Highly infectious tick-borne viral diseases: Kyasanur forest disease and Crimean–Congo haemorrhagic fever in India.

ABSTRACT

Ticks are distributed worldwide and can harbour and transmit a range of pathogenic microorganisms that affect livestock and humans. Most tick-borne diseases are caused by tick-borne viruses. Two major tick-borne virus zoonotic diseases, Kyasanur forest disease (KFD) and Crimean–Congo haemorrhagic fever (CCHF), are notifiable in India and are associated with high mortality rates. KFD virus was first identified in 1957 in Karnataka state; the tick Haemaphysalis spinigera is the main vector. During 2012–2013, cases were reported from previously unaffected areas in Karnataka, and newer areas of Kerala and Tamil Nadu states. These reports may be the result of improved active surveillance or may reflect altered virus transmission because of environmental change. CCHF is distributed in Asia, Africa and some part of Europe; Hyalomma spp. ticks are the main vectors. The existence of CCHF in India was first confirmed in 2011 in Gujarat state. In 2013, a non-nosocomial CCHF outbreak in Amreli district, as well as positive tick, animal and human samples in various areas of Gujarat state, suggested that the virus is widespread in Gujarat state, India. The emergence of KFD and CCHF in various Indian states emphasizes the need for nationwide surveillance among animals and humans. There is a need for improved diagnostic facilities, more containment laboratories, better public awareness, and implementation of thorough tick control in affected areas during epidemics.