The appearance of pyrimethamine resistance in Plasmodium falciparum following self-medication by a rural community in Ghana.

During the preparatory phase of the Malaria Eradication Pilot Project in Ghana, a weekly pyrimethamine regimen was instituted at two hyperendemic villages, primarily to assess the reliability of self-administration techniques under local conditions.After initial supervised individual administrations, weekly distribution of family drug requirements was made to a responsible member of each household by volunteer community leaders.Although parasite rates fell from 71% to 6.5% after four weeks, recurrence of Plasmodium falciparum parasitaemia was observed by the 37th week. Resistance in that species was confirmed, associated with successful sporogony in Anopheles gambiae, after supervised pyrimethamine treatment equivalent to twice the routine dosage.Emergence of this high-grade drug resistance was attributable to irregular self-administration by the local population of the tablets collected for each household. It was therefore concluded that under the conditions obtaining, self-medication was not a reliable method for mass distribution of pyrimethamine.