Financial analysis of animal trypanosomiasis control using cypermethrin pour-on in Kenya.

The financial impact of use of cypermethrin pour-on (Ectopor(R)) in control of animal trypanosomiosis was determined in a trial undertaken by the Kenya Trypanosomiasis Research Institute (KETRI). This trial started in December 1990 and ended in February 1992. It was undertaken in two adjacent ranches in the coast province of Kenya. The trial site was in an area of high apparent density (AD) of tsetse flies, and at the start of the trial no cattle were kept in this area. Cypermethrin was applied fortnightly to the 1100 steers which were kept in pour-on ranch 'A' while another 100 steers were kept in control ranch 'B' to act as control sentinels. From the main pour-on group, 100 animals were identified as the pour-on sentinels and compared to the control sentinels which received no pour-on.Pour-on application led to a significant decrease in the tsetse AD in the pour-on ranch A to 90% of the initial AD in some areas. The animals treated with pour-on had a significantly higher mean packed-cell volume (PCV). The weekly prevalence of trypanosome infections in animals treated with pour-on was <4% with only one exception when it was <10%. In the control animals, the prevalence ranged between 10 and 50% (with a few exceptions when it was <10%). The incidence of tick-borne diseases was lower in the pour-on animals. The mean monthly weights of the pour-on animals was significantly higher, and at the end of the trial the pour-on animals had a mean weight gain of 136.70+/-16.7kg while the control animals had gained 97.16+/-22.6kg. The financial net return of using cypermethrin pour-on was positive and the financial rate of return of 122.6% indicated that use of the pour-on was highly beneficial despite the high cost of the product.

Disposition of diminazene aceturate (Berenil) in trypanosome-infected pregnant and lactating cows.

Three cows were repeatedly infected with different strains of Trypanosoma congolense and treated intramuscularly each time with a different dose of diminazene aceturate (Berenil). Biphasic decline was observed of the maximal plasma drug levels, which were attained at 15 min after the first treatment and at 30 min after the second and third treatments. The rate constants for the distribution and terminal phases depended on the period of exposure to parasitaemia of the animal at the time of treatment. Maximal diminazene aceturate residue levels were found in milk 8 h post treatment and declined biexponentially to 4.56 ng ml-1 and 8.76 ng ml-1 at 21 days post treatment after 3.5 mg kg-1 and 7.0 mg kg-1 doses, respectively. In the three cows, higher drug residues were found in the kidney (7.04, 3.92 and 7.99 micrograms g-1) than in liver (3.26, 2.87 and 1.24 micrograms g-1) and heart (1.79, 1.25 and 1.03 micrograms g-1). The results of this study indicate that the level of parasitaemia (degree of anaemia) in the animal at the time of treatment affects the distribution, disposition and elimination of diminazene aceturate in the animal. Furthermore, the residue level in milk after treatment depends on the treatment dose and could easily be bioavailable to the consumer.

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.