First detection of avian malaria parasite DNA from mosquitoes collected in Nagasaki City, Japan

Avian malaria parasites mainly circulate between mosquitoes and birds, sometimes threatening captive naïve birds in zoos and aquariums. In Japan, research on avian malaria has been conducted in limited areas and is insufficient to understand the situation of avian malaria transmission in the country. In this study, we collected mosquitoes using traps and sweeping at the Sakamoto Campus of Nagasaki University and the Nagasaki Penguin Aquarium in Nagasaki Prefecture, Japan. We detected Plasmodium parasites based on dissection and the nested PCR. Of the 1392 females collected, 208 were dissected, and the remaining were pooled into 488 pools for PCR analysis. Five positive samples were obtained using nested PCR, and all of which were Lutzia vorax collected using gravid traps at the Sakamoto Campus only. All obtained DNA sequences were identical to Plasmodium spp. CXPIP12 genetic lineage, which has been reported in a wide range in Japan. Furthermore, the composition of the collected mosquitoes differed among the traps. Compared to the dry ice trap, the gravid trap was more effective in collecting Culex pipiens pallens, Cx. qunquefasciatus and Lt. vorax. Our results suggest that the aquarium may not be at a high risk of avian malaria transmission at study period. However, it must be monitored for the infection continuously, as fed mosquitoes were collected near the penguins and the malaria strain was obtained in the city. Continuous surveys using appropriate methods are required to understand avian malaria transmission in this area.