#13,766
While avian flu activity in China - and around the world - has been fairly subdued over the past year, this morning the Government Portal in Macao has announced a new H9N2 case in neighboring Guangdong Province: China's 6th announced case for 2018.
Most infections tend to be mild (or asymptomatic) - and the virus is endemic in poultry in placed where influenza testing is relatively uncommon - all of which likely contributes to its under count.Despite relatively few documented human infections (see FluTrackers List) - and having a reputation for causing generally less severe human illness than its avian H5 & H7 cousins - LPAI H9N2 is still regarded as having some pandemic potential because:
- H9N2 has become widespread - even ubiquitous - among poultry across Europe and the Middle East
- Serological studies suggest human infection is far more common than standard surveillance would have us believe (see J. Infect & Public Health: High Seroprevalence Of Avian Influenza H9 Among Poultry Professionals In Pakistan)
- H9N2 reassorts easily with other viruses, and its internal genes are often found inside many HPAI viruses (including H5N1, H5N6, and H7N9) - (see The Lancet's Poultry carrying H9N2 act as incubators for novel human avian influenza viruses)
- H9N2 viruses continue to accrue evolutionary changes, which include mammalian adaptations, and increased binding to human receptor cells (see PLoS Path: Genetics, Receptor Binding, and Transmissibility Of Avian H9N2).
While both Egypt and Bangladesh have reported cases in the past decade, China - by far - has reported the most human infections. This is probably because they are engaged in enhanced surveillance for both H5 and H7 infections.
Last month, the WHO announced China's 4th and 5th H9N2 cases of 2018, in their latest Influenza at the Human - Animal Interface report.
Avian influenza A(H9N2) viruses
Since the last update on 1 November 2018, two new laboratory-confirmed human cases of influenza A(H9N2) virus infections were reported to WHO. On 11 December 2018, China reported the detection of avian influenza A(H9N2) viruses in two children aged < 5 years, one from Guangdong (with illness onset on 16 October 2018) province and one from Guangxi province (with illness onset on 10 October 2018).
The case from Guangdong province reportedly had exposure to backyard poultry while the case from Guangxi did not have known contact with live poultry. During epidemiological investigations, no further cases among family members were reported. Avian influenza A(H9N2) viruses are enzootic in poultry in China.Today Macao's Health Bureau published the following statement on China's 6th reported case of 2018.
While H9N2 hasn't shown the sort of virulence in humans that we've seen with H5N1 or H7N9, it is regarded as having at least some pandemic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed over the years.
Guangdong confirmed H9N2 avian influenza human infection cases
source: Health Bureau
Release date: January 2, 2019 18:16
The Health Bureau received a notification from the Mainland Health Department today (January 2) that a case of human infection with H9N2 avian influenza was confirmed in Guangdong Province. According to the report, the patient is a 32-year-old woman who lives in Shenzhen, developed symptoms on December 19, 2018, and was admitted to hospital on December 25, and her condition is mild.
Influenza viruses are classified 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 causes only local epidemics, and Type C usually causes only sporadic cases. . Influenza A virus has two main antigens: Hemagglutinin (H) and Neuraminidase (N); hemagglutinin has 1 to 16 types, and neuraminidase has 1 to 9 types. . Influenza A viruses are named after a combination of different H and N, such as the 2009 pandemic H1N1 and the current H7N9, H10N8 and so on.
The reason why influenza A is important is that H and N antigens are easy to change to produce new subtypes; but humans are not immune to new subtypes, so they often cause different degrees of prevalence. When a new type of flu virus appears in humans, there is a possibility of a worldwide pandemic because people are completely unresisting. The reason for the emergence of the new influenza virus is the recombination of the genes of the human flu virus and the non-human flu virus (such as the avian flu virus), or the re-emergence of the old subtype strain, or the animal flu virus changes the host traits.
To prevent the spread of influenza A, the Health Bureau appeals to the public to pay attention to the following matters:
The information can be found on the Health Bureau website (www.ssm.gov.mo) or by calling the Health Bureau's Infectious Disease Enquiry Hotline (28 700 800).
- Avoid places where there are many people, and places where there are people selling or displaying birds in markets such as areas where people are infected with the Avian Influenza A;
- Avoid contact with patients, birds or other animals and their secretions, excretions; if contact, wash hands immediately;
- Do not eat birds, viscera, blood products and eggs that have not been thoroughly cooked;
- Pay attention to personal hygiene and wash your hands often;
- If you have symptoms such as fever, cough, or difficulty breathing, wear a mask, seek medical attention as soon as possible, and detail the history of travel and animal contact to the doctor.
