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As noted in the previous post, there have been at least 460 human cases of H7N9 reported in the current H7N9 outbreak between November 1, 2016 and February 27, 2017. Of great concern is a possibility that many of these cases are a result of human-to-human transmission. There is little publicly available information about the relationships, if any, among these hundreds of cases. To date, only four two-person clusters have been reported by the World Health Organization (WHO, January 17 and February 20) with family members comprising three of the clusters. For all four of these clusters, the WHO notes that human-to-human transmission cannot be ruled out. One important clue to the nature of the outbreak is the geographic distribution of the reported cases. An indirect signal of human-to-human transmission can be multiple cases occurring in a localized geographic area within a short period of time. The recent WHO line listing of H7N9 cases from China ( Influenza at the Human Animal Interfa...

About 230 human cases of H7N9 have been reported during the second wave of this disease outbreak since November 1, 2013.  The map below depicts the geographic distribution of these cases by second level administrative units (counties) in the People's Republic of China (China), and by level 1 (state) in Malaysia.  The case in Malaysia was imported from China, however, cases have occurred in latitudes ranging from 21 to 43 degrees North.  The map is current through March 3, 2014.

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.

Since novel A(H7N9) human infections were first discovered last year in the People's Republic of China, Zhejiang Province has reported the most cases. The map below depicts in aggregate, the general locations of 80 confirmed and unconfirmed cases through January 21, 2014. The cases are concentrated in the northern portion of the country in the Hangzhou and Huzhou. About 70% of all H7N9 cases reported from Zhejiang are from these two prefectures. 

The map shows the frequency range of human H7N9 cases by second level administrative divisions (generally prefecture-level cities) in the People’s Republic of China and Taiwan through January 17, 2014. The map is based on geolocational information for more than 190 confirmed and probable cases. Geolocational information for individual cases is derived from numerous online reports and believe to be relatively accurate.

Map: Approximate Geolocation of A(H7N9) cases in Eastern China   by Flu Season (through January 12, 2014) Map notes: Human infections of Influenza A(H7N9) were not identified until about half way through the 2012-2013 flu season. The start of the 2013-2014 flu season begins on September 29, 2013 for week number 40 (following the Center for Disease Control [USA] week numbering system). Some probable and cases as yet unconfirmed by the World Health Organization are included on this map. This map is current through January 12, 2014. Because the 2013-2014  flu season will continue for several more months additional A(H7N9) cases are expected.