Avian influenza is caused by influenza A viruses that mainly affect birds and poultry, such as chickens or ducks. Some avian influenza viruses can infect and spread to other animals, such as mammals, as well. Human cases infected with avian influenza A (e.g. H3N8,H5N1, H5N6, H7N9, H9N2, H10N3 and H10N5) viruses have been identified in recent years.
2. What are the symptoms of human infection with avian influenza?
Illness in humans from avian influenza virus infections have ranged in severity from no symptoms or mild, flu-like symptoms (e.g. fever, cough, sore throat, muscle aches) to severe respiratory disease (e.g. chest infection) that resulted in multi-organ failure and even death. Eye infection (conjunctivitis), gastrointestinal symptoms (e.g. nausea, vomiting and diarrhoea) and neurological symptoms (e.g. seizures) have also been reported.
3. How do people become infected with avian influenza virus?
People mainly become infected with avian influenza virus through contact with infected birds, poultry or other animals (live or dead) or contaminated surfaces with saliva, mucous and animal faeces or environments (such as wet markets and live poultry markets). Human-to-human transmission is inefficient.
4. How to prevent avian influenza infection?
Infected birds, poultry or other animals (live or dead) or their excrement may carry avian influenza virus. Therefore, members of the public should avoid touching their secretions and excrement, and pay attention to the following issues to prevent avian influenza:
1. Handling poultry5. Is it safe to eat poultry products?
It is safe to eat properly prepared and cooked meat because influenza viruses can be inactivated by sufficient heating. Therefore, poultry should be cooked thoroughly. If there is pinkish juice running from the cooked poultry or the middle part of its bone is still red in colour, the poultry should be cooked again until fully cooked. Eggs should be cooked well until the white and yolk become firm. Do not eat raw eggs or dip cooked food into any sauce containing raw eggs. Moreover, consumption of uncooked blood-based dishes is considered a high-risk practice and is discouraged. Sick poultry should also not be eaten.
6. Is it safe to visit live poultry markets or farms?
Members of the public should minimize visit to live poultry markets or farms and avoid contact with contaminated surfaces as exposure to infected poultry or its contaminated environment are important risk factors of human infection of avian influenza. People should maintain good hand hygiene before and after contact with live poultry and their environments.
7. Is there a vaccine for prevention of human infection with avian influenza virus?
There is no registered vaccine for use in humans specific for avian influenza in Hong Kong.
Seasonal influenza vaccine cannot prevent avian influenza, however it can help reduce the chance of complications and hospitalisation from seasonal influenza as well as reduce the risk of co-infection with human and avian influenza A viruses. All persons aged 6 months or above except those with known contraindications are suitable to receive seasonal influenza vaccination for personal protection. The Scientific Committee on Vaccine Preventable Diseases recommends a number of priority groups for seasonal influenza vaccination based on a range of scientific considerations taking into account local disease burden and international experience.
8. How to treat human infection with avian influenza virus?
Symptoms are mainly relieved by supportive treatment. Patients should get adequate rest and drink plenty of fluids. People with flu-like symptoms should seek medical advice, especially those with weakened immunity, or if their condition deteriorates (e.g. developing persistent high fever or shortness of breath). Some anti-viral drugs may be effective in treating the condition. Doctor will prescribe antiviral drugs (e.g. Tamiflu) to a patient depending on the circumstances and health needs of the patient.
9. Are health care workers at risk from getting avian influenza virus?
As health care workers often come into contact with patients with infectious diseases, appropriate infection prevention and control measures should be consistently applied in health care settings, and the health status of health care workers should be closely monitored. Please refer to the relevant guidelines for health professionals at http://www.chp.gov.hk/en/view_content/28620.html
10. Do avian influenza viruses pose a pandemic threat to humans?
Since avian influenza viruses do not commonly infect humans, there is little or no immune protection against them in the human population. If an avian influenza virus acquired the capacity to spread easily from person to person, either through adaptation or acquisition of certain genes from human viruses, an influenza pandemic can occur.