Zhejiang Province - Credit Wikipedia
With two new cases of H7N9 reported in China after a prolonged summer lull, concerns over seeing a wider epidemic later this winter are running high (see Eurosurveillance: Rapid Communications On Recent H7N9 Case In China). For now, this emerging avian virus has only shown an ability to jump from poultry to humans. While a handful of clusters have been reported, so far we’ve seen no evidence that it can spread efficiently from human-to-human.
Despite enhanced surveillance for unusual pneumonia cases in China, we really don’t know how many infections go undetected. Mild, or even moderate flu-like illnesses – those that don’t result in hospitalization for pneumonia – may never seek medical care, and may simply never be tested.
The assumption has been, that while just over 130 cases were documented in China last spring, the actual number of infections was likely much higher. In Lancet: Clinical Severity Of Human H7N9 Infection. we looked at a study that estimated that between 1500 and 27 000 symptomatic infections with avian influenza A H7N9 virus might have occurred as of May 28, 2013.
Admittedly a wide range, and until comprehensive serological studies can be conducted, we really won’t have a good idea of how good those estimates are.
Suffice to say, some cases were likely never counted. The only question is how many?
And the same question can reasonably be asked today, in the wake of two new cases recently reported. If surveillance picked up two cases, how many others are there?
All of which helps put a statement, issued yesterday by China’s CDC Influenza Center Director - Shu Yuelong – into context. Not surprisingly, the director warned the public to avoid contact with live poultry, and suggests that other `sporadic infections’ may have occurred.
The following (machine translated) report from the China Radio Network.
2013-10-26 09:46:17 | Source: China Radio Network
Central Broadcasting Network Beijing October 25 news, according to Voice of China "National Network News" reported that for the recent emergence of bird flu Zhejiang Province, China CDC experts said that winter is the peak season of influenza virus, as temperatures drop, the virus active , 7N9 sporadic cases may have occurred.
After following the Shaoxing, Jiaxing, Zhejiang No. 23 has added an H7N9 avian influenza, which is Zhejiang since October this year reported a second case of human infection with avian influenza. Currently two patient's condition is still critical.
China CDC Influenza Center director Shu Yuelong said that due to H7N9 virus has been present in poultry, plus winter is high season for influenza virus, h7N9 sporadic cases may have occurred.
Shu Yuelong: Because H7N9 in poultry there still exist, people through indirect or direct contact can be infected. As usually referred to arrival of the peak influenza season, there may Reporter Feng Huiling avian influenza infection may have occurred.
Shu Yuelong said that at present the public do not have to do anything special protection, but should avoid contact with live poultry.
Shu Yuelong: Usually people still avoid contact with live poultry, including live bird markets. It seems from this spring, live poultry market is indeed a high-risk places. With the increasing number of cases, we still recommend the closure of live bird markets, or live poultry markets strict disinfection, should be an important protective measures. Because this virus is still transmitted from birds to humans is not contagious between people, so people do not have to do anything special protection.