A surge in Japanese encephalitis cases in Assam

According to the health minister of Assam, the death toll from an outbreak of Japanese encephalitis in Assam has tripled in the last 2 weeks (to July 6, 2026). The outbreak started in mid-June.

Deaths have been reported in the districts of Kamrup, Barpeta, Jorhat and Lakhimpur. A similar outbreak was reported in 2025.

Ten districts of Assam are identified as priority areas for Japanese encephalitis surveillance. These include Barpeta, Lakhimpur, Dhemaji, Sibsagar, Dibrugarh, Sonitpur, Golaghat, Tinsukia, Jorhat and Udalgiri.

These areas are prone to outbreaks and offer ideal conditions for transmission during the wetter months of the year. Sporadic outbreaks have been identified in the region for over 50 years.

A pattern repeating from 2025

This is the second consecutive year Assam has reported a cluster of Japanese encephalitis deaths during the wet season. In July 2025 we reported on Japanese encephalitis deaths in Assam, where a total of 14 deaths had been notified across districts including Kamrup, Nalbari, Darrang, Golaghat and Nagaon.

Kamrup features in both years. Golaghat, named in the 2025 outbreak, is also one of the ten priority surveillance districts listed above. The timing is consistent as well, with both clusters emerging through the wetter months rather than as isolated events.

For travellers, the value of this repetition is not the individual case numbers, which change week to week, but what it confirms about the region. Assam is not experiencing an unusual one off event. It is an area where the conditions for transmission are present every wet season, and where the risk is best understood as seasonal and geographic rather than as a passing outbreak.

Agriculture, pigs and mosquitoes

Assam is very dependent on agriculture for economic activity. Rice is the main crop. It is also home to the largest population of pigs. Almost 18% of the country's total population of pigs is in Assam.

Water, pigs and mosquitoes is a good recipe for endemic Japanese encephalitis. In a study of pig positivity for JE antibodies in 2018, almost 23% were found to be positive. In this study, the risk of disease was highest from June to September. The virus doesn't cause any disease among its natural host.

A comprehensive document on a program aimed at the prevention and control of Japanese encephalitis can be found in the National Programme for Prevention and Control of JE/AES (PDF), administered by India's National Center for Vector Borne Diseases Control. It sets out how surveillance, mosquito control, case management and vaccination are delivered in affected districts.

The guidelines provide an epidemiological analysis for the years 2008 to 2015. Observations include:

• Most vulnerable age group 1-5 years followed by the 5-10 years cohort
• Least infections in infants (< 12 months)
• All the endemic States except Assam start reporting cases from July onwards, peaking in September-October
• In Assam cases start appearing from early February and attain a peak in July

The program has several objectives, including the strengthening and expansion of vaccination in high-risk districts. Japanese encephalitis vaccination is now included in the national immunisation program for children.

About Japanese encephalitis

Japanese encephalitis is a viral disease transmitted by mosquitoes from wild birds and pigs to humans. It is the leading cause of vaccine preventable encephalitis in Asia.

Japanese encephalitis is a health concern in 24 countries in Southeast Asia and the Western Pacific region. More than 3 billion people live in endemic areas.

Environmental determinants of Japanese encephalitis include climate, rainfall, temperature, water bodies and proximity to irrigation and pig farming. It is most prevalent in rural areas.

In temperate regions of Asia, transmission is seasonal, with peak cases of infection in the summer and autumn months. In the tropics and subtropics, transmission can occur year-round, peaking during the wet season.

For more information on the disease, see Japanese encephalitis.

Japanese encephalitis risk to travellers

For most travellers to Asia and parts of the Western Pacific, the risk of Japanese encephalitis is low, particularly for short term visitors to urban areas. This risk is estimated to be less than 1 in a million per month of stay but will change according to season, destination, duration of travel and intended activities. The standard of accommodation is important when assessing risk.

JE Vaccination is available to those considered more at risk. These would include expatriate workers (cumulative risk), long term backpackers and travellers off the beaten path.

Two vaccines are available in Australia. (Imojev, JEspect). Imojev is a live vaccine, and care must be taken in prescribing it. JEspect is inactivated.

Travellers heading to rural or agricultural parts of India during the wet season can weigh their itinerary and vaccination needs in a virtual travel consultation before departure.