Spurt in chikungunya cases highlights need to check vector population

Intense monsoon rains and hot weather have caused a surge in Aedes mosquito populations, leading to an increase in both dengue and chikungunya virus (CHIKV) transmission in the state. The state has witnessed a resurgence of CHIKV cases this year, with 105 confirmed and 62 probable cases reported as of August 4, primarily in Thiruvananthapuram.

Public health experts warn that the actual number of cases could be significantly higher, as many untested cases are not included in the state's surveillance list. The WHO issued an urgent global alert in July 2025, highlighting the risk of a repeat of the 2004-05 chikungunya epidemic, which originated in the French Reunion islands and had previously hit Kerala in 2006-07.

While the threat level has since been downgraded to "moderate," the WHO warns that localised outbreaks can strain health systems, particularly in vulnerable groups like pregnant women, newborns, and those with preexisting health conditions. Experts attribute the resurgence to favorable monsoon conditions that promote Aedes mosquito breeding and efficient virus transmission.

The virus, while not typically fatal, can cause severe joint inflammation, pain, and long-term disability. The 2007 chikungunya epidemic left hundreds of thousands of people in Kerala with debilitating long-term morbidities, resulting in significant economic losses and productivity losses. CHIKV is highly immunogenic, providing lasting immunity to previously infected individuals, but the constant population turnover means a new generation is now vulnerable, as the last major outbreak was nearly two decades ago.