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| Range Of Endemic H9N2 Viruses |
#16,799
When it comes to novel flu viruses with pandemic potential, LPAI H9N2 - which is ubiquitous in poultry across much of Asia - is pretty far down our worry list. While we've seen an uptick in human infections the past few years, most (but not all) have been mild.
In May of 2020, the CDC added a new lineage (H9N2 Y280 lineage [A/Anhui-Lujiang/13/2018]) to their short list of novel flu viruses with at least some pandemic potential, although it would not be expected to have the same impact as an H5 or H7 avian flu.Although human infection with H9N2 has only rarely been reprted over the past 2 decades (roughly 100 cases), it is almost certainly happens more often than we know (see J. Infect & Public Health: High Seroprevalence Of Avian Influenza H9 Among Poultry Professionals In Pakistan).
In their 2019 analysis, they do note the following traits :
- Human Infections: Sporadic human cases were reported. Limited information exists, but no confirmed reports of spread between humans. Information meets the definition of moderate risk for this element.
- Transmission in Laboratory Animals: In ferret studies, this virus transmitted well by direct contact between animals, and consistently by respiratory droplets, suggesting a high risk for this element.
- Receptor Binding: The predicted amino acid sequence of HA protein indicates that this virus possesses residues that may promote binding to human receptors. Only weak binding to 2,3 and 2,6 glycans has been observed in glycan array studies with recombinant HA.
- Population Immunity: Limited data are available, but the expectation of cross-reactive antibodies in humans to this virus is low. However, some level of cross-reactive antibodies may be possible in individuals with past exposure to seasonal viruses.
H9N2's greatest claim to fame, however, is its ability to reassort with other - sometimes far more worrisome - viruses. Often, when new HPAI flu strains emerge – if you look deep enough – you’ll find LPAI H9N2 was part of the process (see PNAS: Evolution Of H9N2 And It’s Effect On The Genesis Of H7N9).
Three years ago, in EID Journal: Two H9N2 Studies Of Note, we looked at two reports which suggest that H9N2 continues to evolve away from current (pre-pandemic and poultry) vaccines and is potentially on a path towards better adaptation to human hosts.
So, while its impact remains limited, and its pandemic potential fairly low, we track (as best as we can) reports of human infection with this H9 virus.
Today Macao's Health Service is reporting on two mild cases, reported on the Mainland.
2 confirmed cases of human infection with H9N2 avian influenza in Hunan and Guizhou provinces
source: Health Service (SS) release date:2 June 2022 19:00
The Health Bureau stated that according to the latest notification from the mainland health department, a total of 2 cases of human infection with H9N2 avian influenza were confirmed in Hunan and Guizhou provinces, and residents were urged to avoid contact with birds and pay attention to personal and food hygiene.
According to the report, one of the patients is a 5-year-old boy who lives in Yueyang City, Hunan Province. He developed symptoms on April 26, 2022, and was diagnosed on June 2, 2022. His condition is mild and there were live poultry market activities before the onset. history. The other patient is a 2-year-old boy who lives in Bijie City, Guizhou Province. He developed symptoms on May 8, 2022, and was diagnosed on June 1, 2022. His condition is mild and he has a history of live poultry market activity before the onset.
Influenza viruses are mainly divided into three types: A (A), B (B), and C (C). Type A can cause a worldwide pandemic, so it is particularly important; type B generally only causes local epidemics, and type C often only causes sporadic case. Influenza A virus has two main antigens on the surface of hemagglutinin ( H emagglutinin, H) and neuraminidase ( N euraminidase, N); hemagglutinin has 1 to 16 types, and neuraminidase has 1 to 16 types. Type 9. Influenza A viruses are named after different combinations of H and N, such as H1N1 in the 2009 pandemic and now H7N9, H10N8, etc. Influenza A is important because the H and N antigens are easy to change to produce new subtypes; but humans are not immune to the new subtypes, so they often cause different degrees of prevalence; when a brand new influenza virus appears in humans At that time, because human beings have no resistance at all, there is a possibility of a worldwide pandemic. The reasons for the generation of new influenza viruses are the recombination of the genes of human influenza viruses and non-human influenza viruses (such as avian influenza viruses), or the re-emergence of old subtype strains, or the change of host specificity of animal influenza viruses.
To prevent influenza A infection, the Health Bureau urges the public to pay attention to the following:
For more information, please refer to the Health Bureau's website (www.ssm.gov.mo) or call the Health Bureau's Infectious Disease Enquiry Hotline (28 700 800).
- Avoid going to markets and farms where there are many people and where there are outbreaks of avian influenza A, where poultry is sold or displayed;
- Avoid contact with sick people, birds or other animals and their secretions and excrement; if there is contact, wash hands immediately;
- Do not eat undercooked poultry meat, offal, blood products and eggs;
- Pay attention to personal hygiene and wash your hands frequently;
- If you have symptoms such as fever, cough, and difficulty breathing, you should wear a mask, seek medical attention as soon as possible, and report your travel history and animal contact history to the doctor.
