We’ve known about Nipah virus—and that it could cause a global pandemic—for twenty years. But we’re still in the first stages of fighting it.
There’s “currently no specific drugs or vaccines for Nipah virus infection,” Linfa Wang, a bat-borne virus expert at Duke University’s Global Health Institute and conference co-chair, told Reuters this week. Wang and other experts are currently gathered in Singapore for the first-ever Nipah virus conference. At the two-day event they’re talking about everything from the history of Nipah outbreaks to ways forward for containing the disease. They’re also hoping to raise its profile.
Nipah’s first recorded outbreak, which hit Malaysia in 1999, killed 105 of the 265 people known to be infected. We’ve since seen numerous outbreaks in South Asian countries like Singapore, Bangladesh, and India. In Bangladesh, the World Health Organization notes, Nipah outbreaks have occurred “nearly annually” since 2001.
The Nipah virus (NiV) is named after Sungai Nipah, a Malaysian village where it was found to have infected pig farmers. The first outbreaks in Malaysia and Singapore were halted after authorities killed more than a million pigs in the country’s largest-ever animal culling, which also represented a huge financial loss, the CDC notes
But it turned out that pigs were just incubators for a disease that had been around for a while in fruit bats. “It doesn’t affect the fruit bat,” says epidemiologist Micah Hahn of the University of Alaska-Anchorage, whose work on Nipah was published in 2014. “But the virus can be transmitted by saliva, urine, or feces.” When people (or pigs) come into contact with the fruit bat’s bodily fluids, they can get the disease.
In humans, an early-stage Nipah infection can resemble the flu: vomiting, dizziness, and a sore throat are the usual symptoms. Some people also have a cough. But as it progresses, Nipah can cause potentially-fatal brain inflammation. The WHO estimates that between 40-75% of people who contract Nipah die, depending on how quickly doctors can identify the disease and what kind of care is available. People suffering from the virus belong in intensive care settings where their symptoms can be treated and they can be closely monitored by medical professionals, according to the WHO’s recommendations. However, such environments are few and far between in many of the places where Nipah is found, and a common way for a single case to spread is when loved ones take care of the sick and subsequently become infected.
“Although Nipah virus has caused only a few known outbreaks in Asia, it infects a wide range of animals and causes severe disease and death in people,” according to a statement from WHO. Fruit bats are the disease’s only known reservoir, but the illness can infect pigs and other domesticated animals like cats and dogs.
In the case of the Malaysia and Singapore outbreaks, it’s thought that the disease jumped from bats to pigs, who passed it to the humans who ate or worked around them via their bodily fluids. But in Bangladesh’s “Nipah belt,” which stretches diagonally across the country, outbreaks have been traced to the body fluids of fruit bats hanging around on date palms.
Untreated date palm sap is a popular drink in Bangladesh tapped straight from the tree or fermented. If fruit bats are urinating or eating or pooping in the sap, Hahn says, they can contaminate the supply. That’s the pipeline behind most outbreaks of the disease, although it’s also possible for people to transmit the virus to one another—particularly, research has shown, if they are extremely sick or suffering from symptoms that make them cough.
As with many zoonotic diseases (ones we can catch from animals) environmental pressures are a huge factor in how the ailment spreads. In Malaysia and Singapore, for example, outbreaks were more common when farmers had more pigs.
In Bangladesh, “We found that in the areas where most of the cases were happening [the forest] was really fragmented,” Hahn says. Although there are date palms all over the country and drinking palm sap is as common as having a beer in the evening, she says, areas with Nipah issues had people and bats living in closer proximity, the result of deforestation for farming, timber, or to make way for human settlement. “These bats are roosting in people’s backyards, essentially,” Hahn says. Areas with more space saw less of the disease. Hahn’s team is working to help farmers figure out how to keep bats out of their palms so the virus doesn’t spread.
These kind of preventative measures are urgently needed, since there’s no vaccine for the virus yet. This year’s meeting in Singapore is aiming to change that by bringing Nipah researchers together and helping to raise the disease’s public profile in the West.
Nipah isn’t here yet, it’s true—but it could come here, especially if it mutates further to be more easily passed from person to person. The human and animal suffering already caused by the disease is reason enough to try and find a vaccine, but the consequences of inaction could impact us all.
