In 2019, stakeholders began to make recommendations on research and development goals for the paramyxovirus called Nipah virus (NiV), which has a case-fatality rate of 40% to 100% and causes severe encephalitis (brain inflammation) in humans.
Then the COVID-19 pandemic happened, and a roadmap for developing medical countermeasures like vaccines and drugs against the virus advanced in stops and starts.
In 2023 the Center for Infectious Disease Research and Policy (CIDRAP), at the University of Minnesota, with funding from the Wellcome Trust, engaged an expert working group for NiV to update the 2019 version of the research and development roadmap. The updates reflect recent literature and consensus opinion of the experts. The updated 2024 roadmap was published yesterday.
"So far NiV is not transmissible enough to become a pandemic," explained Stephen Luby, MD, of Stanford University, one of the authors of the roadmap. "But the virus is important, and the current roadmap appreciates the risk this represents so work to develop a set of countermeasures that helps prevent a catastrophe."
Potential for wide geographic spread
The animal reservoir for the virus is the Pteropus genus of fruit bats. Outbreaks in humans have occurred when the virus has jumped from bats to pigs to humans, as was seen in the initial Malaysian outbreak in 1998 and 1999: At that time, at least 265 human cases of encephalitis were identified, and most patients had close contact with pigs.
"The overall case-fatality rate for the Malaysia outbreak was approximately 40%, whereas case-fatality rates in Bangladesh and India have generally ranged from 50% to 100%, making NiV one of the most lethal viruses known to infect humans," the authors of the roadmap write.
Virus transmission can also occur by eating food that has been contaminated by the body fluids of infected bats, such as palm sap or fruit tainted by an infected fruit bat. Human-to-human contact also spreads the disease.
So far NiV has caused only isolated outbreaks, but some researchers have raised concerns about the possibility of larger outbreaks if the virus takes hold in urban areas or if the virus becomes more transmissible to humans. “The COVID-19 pandemic dramatically demonstrated that new virus strains can emerge that are far more transmissible than their genetically related predecessors. We need to be prepared for this possibility with Nipah virus, particularly given the high case-fatality rate,” said Kristine Moore, MD, MPH, the lead author of the roadmap.
The COVID-19 pandemic dramatically demonstrated that new virus strains can emerge that are far more transmissible than their genetically related predecessors. We need to be prepared for this possibility with Nipah virus.
The fruit bat that carries the virus, after all, can be found across much of the Western Pacific, Southeast and South Asia, and Madagascar. This wide potential range of natural reservoir hosts raises concerns about the occurrence of outbreaks in new geographic areas, thereby greatly expanding the global at-risk population.
"We can only anticipate based on growing human populations, challenges in food supplies, which can lead to more human-animal interactions at the human-animal interface. Owing in part to the greater likelihood of exposures, the risk for these infectious diseases causing more serious illness and death only goes up and not down," said Michael Osterholm, PhD, MPH, director of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), which publishes CIDRAP News. He is the roadmap’s principal investigatory.
New countermeasures by 2030
As of today, there are no vaccines or other medical countermeasures, including diagnostics, for NiV. The roadmap focuses on research and development for those tools, as well as establishing more rapid, point-of-care diagnostic tests for the virus.
The small size of outbreaks makes establishing phase 3 clinical trials for treatments or vaccines a challenge, the authors said, so the roadmap's emphasis on specific action steps are doubly needed.
"The roadmap is a way to move the ball forward," said Emily Gurley, PhD, MPH, of Johns Hopkins University, another roadmap coauthor.
The roadmap focuses on diagnostics therapeutics, and vaccines, with the goal of effective and available NiV medical countermeasures by 2030.
"Time is of the essence," said Osterholm.
For Luby, the stark numbers add to urgency. "Seventy-five percent of people infected with Nipah die. That's a very high case-fatality rate. The roadmap lets us think about this in a careful way and produce a clear vision of where to go."
“We want to thank the many subject matter experts who provided their input into the roadmap development process and helped to identify the key gaps in progress so those issues can effectively be addressed through the goals and milestones outlined in the report,” said Moore.