Soil-transmitted helminths and Plasmodium falciparum malaria: epidemiology, clinical manifestations, and the role of nitric oxide in malaria and geohelminth co-infection. Do worms have a protective role in P. falciparum infection?

Malaria and intestinal helminths are sources of significant morbidity worldwide. Given the nature of shared endemicity, these diseases often co-exist in the same populations. Therefore, much attention is now being given to the interaction between helminths and Plasmodium in the situation of co-infection. Existing evidence is consistent with the hypothesis that helminths are associated with continued and possibly increased incidence of malaria infection. However, data from some recent clinical fieldwork suggest protection from cerebral malaria in the setting of helminth co-infection. Nitric oxide, coupled with the immunoglobulin E (IgE) receptor, CD23, appears to be a crucial factor in preventing the development of cerebral malaria, thus improving chances for the survival of both host and parasite. In this work, we review literature on the subject of helminth and malaria co-infection, and offer a theoretical explanation of the helminth modulation of clinical malaria. In doing so, we advocate further research on this subject and also the need for a dual approach in global disease control intervention, which simultaneously targets both malaria and geohelminth infection.