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Background Little data on malaria morbidity among African adults exposed since birth to intense malaria transmission are available. This study aimed to investigate malaria morbidity determinants among adults living in Dielmo village, Senegal, where a longitudinal epidemiological study was carried out over an 18-year period before the introduction of insecticide treated nets. Methods Between July 1990 and June 2008, a longitudinal study was carried out in Dielmo, a Senegalese village, among adults aged at least 15 years to evaluate determinants of P. falciparum clinical malaria attacks. Malaria diagnosis was confirmed by thick blood smear. Data were analyzed using a random-effect negative binomial regression. Results Of a total of 12,253 person-trimester observations, 768 P. falciparum uncomplicated clinical malaria attacks, and a series of biological and epidemiological parameters were analyzed. To be aged 30 years or more, combination therapy treatment period, and being born in the village of Dielmo were significantly associated with a lower risk of clinical malaria; while the third trimester of the year (rainy season) and pregnancy were significantly associated with an increased risk of clinical malaria. None of the biological parameters investigated were associated with the occurrence of malaria attacks. Conclusion This study provides longitudinal data on malaria among adults exposed to intense perennial transmission. It shows that the incidence of the disease among adults decreased first rapidly then progressively with age during the different treatment policies periods, with pregnancy as only individual major factor of increased risk of clinical malaria among those investigated in our study.

Keywords: malaria, adults, pregnancy, Dielmo, Senegal