Widespread avian flu continues; China details H5N8 clues

Poland today reported another highly pathogenic H5N5 avian flu detection, as Nigeria reported another outbreak involving the H5N8 strain in poultry, signaling that the virus is still circulating in parts of Africa.

In other developments, more European countries reported new H5N8 outbreaks, Chile reported another outbreak involving low-pathogenic H7N6, and Chinese researchers described H5N8 findings in wild birds found dead in Qinghai Lake in central China.

Poland reports H5N5 for the second time

Poland's agriculture ministry today said H5N5 has been detected again, this time in a mute swan found dead on Jan 31in Lower Silesia province in the country's southwest, according to a report to the World Organization for Animal Health (OIE).

The announcement comes just 5 days after Poland's first report of H5N5, also involving mute swans from the same province.

Poland is among seven European countries to report recent H5N5 outbreaks.

H5N8 in Nigeria

Elsewhere, Nigerian officials today reported a second H5N8 outbreak to the OIE, which involves poultry at a livestock market. The report said that tracheal sampling that revealed the virus in four ducks was done at a market in Kano province as part of a trace-back investigation.

Kano province is in north central Nigeria and is where H5N8 was first detected in mixed poultry in the middle of December. Since then the virus has been linked to outbreaks in Uganda. H5N8 has been spreading from wild birds to poultry over the past few months in countries along migration routes from Europe to Africa.

Nigeria has also been battling a spate of H5N1 outbreaks, as well.

Three European nations report more H5N8

In their latest reports to the OIE, three European countries reported more H5N8 outbreaks in wild birds and poultry:

  • Czech Republic officials reported 9 more outbreaks, 8 in backyard poultry and 1 on a farm housing 21,300 ducks. The events began from Feb 3 to Feb 7, affecting birds in five different regions across a wide part of the country. The virus killed 367 of 21,800 birds, with the remaining ones culled as a response step.
  • The Netherlands reported two more outbreaks in wild birds found dead in different villages in North Holland province on Jan 31 and Feb 1.
  • Poland reported eight more outbreaks in wild birds, mainly swans and mallards, found dead in five different provinces from Jan 30 to Feb 6.

Chile confirms more H7N6

Signaling its third such outbreak since early January, Chile's agriculture ministry yesterday reported another low-pathogenic H7N6 outbreak, according to another OIE report.

All three of the outbreaks have occurred in Valparaiso in central Chile, with the first two events occurring at farms that were related to each other. However, the latest outbreak, which began in Jan 28, struck backyard birds. The five birds that tested positive were all chickens, but the facility also housed ducks, geese, and turkeys.

Investigators found that the outbreak is near the site of the second H7N6 outbreak, and that a business located there has connections to the two earlier outbreaks, reflecting a strong epidemiologic link. Authorities have isolated the new outbreak location and have preemptively culled birds there and on nearby farms. Further tests on other backyard birds in the area have been negative for the virus.

China shares H5N8 findings

Meanwhile, Chinese researchers yesterday described H5N8 findings in a wild bird die-off at Qinghai Lake, a breeding and stopover site for waterfowl along the Central Asian Flyway, that killed 158 birds in May 2016. They published their results in an early online edition of Emerging Infectious Diseases.

The team sequenced 48 isolates, identifying a group B H5N8 virus that emerged in Qinghai Lake, causing the deaths of the birds. They said the virus descended from a triple-reassortant strain. The reassortment may have occurred in waterfowl and can be traced to early 2016, but the investigators said they can't pinpoint the location where it occurred, because the genes came from different sites.

The researchers noted that the lack of poultry around Qinghai Lake is a strong clue that the virus was introduced by wild birds, and they noted that the timing of the deaths there coincides with the detection of H5N8 in wild migratory birds in Ubsu-Nur Lake on the Mongolia-Russia border.

"This finding suggests that the early summer movement of wild migratory birds from unknown southern sites to northern breeding grounds resulted in the introduction of H5N8 to Qinghai Lake and to Ubsu-Nur Lake, infecting a diverse population of breeding waterbirds," the authors wrote. They added that recent H5N8 strains from other countries are highly similar to the H5N8 strain found at Qinghai Lake, suggesting that the viruses may have already spread to other areas along the flyways.

Last September, the United Nations Food and Agriculture Organization warned countries to be on the lookout and to prepare for a highly pathogenic H5N8 clade that had been detected in Russian migratory birds in early June. Since then, several countries in Asia, Europe, the Middle East, and Africa have reported detections.

See also:

Feb 8 OIE report on H5N5 in Poland

Feb 8 OIE report on H5N8 in Nigeria

Feb 8 OIE report on H5N8 in the Czech Republic

Feb 8 OIE report on H5N8 in the Netherlands

Feb 8 OIE report on H5N8 in Poland

Feb 8 OIE report on H7N6 in Chile

Feb 7 Emerg Infect Dis report

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