Questions and Answers on Avian Influenza A (H7N9) or ‘Bird Flu’

What is the avian influenza A (H7N9) virus?

Avian influenza (also known as ‘bird flu’) viruses normally circulate among birds. Although some avian H7 viruses (H7N2, H7N3 and H7N7) have occasionally been found to infect humans, no human infections with H7N9 virus were reported until reports began from China in March 2013. To date there have been no avian influenza H7N9 detected in human nor chicken in Viet Nam.

What are the main symptoms of human infection with this H7N9 virus?

Thus far, most people with this infection have had severe pneumonia. Common symptoms include fever, cough and shortness of breath. In severe cases of avian influenza, especially when those infected do not receive proper medical care, people may die. We know of only a small number of people, infected with H7N9, who display influenza-like symptoms and then recovered without medical attention.

How many human cases of H7N9 virus infection have been reported in China to date?

Between February 2013 and January 2018 1,624 laboratory-confirmed cases of human infection with avian influenza A(H7N9) viruses, including at least 621 deaths in China (1). A marked increase in human cases has been observed in winter 2016-17 compared to previous years.

How are people becoming infected with H7N9 virus?

The available epidemiological and virological information strongly indicates that most known human H7N9 infections result from direct or indirect contact with infected poultry (for example, by visiting wet markets and having contact with environments where infected poultry have been kept or slaughtered).

Poultry infected with the low pathogenic H7N9 virus show little to no signs of illness, making it hard to identify infected birds. However, a change of the H7N9 virus from low to high pathogenicity in chickens has been detected in January 2017 and currently both forms are currently co-circulating. Healthy or sick poultry from infected area can both be a source of infection.

Although there have been clusters of infection (infections in people in close proximity to one another), sustained human-to-human transmission has not been reported.

How can infection with H7N9 virus be prevented?

It is recommended to follow basic hygienic practices to prevent infection. They include ensuring appropriate hand hygiene, respiratory hygiene and taking food-safety precautions.

  • Hand hygiene: Wash your hands before, during, and after preparing food; before eating; after using the toilet; after handling animals or animal waste; and before and after providing care to anyone who is sick. Hand hygiene will also prevent the spread of infections to yourself (from touching contaminated surfaces) and in hospitals to patients, health care workers and others.
  • Respiratory hygiene: When coughing or sneezing, cover your mouth and nose with a medical mask, tissue, a sleeve or flexed elbow; throw the used tissue into a closed bin immediately after use; perform hand hygiene after contact with respiratory secretions.
  • Food safety: Because influenza viruses are killed by normal temperatures used for cooking, meat products and eggs can be safely consumed provided they are properly handled during food preparation and thoroughly cooked. Animals that are clearly sick or that have died of diseases or died unexpectedly should not be eaten. Always keep raw meat and eggs separate from cooked or ready-to-eat foods to avoid contamination.

To reduce the risk of virus introduction and spread in Viet Nam, only buy healthy poultry from reliable source and report any unusual poultry death to the authorities immediately.

Is there a vaccine for the H7N9 virus?

Currently, no vaccine for the prevention of H7N9 infections in humans is commercially available. WHO is working with partners for vaccine development and some products are now being tested for efficacy and safety.

(1)FAO H7N9 situation update