Trypanosomiasis control in Boran cattle in Kenya: a comparison between chemoprophylaxis and a parasite detection and intravenous treatment method using isometamidium chloride.

Two methods of trypanosome control in Boran cattle kept under very high trypanosomiasis risk were compared: the traditional intramuscular isometamidium chloride prophylaxis with a parasite detection and intravenous isometamidium chloride treatment method. The results were related to a control group under diminazene aceturate treatment. Isometamidium chloride at 0.25 mg/kg as routinely used by the ranch was of little benefit by either method, with breakthrough infections occurring as early as one week after treatment. When isometamidium chloride at 1 mg/kg was used, the curative intravenous method appeared to be superior to the intramuscular prophylaxis with regard to cost of drugs and to a 31% higher weight gain over a 30 week period. Weekly infection rates in the intravenous group decreased over time, despite an increasing trypanosomiasis challenge, with a mean interval of 6.4 weeks between treatments as compared with 4.3 weeks in a diminazene aceturate control group. It was concluded that isometamidium chloride given intravenously had not only a very good therapeutic but also a considerable prophylactic effect of not less than four weeks.

Investigation of the efficacy of flumethrin pour-on for the control of high tsetse and trypanosomiasis challenge in Kenya.

The effects of bi-weekly flumethrin pour-on treatments at 1 mg kg bodyweight on tsetse fly population and trypanosome infection rates were monitored over a one-year period (2/89-2/90) in 2000 head of cattle on a trial farm, located in the Lamu District in East Kenya, an adjacent control farm and a transsecting road for additional fly monitoring. The tsetse fly population on the trial farm dropped from pretreatment counts of 118 flies/trap/week (Feb. 1989) to 13 in June 1989 and 32 in Jan. 1990. During the same period and months the fly population in the control farm was 90.34 and 87 flies/trap/week. Fly counts on the transsecting road, however, increased from 72.53 to 163 flies/trap/week. The impact of tsetse fly control is clearly reflected in the reduction of trypanosome infection rates on the trial farm, e.g. 37% (pre-treatment infection rate), 10% and 11% in January, June and December 1989 respectively. On the control farm the infection rates remained at distinctly higher levels of 34%, 17% and 24% during the same period. Mean weekly weight gains were 66% higher in the treated herd as compared to the untreated control herd.

Metaphylactic deworming program for buffalo calves (Bubalis bubalis) in North-East Thailand.

One hundred newborn swamp buffalo calves (Bubalis bubalis) from three villages in North-East Thailand were divided equally into treatment and control groups. Treated calves received two doses of a piperazine/thiabendazole mixture (196.6 and 50 mg/kg bodyweight respectively) at three, and again at ten weeks of age. Control calves received placebo treatments at the same times. Egg excretion rates for the roundworms Strongyloides papillosus and Toxocara vitulorum were recorded as high as 85% and 58% respectively during the first three months of life. During the trial period, four calves in the treated group died and one was treated for coccidiosis, compared to seven deaths and nine additional anthelmintic treatments required in the control group. All calves that either died or required additional anthelmintic treatment showed signs of severe enteritis, anorexia and emaciation that was attributed to parasitic infestation. Calves receiving emergency anthelmintic treatment all recovered uneventfully. All except four of the calves that died or became sick did so between 25 and 40 days post partum, with the remainder developing clinical signs of parasitosis before day 50. There was no difference in weight gains between treated and untreated calves over the trial period (16 weeks). Thus, the advantage of anthelmintic treatments as described at three and ten weeks of age in buffalo calves under village conditions was seen as a reduction in the combined morbidity/mortality rate from 32% to 10% (P less than 0.05). From the pattern of infection observed in this study it is suggested that further gains could be made by giving the second treatment at six (instead of ten) weeks of age, and by increasing the dosage of anthelmintic used.

Trypanosoma evansi infection in buffaloes in North-East Thailand. II. Abortions.

By exclusion of other possible aetiological agents, strong circumstantial evidence is presented of Trypanosoma evansi infection being the cause of late gestation abortion and stillbirth in buffaloes.

Trypanosoma evansi infection in buffaloes in north-east Thailand. I. Field investigations.

Clinical, parasitological and serological findings of Trypanosoma evansi infections in buffaloes (Bubalis bubalis) from north-eastern Thailand are reported. The overall infection rate was found to be around 20% with a distinct peak of acute infections during the rainy season. The disease is aggravated by normally well tolerated concomitant infections such as liver fluke infestations and by other stress factors.