Nipah Virus: A deadly zoonotic threat

2026-02-06 - 22:36

Nipah virus is a zoonotic pathogen transmitted from animals to humans and can also spread through contaminated food or direct human-to-human contact. It was first identified in 1998 during an outbreak among pig farmers in Malaysia, followed by cases in Singapore in 1999 linked to imported infected pigs. No further outbreaks have been reported in Malaysia or Singapore since then. Subsequent outbreaks have occurred mainly in Bangladesh and India. Bangladesh reports cases almost every year, while India has experienced periodic outbreaks, including the latest reported in 2026. A single outbreak was reported in the Philippines in 2014, with no new cases since. The virus has a high case fatality rate, ranging from 40% to 75%, making it a serious public health concern. Fruit bats of the Pteropodidae family are the natural reservoir of Nipah virus and usually show no signs of illness. Antibodies have also been detected in African fruit bats of the genus Eidolon, suggesting a wider geographic presence. Humans may become infected through direct contact with infected bats, pigs or horses, consumption of contaminated food or drinks such as raw date palm juice or partially eaten fruits and through person-to-person transmission, particularly among family members, caregivers and health-care workers. The virus causes severe disease in animals, especially pigs, which can amplify transmission. In hospitals, spread is more likely in overcrowded and poorly ventilated settings with inadequate infection prevention measures, including poor hand hygiene, insufficient cleaning and lack of personal protective equipment. These factors significantly increase the risk of outbreaks in health-care environments. The incubation period is usually 3–14 days, though rare cases up to 45 days have been reported. While some infections remain asymptomatic, most patients develop fever, neurological symptoms such as headache, confusion, drowsiness and dizziness, along with respiratory symptoms including cough and breathing difficulty. Severe cases may progress to encephalitis and death, while about one in five survivors experience long-term neurological complications. Diagnosis is challenging because clinical features resemble other causes of encephalitis or pneumonia, making laboratory confirmation essential. Key diagnostic tests include RT-PCR on respiratory samples, blood or cerebrospinal fluid and ELISA for antibody detection in blood. Patient samples are highly biohazardous and must be handled only by trained personnel in properly equipped high-containment laboratories. There is currently no specific antiviral treatment or approved vaccine for Nipah virus. Early diagnosis and intensive supportive care are critical to improving survival. Management includes monitoring and treating complications such as brain swelling and pneumonia, oxygen therapy and organ support, adequate hydration and nutrition and individualized care based on co-existing conditions. The World Health Organization lists Nipah as a priority disease under its Research and Development Blueprint, with several candidate drugs and vaccines under development. Prevention focuses on reducing transmission at multiple levels. Measures include preventing bat access to date palm sap, boiling fresh sap, washing and peeling fruits thoroughly and avoiding fruits with bat bite marks. Animal-to-human transmission can be reduced by using protective clothing when handling sick animals and protecting farms from bat exposure. In health-care settings, WHO recommends strict infection prevention, including isolation of cases, use of personal protective equipment and adherence to contact, droplet and airborne precautions. —The writer is contributing columnist, based in Islamabad. (tariqali@hsa.edu.pk)