The Hong Kong Centre for Health Protection (CHP) reports investigating a case of human infection with influenza A (H9) in a two-year-old boy in Sha Tin District.
Officials say the child developed a fever and mild diarrhea on June 9. On the following day (June 10), he was brought to Prince of Wales Hospital and was admitted for treatment. His clinical specimen tested positive for the influenza A (H9) virus by the Public Health Laboratory Services Branch (PHLSB) of the CHP. The subtyping result is pending.
His clinical diagnosis was novel influenza. He is currently in stable condition and has been admitted to an isolation ward at Princess Margaret Hospital for treatment.
The CHP's preliminary investigation revealed that the patient had no travel history during the incubation period. The case has been classified as a locally acquired case. The patient does not attend school or receive daycare services. He is primarily cared for by his family members and spends most of his time at home or nearby. His household does not keep poultry.
According to information provided by his family members, he has neither consumed undercooked poultry nor come into contact with any patients. In early June, one of his family members took him to Wo Che Market on two occasions. During these visits, the patient stayed at a fresh provision shop in the market that sells live chickens to watch the poultry and touched the surroundings of the fresh provision shop. The CHP conducted an investigation with the Food and Environmental Hygiene Department (FEHD) and collected environmental samples from the shop concerned. The shop staff remained asymptomatic. The patient has six household contacts and they remain asymptomatic so far.
The CHP is continuing to investigate the source of infection of the case and is conducting whole genome sequencing of the virus sample.
In the past ten years, the WHO has received reports of a total of over 160 cases of human infection with influenza A (H9) worldwide. To date, most case of human infection with influenza A (H9) have presented with only mild clinical illness. According to the WHO's risk assessment, the influenza A (H9) virus has not acquired the ability for sustained human-to-human transmissions.