The molecular epidemiology of Plasmodium falciparum infection in Malian children: A cohort study
Description
This study examines the molecular epidemiology of Plasmodium falciparum parasite infection in Malian children living in a village where malaria transmission is endemic. Previous epidemiological studies of malaria typically focused on symptomatic infection or clinical cases of malaria with a diagnoses confirmed by slide smears without a capacity to examine simultaneous infection with multiple parasites of the same species. Multiple malaria infections in the same individuals were detected by using molecular markers that target the genetic diversity in Plasmodium falciparum by examining three merozoite surface protein-1 (MSP-1) variants genetically characterized as the K1, MAD20, and R033 allotypes. Detecting these allotypes using PCR provided results that were used to calculate the molecular-based frequency of simultaneous infection with multiple malaria parasites. We report estimates of malaria parasite infection and clearance observed in a fixed cohort of 80 children aged 0--9 years from September 1995 to August 1996. Our findings are as follows; (1) infection rates exceed estimates based upon slide smears, (2) infection clearance and re-infection is common, and (3) seasonal shifts occur in allotype-specific rates of infection. Our data also suggest that competition may take place between two of the allotypes. We have concluded that the infection dynamics of malaria parasites in endemic regions merits more attention especially in the context of infection dynamics the potential role it may have for risk to disease The broader conclusions concerning this study are three-fold. First, we believe examining multiple infections with malaria parasite in humans is an important step toward understanding both immunity and susceptibility to malaria parasite infection and provides a way to examine the risk for disease. Second, results reported here validate the usefulness for using a molecular approach for examining the epidemiology of malaria parasite infection in humans. Finally, we suggest that our findings demonstrate that combining classical measurement strategies with molecular methods provides researchers with robust methods for conducting future epidemiological studies of malaria infection and that these methods can be applied to the study of other parasites and infectious pathogens