What is avian
influenza?
Avian influenza, or “bird flu”, is a contagious disease of animals caused by
viruses that
normally infect only birds and, less commonly, pigs.
Avian
influenza viruses are highly species-specific, but have, on rare occasions, crossed the species barrier to infect humans.
Which viruses cause highly pathogenic disease?
Influenza A viruses have 16 H subtypes and 9 N subtypes. Only viruses of the H5 and H7 subtypes are known to cause the highly pathogenic form of the disease.
Does the virus spread easily from birds to humans?
No. Though more than 100 human cases have occurred in the current outbreaks, this is a small number compared with the huge number of birds affected and the numerous associated opportunities for human exposure, especially in areas where backyard flocks are common.
How do people become infected?
Direct
contact with infected poultry, or surfaces and objects contaminated by their faeces, is presently considered the main route of human infection. To date, most human cases have occurred in rural or semi urban areas where many households keep small poultry flocks, which often roam freely, sometimes entering homes or sharing outdoor areas where children play. As infected birds shed large quantities of virus in their faeces, opportunities for exposure to infected droppings or to environments contaminated by the virus are abundant under such conditions. Exposure is considered most likely during slaughter, defeathering, butchering, and preparation of poultry for cooking.
What are the major symptoms and implications for human health?
The widespread persistence of H5N1 in poultry populations poses two main risks for human health. The first is the risk of direct infection when the virus passes from poultry to humans, resulting in very severe disease. Of the few avian influenza viruses that have crossed the species barrier to infect humans, H5N1 has caused the largest number of cases of severe disease and death in humans. Unlike normal seasonal influenza, where infection causes only mild respiratory symptoms in most people, the disease caused by H5N1 follows an unusually aggressive clinical course, with rapid deterioration and high fatality.
Symptoms may start similar to a common cold with cough and cold with fever. However there may be rapid progression to pneumonia and multiple organ failure could result. Primary viral pneumonia and multi-organ failure are common. A second risk, of even greater concern, is that the virus – if given enough opportunities will change into a form that is highly infectious for humans and spreads easily from person to person. Such a change could mark the start of a global outbreak (a pandemic).
What drugs are available for treatment?
Two drugs (in the neuraminidase inhibitors class), oseltamivir (commercially known as Tamiflu) and zanamivir (commercially known as Relenza) can reduce the severity and duration of illness caused by seasonal influenza. The efficacy of the neuraminidase inhibitors depends on their administration within 48 hours after symptom onset. For cases of human infection with H5N1, the drugs may improve prospects of survival, if administered early, but clinical data are limited. The H5N1 virus is expected to be susceptible to the neuraminidase inhibitors.
What precautions do I need to take if I am in an area affected by Avian influenza?
If you are passing through, or live in an area affected by Avian influenza, please bear in mind that bird flu can be prevented with some basic precautions:
People should avoid contact with chickens, ducks or other poultry unless absolutely necessary. This is the best way to prevent infection with the bird flu virus.
Children are at high risk because they may play where poultry are found. Teach your children the following basic guidelines:
Avoid contact with any birds, their feathers, faeces and other waste.
Do not keep birds as pets.
Wash hands with soap and water after any contact.
Not to sleep near poultry.
Do not prepare poultry from affected areas as food for your family or animals. The slaughter and preparation of such birds for food is dangerous.
If you unintentionally come into contact with poultry in an affected area, such as touching the bird's body, touching its faeces or other animal dirt, or walking on soil contaminated with poultry faeces:
wash your hands well with soap and water after each contact;
remove your shoes outside the house and clean them of all dirt; and
check your temperature for 7 days at least once daily. If you develop a high temperature (>37.5°C), visit a doctor or the nearest health care facility immediately.
Precautions can be taken when visiting friends or relatives in health-care facilities.
If you visit a patient who has bird flu, follow the advice from the hospital staff to wear protective clothing, including a mask, gown, gloves and goggles.
Such special protective clothing is required when you have direct contact with the patient and/or the patient's environment.
It is important that the protective mask fits properly. If it doesn't, seek advice from the hospital staff.
When you leave the patient's room you must remove these items and wash your hands with soap and water.
Useful Links (Internet connection required):
WHO:
http://www.who.int/csr/disease/avian_influenza/en/
http://www.who.int/mediacentre/factsheets/avian_influenza/en/index.html
Centers for Disease Control (US):
http://www.cdc.gov/flu/avian/index.htm