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One of the side benefits of China’s stepped up surveillance for the H7N9 influenza virus is that other, uncommon influenza infections are being detected as well. Earlier this month, in HK CHP Notified Of Fatal H10N8 Infection In Jiangxi, we saw the first confirmation of a human H10N8 infection, and last summer, Taiwan CDC Reports Human Infection With Avian H6N1.
While we normally talk about the seasonal (and variant) H1N1 and H3N2 viruses, along with the avian H5N1 and newly emerging H7N9 viruses, we’ve covered other rarely seen flu viruses that have been detected in humans, as well. A small sampling includes:
In 2003, an outbreak of H7N7 at a poultry farm in the Netherlands went on to infect at least 89 people (mostly mildly, but 1 death), and many more may have been infected subclinically.
In Egypt - in 2004 - 2 infants were shown to be infected by the H10N7 avian flu virus.
In 2006 1 person in the UK was confirmed to have contracted H7N3, and the following year, 4 people tested positive for H7N2 – both following local outbreaks in poultry.
In 2012, in EID Journal: Human Infection With H10N7 Avian Influenza, we learned of H10N7 avian influenza virus detected in two poultry abattoir workers in Australia from 2010. Although 7 abattoir workers reported symptoms, only 2 tested positive for the H10 virus.
And this past summer, in ECDC Update & Assessment: Human Infection By Avian H7N7 In Italy, we saw 3 human infections with this H7 virus.
Since testing for non-standard influenza viruses is rarely done, we honestly don’t know how often these seldom seen influenza strains infect humans. But it is probably more common than the numbers above would have us think.
Not mentioned above, but also a `player’ in the world of avian influenza, is the H9N2 virus, which is ubiquitous in poultry across much of Asia, has been known to infect humans in the past - and perhaps most notoriously - contributed some of its internal genes to both H5N1 and the H7N9 virus.
In September of 2013, in the World Health Organization document Antigenic and genetic characteristics of A(H5N1), A(H7N3), A(H9N2) and variant influenza viruses and candidate vaccine viruses developed for potential use in human vaccines, H9N2 is described:
Influenza A(H9N2)
Influenza A(H9N2) viruses are enzootic in poultry populations in parts of Africa, Asia and the Middle East. The majority of viruses that have been sequenced belong to the G1, chicken/Beijing (Y280/G9), or Eurasian clades. Since 1998, when the first human infection was detected, the isolation of A(H9N2) viruses from humans and swine has been reported infrequently. In all human cases the associated disease symptoms have been mild and there has been no evidence of human-to-human transmission.
Over the past 15 years H9N2 has been reported a handful of times, including in Hong Kong in 1999 (2 cases), 2003 (1 case), and 2007 (1 case). . Several additional human H9N2 virus infections were reported from China in 1998-99, and all known cases were mild. More recently, in 2011 we learned Bangladesh To Share H9N2 Bird Flu Virus after detecting a case there.
Today, we get the following statement on a case from Shenzhen, China which is being treated at a hospital in neighboring Hong Kong.
The Centre for Health Protection (CHP) of the Department of Health (DH) is today (December 30) investigating a confirmed human case of influenza A(H9N2) affecting a man aged 86.
The patient is a Hong Kong resident living in Huangbeiling, Luohu, Shenzhen. He has underlying illnesses and has developed chills and cough with sputum since December 28. Upon entry at Lo Wu Border Control Point (BCP) on the same day, he was transferred by ambulance direct to the Accident and Emergency Department of North District Hospital (NDH), where he presented with low fever. He was then admitted to the isolation ward. He was transferred to Princess Margaret Hospital today for further management.
His clinical diagnosis was chest infection. He has been in stable condition all along and is currently afebrile.
His sputum specimen tested positive for the influenza A(H9N2) virus upon testing by the CHP's Public Health Laboratory Services Branch.
"The epidemiological investigations, enhanced disease surveillance, port health measures and health education against avian influenza are all ongoing," a spokesman for the DH remarked.
Investigations by the CHP revealed that the patient had no recent poultry contact, consumption of undercooked poultry, or contact with patients. His home contact in Shenzhen has remained asymptomatic.
Over 50 health-care workers of NDH and the ambulance service have been put under medical surveillance.
"The H9N2 virus is of avian origin and has been isolated mainly from poultry. Rare and sporadic human cases have been reported and are generally mild respiratory tract infections. The public should avoid contact with poultry and other birds, including chickens, ducks and sparrows," the spokesman explained.
