The Centre for Health Protection on Saturday said it was closely monitoring a mainland case of H5N6 bird flu, involving a 68-year-old man from Huizhou in Guangdong.
He kept poultry at home and developed symptoms a week last Friday.
The man was admitted to hospital four days later and is now in a critical condition.
The centre said since 2014, mainland health authorities had reported 53 human cases of H5N6 bird flu.