Avian flu studies reveal climate change impacts, unknown virus presence

Additional cases of highly pathogenic avian influenza (HPAI) have been confirmed in the poultry sectors of Nigeria and Taiwan, while a new virus has been detected at live bird markets in Bangladesh for the first time. A health professional considers there may have been more human cases of the disease in Nepal, and disease experts have been examining the likely impacts of climate change on avian flu viruses.

(Wol Wol | Freeimages.com)
(Wol Wol | Freeimages.com)

Additional cases of highly pathogenic avian influenza (HPAI) have been confirmed in the poultry sectors of Nigeria and Taiwan, while a new virus has been detected at live bird markets in Bangladesh for the first time. A health professional considers there may have been more human cases of the disease in Nepal, and disease experts have been examining the likely impacts of climate change on avian flu viruses.

In the long-running battle to control the H5N2 HPAI virus in Taiwan, a further five recent outbreaks of the disease in poultry have been confirmed. Almost 43,000 more birds have succumbed to the disease directly as the result of mortality or culling.

In the period May 14-24, according to the official report from the Council of Agriculture to the World Organisation for Animal Health (OIE), the presence of the virus was confirmed in three flocks of native chickens, and one each of meat ducks and laying ducks. Three of the farms were located in the county of Yunlin, and the others in Pingtung and Changhua.

New avian flu outbreak in Nigerian poultry

A total of 20 cases of HPAI caused by the H5N8 virus variant were identified among chickens, ducks, and turkeys at a livestock market in the Oba area of Edo state in April, according to the latest official report from the federal agriculture ministry to the OIE.

Surveillance at the market may have been linked to an outbreak of HPAI at a farm in the same state earlier in the month.

Evidence of the H5N6 HPAI virus in Bangladesh

The H5N6 subtype of the HPAI virus was detected in waterfowl in Bangladesh in 2016 and 2017, according to a paper published recently in Virology.

There have been several waves of HPAI outbreaks in poultry and people linked to the H5N1 virus variant in the south Asian country since 2007, but this work provides the first evidence of the presence of the H5N6 subtype, according to Genyan Yang of the Centers for Disease Control in Atlanta, and co-authors.

Surveillance of live bird markets was set up to identify emerging disease risks to both poultry and people, but no infections linked to this virus variant have so far been confirmed in Bangladesh.

How climate change could impact avian influenza

Researchers based in the U.S. have identified some of the factors linked to climate change that could impact on avian influenza viruses.

Key for the intercontinental transport of the virus is known to be meeting points for migrating birds. According to Matthew Scotch of Arizona State University (ASU), changes to the climate in East Asia and Beringia — which covers the area between western Alaska and Russia’s Far East — could affect migration patterns, the overlap of species, and viral shedding and reassortment.

These same factors could combine with different effects on intracontinental transport of the virus, and on its local transmission from wild birds to domestic poultry.

Together with ASU colleagues and scientists at the University of Washington, Scotch co-authored a paper about the impacts of climate change in avian flu viruses published in Environment International in October 2018.

More human cases of avian flu suspected in Nepal

Confirmed earlier this month, Nepal’s first known human case of avian influenza A (H5N1) occurred in March. The patient — a young man from Kathmandu—died at the end of that month.

According to the chief of a tropical and infectious diseases hospital in the country, there are likely to have been other cases, but a lack of laboratory facilities has prevented verification of the infection.

In an opinion piece in The Himalayan Times, Dr. Sher Bahadur Pun reports knowing of three patients with typical symptoms of respiratory disease and fever who had had contact with sick or dead poultry prior to their illness.

Recent mass mortality of crows in the capital, Kathmandu, may also have been caused by the H5N1 virus, according to Pun. He called for nationwide virus screening to be put in place for the country’s farmers, veterinarians, and others involved in the poultry chain, as well as healthcare providers.

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