Arguments against Chemoprophylaxis in Areas at Low Risk for Chloroquine-Resistant Plasmodium falciparum

The role of imported cases in the epidemiology of urban Plasmodium falciparum malaria in Quibdó, Colombia

OBJECTIVE

To assess the role of imported cases in the local epidemiology of malaria and population genetics of Plasmodium falciparum in an urban endemic area in Colombia.

METHOD

A total of 679 P. falciparum cases presenting in the city were interviewed, mapped, and genotyped using msp1 and msp2 molecular markers.

RESULTS

Among the cases, 75% were classified as imported and harboured single-clone infections. The P. falciparum parasite population had low genetic diversity with a preponderant haplotype (mean genetic diversity H = 0.36), even when microsatellite markers were used (H = 0.49), partly because of the small scale at which population movement was studied. Nevertheless, indigenous and potentially introduced cases were identified.

CONCLUSION

Migration is a confounder in planning malaria control in this endemic urban area. Longitudinal studies which monitor the P. falciparum population in imported and autochthonous cases at larger spatial scales would be necessary to study the effect of population movement on malaria transmission and, with suitable molecular markers, on the spread of drug resistance.

The prevention of malaria

Long before the advent of modern chemoprophylaxis drugs, many practitioners successfully prevented the debilitating and fatal outcomes associated with infection by the Plasmodium parasites that cause malaria. Today, with effective insect repellents and several excellent medications available for chemoprophylaxis, there has never been a better array of quality products to prevent mosquito bites and infection and to suppress parasites once in the blood stream; however, there are thousands of imported cases into nonendemic countries and scores of deaths and near-fatal outcomes every year in returning travelers, soldiers, immigrants, and refugees. In this article, the author focuses on practical uses of currently available prevention tools.