Efficacy of a high dose of isometamidium chloride treatment in single and mixed experimental infections with T. congolense and T. brucei brucei in dogs

Canine African trypanosomosis is endemic in sub-Saharan Africa. Chemotherapy remains the commonly employed approach to trypanosomosis control. However, it is beleaguered by the absence of new drugs, treatment failures, relapse infection and resistance. The efficacy of a high dose of isometamidium chloride (ISM) in single and mixed infections of T. congolense and T. brucei brucei therapy was assessed in dogs. Fifteen dogs employed in this study were allocated into four groups at random, each with four dogs except group I which had three dogs. Group I dogs were not infected while groups II and III dogs received 10⁶ T. congolense and T. brucei brucei respectively. Group IV dogs received both (5 × 10⁵) T. congolense and T. brucei brucei. Groups II-IV dogs were dosed with 1 mg/kg ISM (Trypamidium-Samorin®) intraperitoneally on day 14 post-infection (PI). Parasitaemia levels, live body weight changes (LBWC), clinical signs, rectal temperature (RT), some haematological and serum biochemical parameters were used to evaluate the efficacy of high dose of ISM. Following infection, all the infected dogs became parasitaemic by the 14th day PI, with obvious clinical signs. Treatment with ISM cleared parasitaemia within 72 hours post-treatment, caused the reversal of the clinical signs, and enhanced the RT, LBWC, haematological and serum biochemical parameters of the dogs. Relapse infection was not recorded throughout the study duration (84 days post-infection). In conclusion, 1 mg/kg of ISM is effective in treating African trypanosomosis in dogs and should be adopted as a first-line treatment for the disease.