Surveillance of Influenza A Virus and Its Subtypes in Migratory Wild Birds of Nepal

Abstract

Nepal boarders India and China and all three countries lie within the Central Asian Flyway for migratory birds. Novel influenza A H7N9 caused human fatalities in China in 2013. Subclinical infections of influenza A H7N9 in birds and the potential for virus dispersal by migratory birds prompted this study to assess avian H7N9 viral intrusion into Nepal. Surveillance of influenza A virus in migratory birds was implemented in early 2014 with assistance from the Food and Agricultural Organization (FAO). Of 1811 environmental fecal samples collected from seven wetland migratory bird roosting areas, influenza A H9N2 was found in one sample from a ruddy shelduck in Koshi Tappu Wildlife Reserve located in southern Nepal. Avian H7N9 and other highly pathogenic avian influenza viruses were not detected. This study provides baseline data on the status of avian influenza virus in migratory bird populations in Nepal.

Serological Surveillance of Avian Influenza Virus in Nepal

“…In similar study by Karamcharya et al [3], they found only one Influenza A H9N2 positive out of 1811 environmental fecal samples collected from seven wetland migratory bird roosting areas. It was found in one sample from a ruddy shelduck in Koshi Tappu Wildlife Reserve located in southern Nepal.…”

“…While all birds are thought to be susceptible to infection with AI viruses, many wild bird species particularly birds of the orders Anseriformes (ducks, geese and swans) and Charadriiformes (gulls, waders and terns) are known as reservoirs (CDC). The domestic ducks in South East Asia is the principal host of Influenza A viruses where free-grazing duck feed year round in rice paddies appear to be a critical factor in HPAI persistence and spread and also has a central role in the generation and maintenance of the H5N1 virus [1][2][3].…”

“…The domestic duck in Southeast Asia is the principal host of Influenza A viruses and also has a central role in the generation and maintenance of the H5N1 virus [1,3]. Several duck species are naturally resistant to HP Asian H5N1 influenza viruses and can transmit the virus to domestic animals including humans.…”

“…Clearly, ducks play a complex and vital role in the biology and the overall natural history of influenza including H5N1 HPAI viruses [8]. Following this study, Nepal has suffered perennial H5N1 outbreaks in poultry, over 234 outbreaks have occurred since 2009 [3,9]. The main objective of this study was to assess the presence of Avian Influenza Virus (AIV) subtype H5, H7 and H9 antibodies in domestic ducks in Nepal prior to this outbreak.…”

When Micro Drives the Macro: A Fresh Look at Disease and its Massive Contributions in the Hindu Kush-Himalaya

“…The strain, H5N1 serotype, has been evidenced to kill chicken and ducks in the high altitude area (OIE 2017b), whereas both H5N1 and H5N8 have killed several chicken, Asian Openbill (Anas tomus oscitans), and the Whooper Swan (Cygnus cygnus) in the low altitude area (OIE 2017a) suggesting Nepal to be highly endemic region for HPAI despite Her geography. One study found H9N2 in the stool of a ruddy shelduck (Tadorna ferruginea) in seven wetland migratory bird roosting areas (Karmacharya et al 2015). This suggested that this strain leads to endemicity in poultry and may evolve into H7N9 to facilitate transmission into human Chen et al 2014).…”