[Malaria study in the cyclone risk zone: entomological , diagnostic and therapeutic approach in the southeastern region of Madagascar].

Madagascar is a tropical island affected by many natural disasters. The eastern coastal zone--an area of perennial malaria transmission--is regularly exposed to cyclones. Few malaria studies have been done in this area of Madagascar, and none have examined the potential relationship between malaria and natural disasters. A mobile team spent six weeks in the fields doing three lines of research: an entomological study by catching mosquitoes and determining their species: a therapeutic study of chloroquine (CQ) and sulphadoxine-pyrimethamine (SP) according to a 14 days WHO protocol and also a study of physician's diagnostic ability. Physicians were asked to make a presumptive clinical diagnosis of all febrile patients, and these results were compared to those obtained from blood smear examinations. The entomological study found three major vectors species: Anopheles gambiae, An. funestus and An. mascarensis. The therapeutic study showed that SP was 100% effective (n = 13) and only one case of CQ treatment failure was recorded (1/15). Finally the diagnostic study demonstrated that presumptive diagnosis of malaria based on the only clinical signs leads to an over-estimation of malaria frequency. Over 68% (102/149) of febrile patients were diagnosed by physicians to have malaria while only 52 (34.9%) were proven positive. Of the 47 patients diagnosed clinically as malaria-negative, 12 (25.5%) turned out to be positive. Outbreaks of malaria during or after natural disasters in Madagascar can be successfully treated with either CQ or SP, but compliance may be better with SP since it requires only one dose. Perhaps equally important in the context of natural disasters is to have the capacity to make a definitive diagnosis, and the dipsticks should be made available.