The Hong Kong Centre for Health Protection said on Monday that it was notified of a human case of avian influenza in Shenzhen by the Health and Family Planning Commission of Guangdong Province.
The patient is a 49-year-old man who has been hospitalized for treatment.
CHP said a total of 389 human cases of avian influenza A H7N9 have been confirmed.
"In view of human cases of avian influenza A (H7N9) confirmed locally and multiple cases notified by the Mainland, further cases are expected in affected and possibly neighboring areas," a CHP spokesman said. "Those planning to travel outside Hong Kong should maintain good personal, environmental and food hygiene at all times."
The spokesman said enhanced disease surveillance, port health measures and health education are ongoing.
"We will remain vigilant and maintain liaison with the World Health Organization and relevant health authorities," the CHP spokesman said. "Local surveillance activities will be modified upon the WHO's recommendations."
CPH advised travelers to wear masks and seek medical attention if they develop symptoms, especially if they are returning from affected areas.
Citizens were advised to avoid contact with poultry and their droppings, and to avoid areas and surfaces where birds are slaughtered.