April 26, 2013
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H7N9 this week
This week, the world has witnessed the geographical spread of H7N9 to Shandong, Taiwan, Jiangxi and Fujian. Given that H7N9 influenza virus is low pathogenic among birds – that is, it causes only mild symptoms among birds (unlike H5N1 virus which is high pathogenic, killing many birds), this virus may have spread to many communities of birds / poultry already. Otherwise, it is difficult to understand why >100 people have been infected across such a large geographical space.
An article in Scientific American this week, highlights the fact that the geographical locations of this H7N9 outbreak is highly similar to a previously published risk map created for H5N1 (Martin et al. 2011, PLoS Pathog 7(3): e1001308).Another article, in Foreign Policy by Laurie Garrett, proposes an alternative hypothesis, that the virus may have adapted to mammalian species and the current outbreak may be spread by an mammalian species. This is an interesting hypothesis that cannot be ruled out. However, in my opinion, the current available evidences seem to point to the direction that contacts with poultry poses the highest risk to a given individual.Researchers in Zhejiang University and Hong Kong University (with the famous Prof. Kwok-Yung Yuen) has published an article in The Lancet, that summarizes the clinical details of the first four H7N9 patients in Zhejiang province, the biology of the virus detected in these patients and some epidemiological details.Also, today, the Taiwanese doctors have published the case report of the Taiwanese H7N9 case in The Lancet.Starting this Wednesday (April 24), the Chinese government has changed from a daily report to the WHO to a weekly report. Therefore, the official toll of H7N9 human infections that is released by China’s Health and Family Planning Commission (and therefore that of the WHO) will remain the same for the whole week until its next update. Luckily, the provinces continue to release data about new cases online. That is why we know that confirmed cases have now been identified in Jiangxi and Fujian provinces. While it is worrying to see the geographical spread of H7N9 virus, it is also important to highlight that Shanghai has reported zero confirmed cases for a few days. Given that the incubation period of this H7N9 virus can be as long as 10 days, if Shanghai can be free of new cases for long enough, Shanghai can prove that they have successfully control the spread of the disease within their jurisdiction.However, given the fact that a certain proportion of confirmed cases do not report contact with poultry or birds, it is still a mystery how these people get infected. Some people may suggest that the self-reports of these patients may not be accurate. They might forget the one or two instances that they have contacts with poultry. The alternative hypothesis, as suggested by Laurie Garrett, would be that there may be some mammalian hosts that help transmit the disease. We just know too little now to rule out such possibilities.No matter what, personal hygiene and avoidance of any contacts with birds and poultry, seem to be a reasonable measure to take care of yourself, at this uncertain hour.***Sometimes it is both amusing and alarming to see a sina weibo post like this one (published today):SJYTH：Ｈ７Ｎ９世界多地发现已多年。今天有微博提出质疑：为什么Ｈ７Ｎ９一到中国就变异？中国要加紧研究，有证据时要对相关国家的阴谋进行反击。即使没有证据也要进行相关行动。只有这样类似事件才会截止。在重大事件面前不要拘泥…Such ultra-nationalists who “see” foreign plots everywhere and who spread such conspiracy theories online are really a burden to the peaceful development of China. Luckily, such people are not in power right now.***Saturday (April 27): Hunan provincial department of health has reported two confirmed cases of human infection of avian influenza H7N9.See: Official press release. Also see news report: 湖南通报两例H7N9禽流感确诊病例 一例为收治江西省病例 (source: Sina, April 27, 2013)The first Hunan case is a woman from Shaoyang City 邵陽市. She has a fever on April 14, sought healthcare at a private clinic on April 18, hospitalized on April 19. On April 25 morning, she was tested H7N9 positive by Shaoyang City CDC. The sample was re-tested and confirmed positive by the provincial CDC in the evening. On April 27, the national CDC re-tested and confirmed positive.The other case is an imported case from Jiangxi. A man with respiratory illness (onset: April 15) sought healthcare in his hometown (宜春市銅鼓縣) in Jiangxi, but did not get well. Later he was transferred to a hospital in Hunan, where he is confirmed to be H7N9 positive.Some good news (April 27): Six patients recovered and have been discharged from the hospital in Hangzhou, Zhejiang, today. (Xinhua News Agency: photo)
