Search

Laboratory examination of blood smears from water buffaloes in an area of high fly challenge indicated an infection rate of 51.11 % caused by both Trypanosoma congolenseand T. vivax.A similar study in cattle raised in a low fly challenge area showed an infection rate of 22.73% caused by T. congolenseonly. Diminazene aceturate administered as a single dose at 3.5 mg/kg body weight cured the infection in cattle, while a similar dose at 7 mg/kg body weight failed to cure the water buffaloes. Cattle were further protected by a single dose of isometamidium chloride administered at 0.5 mg/kg body weight for 6 weeks of this study. On the other hand, isometamidium chloride administered at 1 mg/kg body weight cured transiently 90% of the infected water buffaloes and 10% persisted with a T. congolenseinfection. It was concluded that the lower dose rates approved by the manufacturers for the two trypanocides treated adequately infected cattle in a low challenge area, but such results were not achieved with the higher dose rates for infected water buffaloes in a high fly challenge area. L’examen de frottis sanguins de buffles (Bubalus bubalus)provenant d’une région fortement infestée de mouches tsé-tsé indique un taux d’infection de 51.11%, dû à Trypanosoma congolenseet T. vivax.Une étude similaire concernant les vaches dans une zone peu infestée montre un taux d’infection de 22.73%, causé par T. congolenseuniquement. De l’acéturate de diminazene administré en une dose de 3.5 mg/kg de poids vif soigne l’infection des vaches, alors que les buffles ne sont pas soignés par une dose de 7 mg/kg. Les vaches ont ensuite été protégées pendant 6 semaines grâce à une dose unique de 0.5 mg/kg de chlorure d’isométamidium, tandis que cette même drogue administrée à raison de 1 mg/kg ne soignait transitoirement que 90% des buffles, les 10% restant présentant une infection à T. congolense.On peut donc en conclure que les faibles doses recommandées par les fabricants pour chaque trypanocides sont adaptées à des vaches exposés à de faibles infestations, mais non à des buffles vivant dans des zones lourdement infestées par les glossines.

Anorexia in forty-six (6.1%) out of 753 neonatal lambs was investigated. Thirty-five of these lambs (76.1%) died while eleven (23.9%) recovered after treatment. Coagulated rubber-like milk clots were found in fifteen (42.9%), phytobezoars in nine (25.7%) and trichophytobezoars and coarse straws in eleven (31.4%) of the dead lambs.

The probability of a Glossina pallidipespicking up an infection from a single blood meal in Lambwe Valley was estimated to be 0.0092 for Trypanosoma vivax, 0.0028 for T. congolense, 0.00097 for T. bruceiand 0.00024 for the human infective T, brucei.In cattle, the prevalence of blood protozoa was Trypanosomaspp. 5.55%, Babesiaspp. 2% and Theileriaspp. 33.06%. Thirty-eight point three per cent of the cattle with trypanosomes also had Theileriaspp., 2.12% of the cattle with trypanosomes also had Babesiaspp. and 88.28% of the cattle with babesia had also Theileriaspp. La probabilité pour un Glossina pallidipesde transmettre une infection à partir d’une sucée de sang dans la Vallée le Lambwe a été estimée à 0,0092 pour la Trypanosoma vivax, 0,0028 pour T. congolense, 0,00097 pour T. bruceiet 0,00024 pour contagieux humain T. brucei.Chez les bovins, la prevalence du protozoaire du sang était: Trypanosomaspp. 5,55% Babesiaspp. 2% et Theileriaspp. 33,06. Trente huit virgule trois pour cent de bovins ayant le trypanosomes avaient aussi le Theileriaspp. 2,12% des bovins ayant des trypanosomes avaient aussi le Babesiaspp. et 88,28% des bovins ayant le babesia avaient aussi le Theileriaspp.

In a series of field trials 48 (55%) of 88 field cases of East Coast fever treated with halofuginone lactate recovered and survived and 40 (45%) died while 31 (86%) of 36 untreated control animals died of East Coast fever and five (14%) recovered. For cases diagnosed and treated early a 100% recovery rate was achieved. A single dose at 1·2 mg/kg body weightper os was adequate. Recovery rate was only 36% for cases diagnosed and treated at an advanced stage. Such cases required two doses at 1·2 mg/kg or a combination of 1·2 and 2·4 mg/kg body weight given at about two days interval. The temperature dropped to normal levels within 48h of treatment and schizonts started degenerating as early as 24 h after treatment and had disappeared by 48 to 72 h. Piroplasms were not affected by the drug. Recovered animals remained free of East Coast fever for periods up to 12 months of observation despite continuous tick challenge. It was concluded that, with early detection and treatment augmented with proper tick control, outbreaks of East Coast fever can be effectively controlled with halofuginone lactate.

As many ewes and lambs watered at concrete ponds in well-drained sites acquired fluke infection as those watered at natural ponds in areas suitable for the snail intermediate hosts of Fasciola hepatica. Fasciola transmission, as evidenced by the increasing number of seropositive hosts in an enzyme-linked immunosorbent assay (ELISA), occurred during the heavy rainy period of July–September and declined with the onset of the dry season, being succeeded by the emergence of faecal positive hosts. This indicates the superiority of ELISA over coprological techniques in the early diagnosis and seroepidemiology of this parasitic infection. Host productivity, as reflected in weight gains and haematological parameters, was not significantly affected by the fluke infections.

Laboratory mice infected with a Trypanosoma congolenseisolate of water-buffalo origin did not respond when treated with diminazene aceturate (Berenil, Hoechst, West Germany) at 3.5 mg/kg and 7 mg/kg body weight (b.wt.) and also isometamidium chloride (Samorin, May & Baker, Dagenham, England) at doses less than 3 mg/kg b.wt. Effective cure was achieved with isometamidium and diminazene at 3 mg/kg and 14 mg/kg b.wt. respectively; doses in excess of those recommended for use in the field to treat animal trypanosomiasis by the manufacturers. Irregular use of the two drugs on infected water-buffaloes while improperly restrained may be one of the factors responsible for the dual drug resistant T. congolenseisolate emerging. Des souris de laboratoire infectées par inoculation avec des isolats de Trypanosoma congolenseprélevés sur des buffles n’ont pas réagi à un traitement à l’acéturate de diminazène (B>erénil, Hoechst, Rép. féd. d’Allemagne) dosé à 3,5 et 7 mg/kg de poids vif, ni á des doses de moins de 3 mg/kg de poids vif de chlorure d’isométamidium (Samorin, May & Baker, Dagenham, Angleterre). Pour obtenir une guérison, il a fallu employer des doses de 3 mg/kg de poids vif d’isométamidium et de 14 mg/kg de poids vif de diminazène. Ces doses excèdent celles recommandées par les fabricants pour traiter la trypanosomiase animale sur le terrain. L’usage irrégulier et mal contrôlé de ces deux produits pour le traitement de buffles infectés explique en partie l’émergence d’isolats de T. congolenserésistants à ces deux médicaments.