Via Hong Kong’s CHP’s excellent bi-weekly online journal Communicable Diseases Watch, we get a detailed Summary of the second wave of human infections with avian influenza A(H7N9) virus reported by Miss Amy Li, Scientific Officer, Respiratory Disease Office, Surveillance and Epidemiology Branch, CHP.
As you can readily tell by the graphic at the top of this post, the second wave was considerably greater (both in numbers and duration) than the first, and while cases have now largely halted for the summer, there are ample reasons to expect this virus to return in the fall.
This is a data-rich summary, with a number of good graphics, so you’ll want to download the PDF and read the analysis in its entirety.
In it you’ll also find reports on CA-MRSA in a Hong Kong boarding school, the findings of 15 years of acute flaccid paralysis surveillance in Hong Kong, and a variety of other infectious disease reports.
Reported by Miss Amy Li, Scientific Officer, Respiratory Disease Office, Surveillance and Epidemiology Branch, CHP.
Human infections with avian influenza A(H7N9) virus first emerged in Mainland China in early 2013. Two distinct waves of human infections have been observed. The first wave occurred from February to May 2013 involving a total of 133 human cases (including 43 deaths). Subsequently, two sporadic cases occurred in the summer of 2013 before the increase in cases from October 2013 that gave rise to the second wave of human infections which has largely subsided in June 2014. Figure 1 shows the epidemic curve of the first and second waves. Cumulatively, a total of 448 human H7N9 infections have been reported, including at least 157 deaths (as of June 9, 2014). The number of cases in the second wave starting in October 2013 was much greater than the first wave, with 313 cases reported as compared with 133 cases in the first wave.
The second wave reached a peak in late January 2014 and has started to subside since then. Although there were still sporadic cases occurring occasionally in May 2014, the number of reported cases has markedly decreased, indicating that the situation has been under control during summer time. In the past four weeks (from May 11 to June 7, 2014), only 12 new human cases were reported with three cases reported per week on average, as compared with 32 to 45 cases reported per week during the peak in early 2014. The last reported case had onset on May 22, 2014 and occurred in Jiangsu while the last case in Guangdong had onset on May 12, 2014.