Listen to the audio version of the article
India is taking urgent measures to stop the transmission of a rare but deadly virus that spreads from bats to humans. Is this the precursor to a new pandemic? The history of Nipah, an RNA virus that appeared for the first time in Malaysia in 1998, would rule out this possibility, as to date it is not easily transmitted.
Diffusion not easy
“Despite its lethal potential, Nipah virus does not spread as easily between people as other animal-borne infections do, making it less likely to spread across national borders,” says Danielle Anderson, a virologist at the Royal Melbourne Hospital in Australia. – I don’t expect it to spread globally to the extent of what we’ve seen with Covid-19.”
Also for Christopher Broder, specialized in emerging infectious diseases at the Uniformed Services University Medical School in Bethesda, Maryland, “the high mortality rate of the virus offers less opportunity to spread rapidly among populations” and adds that “the strain circulating in Kerala it hasn’t changed much since it first emerged more than two decades ago in Bangladesh, although future outbreaks could be larger if it morphs into a milder but more contagious strain. And it is likely that variants already exist that have not yet been detected.”
Some scientists, however, fear that the Indian epidemic – the fourth to hit Kerala in five years – and therefore the greater spread of infections among people could lead to the virus becoming increasingly contagious: «Every epidemic offers the pathogen the opportunity to change.”
Risks from infected animals
Indeed, even if the R value of Nipah (a factor that measures the spread of the infection in a population) is low (around 0.33, which means that the infection is unlikely to spread far from its animal source), if infected animals were to be transported to large cities, the increased population density would increase the risk of person-to-person transmission which could allow the virus to evolve, triggering a new pandemic over time. A scenario we have already seen.