Curent research

Avian influenza (AI) and Newcastle disease (ND) are two important diseases for poultry husbandry because the diseases are highly susceptibility as well as high mortality in domestic poultry (4, 5).  The virus causing avian influenza belongs to family Orthomyxoviridae. Influenza virus subtypes of 16 hemagglutinin (HA) and nine neuraminidase (NA) in various combinations have been recognized over the world (1, 2, 3). Newcastle disease virus (NDV) is a member of family Paramixoviridae. Avian paramyxovirus has nine serosubtypes and NDV is considered as avian paramyxovirus serotype 1. Wild birds are considered as reservoirs of AIV and NDV in nature. It has been known that virus can spread widely during the migration time of wild birds (3). When the high pathogenic virus such as H5N1 is infected into domestic poultry, the outbreaks will be occurred. It not only causes the big loss for the economic but also threatens public heath.

Japan is located in the mid-latitudes, there are many migratory bird inhabitants, which can be divided for the most part between summer visitor, passage birds and winter visitor. Summer visitor spend the winter in the areas spanning from southern China to Southeast Asia and migrate to Japan for breeding in April and May (summer in Japan). Passage birds are species that use Japan as a stopover when migrating in the spring from April to early May and in the autumn from August to October. Winter visitor breed in Siberia and the Arctic and migrate to Japan for wintering such as geese, ducks, swan (6).Over all, about 220 species of birds pass through Japan during their migrating time. According to our observation, resident birds and migratory birds share the same habitat with source of water and feed in Japan. Japanese people keep their custom to feed the wild bird during the winter in close distance, so that there is a chance for transmission of the pathogens to resident birds and also human in such places.

In this study, the primary examination was performed for understanding the situation of AIV and NDV infection or virus carrying in wild birds in Tokachi area where located in Hokkaido island of Japan. Even some other surveillances have been carried out to check prevalence of AI in Hokkaido - Japan but there is limited information of AI and NDV circulation in wild birds at Tokachi area. The objective of the research was to clarify more about the role if wild birds in spread of the pathogens and provide more some information to prevent and control the AIV and NDV in order to reduce and avoid the transmission of the pathogens in wild bird to poultry and human.