Seasonality of H7N9 - Credit Hong Kong’s CHP
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In the dozen years we’ve been following avian flu outbreaks (H5N1, H7N9, H9N2, etc) we’ve seen a decided seasonality with these viruses, with the warmer summer months generally the least active time, and winter and spring showing the most activity. As you can see by the chart above, by this time last year, China’s H7N9 spring outbreak had pretty much gone dormant.
This year, we continue to see a trickle of cases being reported – one or two a week – well into the summer.
Today Guangdong Province is reporting a recent H7N9 fatality, that of a 42 year-old man from Jiangmen City (pop. 4.2 million), who was diagnosed on June 9th. No details regarding route of exposure have been provided.
First the brief statement by the Guangdong Ministry of Health, then a report from Xinhua News.
Province 1 new confirmed cases of human infection with H7N9 avian influenza
2014-06-17 11:11:35 Ministry of Health and Family Planning Commission
Health and Family Planning Commission of Guangdong Province on June 17 briefing, the province last week new confirmed cases of H7N9 avian influenza case of human infection.
Patients Wu, male, 42 years old, Jiangmen City native, currently residing in Jiangmen, Kaiping. June 9 confirmed human cases of avian influenza H7N9 infection. Patients died due to critical condition.
And this report, with some interesting downplaying of the numbers, from Xinhua News.
English.news.cn 2014-06-17 17:51:16
GUANGZHOU, June 17 (Xinhua) -- A 42-year-old man has died from the H7N9 strain of bird flu in south China's Guangdong Province, provincial health authorities said on Tuesday.
The patient, surnamed Wu, lived in Jiangmen City and was confirmed to be infected on June 9, according to the provincial health and family planning committee.
Wu was in critical condition and died in hospital after treatment failed, it said.
A H7N9 patient from Guangzhou, the provincial capital, died on May 4 due to respiratory failure.
In April alone, five H7N9 patients died in Guangdong Province.
So far, more than 120 people in China have been infected by H7N9 this year, with dozens of deaths.
The statement `more than 120 people in China have been infected by H7N9 this year, with dozens of deaths’ - while technically true – badly understates the actual numbers. According to last week’s CHP: Epidemiological Summary Of The Second Wave Of H7N9, the first wave (spring of 2013) saw a total of 133 human cases (including 43 deaths), while the second wave (fall-winter-spring) added 315 new cases, and more than 100 deaths.
According to FluTracker’s H7N9 Case List, nearly 300 of those cases have been announced since the first of the year – a far cry from the 120 mentioned above.
Despite more than doubling the numbers of the first wave, this second wave of H7N9 did not show any signs of efficient of sustained human-to-human transmission of the virus. Most of the cases are believed to have contracted the virus from contact with infected birds, mainly via live bird markets.
The good news is, the evidence continues to suggest that H7N9 remains an avian-adapted virus.
The caveat being, that these viruses are constantly changing (see EID Journal: H7N9 As A Work In Progress) and that what we say about their behavior today may not hold true next fall or winter.
