Identification of influenza A viruses in ducks and the relation between the prevalence of influenza A viruses in ducks and risk factors in Cipunagara, Java, Indonesia

Abstract

Indonesia is one of the countries where Avian Influenza (AI) is endemic. In several parts of Indonesia, nomadic ducks are being used after harvesting the rice for cleaning the rice fields from weed, snails and insects. Nomadic ducks might play an important role in spreading all different types of influenza A viruses, because it is well known that aquatic birds form a reservoir for most influenza A types. In this project, questionnaires were used to obtain information about nomadic duck flocks. Next to this, trachea, cloaca and blood samples have been taken to test for the presence of influenza A virus (including H5-subtype) and antibodies against influenza A (including antibodies against H5-subtype). The aim of this study is to investigate the types of influenza A that are present in nomadic ducks in Cipunagara subdistrict (Subang district, Java, Indonesia) by taking trachea, cloaca and bloodsamples, and to relate the acquired data to flock size, origin of the ducks, duck breed, keeping reason, type of housing system, location of the ducks at night, transportation methods of the ducks, movements of the flocks and vaccination. 32% of the flocks tested positive with the PCR-test for the presence of influenza A. Influenza A subtype H5 was not found in the flocks. 100% of the flocks showed the presence of antibodies against influenza A. 6% of the flocks have antibodies against H5-subtype. These results were combined with the results of the questionnaire. This showed a relation between flock size and the presence of influenza A. Bigger flocks have a bigger chance of being influenza A positive. Next to this, there is a relation between flocks which are being removed from the rice fields at night and the presence of H5-subtype specific antibodies. Flocks that are being removed from the rice fields at night show more antibodies against H5-subtype.