Research Article: Serological Evidence of Henipavirus Exposure in Cattle, Goats and Pigs in Bangladesh

Date Published: November 20, 2014

Publisher: Public Library of Science

Author(s): Sukanta Chowdhury, Salah Uddin Khan, Gary Crameri, Jonathan H. Epstein, Christopher C. Broder, Ausraful Islam, Alison J. Peel, Jennifer Barr, Peter Daszak, Lin-Fa Wang, Stephen P. Luby, Thomas Geisbert.

Abstract: BackgroundNipah virus (NiV) is an emerging disease that causes severe encephalitis and respiratory illness in humans. Pigs were identified as an intermediate host for NiV transmission in Malaysia. In Bangladesh, NiV has caused recognized human outbreaks since 2001 and three outbreak investigations identified an epidemiological association between close contact with sick or dead animals and human illness.MethodologyWe examined cattle and goats reared around Pteropus bat roosts in human NiV outbreak areas. We also tested pig sera collected under another study focused on Japanese encephalitis.Principal FindingsWe detected antibodies against NiV glycoprotein in 26 (6.5%) cattle, 17 (4.3%) goats and 138 (44.2%) pigs by a Luminex-based multiplexed microsphere assay; however, these antibodies did not neutralize NiV. Cattle and goats with NiVsG antibodies were more likely to have a history of feeding on fruits partially eaten by bats or birds (PR = 3.1, 95% CI 1.6–5.7) and drinking palmyra palm juice (PR = 3.9, 95% CI 1.5–10.2).ConclusionsThis difference in test results may be due to the exposure of animals to one or more novel viruses with antigenic similarity to NiV. Further research may identify a novel organism of public health importance.

Partial Text: Nipah virus (NiV) is a zoonotic paramyxovirus whose reservoir host is fruit bats of the genus Pteropus[1]–[3]. NiV was first recognized in a large outbreak in Malaysia where pigs were an intermediate host for the transmission of NiV infection in humans [4], [5]. Outbreak investigators speculated that pigs were infected with NiV by ingesting partially eaten saliva-contaminated fruit dropped by Pteropus bats [6]. Pig farmers were more likely to be infected with NiV suggesting infected pigs transmitted NiV to humans through close contact [7]. Between 2001 and 2013 NiV has caused 227 recognized human infections in Bangladesh with a case fatality of over 75% [8]–[15]. Although there is no serological or microbiological confirmation of NiV infection in domestic animals in Bangladesh, three outbreak investigations have identified suggestive associations between domestic animals and human infection. In the 2001 outbreak in Meherpur, Bangladesh, human Nipah cases were 7.9 times more likely than controls to have contact with a sick cow (odds ratio[OR] 7.9, 95% confidence interval [CI] 2.2–27.7) [8]. In a 2004 outbreak, a NiV-infected child had a close contact history with two sick goats and in a 2003 human Nipah outbreak at Naogaon, Bangladesh, cases were more likely than controls to have had contact with a nomadic pig herd (OR 6.1, 95% CI 1.3–27.8) [16], [17]. Bats frequently visited date palm trees and licked shaved surfaces of the trees to drink sap at night [18]. Date palm sap spoiled by bat feces is occasionally fed to cattle in Bangladesh [19]. Domestic animal infection with NiV may represent an immediate risk to human infection as well as a risk for further evolution of the virus for adaptation to mammals other than bats. We conducted a cross-sectional study to look for evidence of NiV antibodies in domestic livestock, including cattle, goats and pigs, and to identify exposures associated with NiV antibodies.

This study identified antibodies against NiVsG in 26 cattle, 17 goats and 138 pigs; however these antibodies did not neutralize NiV, and did not react against NiV antigens in an ELISA, though 2 cattle and 2 pig sera reacted with NiV N protein by WB. Animals that were fed fruit that had been partially eaten by bats or birds were >3 times more likely to have antibodies against NiVsG compared with animals not fed partially eaten fruit.



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