Species distribution and ecological suitability analysis for potential tick vectors of Kyasanur forest disease in the Western Ghats of Kerala

Abstract

Kyasanur forest disease (KFD) is a tick-borne zoonotic viral disease with an estimated case fatality rate of 3% to 5% in humans. The KFD virus is transmitted to both humans and animals by infected ticks, primarily the Haemaphysalis species. Our study was undertaken following reports of five confirmed cases and three deaths due to KFD in Malappuram district of Kerala in 2014 to determine the diversity of Ixodidae ticks on vegetation and their possible infection with the KFD virus. Overall, 3502 hard ticks belonging to three genera and eight species were collected from two forest divisions. Haemaphysalis was the predominant tick species (92.72%). Tick positivity for the KFD virus was 4 (5.33%) of 75 pools of ticks tested. Kyasanur forest disease viral RNA was detected from the genera Haemaphysalis and Amblyomma. The KFD virus was detected in 2 of 35 pools (5.71%) of Haemaphysalis spinigera, 1 of 30 pools (3.33%) of Haemaphysalis turturis, and 1 of 3 pools (3.33%) of Amblyomma integrum from the south forest division. The ticks reached their peak density between December and February and then decreased from the end of May. The temperature in the area ranges from 28°C to 30°C, which is suitable for tick survival.