Tuesday, September 11, 2012

PRO/AH/EDR> Avian influenza (53): Viet Nam, H5N1 virus evolution

[editing is mine]
Published Date: 2012-09-10
A new bird flu strain is developing unexpectedly in Viet Nam and causing great concern to the government and public.
According to the National Animal Health Diagnosis Center, the new strain of bird flu virus, which is suspected to have higher risk of causing human death than previously known ones [see comment], appeared in July 2012 and widely spread in August 2012 in Viet Nam’s 7 central and northern provinces.
Hoang Van Nam, head of Ministry of Agriculture and Rural Development (MARD)’s Animal Health Department, said that this virus, thought to belong to H5N1 Clade, is different from the 2 strains of A and B that appeared in Viet Nam in 2011, due to its higher pathogenic risk [pathogenicity].
According to the department, as of 6 Sep 2012, the new virus strain has attacked 7 central and northern cities and provinces, including Hai Phong, Thanh Hoa, Ha Tinh, Ninh Binh, Nam Dinh, Bac Can and Quang Ngai, and over 180 000 infected poultry have been culled so far this year [2012].
Apart from the newly-found strain of the virus, the bird flu has developed unexpectedly in the country so far this year [2012]. Normally, avian influenza appears shortly before or after the traditional lunar Tet holidays (which often fall in late January and early February). However, it has appeared since July this year [2012] and spread fast without warning. In the Central Highlands’ Dak Lak province, about 30 influenza epidemic spots were found in only one day.
According to local experts, the epidemic will become more complicated once it reaches its peak in the coming months.
MARD has instructed the department to strictly supervise the import of poultry, especially breeding chicks, which are believed to make the suspected new strain virus spread faster [Are imported breeding chicks (from where?) suspected of introducing infection or of being excessively susceptible to local infection? Clarification will help. - Mod.AS].

Meanwhile, according to the Central Epidemic Prevention Institute, since August last year [2011], the UN Food and Agriculture Organization (FAO) has warned of the change of the virus A/H5N1. Clade 2.3.2 is in many Asian countries, including Viet Nam, and that change is usual during the natural evolution of the virus.
“This is a small change of the virus that creates a new strain, not yet a new virus. However, close supervision of the virus which is spreading among poultry should be taken so as to discover its change and set forth an appropriate strategy to fight the epidemic and protect human health,” the Institute Director Nguyen Tran Hien told local media late last week.
“Through strict supervision on human flu infected cases, we found nothing unusual. The most concern is that the virus A/H5N1 is spreading among poultry, and it can continue to have small changes, re-arrange the gene, and reunite with virus circulated among animals and human beings to become a new, highly-toxic strain and transmissible to human beings,” Hien said.
He also suggested the veterinary sector closely cooperate with the health service to enhance supervision on the avian flu among poultry and human beings as well as apply preventive measures so as to prevent the spreading of the disease among poultry and from poultry to human beings.
As of 6 Sep 2012 [since the beginning of 2012], 4 [human] cases of A/H5N1 infection have been recorded with 2 deaths in Viet Nam, but the new strain of bird flu virus has not yet been found in humans, reported MARD.

Communicated by:
Nati Elkin
[The above report, from Chinese sources, adds complementary information to posting 20120908.1286497.
We are indebted to Joseph P. Dudley, Ph.D. for the following comment, following the information included in posting 20120909.1287382:
"The cross-border smuggling trade in spent layers [hens] between China and Viet Nam is huge, highly sophisticated, and has been going on for at least a decade and probably longer.
The spent layer trade may have played a significant role in the H5N1 outbreaks in Turkey during 2006, and may potentially be [or] have been a major enabling factor in the establishment and proliferation of H5N1 in Egypt.”
The statement included in the above Xinhua report, arguing that the new strain of bird flu virus “is suspected to have higher risk of causing human death than previously known ones” is not supported by evidence and is in need of substantiation.
According to WHO data, since 2003, Viet Nam has suffered 123 human cases of H5N1, of which 61 died. Most of the cases occurred during 2004/5. – Mod.AS


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