Wednesday, August 01, 2018

Macao Health: Guangdong Province Reports Human H9N2 Infection


While I haven't found anything official yet on the Guangdong and Hong Kong health authority websites, Macao's Government Information Bureau is carrying the following (very) brief report on what appears to be the third H9N2 case reported out of China in 2018.

Guangdong confirmed case of human infection cases of H9N2 bird flu

2018-07-31 19:37:00

Source: Health Bureau

Health Bureau today (July 31) received notification of the Mainland health authorities in Guangdong Province confirmed case of human infection of H9N2 avian influenza. According to the briefing refers the patient was a 24-year-old woman, now living in Shenzhen. On July 21 symptoms, July 23 hospitalized, are less severe.
(Continue . . . )

Of note, there is no mention of poultry exposure in this statement.  Most (but not all) avian flu infections have been linked to recent exposure to live birds.  Hopefully we'll get a more detailed report in the days to come.

Surveillance for mild human novel flu infection in China (and for pretty much the rest of the world) is spotty at best, with only those sick enough to be admitted to a hospital usually tested.  
Even then, only sentinel hospitals participating in the Chinese Influenza Surveillance System (CISS), are likely to submit samples for testing.
This limitation was described in last June's Clinical & Epidemiological Characteristics of A(H9N2) Infection In A Young Child - China, 2017:
Because of the mild symptoms, children infected with H9N2 and other subtypes of avian influenza virus were commonly detected by sentinel hospitals of the CISS system. However, a large amount of hospitals are not covered by this system. In Changsha, there are more than 50 hospitals, excluding private clinics and health care centres, but only two hospitals are included in the CISS system.
Over the past 20 years, a little more than 3 dozen human H9N2 infections have been reported by 3 countries - China, Pakistan & Egypt - (see FluTrackers Global Cumulative H9N2 Partial Case List 1998-2017), although a 2014 seroprevalence study, found antibodies against H9N2 ranged from 5.9% to 7.5% among poultry exposed individuals in Egypt, suggesting human infection is far more common than the official numbers would suggest.  
Last March (see WHO Reports 3 H9N2 Cases In China (2017 - 2018)) we looked at 3 cases reported by China over the winter.  All three cases were described as `mild', and 2 of the 3 had recent exposure to poultry.
On the positive side, H9N2 infection in humans have generally been mild, and no human-to-human spread has been detected. Nevertheless, H9N2 is viewed as having at least some pandemic potential (see CDC IRAT SCORE), and so several candidate vaccines have been developed over the years.
Although human infections are always a concern, avian H9N2 occupies a special spot in our bird flu coverage because its internal genes routinely make up the backbone of many of the HPAI viruses that pose the greatest risks to both poultry, and human health.
For more on this fascinating, and highly promiscuous, avian flu virus you may wish to revisit:
Frontiers Public Health: Live Poultry Trading Drives China's H7N9 Viral Evolution

FAO: H9N2 In Indonesia

Reassortment After Co-infection Of Chickens With H4N6 and H9N2 influenza Viruses

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