What is H7N9?

Influenza A H7 viruses are a group of influenza viruses that normally circulate among birds. The H7N9 virus is one subgroup among the larger group of H7 viruses. Although some H7 viruses (H7N2, H7N3 and H7N7) have occasionally been found to infect humans, no human infections with H7N9 viruses have been reported until recent reports from China.

What are the symptoms?

Most infected patients have exhibited severe pneumonia. Symptoms include fever, cough and shortness of breath. However, information is still limited about the full spectrum of disease that infection with H7N9 might cause.

How can infection be prevented?

No vaccine for the prevention of H7N9 infections is currently available. Although both the source of infection and the mode of transmission are uncertain, it is prudent to follow basic hygienic practices to prevent infection. They include hand and respiratory hygiene and food safety measures.

Hand hygiene:

- Wash your hands before, during, and after preparing food; before eating; after using the toilet; after handling animals or animal waste; when the hands are dirty; and when providing care when someone in your home is sick.

- Wash hands with soap and running water when visibly dirty; if not visibly dirty, wash hands with soap and water or use an alcohol-based hand cleanser.

Respiratory hygiene:

Cover your mouth and nose with a medical mask, tissue, or a sleeve or flexed elbow when coughing or sneezing; throw the used tissue into a closed bin immediately after use; perform hand hygiene after contact with respiratory secretions.

Food safety:

It is safe to eat properly prepared and cooked meat, including from poultry and game birds. Diseased animals and animals that have died of diseases should not be eaten. The consumption of raw meat and uncooked blood-based dishes is a high-risk practice and should be discouraged.

What is known about previous H7 outbreaks?

Human infections with H7 influenza viruses (H7N2, H7N3, and H7N7) were reported in the Netherlands, Italy, Canada, United States of America, Mexico and the United Kingdom from 1996 to 2012. Most of these infections occurred in association with poultry outbreaks. The infections mainly resulted in conjunctivitis and mild upper respiratory symptoms, with the exception of one death, which occurred in the Netherlands.

What are the differences between H7N9, H1N1 and H5N1 viruses?

All three viruses are influenza A viruses but they are distinct from each other. H7N9 and H5N1 are considered animal influenza viruses that sometimes infect people. H1N1 viruses can be divided into those that normally infect people and those that normally infect animals.

(Source: World Health Organization)