense in adult cattle increased significantly from 11% in 1986 to 24% in 1989 following a concomitant increase in the tsetse challenge. The corresponding increase in overall prevalence of T. congolense was from 17% to 38% and the mean prevalence of recurrent infections increased significantly from 6% to 14%. These findings ruled out the possibility that the high prevalence of trypanosome infections in cattle was due only to a high tsetse challenge and pointed to the existence of T. congolense populations which expressed resistance to diminazene. There were variations associated with season, herd, age and sex in the incidence of new infections, prevalence of recurrent infections and relapse to treatment.

Animals↗
PubMed1993

Epidemiology of bovine trypanosomiasis in the Ghibe valley, southwest Ethiopia. 3. Occurrence of populations of Trypanosoma congolense resistant to diminazene, isometamidium and homidium.

In July 1989, blood samples were collected from parasitaemic cattle in the Ghibe valley, Ethiopia, frozen in liquid nitrogen and transported to Nairobi, Kenya. Twelve of the stabilates were inoculated into individual Boran (Bos indicus) calves and characterised for their sensitivity, in turn, to diminazene aceturate (Berenil), isometamidium chloride (Samorin) and homidium chloride (Novidium). All 12 stabilates produced infections which were shown to be Trypanosoma congolense and resistant to treatment with diminazene aceturate at a dose of 7.0 mg kg-1 body weight (b.w.). Eleven of the infections were also resistant to isometamidium chloride at a dose of 0.5 mg kg-1 b.w. and homidium chloride at a dose of 1.0 mg kg-1 b.w. The drug-sensitivity phenotypes of three of the same isolates were also determined in goats which were each treated with only one of the three trypanocides: all expressed the same phenotypes as the populations expressed in the aforementioned Boran calves. Five clones were derived from one of the isolates which expressed a high level of resistance to all three trypanocides; each clone expressed high levels of resistance to all three trypanocides when characterised in mice. Thus, the multi-resistance phenotype of the parental isolate was associated with expression of mutli-resistance by individual trypanosomes. Finally, molecular karyotypes and electrophoretic variants of six enzymes were determined for seven and eight of the isolates, respectively. Six different karyotypes were observed and all eight of the latter isolates belonged to different zymodemes, indicating that the multi-resistance phenotype at Ghibe was associated with many genetically distinct populations.

Animals↗