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2021-4-23 11:15:18


WHO: Disease Outbreak News [H5N8 detected in human clinical specimens in Russia]
submited by kickingbird at Mar, 1, 2021 9:41 AM from WHO

On 18 Feb 2021, the National IHR Focal Point for the Russian
Federation notified WHO of detection of avian influenza A(H5N8) in 7
human clinical specimens. These are the 1st reported detections of
avian influenza A(H5N8) in humans.

Positive clinical specimens were collected from poultry farm workers
who participated in a response operation to contain an avian influenza
A(H5N8) outbreak detected in a poultry farm in Astrakhan Oblast in the
Russian Federation. The laboratory confirmation of the 7 specimens was
performed by the State Research Centre for Virology and Biotechnology
VECTOR (WHO H5 Reference Laboratory). The ages of the 7 positive cases
ranged between 29 to 60 years, and 5 were female.

Between 3 and 11 Dec 2020, a total of 101 000 out of 900 000
egg-laying hens on the farm died. This high mortality rate prompted an
investigation. Samples were collected from these birds, and an initial
detection of avian influenza A(H5N8) was performed by the Russian
regional veterinary laboratory. On 11 Dec 2020, the outbreak was
confirmed by the World Organisation for Animal Health (OIE) Reference
laboratory, and the Federal Centre for Animal Health (FGBI-ARRIAH), in
Vladimir, the Russian Federation. Outbreak containment operations
started immediately and continued for several days due to the large
size of the poultry farm.

The cases remained asymptomatic for the whole follow up duration
(several weeks). Follow up nasopharyngeal swabs were collected during
the medical observation period and were tested negative for avian
influenza A(H5N8). No obvious clinical manifestations were reported
from any farm workers under medical surveillance, their family
members, or other close contacts of the 7 cases. Additionally, acute
and convalescent sera were collected from the 7 positive human cases
for serological testing. The results were suggestive of recent
infection.

Influenza A(H5N8) viruses isolated from this poultry outbreak in
Astrakhan belonged to clade 2.3.4.4b of avian influenza A(H5Nx)
viruses. In 2020, avian influenza A (H5N8) viruses were also detected
in poultry or wild birds in Bulgaria, the Czech Republic, Egypt,
Germany, Hungary, Iraq, Japan, Kazakhstan, the Netherlands, Poland,
Romania, the United Kingdom, and the Russian Federation.

On receiving the initial signal of a probable outbreak of highly
pathogenic avian influenza (HPAI) at the poultry farm on 3 Dec 2020,
the national authorities took immediate measures including cessation
of poultry production cycles and product transportation from the
affected farm.

Between 11 and 18 Dec 2020, several measures, including culling and
disposing of poultry, eggs, and litter, and disinfection of
contaminated premises, were taken as part of outbreak response
activities.

During and after the culling of all the poultry, nasopharyngeal swabs
and serum samples were collected from poultry farm workers and
personnel involved in outbreak response at the farm. Surveillance
activities, both within and outside of the containment area, were
intensified. A total of 24 close contacts of the confirmed cases have
been identified and traced. In total, 150 individuals were monitored
for clinical indication of respiratory disease, and they received
antiviral prophylaxis therapy. No symptoms were reported among these
individuals.

Whole Genome Sequencing of avian influenza A (H5N8) viruses isolated
from poultry and from one of the 7 human cases was performed and
uploaded to the Global Initiative on Sharing All Influenza Data
(GISAID) database on 20 Feb 2021. Genetic and phenotypic
characterization of the virus is ongoing.

WHO is following up with public health authorities in the Russian
Federation, including implementation of public health measures
warranted by such events, and with the WHO Global Influenza
Surveillance and Response System (GISRS) on further analysis and
assessment of the virus materials and serum samples. On 20 Feb 2021, a
special briefing by the head of the Federal Service for Surveillance
on Consumer Rights Protection and Human Wellbeing was organized for
the state Russian media to inform the public about these cases and the
implications.

