Western Pacific Surveillance and Response

Human infection with influenza A(H7N9) in China

Emerging Disease Surveillance and Response Teama

a Division of Health Security and Emergencies, World Health Organization Regional Office for the Western Pacific, Manila, Philippines.

We report on the current human infection with influenza A(H7N9) in China. As of 12 April 2013, there have been 38 confirmed cases, with 10 deaths (CFR 26%). The median age of cases is 64 years (range 4-87 years) with 26 male and 12 female cases (ratio of 2.2:1). The cases were from four provinces: Shanghai (18), Jiangsu (12), Zhejiang (6) and Anhui (2), within 550km of each other (Table 1).19 No epidemiological links have been established between any of the cases. There have been no confirmed cases among the more than 800 close contacts that have been tested and no evidence of sustained human to human transmission, although investigations are ongoing.

This is the first time that human infection with influenza A(H7N9) virus has been identified. The exact source of infection, reservoir and mode of transmission of the H7N9 virus is still being investigated. The Ministry of Agriculture in China has detected H7N9 virus from pigeons, chickens and the environment in Shanghai. Authorities have culled poultry and issued a temporary ban on the trading of live poultry.

Table 1. Line list of confirmed cases of confirmed human infection with influenza A(H7N9) virus, China, February – April 2013