What human behavior was the cause of the Nipah virus outbreak in Bangladesh? How did scientists determine this?

Humans drinking raw date palm sap was the cause of the Nipah virus outbreak in Bangladesh. Scientists found Nipah virus in bat excretions and discovered that bats were contaminating date palm juice with their excretions (saliva, urine).

Explanation:

Nipah virus can spread to people from:

1) Direct contact with infected animals, such as bats or pigs, or their body fluids (such as blood, urine or saliva).

2) Consuming food products that have been contaminated by body fluids of infected animals (such as palm sap or fruit contaminated by an infected bat).