Two cases of the deadly Nipah virus in India have prompted authorities in Thailand, Singapore, Hong Kong and Malaysia to step up airport screening in an effort to prevent the infection from spreading.

The virus, which is carried by fruit bats and animals such as pigs, can cause fever and brain inflammation ?and has a fatality rate of between 40% and 75%. Although it can spread from person to person, transmission is not easy and typically requires prolonged ?contact with ?an infected individual.

It more commonly spreads to humans from infected bats, or fruit contaminated by them.