Influenza A(H9) is a local statutorily notifiable infectious disease. Two local cases were reported in 1999. One local case was respectively filed each in 2003 and 2007. An imported case was recorded in 2008 while an imported case and one with the source of infection unclassified were filed in 2009. All are mild infections and the patients have recovered. No deaths have been recorded so far.
Locally, enhanced surveillance over suspected cases in public and private hospitals is under way.
As the patient was staying in Shenzhen for the whole incubation period, the CHP will inform the health authority of Guangdong of the case for necessary investigation and follow-up action.
The case will also be notified to the World Health Organization (WHO), the National Health and Family Planning Commission, and the health authority of Macau.
The CHP will issue letters to doctors and hospitals to keep them abreast of the latest situation.
"We will remain vigilant and maintain liaison with the WHO, the Mainland and overseas health authorities. Local surveillance activities will be modified according to the WHO's recommendations," the spokesman said.
"All BCPs have implemented disease prevention and control measures. Thermal imaging systems are in place for body temperature checks of inbound travellers. Suspected cases will be immediately referred to public hospitals for follow-up investigation," the spokesman added.
Regarding health education for travellers, distribution of pamphlets, display of posters in departure and arrival halls, in-flight public announcements, environmental health inspection and provision of regular updates to the travel industry via meetings and correspondence are all proceeding.
"We have enhanced publicity and health education against avian influenza. The CHP has also sent letters to government departments and related organisations to reinforce health advice against avian influenza," the spokesman said.
"Travellers, especially those returning from avian influenza-affected areas and provinces with fever or respiratory symptoms, should immediately wear masks, seek medical attention and reveal their travel history to doctors. Health-care professionals should pay special attention to patients who might have had contact with poultry, birds or their droppings in affected areas and provinces," the spokesman advised.
Members of the public should remain vigilant and take heed of the preventive advice against avian influenza below:
- Do not visit live poultry markets. Avoid contact with poultry, birds and their droppings. If contact has been made, thoroughly wash hands with soap;
- Poultry and eggs should be thoroughly cooked before eating;
- Wash hands frequently with soap, especially before touching the mouth, nose or eyes, handling food or eating; after going to the toilet or touching public installations or equipment (including escalator handrails, elevator control panels and door knobs); or when hands are dirtied by respiratory secretions after coughing or sneezing;
- Cover the nose and mouth while sneezing or coughing, hold the spit with a tissue and put it into a covered dustbin;
- Avoid crowded places and contact with fever patients; and
- Wear masks when respiratory symptoms develop or when taking care of fever patients.
The public may visit the CHP's avian influenza page (www.chp.gov.hk/en/view_content/24244.html) and website (www.chp.gov.hk/files/pdf/global_statistics_avian_influenza_e.pdf) for more information on avian influenza-affected areas and provinces.Ends/Monday, December 30, 2013
Issued at HKT 18:43
Although human infections with the H9N2 virus have generally been mild, until the spring of this year, the same could have been said for the H7 avian viruses. Then H7N9 changed the rules.
While we shouldn’t make too much out of today’s announcement of a single H9N2 virus in Hong Kong, it as been the subject of a fair amount of study in recent years, and is one of the avian viruses that the WHO, and other agencies, watch carefully for signs of adaptation or change.
In early 2011, in PNAS: Reassortment Of H1N1 And H9N2 Avian viruses we saw research from Chinese scientists that created – using reverse genetics – 128 reassorted viruses from the avian H9N2 virus and the (formerly pandemic) H1N1 virus.
In mouse testing, they found half of the hybrid viruses were biologically `fit’ as far as replication goes, and 8 hybrids were significantly more pathogenic than either of their parental viruses.
Research such as this shows the potential for the H9N2 virus to move towards a more `humanized’ pathogen. And with H1N1 and H9N2 both known to be circulating in pigs in Asia, there are ample opportunities for them to co-infect the same host.
A few notable H9N2 stories from the past include:
- In December 2008 Revisiting A Malik Peiris Interview On H9N2
- In January of 2010, in H9N2: The Other Bird Flu Threat
- And in November of 2010, Study: The Continuing Evolution Of Avian H9N2
Unlike the H7 and H5 avian flu strains, poultry (and swine) infections by the H9N2 virus are not required to be reported to the OIE. So we have far less data on how widespread H9N2 might be.
In 2009, we saw that sometimes a pandemic virus will emerge from an unexpected source, and with a surprising lineage. While the world was waiting for an H5 bird flu to emerge from Asia, we were blindsided by a H1N1 swine flu from North America.
All of which highlights the importance of establishing better global surveillance of humans, and farm animals, for the next emerging influenza virus.
