Two cases of the deadly Nipah virus in India have prompted countries in Asia to step up airport screening to prevent the spread of the infection. But what is Nipah virus, and how worried should people be? What is Nipah virus? Nipah is a rare viral infection that spreads largely from infected animals, mainly fruit bats, to humans. It can be asymptomatic, but it is often very dangerous, with a case fatality rate of 40 to 75 per cent, depending on the local healthcare system’s capacity for detection and management, the World Health Organisation (WHO) says. An undated image of fruit bats in Kerala, India. — Reuters/File However, while it can also spread from person to person, it does not do this easily, and outbreaks are usually small and fairly contained, according to experts and the European Centre for Disease Prevention and Control. Candidate vaccines are under development, although none have been approved yet. How common is it? Nipah was first identified in Malaysia in 1999. Since then, there have been small ...