Update on prevalence and distribution pattern of tick-borne diseases among humans in India: a review.

In the present scenario, tick-borne diseases (TBDs) are well known for their negative impacts on humans as well as animal health in India. The reason lies in their increased incidences due to global warming, environmental and ecological changes, and availability of suitable habitats. On a global basis, they are now considered a serious threat to human as well as livestock health. The major tick-borne diseases in India include Kyasanur forest disease (KFD), Crimean-congo hemorrhagic fever (CCHF), Lyme disease (LD), Q fever (also known as coxiellosis), and Rickettsial infections. In recent years, other tick-borne diseases such as Babesiosis, Ganjam virus (GANV), and Bhanja virus (BHAV) infections have also been reported in India. The purpose of this paper is to review the history and the current state of knowledge of tick-borne diseases in the country. The conclusion of this review is extending the requirement of greater efforts in research and government management for the diagnosis and treatment and as well as prevention of these diseases so that tick-borne disease burden should be minimizing in India.

Phylogeography of Kyasanur Forest Disease virus in India (1957-2017) reveals evolution and spread in the Western Ghats region.

The Kyasanur Forest Disease (KFD) has become a major public health problem in the State of Karnataka, India where the disease was first identified and in Tamil Nadu, Maharashtra, Kerala, and Goa covering the Western Ghats region of India. The incidence of positive cases and distribution of the Kyasanur Forest Disease virus (KFDV) in different geographical regions raises the need to understand the evolution and spatiotemporal transmission dynamics. Phylogeography analysis based on 48 whole genomes (46 from this study) and additionally 28 E-gene sequences of KFDV isolated from different regions spanning the period 1957-2017 was thus undertaken. The mean evolutionary rates based the E-gene was marginally higher than that based on the whole genomes. A subgroup of KFDV strains (2006-2017) differing from the early Karnataka strains (1957-1972) by ~2.76% in their whole genomes and representing spread to different geographical areas diverged around 1980. Dispersal from Karnataka to Goa and Maharashtra was indicated. Maharashtra represented a new source for transmission of KFDV since ~2013. Significant evidence of adaptive evolution at site 123 A/T located in the vicinity of the envelope protein dimer interface may have functional implications. The findings indicate the need to curtail the spread of KFDV by surveillance measures and improved vaccination strategies.

Epidemiology, Pathogenesis, and Control of a Tick-Borne Disease- Kyasanur Forest Disease: Current Status and Future Directions.

In South Asia, Haemaphysalis spinigera tick transmits Kyasanur Forest Disease Virus (KFDV), a flavivirus that causes severe hemorrhagic fever with neurological manifestations such as mental disturbances, severe headache, tremors, and vision deficits in infected human beings with a fatality rate of 3-10%. The disease was first reported in March 1957 from Kyasanur forest of Karnataka (India) from sick and dying monkeys. Since then, between 400 and 500 humans cases per year have been recorded; monkeys and small mammals are common hosts of this virus. KFDV can cause epizootics with high fatality in primates and is a level-4 virus according to the international biosafety rules. The density of tick vectors in a given year correlates with the incidence of human disease. The virus is a positive strand RNA virus and its genome was discovered to code for one polyprotein that is cleaved post-translationally into 3 structural proteins (Capsid protein, Envelope Glycoprotein M and Envelope Glycoprotein E) and 7 non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5). KFDV has a high degree of sequence homology with most members of the TBEV serocomplex. Alkhurma virus is a KFDV variant sharing a sequence similarity of 97%. KFDV is classified as a NIAID Category C priority pathogen due to its extreme pathogenicity and lack of US FDA approved vaccines and therapeutics; also, the infectious dose is currently unknown for KFD. In India, formalin-inactivated KFDV vaccine produced in chick embryo fibroblast is being used. Nevertheless, further efforts are required to enhance its long-term efficacy. KFDV remains an understudied virus and there remains a lack of insight into its pathogenesis; moreover, specific treatment to the disease is not available to date. Environmental and climatic factors involved in disseminating Kyasanur Forest Disease are required to be fully explored. There should be a mapping of endemic areas and cross-border veterinary surveillance needs to be developed in high-risk regions. The involvement of both animal and health sector is pivotal for circumscribing the spread of this disease to new areas.

