Wildlife farming is common in Vietnam, where people breed and trade wild animals for pets, food, and traditional medicine.
By 2021, the country had around 6,744 wildlife farms housing 1.8 million animals across 371 species.
Although these farms support many families, they also bring people into close contact with wild animals. This creates opportunities for zoonotic diseases to spill over into humans.
A recent outbreak highlights the potential danger. The Andes hantavirus, which spreads between people, infected 13 cruise ship passengers on the MV Hondius and killed three.
Investigators believe it happened by inhaling contaminated dust while ashore in South America, where the virus is endemic, and later spread person-to-person on the ship.
Our 2025 study found hantavirus exposure in people farming bats, bamboo rats, civets, and wild boars in Vietnam. The findings should serve as an early warning for other Southeast Asian countries, including Indonesia, where wildlife farming and markets are also common.
How does hantavirus spread on farms?
We tested 210 wildlife farmers in Lao Cai and Dong Nai provinces in Vietnam.
Nearly 9% had anti-hantavirus immunoglobulin G (IgG) antibodies, showing they had been exposed before. Another 1.9% had active infections when we collected samples between August 2023 and March 2024, however no hantavirus outbreaks were reported during the study period.
Farmers who only managed the farms faced the highest risk, even if they did not hunt, trade, slaughter, or eat the animals.
Poor hygiene and a lack of protective equipment may explain this risk. Humans can become infected by inhaling tiny particles contaminated with infected rodents’ urine, droppings, or saliva.
We still do not know which virus is involved
Our study cannot yet tell us exactly where the infections came from.
The farmers may have been exposed to infected wild rodents outside the farms. We also do not know which variant of hantavirus infected them.
Read more: Hantavirus is very different to COVID. Here’s why the ‘Andes virus’ won’t cause the next pandemic
Our study used antibody tests (ELISA), which can show previous exposure but cannot identify the specific virus. Tests of samples from farmers and animals also found no viral genetic material.
Identifying the virus and its host will require genetic testing, including (RT-PCR and sequencing). Given Vietnam’s high biodiversity, an undetected hantavirus variant could potentially be circulating.
Preventing the next spillover
Preventing the virus from jumping to humans is much better than reacting to an outbreak.
Farmers need practical safety measures, including consistent use of protective equipment when handling animals or cleaning cages.
This requires cooperation between different doctors, veterinarians, wildlife experts, and farmers otherwise known as One Health approach – to develop safety measures that are both effective and practical.
Vietnam already has laws governing wildlife farming, but enforcement remains weak. Animal health monitoring is limited, and coordination between government agencies has room for improvement.
Read more: The hantavirus outbreak is the warning the world needs to improve pandemic preparedness
Better surveillance could help detect emerging diseases earlier and reduce the risk of future outbreaks. This is important not only for Vietnam but also for other countries where people live and work closely with wildlife, including Indonesia.
Governments should also use social media and other accessible channels to inform farmers and the public about the risks of zoonotic diseases.
Clear, practical information can help people understand the risks and follow safer farming practices.
Preventing disease spillover requires action before an outbreak occurs. As people, animals, and economies become increasingly connected, strengthening surveillance and safety measures is essential to protecting both local communities and global health.
This article was originally published in Indonesian
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