The Study of Persistence and Transmission of Avian Influenza Virus in Duck Farm using Real Time RT-PCR Technique

Abstract

Highly pathogenic avian influenza (HPAI) H5N1 virus has been a major threat to poultry industry and human health in Indonesia over the past several years. The existence of backyard and free-range duck raising system has been hypothesized to play role in the disease circulation. This study investigated H5 virus infection and circulation occurring in three types of free-range duck farms in Indramayu District, West Java, Indonesia from September 2009 to March 2010. One hundred and eighty pairs of cloacal-oropharyngeal swab samples from sentinel ducks placed in six farms of the three farm types were collected every month for seven months period and screened in pools for influenza A virus. In addition to the sentinel ducks, 30 non-sentinel ducks were included at the first and the last sampling month. Of the total 648 pool samples collected for seven months, 91 pools (14%) were found influenza A positive at repeated events. The virus was more commonly found on type 1 farms followed by type 2 and 3 farms. The individual swab samples of influenza A positive pools were tested for H5 subtype. Of the total 91 pools of influenza A positive samples, 455 individual samples were tested for H5 subtype and 50 (11%) individual samples were found H5 positive. The H5 subtype was found at certain points of sampling time and was more commonly found in type 2 farms followed by type 1 and was not found on type 3 farms. The H5 virus was likely to be transmitted within duck farm but was unlikely to be maintained for a long time.