Preliminary risk maps for transmission of kyasanur forest disease in Southern India.

Kyasanur forest disease is known to be transmitted across forested regions of Southern India. The disease appears to be hosted in wild mammals and transmitted by tick vectors although the diversity and identity of host and vector species remain unclear. The area across which risk exists of contracting the disease through transfer from the hosts or vectors, however, has never been mapped in detail, such that the area that surveillance, education, and investment in diagnostic facilities should cover remains unknown. This contribution uses known occurrences of the disease from the year 2000 till date to create and test a correlational ecological niche model that translates into preliminary transmission risk maps, which are summarized in terms of risk presented in each district in the region, as well as across peninsular India.

Kyasanur Forest Disease (KFD): Rare Disease of Zoonotic Origin.

Kyasanur forest disease (KFD) is a rare tick borne zoonotic disease that causes acute febrile hemorrhagic illness in humans and monkeys especially in southern part of India. The disease is caused by highly pathogenic KFD virus (KFDV) which belongs to member of the genus Flavivirus and family Flaviviridae. The disease is transmitted to monkeys and humans by infective tick Haemaphysalisspinigera. Seasonal outbreaks are expected to occur during the months of January to June. The aim of this paper is to briefly summarize the epidemiology, mode of transmission of KFD virus, clinical findings, diagnosis, treatment, control and prevention of the disease..

On the transmission pattern of Kyasanur Forest disease (KFD) in India.

Kyasanur Forest disease (KFD), a tick-borne viral hemorrhagic fever, is endemic in five districts of Karnataka state, India. Recent reports of the spread of disease to neighboring districts of the Western Ghats, namely Chamarajanagar district in Karnataka, Nilgiri district in Tamil Nadu, Wayanad and Malappuram districts in Kerala, and Pali village in Goa are a cause for concern. Besides vaccination of the affected population, establishing an event-based surveillance system for monkey deaths in the national parks, wildlife sanctuaries and reserve forests of the Western Ghats would help detect the disease early and thereby help implement appropriate control measures.

Recent ancestry of Kyasanur Forest disease virus.

Kyasanur Forest disease virus (KFDV) is enzootic to India and maintained in ticks, mammals, and birds. It causes severe febrile illness in humans and was first recognized in 1957 associated with a high number of deaths among monkeys in Kyasanur Forest. Genetic analysis of 48 viruses isolated in India during 1957-2006 showed low diversity (1.2%). Bayesian coalescence analysis of these sequences and those of KFDVs from Saudi Arabia and the People's Republic of China estimated that KFDVs have evolved at a mean rate of approximately 6.4 x 10(-4) substitutions/site/year, which is similar to rates estimated for mosquito-borne flaviviruses. KFDVs were estimated to have shared a common ancestor in approximately 1942, fifteen years before identification of the disease in India. These data are consistent with the view that KFD represented a newly emerged disease when first recognized. Recent common ancestry of KFDVs from India and Saudi Arabia, despite their large geographic separation, indicates long-range movement of virus, possibly by birds.

The epizootics of Kyasanur Forest disease in wild monkeys during 1964 to 1973.

In the Kyasanur Forest disease area two species of wild monkeys, Presbytis entellus and Macaca radiata, succumb to the natural infection with Kyasanur Forest disease (KFD) virus (family Flaviviridae). Between October 1964 and September 1973, 1046 monkeys (860 P. entellus and 186 M. radiata) died. Of these, KFD virus was isolated from 118 P. entellus and 13 M. radiata. Maximum mortality of monkeys was reported during December through May coinciding with the season of activity of immature stages of Haemaphysalis ticks, incriminated vectors of KFD. The epizootic showed an initial spread of the disease to the areas contiguous with the original focus of infection. This was followed by the recognition of epizootics and epidemics in three new foci, removed from the original focus, by the end of 1973. It was also observed that, in certain localities in the original focus, KFD virus activity persisted over several years.