Infectious Diseases 2021

Infectious Diseases 2021

Eurosurveillance: data on H5N8 isolated from a Russian poultry worker

Eurosurveillance: Vol 26, Issue 24, 17/Jun/2021 19 June, 2021

In December 2020, the RNA of avian influenza A(H5N8) virus was detected in nasopharyngeal swabs taken from seven poultry workers during an outbreak at a large poultry farm in the Astrakhan region on the Volga River in southern Russia. An influenza A(H5N8) virus isolate was obtained from one human clinical specimen.
The outbreak of highly pathogenic avian influenza (HPAI) occurred at the Vladimirovskaya poultry farm located in Astrakhan region, Russia. The total flock size at the poultry farm was 924,612 chickens of all ages. On 3 December 2020, the first 750 chickens died and additional mortality was later observed at the site. All birds had the same symptoms (diarrhoea, conjunctivitis, haemorrhagic lesions of the respiratory and digestive tract). The Astrakhan Veterinary Laboratory preliminarily detected influenza A(H5) viral RNA in poultry tissue samples (lung, trachea, intestine, spleen) from a subset of 18 dead birds on 7 December 2020. On the same day, upon receiving notification about the situation, the Russian Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing (Rospotrebnadzor) immediately ordered the suspension of production on the affected farm and a recall of live birds and poultry products produced on this farm from markets throughout the country. Therefore, by 11 December 2020, 101,000 poultry had died on the farm, and the remaining poultry was slaughtered. Influenza A(H5)-positive specimens from 10 chickens from various representative locations on the farm were selected for further analysis.
Fifty-six farm workers had contact with dead birds or were present at the site since the start of the outbreak. On 12 December 2020, 56 serum samples and 37 nasopharyngeal swabs from these 56 poultry workers were collected simultaneously by the Akhtubinsk District Hospital (for 37 individuals, both serum and swabs were collected). Medical follow-up was established for 150 persons (the poultry farm workers and their family members), and prophylaxis with antiviral drugs was initiated for all 150. According to the district hospital, all of them remained asymptomatic during the 21-day follow-up period.
On 17 December 2020, 10 samples from 10 chickens and 56 serum samples and 37 nasopharyngeal swabs from poultry farm workers were transferred to the State Research Centre of Virology and Biotechnology ‘Vector’ for virological analysis. Serum was re-sampled 14 and 44 days after 12 December 2020 from seven poultry workers in whose swabs influenza A RNA had been detected. The seven persons were aged between 29 and 60 years, five were female and two were male.
The presence of influenza A(H5) viral RNA was detected by RT-PCR (Interlabservice, Moscow, Russia) in all 10 analysed avian samples. Seven human nasopharyngeal swabs were positive for influenza A, five of which were positive for influenza A(H5) in RT-PCR analysis. All seven human samples were subtyped as influenza A(H5N8) by partial sequencing of the haemagglutinin (HA) and neuraminidase (NA) gene amplicons obtained using nested PCR. Avian influenza viruses were isolated from 10 avian samples after one passage in an embryonated chicken egg (ECE). No viruses were isolated from human samples after three passages in ECE. Only one influenza virus, A/Astrakhan/3212/2020(H5N8), was isolated from our human samples when propagated in Madin-Darby Canine Kidney (MDCK) cells.Strain A/Astrakhan/3212/2020 had the polybasic proteolytic cleavage site (PLREKRRKR/G) in HA.