Tuesday, April 18, 2017

HK CHP Avian Flu Report Week 15

Credit HK CHP


Hong Kong's Centre For Health Protection has released their weekly avian influenza report, and as has become common the past few months, it is essentially a recap of the announcement made the end of the previous week by China's NHFPC (see Friday's HK CHP Notified Of Another 14 New H7N9 Cases From The Mainland).
While the number of new infections has dropped considerably since last February when Beijing Ordered Closure Of Live Bird Markets To Control H7N9, the impact has been less dramatic than we've seen in previous years. 
Recent reports of clusters of infection linked to poultry exposure in Beijing and Tibet are reminders that the virus continues to expand its geographic range, an unsettling trend that weighs heavily on the minds of China's Nervous Neighbor.

First the summary from today's report, then I'll return with a bit more.

Avian Influenza Report
Avian Influenza Report is a weekly report produced by the Respiratory Disease Office, Centre for Health Protection of the Department of Health. This report highlights global avian influenza activity in humans and birds.


Reporting period: April 9, 2017 – April 15, 2017 (Week 15)
(Published on April 18, 2017)


1. Since the previous issue of Avian Influenza Report (AIR), there were 14 new human cases of avian influenza A(H7N9) reported by Mainland China health authorities in Sichuan (3 cases), Henan (2 cases), Shandong (2 cases), Tibet (2 cases), Anhui (1 case), Beijing (1 case), Hunan (1 case), Tianjin (1 case) and Zhejiang (1 case). Since March 2013 (as of April 15, 2017), there were a total of 1393 human cases of avian influenza A(H7N9) reported globally. Since October 2016 (as of April 15, 2017), 587 cases have been recorded in Mainland China.

2. Since the previous issue of AIR, there were no new human cases of avian influenza A(H5N6). Since 2014 (as of April 15, 2017), 16 human cases of avian influenza A(H5N6) were reported globally and all occurred in Mainland China. The latest case was reported on December 1, 2016.

3. Since the previous issue of AIR, there were no new human cases of avian influenza A(H5N1). From 2011 to 2016, 10 to 145 confirmed human cases of avian influenza A(H5N1) were reported to the World Health Organization (WHO) annually (according to onset date). In 2017, there have been so far two cases in Egypt.*

This week's case list is typical of what we usually see with H7N9 infections. Patients are predominantly male, generally over 40, and the vast majority are listed as having severe pneumonia.  Mild cases are a rarity, and the fatality rate runs between 30%-40% (often after weeks of hospitalization.)

In today's list, of 14 cases, 11 are male, with the youngest case 39 years of age.  Half (n=7) are listed with Severe Pneumonia.  Two have died, 4 are `Under Investigation', and only one is listed as `mild'.
Unknown are how many `mild' or asymptomatic cases there might be in the community who do not seek out medical care, and are therefore never tested for the virus.
Meanwhile, in addition to expanding its geographic range, the H7N9 virus continues to evolve, recently splitting into two separate lineages (Pearl River Delta & Yangtze River Delta), and spawning a new HPAI version (see MMWR:Increase in Human Infections with Avian Influenza A(H7N9) In China's 5th Wave),
At the end of March, in Eurosurveillance: Preliminary Epidemiology & Analysis Of Jiangsu's 5th H7N9 Wave, we saw a report that suggested the virus may be becoming better adapted to warmer weather and that reported an`accelerated disease progression of H7N9 patients', which they note  `suggests that the viral pathogenicity might have become stronger'.
The expectation - based on past experience - is that between warmer weather, and a continued clamp down on live poultry markets, the number of new H7N9 cases will continue to drop in the weeks ahead.
Whether the continual evolution of the H7N9 virus manages to change that is something we'll be watching closely in the months to come.

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