Compared to the first two waves of H7N9 in China, where we saw daily reports from affected provinces which included both case counts and rudimentary epidemiological information, this year’s reporting has been less detailed and far more haphazard.
Some provinces have just reported an aggregate total in their end of month infectious disease reports, while others have dumped `bulk’ case announcements at irregular intervals (see Jiangsu Province’s Uncertain H7N9 Count).
All of which has made it very difficult to compare this year’s outbreak to previous years. As I mentioned last week, in H7N9: No News Is . . . . Curious, for the past couple of weeks H7N9 case reporting has gone strangely silent. As the first two H7N9 waves didn’t end until May, an abrupt halt in case in early March is unexpected.
Today, Hong Kong’s CHP has published their latest Avian Influenza Report, and for the second week in a row, confirm that no new H7N9 cases have been reported by the Chinese Mainland since March the 9th.
1. There were no new human cases of avian influenza A(H5N1) reported by the World Health Organization (WHO)#. One new human case of avian influenza A(H5N1) involving a 34-year-old man from Yunnan Province was reported by the National Health and Family Planning Commission (NHFPC) on March 23, 2015.
2. From 2010 to 2014, 32 to 62 confirmed human cases of avian influenza A(H5N1) were reported to WHO annually (according to onset date). In 2015 (as of March 23, 2015), 89 cases were reported by WHO* and two additional cases were reported by NHFPC.
3. Since the previous issue of Avian Influenza Report, there were no new human cases of avian influenza A(H7N9). Since March 2013 (as of March 23, 2015), there were a total of 638 cases reported.
It is certainly possible that fewer infections are being recorded this winter, and interventions such as the closing of live poultry markets have dramatically reduced transmission. It is also worth noting that more spring-like weather has returned to many areas of Eastern China over the past several weeks, which could be a mitigating factor.
But this precipitous drop in reporting also comes – perhaps coincidentally – at the same time we saw a major study appear in the Journal Nature (see Dissemination, Divergence & Establishment of H7N9 In China) warning that the H7N9 virus was evolving rapidly, and that it posed a growing pandemic threat.
China is, of course, required to notify the World Health Organization of new H7N9 cases under the terms of the IHR, but how and when they choose to publically disclose case information – even to Hong Kong’s CHP - is pretty much up to them.
If we are truly seeing a less active, and truncated H7N9 wave, then that would be good news indeed. But the inconsistent reporting out of China these past few months makes it difficult to assume the best based simply on the absence of data.