India's Deadly Chandipura Virus Outbreak is Largest in 20 Years

The World Health Organization (WHO) recently confirmed that India's Chandipura virus (CHPV) has become endemic and is a substantive health risk to residents and visitors. 

Between early June and August 15, 2024, the Ministry of Health and Family Welfare of the Government of India reported 245 cases of acute encephalitis syndrome (AES), including 82 deaths and a case-fatality ratio (CFR) of 33%.

Of these, 64 are confirmed cases of CHPV, and 61 have been reported from Gujarat, India.

To date, no human-to-human transmission has been reported, and there is no evidence that CHPV has been detected among those traveling from India to other countries.

Previous CHPV outbreaks have occurred regularly, but the current outbreak is the largest in the past twenty years. Historically, the CFR from CHPV infection is high (56-75%), as no specific treatment exists.

CHPV is a member of the Rhabdoviridae family and is known to cause sporadic cases and outbreaks of AES in the western, central, and southern parts of India, especially during the monsoon season. It is transmitted by vectors such as sandflies, mosquitoes, and ticks.

CHPV has not been detected in other countries but may be present in Asia, as sandfly vectors are abundant in the Southeast Asia Region.

In India, although previous encephalitis outbreaks have been associated with the Japanese encephalitis virus, several outbreaks have remained undiagnosed. 

As of August 29, 2024, the WHO assessed the risk as moderate at the national level based on the above considerations. The risk assessment will be reviewed as the outbreak situation evolves.

The WHO wrote on August 23, 2024, 'Although authorities are working to control CHPV transmission, further virus transmission is possible in the coming weeks, as the monsoon season is creating favorable conditions for vector populations in the affected areas. WHO recommends vector control and protection against bites of sandflies, mosquitos, and ticks to prevent further spread of CHPV.'

As of late August 2024, there are no CHPV vaccines available.