Flu Virus binding to Receptor Cells – Credit CDC
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Although human infection with avian LPAI H9N2 remains only rarely reported (see FluTrackers List)) - and it has a reputation for producing substantially less severe illness in humans than its avian H5 & H7 counterparts - LPAI H9N2 is still considered an important player in the avian flu world.
- H9N2 has become widespread - even ubiquitous - among poultry across Asia and the Middle East, and has made recent inroads into Africa.
- 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).
- Both the CDC and WHO consider the virus to have at least some pandemic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed over the years.
The assumption is, human infection is more common than the reported cases would suggest. And while most infections are mild or moderate, some severe cases have been reported.A couple of weeks ago, in Viruses: Characterization of the H9N2 Avian Influenza Viruses Currently Circulating in South China, we looked at a a new study, published in the journal Viruses, that reported that China's current crop of H9N2 viruses continues on an evolutionary path that increases its pandemic potential.
Until 2019, reports of human cases have been limited to (mostly) China and Hong Kong, plus a few cases from Bangladesh and Pakistan, and since 2015 - a handful of cases reported from Egypt.This year, we've learned of two new countries reporting human H9N2 infections; India and Oman. The Omani case was revealed last May in WHO Novel Flu Summary & Risk Assessment - May 2019.
Earlier this month, the CDC's EID Journal carried the following brief report of a human H9N2 infection from India, which was somewhat serendipitously discovered during an ongoing community-based surveillance study on RSV-associated deaths among children.
Volume 25, Number 12—December 2019
Research Letter
Laboratory-Confirmed Avian Influenza A(H9N2) Virus Infection, India, 2019
Potdar V, Hinge D, Satav A, Simões EF, Yadav PD, Chadha MS.
Abstract
A 17-month-old boy in India with severe acute respiratory infection was laboratory confirmed to have avian influenza A(H9N2) virus infection. Complete genome analysis of the strain indicated a mixed lineage of G1 and H7N3. The strain also was found to be susceptible to adamantanes and neuraminidase inhibitors.
Low-pathogenicity avian influenza A(H9N2) viruses have a wide host range, and outbreaks in poultry have been recorded since the 1990s in China (1). In India, avian specimens indicated no serologic evidence of H5N1 and H9N2 during 1958–1981 (2); however, 5%–6% persons with direct exposure to poultry had H9N2 antibodies (3). Human cases of influenza H9N2 virus infection have been observed in Hong Kong, China, Bangladesh, and Pakistan (4–7).
An institutional review board approved an ongoing community-based surveillance in 93 villages of Korku tribes in Melghat District, Maharashtra State, India, to determine incidence of respiratory syncytial virus (RSV)–associated deaths among children < 2 years of age.
A total of 2,085 nasopharyngeal swabs from children with severe or fatal pneumonia were transported to India’s National Institute of Virology to test for influenza, RSV, and other respiratory viruses. A nasopharyngeal swab from a 17-month-old boy received on February 12, 2019, tested positive by PCR for influenza A(H9N2) virus.
The child, a resident of Melghat, had fever, cough, breathlessness, and difficulty feeding for 2 days after illness onset on January 31, 2019. His high intermittent grade fever had no diurnal variation and no association with rash or mucocutaneous lesions. Examination revealed a conscious, restless child with a respiratory rate of 48 breaths/min and lower chest wall in-drawing with intermittent absence of breathing for >20 seconds. He was fully immunized for his age, with bacillus Calmette–Guérin, diphtheria, hepatitis B, poliovirus, and measles vaccines. Both length and weight for age were less than −3 SD. History of travel with his parents to a local religious gathering 1 week before symptom onset was elicited.
The father had similar symptoms on return from the gathering but could not undergo serologic testing because of his migrant work. No history of poultry exposure was elicited. The child received an antibacterial drug and antipyretics and recovered uneventfully.
(SNIP)
In conclusion, multiple introductions of H9N2 viruses in poultry have been observed in India. The identification of a human case of H9N2 virus infection highlights the importance of systemic surveillance in humans and animals to monitor this threat to human health.
Dr. Potdar is senior scientist heading the Influenza Group at the National Institute of Virology, Pune, India. Her primary research interest is molecular characterization and antiviral susceptibility of influenza viruses.
Today, the International Journal of Infectious Diseases (IJID) has published a report on the Omani infection reported by the WHO in May.
The first report of human infection with avian influenza A(H9N2) virus in Oman: the need for a One Health approach
Zayed Al-Mayahia,Hanan Al Kindib , C. Todd Davisc , Bader Al-Rawahid , Fatma Al-Yaqoubid , Yunho Janga,b,c,d,e, Joyce Jonesc, John R. Barnesa,b,c,d,e , William Davisc, Bo Shuc, Brian Lynchc , David E. Wentwortha,b,c,d,e , Zaina Al-Maskarie , Amal Al Maanid, Seif Al Abrid(Continue . . . )
DOI: https://doi.org/10.1016/j.ijid.2019.11.020
Abstract
Highlights
• First investigated human case in Oman of avian influenza A(H9N2) virus infection in a 14-month-old female.• This single case raises the question of other possible mild unrecognized infections, especially among high risk groups such as poultry workers.
• This single case re-emphasizes urgent need for increased efforts to tackle the threat of avian influenza A(H9N2) virus infection by adapting a multisectoral, One Health approach.
Abstract
After detection of the first human case of avian influenza A subtype H9N2 in 1998, more than 40 cases were diagnosed worldwide. The spread of the virus, on the other hand, is more remarkable and significant in global poultry populations causing notable economic losses despite its low pathogenicity.
Many surveillance studies and activities conducted in several countries proved the predominance of this virus subtype. We present a case report of A(H9N2) virus infection in a 14-month-old female from Oman. It is the first A(H9N2) human case reported from Oman and the Gulf Cooperation Countries and the second country outside of southern and eastern Asia, cases were also detected in Egypt.
The patient had bronchial asthma and presented with high-grade temperature and symptoms of lower respiratory tract infection that necessitated admission to a high dependency unit in a tertiary care hospital.
It is of urgency that a multisectoral One Health approach be established to combat the threat of avian influenza at the animal-human interface. In addition to enhancements of surveillance and control in poultry, there is a need to develop screening and preventive programs for high-risk occupations.
In this case, H9N2 was detected because this patient was severely ill, was admitted to a teriary hospital, and therefore met the criteria for testing under Oman's recently (2017) adopted National Acute Respiratory Illness (NARI) Surveillance program.
How many others are infected, but never tested, across Asia and the Middle East remains unknown. As does the future evolutionary path of H9N2.But what we do know is concerning enough to have inspired a good deal of research, some of which I've covered in these recent blogs.
Virology Journal: Mouse-adapted H9N2 Avian Influenza Virus Causes Systemic Infection in Mice
Viruses: A Global Perspective on H9N2 Avian Influenza Virus
OFID: Avian H5, H7 & H9 Contamination Before & After China's Massive Poultry Vaccination Campaign
J. Virology:Genetic Compatibility of Reassortants Between Avian H5N1 & H9N2 Influenza Viruses
Virology: Receptor Binding Specificity Of H9N2 Avian Influenza Viruses
EID Journal: Two H9N2 Studies Of Note
