Nipah virus is back.

It has not hit the US yet, but it has quietly reminded public health officials why it sits high on the global watch list. This rare but deadly virus has been circulating in parts of South and South East Asia for years, flaring up periodically and leaving behind difficult questions about preparedness, travel safety, and how modern outbreaks begin in the first place.

First identified in 1999 during an outbreak among pig farmers in Malaysia and Singapore, Nipah virus is what scientists call zoonotic. That means it jumps from animals to humans. Its natural hosts are fruit bats, particularly those from the Pteropus genus, although pigs and other animals have also played a role in spreading the virus to people. In some regions, everyday cultural practices have unintentionally opened the door. Raw or partially fermented date palm sap, often collected in open containers, can become contaminated by bat saliva or urine and then consumed by humans.

Once infected, symptoms can appear anywhere from four to 21 days later. Early signs look deceptively mild, often resembling the flu. Fever, headaches, muscle pain, and fatigue may come first, followed by respiratory issues such as pneumonia. The real danger comes when the virus attacks the brain. Encephalitis is the defining feature of severe Nipah infection, and it is here that the virus shows its brutal side. Fatality rates have ranged from 40 to 75 percent, and survivors can experience long term neurological problems, including seizures and personality changes. In rare cases, the virus has even reactivated months or years later.

Despite its severity, Nipah virus remains geographically contained. Human outbreaks have only been reported in Bangladesh, India, Malaysia, Singapore, and the Philippines. No cases have ever been recorded in the UK. For most travelers, the risk is extremely low, especially if basic precautions are followed. Avoiding raw date palm sap, washing and peeling fruit, staying away from bats and sick animals, and practicing good hygiene dramatically reduce the chance of exposure.

There is currently no licensed vaccine or proven antiviral treatment. Care focuses on managing symptoms in intensive medical settings. That gap has pushed research forward. The UK Health Security Agency has now designated Nipah virus as a high priority pathogen, while the World Health Organization lists it as an epidemic threat requiring urgent research. Vaccine candidates and experimental treatments are in development, but for now, awareness and prevention remain the strongest defenses.

Nipah virus is not a cause for panic, but it is a reminder that global health threats often begin quietly, far from headlines, before science and vigilance step in.