The Centre for Health Protection has confirmed the first local case of Japanese encephalitis transmitted by a blood transfusion.
It involves a 52-year-old man who had received an organ transplant and blood transfusions.
He is in critical condition.
The centre tested residual samples of the blood transfused to the patient, and found the transfusion on June 22 tested positive for Japanese encephalitis.
It then traced the source of infection to a 46-year-old male blood donor who gave blood on May 29.
The donor had no travel history to Japanese encephalitis-endemic areas, and he recalled no mosquito bites.
He lives in Kingswood Villas, Tin Shui Wai.
He and his home contacts have remained asymptomatic.
Briefing the media on the case today, Centre for Health Protection Controller Dr Wong Ka-hing said Japanese encephalitis is mainly mosquito-borne, adding there have not been any cases of the virus transmitted by blood transfusions reported in medical literature.
"The Centre for Health Protection will proceed standard public health actions as a precautionary measure.
"The Food & Environmental Hygiene Department and the Agriculture, Fisheries & Conservation Department have been informed for necessary follow-up."
He said the centre will inspect the donor's residence and conduct questionnaire surveys on residents to find whether there are any undiagnosed cases.
The Department of Health has informed Guangdong and Macau health authorities of the case and the centre will issue letters to local doctors and hospitals to alert them to the latest situation.
