The World Health Organization (WHO) has released a statement about the avian influenza A(H3N8) virus in China.

It says that, on Thursday (March 27), the National Health Commission of the People’s Republic of China notified the WHO of one confirmed case of human infection with an avian influenza A(H3N8) virus. This is the third reported case of human infection with an avian influenza A(H3N8) virus; all three cases have been reported from China.

Epidemiological investigation and close contact tracing have been carried out. There have been no other cases found among close contacts of the infected individual.

“Based on available information, it appears that this virus does not have the ability to spread easily from person to person, and therefore the risk of it spreading among humans at the national, regional, and international levels is considered to be low. However, due to the constantly evolving nature of influenza viruses, WHO stresses the importance of global surveillance to detect virological, epidemiological and clinical changes associated with circulating influenza viruses which may affect human (or animal) health,” says WHO. 

Description of the situation

The WHO reports that the patient was a 56-year-old female from Guangdong province with an onset of illness on February 22. She was hospitalised for severe pneumonia on March 3, and subsequently died on March 16.

The case was detected through the severe acute respiratory infection (SARI) surveillance system. The patient had multiple underlying conditions. She had a history of exposure to live poultry before the onset of the disease, and a history of wild bird presence around her home. No close contacts of the case developed an infection or symptoms of illness at the time of reporting.

Environmental samples were collected from the patient’s residence and the wet market where the patient spent time before the onset of illness. The results of testing showed that the samples collected from the wet market were positive for influenza A(H3).

Public health response and WHO risk assessment

In the statement, the WHO says that the Chinese government has taken the following monitoring, prevention, and control measures:

• Enhanced monitoring and disinfection in the surrounding environment of the patient’s residence and suspected exposure areas;
• Public risk communication activities to improve public awareness and adoption of self-protection measures.

Avian influenza A(H3N8) viruses are commonly detected globally in animals. Influenza A(H3N8) viruses are some of the most commonly found subtypes in birds, causing little to no sign of disease in either domestic poultry or wild birds. Cross-species transmission of A(H3N8) avian influenza viruses has been reported for various mammal species, including being endemic in dogs and horses.

The statement said: “One of the previous cases [in China] developed a critical illness, while the other had a mild illness. Both cases likely acquired infection from direct or indirect exposure to infected poultry. So far, no additional cases linked with this case, nor the previous cases, have been reported. According to reports from health officials, the preliminary epidemiological investigation into this event suggests that exposure to a live poultry market may have been the cause of infection. However, it is still unclear what the exact source of this infection is and how this virus is related to other avian influenza A(H3N8) viruses that are circulating in animals. To better understand the current risk to public health, more information is needed from both human and animal investigation.”

“The transmission of avian influenza viruses from birds to humans is usually sporadic and happens in a specific context: most human infections with avian influenza viruses that have been reported previously were due to exposure to infected poultry or contaminated environments. Since avian influenza viruses continue to be detected in poultry populations, further sporadic human cases are expected in the future,” the statement reads.

Human-to-human spread is low

The WHO, in the statement also state that, “The available epidemiological and virological information suggests that avian influenza A(H3N8) viruses do not have the capacity for sustained transmission among humans. Therefore, the current assessment is that the likelihood of human-to-human spread is low. However, due to the constantly evolving nature of influenza viruses, WHO continues to stress the importance of global surveillance to detect virologic, epidemiologic and clinical changes associated with circulating influenza viruses which may affect human (or animal) health.” 

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