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).
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
During the last quarter of 2013, the research team continued its infrared camera observation study, collecting 21 nights of observation data (7 nights per month for 3 months) of bat visits to date palm trees. To date, 220 bat visits have been recorded and the average length of time spent on a date palm tree was 5.5 minutes. In addition, the team recorded 29 rat visits with an average duration of stay of 65 minutes. The team also completed an animal-sero survey, collecting blood samples from 200 domestic (98 cattle, 101 goats and 1 horse) and 188 peri-domestic (36 cats, 47 rats, 42 house shrews and 63 dogs) animals from Rajshahi and Manikgonj, two known outbreak sites for the Nipah virus. The team interviewed 82 livestock owners from Rajshashi and 72 from Manikgonj.
Future plans include sending the livestock serum samples to the Australian Animal Health Laboratory for testing for the Nipah virus antibody. The project team will also conduct Nipah outbreak investigations, and based upon the findings, they will select domestic and peri-domestic animals to be sampled at the two sites in the coming year.