Epidemiology of Plasmodium and Helminth Coinfection and Possible Reasons for Heterogeneity

Understanding the impact of helminth infections on clinical malaria is useful for designing effective malaria control strategies. Plenty of epidemiological studies have been conducted to unravel the nature of interactions between Plasmodium and helminth infection. Careful broad summarization of the existing literature suggests that Schistosoma mansoni and hookworm infections may increase the risk of clinical malaria and associated morbidities, but Trichuris trichiura infection is not associated with the occurrence of clinical malaria and related outcomes. However, findings about effect of Ascaris lumbricoides and Schistosoma haematobium infection on clinical malaria are contradictory. Furthermore, the nature of relationship of helminth infection with severe malaria has also not been determined with certainty. This review summarizes the findings of epidemiological studies of Plasmodium and helminth coinfection, placing greater emphasis on the impact of the coinfection on malaria. Possible reasons for the heterogeneity of the findings on malaria and helminth coinfections are also discussed.