GUANGZHOU — The number of H7N9 human cases in south China’s Guangdong province has climbed to 49, with four new cases confirmed on Feb 13 by the local health authority.

The provincial health and family planning commission said an 82-year-old man from Chaozhou City diagnosed with H7N9, died on Feb 12, the 12th fatality in Guangdong this year.

The other three new cases, including two men aged 51 and 61 and a woman aged 58, in Guangzhou, Shenzhen and Chaozhou, the commission said in a news release.

It said the patients all suffered chronic diseases including high blood pressure and diabetes.

Bird flu is most likely to strike in winter and spring.

In Guangdong province and Hong Kong, thousands of chickens have been culled this year. Several cities in Guangdong have banned the live poultry trade.

Other Chinese localities including Shanghai, Fujian, Jiangxi, Guizhou and Zhejiang have also reported human cases of H7N9 this winter.

H7N9 is a bird flu strain first reported to have infected humans in March 2013.