Seasonal vector density and disease incidence patterns of malaria in an area of Zimbabwe.

Anopheline mosquitoes were studied in an area of Zimbabwe to correlate their population densities with seasonality in malaria incidence. Four trapping methods were employed for adult mosquitoes: pit traps, outdoor and indoor man-baited nets and a sheep-baited net. Anopheles funestus exhibited two population peaks during the year, one in March and the other in September/October. The following over-all proportions of the An. gambiae complex were recorded: An. gambiae Giles (2.5%), An. arabiensis Patton (14.3%) and An. guadriannulatus Theobald (83.2%). Peak populations were observed in March, with most An. gambiae and An. arabiensis preferring outdoor man-baited nets. Approximately equal preference for outdoor nets and pit traps was observed for An. guadriannulatus, which was the only species present throughout the year. The implications of these findings for malaria transmission, which showed a peak in April, and the suitability of the sampling methods employed are discussed.