Category Archives: H7N9 Avian flu (13)

Influenza A virus causes influenza in birds and some mammals, and is the only species of influenza virus A. Influenza virus A is a genus of the Orthomyxoviridae family of viruses. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon. Some isolates of influenza A virus cause severe disease both in domestic poultry and, rarely, in humans.[1] Occasionally, viruses are transmitted from wild aquatic birds to domestic poultry, and this may cause an outbreak or give rise to human influenza pandemics.[2][3]
Influenza A viruses are negative-sense, single-stranded, segmented RNA viruses. The several subtypes are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). There are 18 different H antigens (H1 to H18) and 11 different N antigens (N1 to N11).[4][5] H17 was isolated from fruit bats in 2012.[6][7][8] H18N11 was discovered in a Peruvian bat in 2013.[5]
Each virus subtype has mutated into a variety of strains with differing pathogenic profiles; some are pathogenic to one species but not others, some are pathogenic to multiple species.
A filtered and purified influenza A vaccine for humans has been developed, and many countries have stockpiled it to allow a quick administration to the population in the event of an avian influenza pandemic. Avian influenza is sometimes called avian flu, and colloquially, bird flu. In 2011, researchers reported the discovery of an antibody effective against all types of the influenza A virus.[9]

H7N9 is a bird flu strain of the species Influenza virus A (avian influenza virus or bird flu virus). Avian influenza A H7 viruses normally circulate amongst avian populations with some variants known to occasionally infect humans. An H7N9 virus was first reported to have infected humans in March 2013, in China.[2] Cases continued to be reported throughout April and then dropped to only a few cases during the summer months. At the closing of the year, 144 cases had been reported of which 46 had died.[3][4][5] It is known that influenza tends to strike during the winter months, and the second wave, which began in October, was fanned by a surge in poultry production timed for Chinese New Year feasts that began at the end of January. January 2014 brought a spike in reports of illness with 96 confirmed reports of disease and 19 deaths.[6][7] As of April 11, 2014, the outbreak’s overall total is 419, including 7 in Hong Kong, and the unofficial number of deaths is 127.[8][9][10]

The World Health Organization (WHO) has identified H7N9 as “…an unusually dangerous virus for humans.”[11] Most of the cases resulted in severe respiratory illness, with a mortality rate of roughly 30 percent.[12] [13] Researchers have commented on the unusual prevalence of older males among H7N9-infected patients.[14] While several environmental, behavioral, and biological explanations for this pattern have been proposed,[15] as yet, the reason is unknown.

H5N8 avian flu resurfaces in South Korea

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Highly pathogenic H5N8 avian influenza was confirmed Jul 25 on a duck farm in South Korea, according to a Korea Joongang Daily story today, resulting in the culling of more than 40,000 birds on the farm and others in surrounding areas.

The farm is in Hampyeong county, which is in the southwestern province of South Jeolla. The virus was detected when sanitation officials conducted tests on the farm for approval of its products for sale, says the story. H5N8 was confirmed the same day.

In addition to destroying some 42,000 birds on the farm, about 2,000 chickens on another farm within a 500-meter radius were also killed, and transport of animals from farms within 10 kilometers of the infected farm were restricted.

The avian flu outbreak comes shortly before the Chuseok holidays in early September, when consumer demand for meat increases, and on top of discovery of foot-and-mouth disease in hogs at a farm in Uiseong County, South Gyeongsang.

South Korea had a series of H5N8 outbreaks in January and February, prompting the culling of millions of poultry, and at least one outbreak was reported in June.