How serious is Kerala's Nipah threat?

Kerala is on high alert after a resurgence of the potentially deadly Nipah virus (NiV) in its Kozhikode district. The Nipah virus infections have killed two people in Kerala. Two other adults and a child, who are infected, are quarantined in a hospital. The strain found in Kerala this time has come from Bangladesh and is understood to be less infectious. But it has a higher mortality rate, and health experts say it spreads from human to human.