"Dr. Yong" explains the risk in Thailand despite no recorded cases of infection "Nipah virus" and points out that if it actually occurs, it will severely impact public health and the economy.
On 25 Jan 2026 GMT+7, Professor Dr. Yong Poovorawan, head of the Clinical Virology Specialty Center, Faculty of Medicine, Chulalongkorn University, posted a message titled "Nipah Virus Outbreak and the Risk in Thailand" stating that
Since the first outbreak of Nipah virus disease in 1998–1999, the largest outbreak occurred in Malaysia’s Perak state. It spread south to Singapore, with a total of 265 cases and over 108 deaths. Symptoms then included high fever and brain inflammation.
Initially, it was mistaken for Japanese encephalitis (JE). Even after mosquito control, the disease did not stop. Later, it was found to be linked to pigs, with the virus isolated from them. The disease was very severe, originating from fruit bats whose saliva contaminated fruit in pig pens, spreading from pig to pig and then to humans. The fatality rate was high but the outbreak did not reach Thailand.
Since 2002, sporadic outbreaks have been reported, mainly in South Asia, especially Bangladesh. These differ from the Malaysian cases as transmission is directly from bats to humans via fresh fruit or juice, especially fresh date palm sap. Symptoms shifted toward fever and severe pneumonia. The virus spreads directly from bats to humans, and human-to-human transmission occurs in small clusters, continuing up to recent outbreaks in India.
This disease can transmit between people, as well as from contact with infected pigs through secretions and blood. However, the chance of transmission is not as easy or widespread as with respiratory illnesses like influenza or COVID-19.
Risk in Thailand: Although no human Nipah virus cases have been reported in Thailand, the country has several important risk factors facilitating animal-to-human transmission. Nipah virus is found in fruit bats of the Pteropus genus, natural reservoirs widely distributed across Thailand, especially in communities, temples, and fruit orchards, increasing contamination risk through bat saliva or urine in the environment and food.
Thailand’s agricultural practices and consumption behaviors may increase spillover risk, such as fruit orchards near communities, consumption of fresh fruit or freshly pressed juices, and eating raw or partially cooked foods in some areas.
Additionally, Thailand has a large pig farming industry, which could act as an amplifying host if animal infections occur, similar to the past Malaysian outbreak. Clinically, Nipah patients often develop severe encephalitis or pneumonia, which may be misdiagnosed early as other infections. If a strain capable of human-to-human transmission emerges, it could spread within families or healthcare settings.
Therefore, although the current risk of disease occurrence is low, if it does occur it would have severe public health and economic impacts. Thailand should implement proactive surveillance and preparedness based on the One Health approach, continuously addressing human, animal, and environmental health.
Thanks to Facebook page Yong Poovorawan