Risk of Nipah virus transmission through date palm sap trade in Bangladesh: a qualitative ethnographic study

Nipah virus is an emerging zoonotic pathogen with pandemic potential, primarily transmitted through the consumption of raw date palm sap contaminated with bat excretions. Despite recurring outbreaks in Bangladesh since 2001, limited research has explored sap harvesting and trading practices. This study aimed to understand raw date palm sap collection, trade, and the risk of Nipah virus spillover at the community level in Bangladesh.

A qualitative ethnographic study was conducted in two districts of Bangladesh associated with recurrent outbreaks in February 2021 and March 2022. We recorded participant observations and conducted ethnographic interviews with raw date palm sap collectors to gather data on collection, trading practices, and protective measures they used. Data analysis followed a grounded theory approach, identifying themes related to raw date palm sap harvesting and trading.

Sap collectors sold raw sap locally and also used social media to reach buyers in other districts, where they could earn higher profits. Our observations and participant reports revealed that large fruit bats, small frugivorous bats, and rodents visited the trees and drank and contaminated raw sap with their excreta. A few sap collectors were aware of Nipah virus and used protection to avoid infection from drinking raw sap. Sap collectors prefer to use non-conventional protective apparatuses like jute bags, plastic bags, and polythene sheets due to the time and resource constraints to protect bats' and rodents' access to date palm trees.

This study provides important insights into the knowledge of Nipah virus and understanding of its transmission in the sap collector communities where outbreaks have occurred. It underscores the need for educational outreach programs to raise awareness and promote protective measures among the stakeholders engaged in raw date palm sap harvesting. Future research should explore raw sap distribution and trading networks in large areas to better characterize the geographies, behavioral, and cultural practices that influence Nipah virus transmission. Culture-sensitive interventions with economic incentives, involving harvesters, local governments, and non-governmental organizations, along with testing the effectiveness of protective measures, are essential to prevent the spillover of Nipah and other bat-borne emerging viruses in Bangladesh.