鳥インフルエンザの正体とその克服法

Abstract

Highly pathogenic avian influenza virus (HPAIV) causes lethal infection in gallinaceous poultry such as chickens. HPAIV is generated when a nonpathogenic virus brought in by migratory birds from nesting lakes in the north is transmitted to chickens via domestic ducks, geese, quails, etc. and acquires pathogenicity for chickens with repeated multiple infections in the chicken population. Now H5N1 HPAIV has spread to 62 countries in Eurasia and Africa. H5N1 HPAIVs were isolated from dead water birds in Mongolia and Hokkaido, Japan on the way back to their nesting lakes in Siberia in April to May 2005, 2006, 2008, 2009 and 2010. It is concerned that these HPAI viruses may perpetuate in the lakes where migratory water birds nest in summer. On 14th October in 2010, 2 H5N1 HPAIVs were isolated from fecal samples of ducks who flew from Siberia to Ohnuma Lake in Wakkanai, Hokkaido, Japan. Since then, 24 outbreaks of avian influenza due to infection with the H5N1 viruses closely related to the viruses isolated from fecal samples of ducks in Hokkaido in October 2010 have occurred in 9 different prefectures in Japan until the end of March 2011. The other serious concern is that 620 people have been infected with the H5N1 virus, 60% of whom died in 15 countries since 2004 (as of 15 February 2013). It is noted that most of the human cases (86%) are in China, Viet Nam, Indonesia, and Egypt where bird flu vaccines are used. It is strongly proposed to eradicate the H5N1 HPAIVs from Asia by stamping-out without misuse of vaccine through international collaboration under the umbrella of ”One World, One Health” concept.