India, Jan. 29 -- As Nipah virus cases re-emerge in parts of India, including Kerala and West Bengal, health authorities remain on high alert. With airport screenings, strict isolation protocols and contact tracing back in focus, public concern is growing around one key question: what exactly happens inside the body after the Nipah virus enters, and why does it so often turn fatal?

According to the World Health Organisation (WHO), the Nipah virus carries a fatality rate ranging between 40 per cent and 75 per cent, making it one of the deadliest zoonotic infections known to humans. Medical experts warn that its ability to attack blood vessels and directly invade the brain makes it especially dangerous.

Symptoms often begin mildly but wor...