Nipah: The history, and future, of one of the world’s most lethal viruses

Abstract

The Nipah virus kills around three quarters of people who contract it, making it one of the most lethal viruses known to infect humans. The virus first emerged in 1998, when hundreds of pig farmers in Malaysia fell ill with fevers and encephalitis, or brain inflammation. Nipah has caused smaller outbreaks in nearby Bangladesh nearly every year since then. The Malaysian farmers appeared to have been infected directly from their pigs, rather than from each other. For a time, there was no clear evidence that Nipah could spread from humans to other humans. That changed in April of 2004, when investigators responding to a Nipah outbreak in a remote district in Bangladesh discovered that the virus was spreading person to person. Pteropus fruit bats, which are native to South Asia, were identified as the natural reservoirs of the Nipah virus. Researchers have spent the last two decades studying the virus’ transmission in bats and how the virus spills over into humans. Institutions across the world have even recently started developing Nipah vaccines. Scientists believe the Nipah strains that currently circulate in humans are likely not transmissible enough to ignite a pandemic in people. That could change. Whether the virus one day evolves to spread better within humans, or hits a particularly susceptible place and thrives, officials worry about what could happen if Nipah ever affects larger populations. The Nipah virus is just one of many zoonotic pathogens that scientists are studying to understand how humanity can prepare for future deadly pathogens.