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Earlier in February, I posted a chart showing the possible exponential growth of H7N9 cases in the People’s Republic of China ( link ). Exponential growth of infectious diseases among humans, however, can only occur if there is sustained human to human transmission. Although sporadic H7N9 cases have continued to be reported since early February, there has been no increase in number of family or local clusters that would signal sustained human to human transmission.   Importantly, the number of sporadic H7N9 cases has recently started to decline as depicted by the 2-week moving average in the chart below.     Analysis of the data by reported onset dates indicates that the H7N9 infections started to decline about the middle of  Week 6,    about the same time that I posted the chart ( link ) with the projection of exponential growth of cases.

The World Health Organization  (WHO) has not been providing cumulative case counts of H7N9 cases in their Disease Outbreak News reports. This may be due to incomplete and inconsistent case information that has been provided to WHO by the National Health and Family Planning Commission (NHFPC) of China. Perhaps the most accurate enumeration of H7N9 cases is provided by the Centre for Health Protection (CHP), Department of Health, Hong Kong Special Administrative Region.They report "As of yesterday ( February 27, 2014 ), a total of 367 human cases of avian influenza A(H7N9) have been confirmed in the Mainland, including Zhejiang (136 cases), Guangdong (81 cases), Jiangsu (42 cases), Shanghai (41 cases), Fujian (20 cases), Hunan (16 cases), Anhui (nine cases), Jiangxi (six cases), Beijing (four cases), Henan (four cases), Guangxi (three cases), Shandong (two cases), Guizhou (one case, imported from Zhejiang), Hebei (one case) and Jilin (one case).cases), Shandong (two cases), Guizhou...

The first reported human case of a novel influenza A(H10N8) subtype was reported in November 2013. A 73-year-old woman from the Donghu District, Nanchang, Jiangxi Province in China experienced onset on November 28, 2013. She died nine days later on December 6, 2013.[1]  Since then two additional human cases of H10N8 have been reported. The second is 55-year-old woman who was hospitalized on January 15, 2014. This woman is from Nanchang, Jiangxi Province.[1] And today the third human case of H10N8 has been reported, also from Nanchang, in Jiangxi Province.   This 75-year-old man died on February 8, 2014, just three days after being hospitalized.[2] As with most novel influenza strains, H10N8 seems to be circulating among poultry populations in China resulting in sporadic jumps from poultry to humans.   With only three reported human H10N8 cases it is not possible to assess the pandemic potential of this new influenza virus.[3] Surveillance for human cases and poultry outb...

On January 24 th ,   I posted a graph plotting the growth rate of H7N9 cases in China. Based on the trend (link), I estimated that between 30-40 cases of H7N9 would be reported in the coming weeks. Using current data for onset dates (through February 4, 2014), an updated plot indicates a total of 39 H7N9 cases for both Week 4 and Week 5. More than 30 H7N9 cases (without onset dates) have already been reported for Week 6. If the number of cases continues to increase at an exponential rate, more than 100 people a week will be reported as H7N9 cases by Week 7 or Week 8.   If the rate continues at its current pace, China will be experiencing an H7N9 epidemic within the near future. Current graph of H7N9 cases through Week 5.

This map shows the geographic distribution of  human H7N9 cases by second level administrative divisions (generally prefecture-level cities) in the People’s Republic of China and Taiwan from the period of November 1, 2013 to February 3, 2014.  The map is based on geolocational information for more than 150 confirmed and reported cases since November 1, 2013.  H7N9 cases from the 2012-2013 flu season are not included on this map.  Geolocational information for individual cases is derived from numerous online reports.

The World Health Organization (WHO) is an arm of the United Nations and is tasked with monitoring international public health. One of the most important roles of this public health organization is to identify and track novel infectious diseases. MERS-CoV and Influenza A(H7N9) are two recent novel infectious diseases that WHO has been monitoring and tracking recently. On January 31, 2014, The WHO published a summary of what is known about H7N9 infections, reservoirs, clinical presentation, protection, treatment, and recommendations.   WHO report: Background and summary of human infection with avian influenza A(H7N9) virus – as of 31 January 2014 This the first background and summary provided by WHO on H7N9 infections since April 3, 2013 ( link ). The report summarizes what is known about H7N9 at this time. It is important to understand that WHO provides factual information about the status of H7N9 cases and the disease as it is understood on the day of the report. WHO does not g...