WHO Novel Flu Summary & Risk Assessment - October 2019

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The World Health Organization has published their latest Summary and Risk assessment on novel influenza, which provides additional details on the H5N6 case reported in Beijing in mid-August.  

You may recall the details of this case were somewhat confusing (see A Curious Narrative To The Beijing H5N6 Report), with China Daily reporting:

Beijing confirmed that a 59-year-old female expatriate who came to the city three months ago was carrying avian influenza H5N6, according to the municipal center for disease control and prevention's report on Tuesday.

The woman complained of symptoms on Aug 6. She reportedly contacted with dead poultry before she got sick and the poultry was not from Beijing, according to the authority.

Without elaborating, today's report suggests exposure to `chilled meat' from Southern China may have been the source of her infection. 

In early 2018 Hong Kong detected and removed several batches of `chilled' poultry - sourced from Southern China - from local shops that tested positive for HPAI H5 (see Hong Kong FEHD Finds Another Shop Selling H5 Contaminated Poultry).

While exposure to frozen or chilled meat has only rarely been linked to HPAI H5  infection, two summers ago, in  Appl Environ Microbiol: Survival of HPAI H5N1 In Infected Poultry Tissues, we looked at several studies on the long-term viability of HPAI H5N1. 

They found: 

The maximum period for viral survival was observed in samples stored at +4°C in all tissue types, i.e., 240 days in feather tissues, 160 days in muscle, and 20 days in liver. 

All of which makes infection from chilled chicken plausible, albeit uncommon.  Excerpts from the 3-page WHO update follow, after which I'll return with a short postscript. 

Influenza at the human-animal interface

Summary and assessment, from 25 June 2019 to 27 September 2019•

• New infections 1 : Since the previous update on 24 June 2019, one new human infection with an influenza A(H5N6) virus was 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.
• 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 haemagglutinin 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

Current situation: Avian influenza A(H5) viruses

Since the last update on 24 June 2019, one new laboratory-confirmed human case of influenza A(H5N6) virus infection was reported to WHO. On 18 August 2019, China reported a case in a 59-year-old female from Beijing, who developed symptoms on 6 August. She was admitted to hospital on 11 August with severe pneumonia and remained hospitalized at the time of reporting.

The investigation indicated that the most likely source of the case's exposure to the virus was chilled meat that originated in southern China. No other cases had been detected among the patient’s contacts.

A total of 24 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.

Risk Assessment:

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 to be detected in animals and environments, further human cases can be expected.

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.

(Continue . . . )

Although reports of human infection with novel H5 and H7 flu strains have dropped dramatically the past couple of years, there are large gaps in surveillance - and institutional resistance to reporting `bad news' - in many parts of the world.

We know literally nothing of what goes on in North Korea, and China has a history of treating disease outbreaks (in humans and in animals) - particularly in times of economic or political stress - as national security issues. 

In many places, particularly in low resource regions of Asia and Africa, testing is often not a viable option. And if you can't test, you can't tell. 

A month ago, in  WHO/World Bank GPMB Pandemic Report : `A World At Risk' we looked at a sobering report that warned `. . . an outbreak equivalent to the 1918 influenza pandemic could kill an estimated 50 to 80 million people, spreading around the world in less than 36 hours and wiping out nearly five percent of the global economy.'

One of the harsh realities of life in this highly mobile, interconnected, 21st century is that oceans and vast distances no longer afford protection against infectious diseases, and that without extensive surveillance and timely reporting from all countries, we can easily be blindsided by the next pandemic threat.