Factors affecting the human-feeding behavior of anopheline mosquitoes in Egyptian oases.

Blood meals were tested by a direct enzyme-linked immunosorbent assay (ELISA) for 424 Anopheles sergentii and for 63 An. multicolor collected in Siwa, Farafra and Bahariya oases in the Western Desert of Egypt. Both species were highly zoophilic. Human blood-feeding by An. sergentii was less common in Bahariya (2.3%) and Farafra (1.3%) than in Siwa (15.3%). A likely explanation is that large domestic animals are held at night inside houses in Bahariya and in Farafra whereas in Siwa, animals are usually housed outdoors in sheds. These patterns of An. sergentii human-feeding behavior may contribute to the persistence of low-level Plasmodium vivax transmission in Siwa in contrast to negligible or no transmission in Bahariya and Farafra.