Outbreak Investigation of Kyasanur Forest Disease in North Goa district, Goa, India 2023

Kyasanur forest disease (KFD) is a tick borne zoonotic viral infection endemic to southern India. Despite preventive strategies, including vaccination, an outbreak occurred in March 2023 in Caranzol village, Sattari sub district, North Goa.

This study aimed to describe the outbreak by time, place, and person and to explore contributing factors.

An unmatched case-control study (1:4 ratio) was conducted from February to April 2023 after a village wide active case search among 484 residents. Presumptive and confirmed cases were identified using RT PCR/immunoglobulin M enzyme linked immunosorbent assay. Data on demographics, exposure history, and preventive practices were collected through structured interviews. Attack rates were calculated, and risk factors were assessed through logistic regression. Tick surveillance and verification of monkey mortality were also undertaken.

Thirteen presumptive cases were identified; five were laboratory confirmed. The epidemic curve showed onset in early March with decline by the 5th week. The attack rate was 3.1%, highest among females (4.6%) and those aged 45-59 years (5.1%). Common symptoms included fever, weakness, myalgia, and headache. Forest visits without protective clothing, lack of repellent use, and poor postexposure hygiene were significantly associated with illness. Six cases reported prior vaccination, received 5 years earlier. Tick pools tested negative for KFD virus, and no monkey deaths were recorded.

The outbreak underscores the need for strengthened surveillance, public awareness, and intersectoral collaboration between health, animal husbandry, and forest departments. Emphasis on personal protective measures and reassessment of KFD vaccine efficacy and booster requirements is recommended.