EPIDEMIOLOGY OF ARBOVIRAL DISEASES - METH OD AND APPLICATIONS OF DETERMINATION OF PHYSIOLOGICAL AGE OF MOSQUITO VECTORS

The physiological age of Yellow Fever Aedes females in Africa was stud ied during four years, from 1988 to 1992. We used a method, according to Polovodova's method, which looks for the <<yellow body>> under natu ral light. Those yellow bodies exist in the old females, the <<parous> > ones, and not in the young females, the <<nulliparous>> ones. We pre sent some results to illustrate the interest of studying the physiolog ical age of mosquitoes in the epidemiology of the arboviral diseases. The transmission risk, in relation with abundance and parity rate was illustrated in particular for Aedes africanus and Aedes luteocephalus, which is useful to compare species, or with a given species, to compa re periods. The parity rate of Aedes furcifer females was studied on 6 points along a transect between a forest and a village. The rate and the abundance of the females caught on human bates ave inversely propo rtional. The parity rate is minimum in the canopy forest (about 50 %) and maximum inside a house (100 %). The rains have different consequen ces on the species, according to the period of fall. At the beginning of the dry season they bring about hatching, but not as the end of the dry season. Massive hatching will occur just at the beginning of the rainy season, some weeks later. Studying the physiological age of Ae. africanus females, the number of nulliparous is not related to the vai n. That means a possibility of <<natural>> hatching for part of the eg gs. Among the female of the dry season, young females are found which is important for the transmission capacity. The method, described here in, to determine the physiological age is perfectly applicable to the Yellow Fever vector Haemagogus janthinomys in Southern America. But fo r the Dengue vectors Aedes aegypti and probably Aedes albopictus, the Detinova's method seems better. Actually, it seems important to study the physiological age of the vectors Ae. aegypti and Ae. albopictus, a s well as the evolution of the physiological age in space and time, in order to better know the epidemiology of dengue dengue in Southern Am erica.