An infectious disease outbreak in south India that has left at least 16 people dead has brought the world’s attention to a little-known health threat: the Nipah virus. An emerging zoonotic virus whose natural host is the Pteropus fruit bat, Nipah virus was first recognised in the late 1990s when an outbreak in pigs in Malaysia and Singapore moved to humans, killing 106 people.
Since then, interest in Nipah virus has remained limited to small research communities and affected countries. Annual outbreaks occur in Bangladesh, where humans are exposed through consumption of the sap of date palm trees contaminated by infected bats. Worryingly, Nipah virus can also be transmitted from human to human, as in the current south India outbreak, with most cases occurring in family members or health workers caring for individuals sick with the high fever, vomiting, and breathing difficulties characteristic of infection. Severe cases can lead to respiratory syndrome, encephalitis, and death—the case fatality rate may be up to 75%. There is no cure, vaccine, or specific treatment—supportive care is the most that can be offered to affected individuals. Nipah virus infection has so far been limited to countries in south and east Asia, where 600 cases have been reported between 1998 and 2015, according to WHO.
Yet concerns are growing about the pandemic potential of Nipah virus. The World Organisation for Animal Health, which on May 30 signed an agreement with the Food and Agriculture Organization of the UN and WHO to cooperate against human-animal-environment risks, says Nipah virus has devastating zoonotic potential. While WHO reports the risk of geographical spread of Nipah outbreaks to be low, there is extensive migration of fruit bats and wide distribution of these species. Evidence from Bangladesh shows that viral spillovers from bats to humans happen regularly, providing an opportunity for a more highly transmissible strain to infect and adapt in humans. Fuelled by population density and mobility, such evolution increases the risk of a pandemic. Worse, the relatively weak capacity of health and surveillance systems in the under-resourced settings in which Nipah virus circulates limits outbreak response and control.
Expectation for international leadership on pandemic preparedness is also growing. The slow response to the Ebola virus outbreaks in west Africa in 2014–16, during which 11 000 people died, was a devastating failure. Global public health leaders promised to learn from their mistakes and act more proactively. The current Ebola outbreak in DR Congo is providing one acute opportunity to do that. The Nipah virus case provides another, longer-term, opportunity to put into place adequate pandemic preparedness.
Plans to develop enhanced biomedical tools already exist. Nipah virus infection has joined Ebola, Zika, MERS, Lassa and Crimean-Congo haemorrhagic fevers on the 2018 WHO R&D Blueprint list of priority epidemic threats needing urgent research and development action. A draft Nipah research and development roadmap has been issued by WHO, which prioritises the development of needed countermeasures (diagnostics, therapeutics and vaccines), based on extensive consultations with a Nipah task force comprised of leading national and international experts. It is the most systematic assessment of Nipah virus research needs ever produced, and the roadmap is open for public comment until June 8.
Such explicit and collaborative efforts are crucial in areas like Nipah virus control where commercial potential to drive private sector investment is limited. Encouragingly, the Coalition for Epidemic Preparedness Innovations, funded by the governments of Norway, Germany, and Japan, the Bill & Melinda Gates Foundation, and Wellcome Trust, announced on May 21 a US$25 million investment in two US biotechnology firms to accelerate work on a Nipah virus vaccine that has been in development at the Uniformed Services University of the Health Sciences for 15 years.
However, for true countermeasures and preparedness, a broader and more comprehensive approach and investment are urgently needed. In addition to diagnostics, therapeutics, and vaccines, surveillance infrastructure must be improved to rapidly identify and verify cases, conduct detailed contact tracing, investigate spillovers, and better understand the ecology of bats and Nipah virus infection, especially outside of outbreak scenarios. As important is the need for behavioural change: local communities must be better supported to ensure infection prevention and control measures in health facilities to reduce transmission, and to conduct the community engagement and education required to modify behaviour and reduce risk. We must heed that Nipah virus demands a broad, long-term strategy and pandemic plan.