Detection of asymptomatic malaria infection among the Afghani immigrant population in Iranshahr district of southeastern Iran.

Asymptomatic malaria infection is often associated with subpatent level of parasitaemia and normal clinical examination. Such infection becomes a greater cause for concern when involved in blood transfusion and vector transmission. This study was performed to monitor the situation of asymptomatic malaria among the Afghani immigrants and native residents in Iranshahr district, a malaria endemic area in southeastern Iran, by performing conventional light microscopy. Out of 446 samples collected from Afghani immigrant participants, seven (1.6%) thick blood smears were diagnosed as Plasmodium vivax. None of the individuals who tested positive had malaria symptoms and they did not remember having had any malaria signs during the past two years. Out of 496 samples collected from native resident participants, three (0.6%) thick blood smears were detected as P. vivax and Plasmodium falciparum with mild malaria symptoms. An asymptomatic Plasmodium-infected individual can be a source of malaria parasites for transmission of the agents.