The number of new H7N9 avian flu cases in China declined this week, with 16 infections reported through May 17, down from 23 the previous week, Hong Kong's Centre for Health Protection (CHP) said today in its regular update.
Though illnesses declined, the newly reported cases reflect steady ongoing activity, despite the onset of warmer weather, with illnesses distributed across a number of provinces, especially in the north.
China is experiencing an unprecedented number of H7N9 cases in its fifth and biggest wave of activity, which has also been notable for the emergence of a highly pathogenic strain of the virus in poultry, which has also infected some humans.
First cases in Shanxi province
China's 16 new H7N9 illnesses were reported from May 12 to May 17, and two patients died from their infections.
All of the patients are adults, a pattern common for human H7N9 cases. Ages range from 30 to 84; 11 are men and 5 are women. Illness onsets range from Apr 29 to May 13.
The virus infected people in eight different provinces and the cities of Beijing and Chongqing. Six were from Hebei province in the north. The cases reported today also reflect the first ever H7N9 case in Shanxi province, also in northern China. In an announcement earlier this week, the CHP said the province's first case involves a 66-year-old woman from Datong who is hospitalized in serious condition.
Fifteen of the people had known exposure to poultry, poultry markets, or mobile stalls, all known risk factors for contracting H7N9.
The new cases appear to put China at or slightly above 700 during the fifth wave, which began in October 2016.
Threat from wider geographic spread
Yesterday the World Health Organization (WHO) posted an update on H7N9 cases reported from China through May 5. No clusters were reported in the 24 cases covered by the report.
In its risk assessment, the WHO said the number of infections and geographic distribution in the fifth wave is greater than in earlier waves, which suggests the virus is spreading. It added that the developments underscore the need for more intensive surveillance and control measures, in both the human health and animal health sectors.
Since H7N9 was first detected in humans in 2013, 1,463 cases have been reported to the WHO.
May 19 CHP update
May 17 CHP report on first case in Shanxi province
May 18 WHO update