Monday, June 03, 2019

China MOA: HPAI H5N6 Outbreak In Poultry In Western Xinjiang Province

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Xinjiang Uygur autonomous region Photo Credit- Wikipedia


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While avian flu activity in China had been greatly suppressed for more than a year following their massive (and highly successful) nationwide H5+H7 poultry vaccination campaign which started in 2017, we've begun to see a few small  cracks in the veneer. 

Over the weekend China's MOA announced a new outbreak of HPAI H5N6, this time in western Xinjiang Uygur Autonomous Region, very near the border with Kazakhstan.

The type of poultry is not mentioned. 

A highly pathogenic avian influenza outbreak of poultry H5N6 subtype in Horgos, Xinjiang

Date: 2019-05-30 21:28 Author: Source: Ministry of Agriculture and Rural Press Office

The Information Office of the Ministry of Agriculture and Rural Affairs announced on May 30 that a high-pathogenic avian influenza epidemic of poultry H5N6 subtype occurred in Horgos, Ili Prefecture, Xinjiang Uygur Autonomous Region.

On May 30, the Ministry of Agriculture and Rural Affairs received a report from the China Animal Disease Prevention and Control Center and was diagnosed by the National Avian Influenza Reference Laboratory. H5N6 subtype highly pathogenic avian influenza occurred in poultry raised by some farmers in Horgos, Ili Prefecture. epidemic.
Related farmers a total of 2445 poultry, the onset of 1503 feather, the death of more than 1015 feather.

After the outbreak, the local authorities in accordance with the relevant plans and technical requirements for prevention and control, do a good job in the handling of the epidemic situation, have smashed 11,910 poultry, all the sick and culled poultry have been harmless treatment.
Although the number of H5 and H7 avian flu breakthrough events since 2017 remain limited, they appear to have increased over the past 6 months. Granted, this could simply reflect gaps in the vaccination coverage, but we've also seen some indications that both H5N6 and H7N9 may be evolving away from the current vaccines.

Last February, the World Health Organization announced their intention to create a new H5N6 Candidate Vaccine (A/Guangdong/18SF020/2018-like A(H5N6)), noting that:
Viruses from humans, an increasing number of poultry and environmental samples from China, some poultry in Viet Nam and a wild bird (common gull) in the Russian Federation belonged to an HA subgroup not currently represented by an existing CVV (Fig. 1). 
And two weeks ago in Eurosurveillance: The re-emergence of HPAI H7N9 Human Infection in Mainland China, 2019, we saw signs that the H7N9 virus isolated from last April's Mongolian infection has drifted antigenically, as well.  They wrote:
. . . in late March 2019, we identified one HPAI H7N9 human case with fatal outcome, and HPAI H7N9 viruses with high genome identity to those of the case were detected from environmental samples. Together, these HPAI H7N9 viruses formed a subclade which exhibited a long genetic distance to the previously reported HPAI H7N9 viruses (Figure 1). 

This suggests that H7N9 viruses might still circulate in poultry at a low level in limited locations. In addition, several immune escape mutations, which had not been detected in previously reported HPAI H7N9 viruses, occurred in the HA1 proteins of these viruses (Table 1). The antigenic features of these HPAI H7N9 viruses may differ from the current HPAI H7N9 candidate vaccine strain.
A reminder that although well-suppressed by China's poultry vaccination campaign, that these viruses are far from eradicated - and with the ability to reinvent themselves over time - are fully capable of staging a comeback in the future.