Retrospective Study of Kyasanur Forest Disease and Deaths among Nonhuman Primates, India, 1957–2020
Sulagna Chakraborty, William Sander, Brian F. Allan, Flávia Cristina Drumond Andrade
Abstract
K yasanur Forest disease (KFD) is a highly infec- tious tickborne disease affecting humans and monkeys. The etiologic agent of this disease is the Kyasanur Forest disease virus (KFDV), a fl avivirus. Since its discovery in 1957 in Karnataka State, India, KFD has expanded to 5 states along the western coastline in India (1) and 10,000 reported cases of KFD in humans, averaging 400-500 cases annually (2). After an incubation period of 3-8 days, primary clinical symptoms include fever, myalgia, and gastrointestinal and bleeding problems. In a small subset of patients, a second phase of the disease can include neurologic manifestations and fever. If the disease is detected early, symptomatic supportive care can improve recovery from the disease. Case-fatality rates range from 3% to 15% (1,3). The primary vectors of KFDV are Haemaphysalis spinigera and H. turturis ticks, which are endemic to southern India and transmit the virus to monkeys and humans (4). Larvae and nymphs of these ticks feed on monkeys when the monkeys are ground foraging, providing routes of infection and spread. In addition, KFDV can be transmitted transovarially in these ticks (Figure