Relation of artesunate-mefloquine combination resistance by uncomplicated Plasmodium falciparum and parasitemic on day 3 along Thai-Burma border.

Abstract

Plasmodium falciparum malaria develops rapid resistance to antimalarial drugs. Ten sentinel sites have been set for the antimalarial in vivo monitoring in Thailand since 1980 The antimalarial in vivo monitoring methodology was performed according to the standard protocol recommended by the World Health Organization. Every year, 6-7 sentinel sites were selected for the studies of the efficacy of antimalarials. Unfortunately, the data were not sufficient to draw any solid conclusion. Previous study showed that parasitemia on day 3 can be used as a proxy measurement of P. falciparum resistance to artemisinin derivatives.

In this study, focus will be placed on the relationship between parasitemia on day 3 and 3-day treatment course using artesunate-mefloquine with respect to resistance in falciparum during 2008-2011. Mae Hong Son, Tak, Kanchanaburi Ratchaburi and Ranong were designated as sites for the collection of data from patients. The patients who came in this project were followed 10 times (Day 0, 1, 2, 3, 7, 14, 21, 28, 35 and 42) Blood samples were collected on sides and as dried blood spot on filter papers. They were used for monitoring the treatment and observed for the relationship between drug resistance and parasitemia on day 3 of infection.

Five hundred and fifty-one patients were enrolled for the study. Sixty-four cases were found to have positive blood smear on day 3, thirty-eight of which had recrudescence during day 7 and 42 while 18 had positive parasitemia on day 3. The relationship between drug resistance situation and parasitemia on day 3 in each provinces was then evaluated and the results showed that the number of case with parasitemia on day 3 increase with the number of recrudescence cases. The parasite density in the blood on the first day is not a sight factor that can induce recrudescence case or case with parasite on day 3.