Credit WHO – January 2015
During the first two waves of H7N9 in China we saw cases run from early winter until early May, with the peak numbers falling between February and March. So it is curious that the last official H7N9 notification to be published by Hong Kong’s CHP came 10 days ago, on March 9th (see CHP notified of additional human cases of avian influenza A(H7N9) in Mainland).
Since then, we’ve seen one notification of an H5N1 case in Sichuan, but on the H7N9 front – nothing but silence.
Guangdong Province, China’s hotspot for reporting this winter (35 cases in February), hasn’t publically announced a new case since March 7th (see HK CHP Notified Of 2 More H7N9 Cases In Guangdong Province).
Unlike during the first two waves, this year we’ve seen less robust and timely reporting out of China, with some provinces now only releasing data in monthly epidemiological reports. Most of the reports we get are summations without any standard epidemiological details (age, gender, onset date, locations, exposures, etc.).
As a result, we don’t have a very good sense of how this year’s outbreak compares with the first two years.
It is certainly possible that fewer infections are being recorded this winter, and that the season is ending early. Perhaps due to more aggressive closing of live bird markets or an earlier arrival of spring. But the irregular reporting out of China this year makes it impossible to tell.
It is possible that provinces like Guangdong - that were reporting on a daily basis - have switched to monthly reports, and we’ll get `caught up’ at some point.
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 is pretty much up to them.
As a final note - while it may be entirely coincidental - this sudden drop in reported cases began at roughly the same time that a high profile study appeared 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.
Whatever is behind this recent drop in case reporting – be it a genuine slowdown in cases or simply `strategic’ reporting - this sudden lack of information coming out of China is more than a little curious.