Since 2004, avian influenza A(H5) viruses have spread from Asia to
Europe via wild birds. The genetic clade 2.3.4.4 H5 viruses have often
reassorted among other avian influenza viruses, resulting in avian
influenza A(H5N1), A(H5N2), A(H5N3), A(H5N5), A(H5N6) and A(H5N8)
viruses, some of which have been detected in birds in many countries.

In the Russian Federation, avian influenza A(H5N8) of clade 2.3.4.4
was isolated for the 1st time in 2014 in a wild bird in the northern
region of the Russian Far East.

As mentioned earlier, all the 7 cases with PCR-positive results were
clinically asymptomatic. All close contacts of these cases were
clinically monitored, and no one showed signs of clinical illness.
Infections with avian influenza viruses of the same clade (H5 clade
2.3.4.4) have been reported from China since 2014 in people with
exposure to infected birds. The likelihood of human infections with
influenza A(H5N8) viruses has been considered to be low.

Further genetic and antigenic characterization and information on
seroconversion among contacts of the positive cases is required to
fully assess the risk.

The development of zoonotic influenza candidate vaccine viruses for
potential use in human vaccines, coordinated by WHO, remains an
essential component of the overall global strategy for influenza
pandemic preparedness.

Based on currently available information, the risk of human-to-human
transmission remains low.

These cases do not change the current WHO recommendations on public
health measures and surveillance of animal and seasonal human
influenza, which should continue to be implemented. Respiratory
transmission occurs mainly by droplets, disseminated by unprotected
coughs and sneezes. Short-distance airborne transmission of influenza
viruses may occur, particularly in crowded enclosed spaces. Hand
contamination, direct inoculation of virus, exposure to infected birds
or virus-contaminated materials or environments are potential sources
of infection.

When avian influenza viruses are circulating in an area, the people
involved in specific, high-risk tasks such as sampling sick birds,
culling and disposing of infected birds, eggs, and litter, and
cleaning of contaminated premises should be trained on how to protect
themselves, and on proper use of personal protective equipment (PPE).
People involved in these tasks should be registered and monitored
closely by local health authorities for 7 days following the last day
of contact with poultry or their environments.

Due to the constantly evolving nature of influenza viruses, WHO
continues to stress the importance of global surveillance to detect
virological, epidemiological and clinical changes associated with
circulating influenza viruses that may affect human (or animal) health
and timely virus sharing for risk assessment.

Thorough investigation of all potential novel influenza human
infections is warranted. All human infections caused by a novel
influenza subtype are notifiable under the International Health
Regulations (IHR), and State Parties to the IHR are required to
immediately notify WHO of any laboratory-confirmed case of a recent
human infection caused by a new influenza A subtype with the potential
to cause a pandemic (please see case definitions for diseases
requiring notification under the IHR). Evidence of illness is not
required.

In the case of a confirmed or suspected human infection, a thorough
epidemiological investigation of history of exposure to animals, of
travel, and contact tracing should be conducted, even while awaiting
the confirmatory laboratory results. The epidemiological investigation
should include early identification of unusual respiratory events that
could signal person-to-person transmission of the novel virus.
Clinical samples collected from the time and place that the case
occurred should be tested and sent to a WHO Collaboration Center for
further characterization.

Travelers to countries with known outbreaks of avian influenza should
avoid farms, contact with animals in live animal markets, entering
areas where animals may be slaughtered, or contact with any surfaces
that appear to be contaminated with animal feces. Travelers should
also wash their hands often with soap and water. Travelers should
follow good food safety and good food hygiene practices.

Based on the currently available information, WHO advises against any
special traveler screening at points of entry or restrictions on
travel and/or trade with the Russian Federation.

For further information and details, please see:
- Current technical information including monthly risk assessments at
the Human-Animal Interface WHO
- WHO Influenza virus infections in humans October 2018
- Case definitions for diseases requiring notification under the IHR
(2005)
- International Health Regulations IHR (2005)
- Manual for the laboratory diagnosis and virological surveillance of
influenza (2011)
- Terms of Reference for National Influenza Centers of the Global
Influenza Surveillance and Response System.
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