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Medical experts stress that while antibodies against Nipah were previously detected in some bat populations in Vietnam, the country currently remains at low risk of an outbreak, and the data should not be misinterpreted as evidence of active transmission.

Associate Professor Dr. Do Van Dung, former head of the Department of Public Health at the University of Medicine and Pharmacy at Ho Chi Minh City, on Jan. 28 warned that misunderstanding scientific findings could fuel unnecessary panic.

He noted that studies conducted around 2012 in provinces such as Dak Lak in the Central Highlands and Hoa Binh in the north found antibodies against the Nipah virus in certain bat species through ELISA testing.

Antibodies, he explained, are immune markers left behind after past exposure to a virus. A positive antibody result does not mean bats are currently carrying live, infectious Nipah virus. Instead, it suggests they were exposed in the past and recovered, similar to how humans retain immune “scars” after an infection. This is fundamentally different from detecting active virus, which is required for transmission to humans.

Health experts cite three key reasons why a Nipah outbreak in Vietnam is unlikely at present.

First, Vietnam has not detected Nipah virus in large fruit bats, which are considered the main reservoir linked to severe outbreaks in Malaysia and Bangladesh. The antibodies found earlier were limited to smaller bat species.

Second, more than a decade of epidemiological surveillance in areas where bats carried antibodies has not recorded any human cases of Nipah- encephalitis. This mirrors assessments in Thailand, where the virus has been detected at low levels but without widespread transmission, unlike high-prevalence outbreak zones in India.

Third, Nipah is far less transmissible than Covid-19. With a reproduction number below one, the virus does not spread easily. Infection typically occurs through direct contact with bodily fluids of infected bats or pigs, consumption of contaminated food, or close contact with infected patients, particularly during caregiving.

Despite the low risk, Vietnam’s Ministry of Health on Jan. 28 issued an urgent directive to medical facilities nationwide, ordering heightened preparedness and prevention measures. Authorities emphasized early detection and immediate isolation of suspected cases as the most effective way to prevent community spread.

Hospitals have been instructed to prepare isolation areas, essential medicines and emergency equipment, while healthcare workers are required to strictly follow infection control protocols and strengthen personal protective measures.

Border surveillance has also been raised to a high alert level. Health agencies and epidemiological institutes are closely monitoring incoming travelers for symptoms such as fever, headache, acute encephalitis and altered consciousness. The incubation period typically ranges from four to 14 days.

In neighboring Thailand, officials have assessed domestic outbreak risks as low, with the primary threat coming from imported cases. Measures there include tighter screening at major airports and restrictions on pig farming near bat habitats to cut off potential transmission routes.

Although Nipah is unlikely to trigger a global pandemic due to its limited transmissibility, it remains one of the world’s most dangerous infectious diseases, with fatality rates ranging from 40% to 75%. Doctors warn that early symptoms, including fever, headache, muscle pain, vomiting and sore throat, can closely resemble seasonal flu or dengue fever, making early diagnosis challenging.

Patients are urged to seek immediate medical care if neurological symptoms appear, such as confusion, drowsiness, seizures, slurred speech or rapidly worsening consciousness. There is currently no specific treatment or commercially available vaccine, and care relies on intensive supportive treatment and respiratory support.

To reduce infection risk, health authorities advise the public to follow strict food safety practices, thoroughly wash and peel fruit, avoid eating fruit that shows signs of being bitten by animals, and refrain from consuming raw palm sap or other untreated tree sap products.