Lack of association between falciparum malaria parasitemia and acute diarrhea in Nigerian children

It is widely believed that malaria causes diarrhea. Yet, national and international diarrheal diseases control programs are silent about the overlap between these two major public health problems that coexist in most tropical countries. To test the hypothesis that malaria is associated with diarrhea and to define the role of malaria in morbidity due to diarrhea, 522 children 6-60 months of age presenting with acute diarrhea to the Children's Emergency Ward of the University College Hospital in Ibadan, Nigeria were routinely screened by means of thin and thick blood films for malaria parasitemia. Controls, without diarrhea, were studied in parallel. Detailed clinical features were recorded for every patient. Sixty-eight (13%) of the 522 diarrhea patients screened had malaria parasitemia. Among the controls (who had similar distributions of admission temperature, hemoglobin types, glucose-6-phosphate dehydrogenase deficiency, and prior treatment with antimalarial drugs), parasitemia was not significantly different, occurring in 56 (17.9%) of 313. In the dry season, however, a significantly higher prevalence of parasitemia was observed among the control group (15.5%) than in the diarrhea group (7.0%) (P = 0.004). Parasitemia was significantly more common in the dehydrated diarrhea patients than their well-hydrated counterparts (25% of 56 versus 11% of 466; P < 0.005). There were no significant differences in admission temperature, the presence of vomiting, or the home use of oral rehydration fluids between the dehydrated and the well-hydrated subsets of diarrhea patients. Consideration of parasite densities did not alter any of the foregoing relationships. These data contradict the widely held view that diarrhea is a symptom of malaria or that malaria causes diarrhea. They do, however, provide support for examining blood smears at least in dehydrated children with diarrhea in malaria-endemic areas and giving immediate antimalarial therapy to those who have malaria parasitemia.