Evaluation of mefloquine-praziquantel combination therapy in pre- patent and patent Schistosoma mansoni infection in mice

The reliance on a single drug to treat a population of over 200 million people infected and over 700 million people at risk over three continents seems particularly perilous when considering the threat of drug resistance. An important shortcoming of praziquantel is its relative inactivity against migratory juvenile and subadult worms. Antischistosomal properties of the antimalarial drug, mefloquine were previously noticed and it was found potent against the young developing stages of the parasite. Moreover, the difference in the mechanism of action between the two drugs was encouraging to assess the antischistosomal effect of their combined curative doses (400 mg/kg mefloquine and 500 mg/kg praziquantel) or half-curative doses (200 mg/kg mefloquine and 250 mg/kg praziquantel) in both pre-patent and patent schistosome infections. Therapeutic efficacies of the drugs were assessed using the worm count technique, ova count technique in intestine and liver, oogram pattern, liver function tests and histopatholoical examination of liver sections. With the exception of mild additive reduction of ova count in the liver, mefloquine monotherapy was as potent as the combined full dose regimen. The combined treatment was much potent than praziquantel monotherapy even in its low dose regimen.