The H7N9 avian flu outbreak has spread to 3 more Chinese provinces, but no new cases have been reported since 7 May 2013. Since then, however, the epidemic has gone into a lull, with just one person falling ill with H7N9 since the start of May 2013. The drop might reflect that the authorities’ control measures, such as the closure of live bird markets, are working, but it is also possible that the epidemic will rear its head again later.
The cases that occurred after 14 Apr 2013 show how H7N9 has spread compared to cases that occurred between 1 Feb and 13 Apr 2013. Most cases have appeared in areas designated as at higher risk for the earlier H5N1 avian flu rather than in areas at lower risk. This seems to be consistent with the current thinking that birds – particularly poultry — and live-bird markets may be the main sources of human infection. Comparing the 2 epidemics may help researchers to target efforts to track and control H7N9.
It is unknown whether and to what extent the drop-off may have been caused by the closing of live-bird markets and other control measures.
Another possibility is seasonality. Past avian flu virus outbreaks have often tended to show seasonal patterns of occurrence, with most outbreaks occurring during the colder months of the years and fewer in the warmer months. But after just a week-long lull is too soon to speculate on what turn the epidemic of H7N9 flu will take next.
Time will tell—-stay tuned!