Evaluation of the efficacy of a slow release device containing homidium bromide in rabbits infected with Trypanosoma congolense

The subcutaneous implantation of a slow release device (SRD) containing 1 mg kg−1 homidium bromide (Ethidium) protected 95% of the rabbits for at least 3 months against reinfection with different stocks of Trypanosoma congolense. Only 30.8% of the animals, which received the classical intramuscular injection of 1 mg kg−1 homidium bromide, were protected for more than 1 month. The advantages of an SRD against injection of homidium bromide are a longer protection period, less variation in the percentage of protected animals and the possibility to recover the implants at slaughter. The possible effects on the development of resistance have to be examined further.