Mefloquine resistant malaria in Cameroon and correlation with resistance to quinine.

Based on the results of in vitro sensitivity of Plasmodium falciparum to chloroquine, quinine and mefloquine, and evaluation of drug consumption conducted in 1987-1988 in four areas in the north and south-west of Cameroon, two opposite situations were encountered in this country. In northern Cameroon where mefloquine resistance is prevalent a close correlation was found between the responses of P. falciparum to mefloquine and to quinine, but not between mefloquine and chloroquine. In the south, where chloroquine resistance is highly prevalent, no correlation was found neither between mefloquine and chloroquine nor mefloquine and quinine, but the responses to quinine and chloroquine appear partly correlated. These results lead to formulate the hypothesis of a "southern" type of P. falciparum submitted to a high chloroquine drug pressure inducing a secondary cross resistance, whilst a "northern" type submitted to a relatively high and abortive quinine drug pressure inducing a primary quinine resistance and a secondary cross resistance with mefloquine.