The Centre for Health Protection (CHP) of the Department of Health (DH) is today (June 12) investigating a case of human infection with influenza A (H9) in collaboration with relevant departments. The patient is a two-year-old boy. His condition has remained mild and he is currently in stable condition. The CHP will send a letter to all doctors in Hong Kong to update them on the latest developments regarding avian influenza A and to urge them to remain vigilant and report any suspected cases.
Case information
-------------------
The boy lives in Sha Tin District. He developed a fever and mild diarrhoea 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 has provided them with preventive medication and put them under medical surveillance.
The CHP is continuing to investigate the source of infection of the case and is conducting whole genome sequencing of the virus sample. The CHP will also report the case to the World Health Organization (WHO).
Humans are primarily infected with the influenza A virus through direct contact with infected poultry or through indirect contact with environments contaminated by their droppings. The CHP´s epidemiological investigation indicated that the patient had visited a location where live poultry was sold. It cannot be ruled out that the patient was infected through indirect contact with a contaminated environment at the wet market. As young children have weaker immune systems and are incapable of maintaining good hand hygiene, the CHP advised parents to avoid taking young children to places where live poultry is sold. Transporting poultry may contaminate the ground and the surrounding environment. As young children are shorter in height and easy to be in contact with the surrounding environment, they are at greater risk of coming into contact with poultry droppings or contaminated areas.
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.