Despite a welcomed drop in H7N9 activity in China over the past year following a massive 2017 H5+H7 poultry vaccination campaign, we've continued to see a few sporadic human infections with HPAI H5N6 in the region, with one case reported in September and an other in October (see map above).
The World Health Organization has published their latest Summary and Risk assessment, which highlights these two cases.No other human infections with novel (swine or avian) flu viruses have been reported since the last update. This month's report is therefore fairly brief.
Influenza at the human-animal interface
Summary and assessment, 22 September to 1 November 2018
New infections 1 : Since the previous update, new human infections with avian influenza A(H5N6) viruses were reported.
Risk assessment: The overall public health risk from currently known influenza viruses at the human-animal interface has not changed, and the likelihood of sustained human-to-human transmission of these viruses remains low. Further human infections with viruses of animal origin are expected.
Risk management: Selection of new candidate vaccine viruses (CVVs) for zoonotic influenza for influenza pandemic preparedness purposes was done during a recent WHO consultation. 2
IHR compliance: All human infections caused by a new influenza subtype are required to be reported under the International Health Regulations (IHR, 2005). 3 This includes any influenza A virus that has demonstrated the capacity to infect a human and its heamagglutinin gene (or protein) is not a mutated form of those, i.e. A(H1) or A(H3), circulating widely in the human population. Information from these notifications is critical to inform risk assessments for influenza at the human-animal interface.
Avian Influenza Viruses
Avian influenza A(H5) viruses
Since the last update on 21 September 2018, two new laboratory-confirmed human cases of influenza A(H5N6) virus infection were reported to WHO. On 30 September 2018, China reported a case in a 22-year-old male in Guangdong Province, China, who developed symptoms on 25 September 2018. He was admitted to hospital one day later with severe pneumonia and was in critical condition at the time of reporting. The patient reported exposure to live poultry before illness onset. Monitoring of his close contacts was ongoing at the time of reporting.
On 31 October 2018, a second case was reported to WHO from China: a 44-year-old male in Guangxi Zhuang Autonomous Region, China, who developed symptoms on 18 October 2018. The patient was admitted to hospital on 21 October and passed away on 27 October. According to the report, the patient did not have a history of contact with live poultry before illness onset. Monitoring of his close contacts was ongoing at the time of reporting.
A total of 22 laboratory-confirmed cases of human infection with influenza A(H5N6) virus have been reported to WHO from China since 2014.
According to reports received by the World Organisation for Animal Health (OIE), various influenza A(H5) subtypes continue to be detected in birds in Africa, Europe and Asia.
1. What is the likelihood that additional human cases of infection with avian influenza A(H5) viruses will occur?
Most human cases were exposed to A(H5) viruses through contact with infected poultry or contaminated environments, including live poultry markets. Since the viruses continue tobe detected in animals and environments, further human cases can be expected.(Continue . . )
2. What is the likelihood of human-to-human transmission of avian influenza A(H5) viruses?
Even though small clusters of A(H5) virus infections have been reported previously including those involving healthcare workers, current epidemiological and virological evidence suggests that this and other A(H5) viruses have not acquired the ability of sustained transmission among humans, thus the likelihood is low.
3. What is the likelihood of international spread of avian influenza A(H5) viruses by travellers?
Should infected individuals from affected areas travel internationally, their infection may be detected in another country during travel or after arrival. If this were to occur, further community level spread is considered unlikely as evidence suggests these viruses have not acquired the ability to transmit easily among humans.
Avian influenza A(H7N9) viruses
According to reports from mainland and the Hong Kong Special Administrative Region China and those received by the World Organisation for Animal Health (OIE), A(H7N9) avian influenza viruses continue to be detected in China but at lower levels compared to previous years. A nationwide domestic poultry vaccination campaign began in 2017.
Overall, the risk assessment has not changed.