Relapse infection after chemotherapy in dogs experimentally infected with Trypanosoma brucei brucei

Studies on relapsing Trypanosoma brucei brucei infections in dogs after Berenil treatment revealed that the first relapse occurred 13 to 64 days after chemotherapy and 36 to 79 days after inoculation. A second relapse infection was observed in two dogs 43 and 60 days after a second Berenil treatment. During the aparasitaemic period following chemotherapy in four dogs, successful transmission (as evidenced by subsequent parasitaemia) following the intraperitoneal inoculation of homogenate of brain from two of the dogs into recipient rats was obtained. Transmission with blood collected just before the animals were sacrificed was, however, negative. Hornogenates of other organs (liver, spleen, eyes, testes, kidneys, heart and lymph node) were also non-infective. One dog inoculated with relapsed trypanosomes and treated with Berenil soon after showing parasitaemia was completely cured of the infection. It was considered that the brain is the source of relapse in T b brucei infection after Berenil therapy and that the relapse was not due to drug resistance.