The Japanese encephalitis (JE) virus results in between 30,000 to 50,000 reported cases a year in South and Southeast Asia. Generally, the virus presents mild symptoms in people, but children are especially vulnerable. Acute cases are often fatal as the disease can cause swelling of the brain, tremors, convulsions, and coma. The number of acute cases in the region has been on the rise in the last 20 years, putting more than 3 billion people living in areas of high infection at risk. The rise in infections has been partially attributed to the expansion in rice farming, changes in climate and land use, and an increase in the number of pig farms.
IDRC-funded researchers in India and Nepal are studying the transmission dynamics of the JE virus in an effort to slow the spread of the disease. Teams are working closely with community members and health officials to promote sustainable solutions.
Transmission and risks
The disease is transmitted by mosquitoes; domestic pigs and wading birds act as reservoirs. Because there is no known treatment for the disease, vaccination is the best way to prevent and control the spread of the virus. However, vaccines are not consistently available in the region and populations most at risk have little knowledge about how to prevent infection and few resources for supportive care if infection occurs.
Social exclusion key factor in disease transmission
As the attraction of pig farming as an increasingly profitable business grows, so do the risks of contracting and spreading the JE virus. In India and Nepal, pig farming is typically carried out by socially marginalized members of the community; these farmers tend to have little or no education and have a limited understanding of the disease. They cannot afford to invest in land or healthcare services.
In India, the research team is focusing on the animal-vector-human interactions that spread the disease. The team has collected data from 12 villages in Uttar Pradesh state, the site of 60-90% of India's acute JE cases. Some of these villages are home to pig farmers but others are not. The researchers found that the rate of human infection in both the pig-owning and non-pig-owning villages was similar, raising questions about the belief that the pig-vector-human transmission cycle is the most common means of infection.
In Nepal, the researchers found that pig farmers generally have little education and do not own land. Their lack of knowledge about how to prevent disease in their livestock extends beyond JE. For example, many pigs are also infected with a pork tapeworm that can also be fatal to humans and is spread by eating poorly cooked pork. However, many farmers don’t know that the cysts caused by the tapeworm are a sign of infection and mistake them for “grains of rice, caught in the pigs’ throats.”