Nipah virus (NiV) is an emerging zoonotic virus (a virus transmitted to humans from animals) that causes high mortality in humans. In addition to human-to-human transmission, epidemiological studies have identified another possible transmission pathway, namely from fruit bats of the Pteropodidae family to humans when people drink contaminated date palm sap. Human NiV cases in Bangladesh have been found to be seasonal, coinciding with the date palm harvesting season (November to March), and consumption of date palm wine appears to serve as a major portal for infection due to contamination of palm sap from contact with urine or saliva from infected fruit bats.
In addition to foodborne transmission pathways, animals other than bats may play a role in transmission. The project team has previously studied livestock during outbreak investigations, and as they expand their work under the current PEER grant they will pursue the hypothesis that multiple species of animals (including dogs, cats, cattle, goats, horses, and pigs) may acquire and spread Nipah infection during an outbreak. The Bangladeshi and U.S. researchers will develop sampling strategies and analytical approaches to assess the risk of infection via livestock and food-borne routes. In order to better understand the various possible routes of NiV transmission, this project will involve screening domestic, peri-domestic, and feral animals in a NiV outbreak to look for evidence of NiV infection. Furthermore, the researchers will look at bats’ date palm sap drinking behavior year round, in the locations where harvesters collect and ferment date palm sap for wine production. Beyond its research aspects, this project will also provide training in NiV surveillance, field sampling techniques, biosafety practices, and outbreak response for veterinarians under the Bangladeshi Department of Livestock Services, Ministry of Agriculture, and the Forestry Department.
Summary of Recent Activities
A bat licking sap from the shaved part of a date palm tree (Photo courtesy Dr. Khan).
Two rats licking sap from the shaved part of a date palm tree( Photo courtesy Dr. Khan).
During the third quarter of 2013, the team continued their infrared camera observation study, collecting 21 nights of observation data (7 nights per month for 3 months) regarding bats’ visits to date palm sap trees in Rangpur District. They recorded the visits of 156 bats, while 258 rat visits were recorded during the same period. The researchers also collected blood samples from 100 domestic animals (50 cattle and 50 goats) and 90 peri-domestic animals (14 cats, 28 rats, 12 house shrews, and 36 dogs) from around the Rajshahi Nipah outbreak site. As a result of interviewing 79 local livestock owners, the researchers found that 4 percent raise their cattle only on grazing, while 20 percent use limited grazing and stall feeding and 66 percent use stall feeding only. In addition, 14 percent of the owners feed their livestock date palm sap and 46 percent feed them dropped date palm fruit. In the final months of 2013, the group plans to initiate animal sampling at the Pabna outbreak site, with the goals being to collect oropharyngeal and urinary swabs from sick animals and serum from 190 domestic (cattle, goats, pigs) and peri-domestic animals (dogs and cats).