Nipa fever is spreading: What you need to know about contagious pneumonia and transmission risks

The Nipah virus outbreak in India has attracted worldwide attention and is especially making the population of the Philippines and other Southeast Asian countries cautious. The virus, which is naturally carried by flying foxes, can be transmitted between animals and humans and poses significant health risks. Experts warn of the need for increased border controls and surveillance measures. According to infectious disease specialist Dr. Rontgene Solante, the Philippines should strengthen its sanitary controls at land borders to thoroughly examine travelers from affected regions such as West Bengal.

Transmission Routes: How the Nipah Virus Spreads from Animals to Humans

The virus is known for its contagiousness in certain contexts. Flying foxes carry the Nipah virus but do not show symptoms themselves. In pigs, the virus is particularly infectious—animals are contagious during an incubation period of four to 14 days. The virus can also be transmitted to other domestic animals such as horses, goats, sheep, cats, and dogs.

Human infection mainly occurs through direct contact with sick animals or their contaminated body fluids, as well as through the consumption of fruit contaminated with urine or saliva from infected flying foxes. In previous outbreaks, humans were also infected through direct contact with pigs or their tissues, and by consuming horse meat. Human-to-human transmission occurs through close contact with body secretions and excretions of infected individuals, making healthcare workers especially vulnerable.

Symptoms and Disease Progression: From Non-specific Signs to Contagious Pneumonia

Infected individuals may initially be asymptomatic, showing no obvious signs. When symptoms develop, they often include fever, headache, muscle aches, vomiting, and sore throat. Following these initial symptoms, signs of acute encephalitis—the inflammation of the brain—may occur, including dizziness, extreme drowsiness, altered consciousness, and neurological deficits.

A serious risk is the development of atypical contagious pneumonia with severe respiratory distress. This complication poses a significant transmission risk, especially to close contacts. Critical cases can lead to encephalitis and seizures, progressing to coma within 24 to 48 hours. The World Health Organization (WHO) states that the case fatality rate ranges from 40 to 75 percent—much higher than many other infectious diseases.

Currently, there are no medications or vaccines available against the Nipah virus. Treatment focuses on intensive supportive care to manage severe respiratory and neurological complications.

Diagnostic Challenges and Limited Testing Capacity

Diagnosing the Nipah virus requires specialized tests, which are limited in availability in the Philippines. Dr. Solante explains that only a few laboratories, such as the Research Institute for Tropical Medicine (RITM), can perform these tests. This presents a significant obstacle, as initial symptoms are non-specific and often do not raise suspicion at presentation.

The WHO warns that this diagnostic weakness hampers accurate diagnosis and creates challenges in outbreak detection, effective infection control, and response measures. The combination of non-specific symptoms and limited testing options greatly complicates rapid case identification.

Past Outbreaks and International Precautionary Measures

The Philippines experienced a Nipah virus outbreak in Sultan Kudarat in 2014, where 17 people became ill after consuming horse meat and coming into contact with an infected person. This historical experience highlights the virus’s contagious potential in the region.

Recently, five health officials in West Bengal were infected, leading to about 100 people being quarantined. In response to the current outbreak, several countries have intensified their health controls. Thailand, Nepal, and Taiwan have already tightened border controls for the Nipah virus. Dr. Solante recommends similar measures for the Philippines: temperature checks upon arrival, sampling, and monitoring for initial symptoms, especially for travelers from West Bengal.

The Philippine Department of Health (DOH) emphasizes that, based on its experience in 2014 and the updated guidelines of 2023, it is prepared to respond. Deputy Secretary Albert Domingo assures that the DOH Epidemiology Bureau remains vigilant through continuous monitoring.

Why a Pandemic-Scale Spread Is Not to Be Expected

Despite the serious symptoms and high mortality rate, Dr. Solante warns against undue alarmism. Unlike COVID-19, the Nipah virus is not easily transmissible. To infect another person, the infected individual must have a high viral load, be symptomatic, and exhibit particularly severe symptoms. This greatly limits the speed of spread.

However, the non-specific initial symptoms remain a challenge. They can lead to cases not being quickly recognized and infected individuals unintentionally spreading the virus before diagnosis.

Prevention and Personal Recommendations

To minimize infection risks, people should avoid direct contact with bats and sick animals. The health department advises only consuming meat inspected by the National Meat Inspection Service (NMIS) and thoroughly cooking food. These simple precautions can significantly reduce infection risk and are essential steps in personal disease prevention.