PREDICT investigations of bat guano "farming" in Viet Nam and Cambodia: A new interface for zoonotic disease transmission?

PREDICT, part of USAID’s Emergency Pandemic Threats Program, uses a One Health approach to understanding the dynamics of zoonotic virus evolution, spillover, amplification, and spread to inform prevention and control.... [ view full abstract ]

PREDICT, part of USAID’s Emergency Pandemic Threats Program, uses a One Health approach to understanding the dynamics of zoonotic virus evolution, spillover, amplification, and spread to inform prevention and control. Constructing artificial roosts to attract insectivorous bats and facilitate the collection of guano for application as fertilizer is a practice increasingly adopted as a livelihood option by rural communities in Southeast Asia. Most of the artificial roosts are constructed around human dwellings with backyard farms or are integrated into food crop fields, raising concerns about the risk of pathogen spillover from bats to humans and domestic animals. Bat guano samples from such facilities were screened for the presence of RNA viruses from viral families of public health significance. Bat guano “farms” were selected in Soc Trang and Dong Thap Provinces in Viet Nam and Pursat and Kampong Cham Province in Cambodia. Fresh fecal and urine samples were collected with sterile swabs from clear tarpaulins placed under the artificial roosts. Rectal and oral swabs and tissue samples were collected from individual bats found dead at the sampling sites. Each sample was split into two separate cryovials containing Viral Transport Media or RNA-later. Samples were stored in liquid nitrogen in the field and transported to -80°C freezers at laboratory facilities in Cambodia and Viet Nam. Family-level conventional PCR assays were applied in the laboratories, followed by cloning and sequencing for virus identification. The analysis of 1,211 samples resulted in the detection of 20 novel viruses (9 Rhabdo-, 5 Paramyxo-, 2 Corona-, 2 Astro-, 1 Flavi-, and 1 Seadornavirus) and 4 previously described viruses (3 Astro- and 1 Coronavirus). These laboratory results, coupled with observations of limited use of protective equipment by bat guano collectors, suggests that this interface warrants more attention from the public health community and application of occupational safety guidelines.