Website of the Department of Health

2.1.1 Where does avian flu occur?

Avian flu occurs worldwide. The current outbreak of highly pathogenic avian flu (A/H5N1), which began in mid-December 2003 in Korea, has to date affected poultry in nine countries (including Hong Kong) all of which are in Asia. In three of these countries, this A/H5N1 strain has also infected people. By the middle of March 2004, the virus had resulted in the loss of more than 100 million poultry. An up-to-date list of countries with A/H5N1 infections in poultry can be found at the website of the World Organisation for Animal Health. More information on avian flu can also be obtained from the Department of the Environment, Food and Rural Affairs.

'Never before have we seen so many countries so widely affected by this disease, and with such devastating economic consequences, for rural farms and households as well as for the poultry industry.'
Dr Anarfi Asamoa-Baah, Assistant Director-General,
Department of Communicable Diseases,
World Health Organization

• World Organisation for Animal Health: Avian influenza (opens new window)
• Avian influenza contingency plan from Department for Environment, Food and Rural Affairs (Defra) (opens new window)

2.1.2 Avian flu in people

Avian flu viruses do not normally infect species other than birds or pigs. Historically, human infections with avian influenza viruses have been rare and usually mild. However, when the first documented infection of people with an H5N1 avian flu virus occurred in Hong Kong in 1997, causing severe respiratory disease in 18 people, six of them died. Investigation into this outbreak showed that close contact with live infected poultry was the source of human infection.

A/H5N1 emerged again in February 2003 in Hong Kong infecting two people and killing one. The current outbreak of A/H5N1 began in mid- infected 55 people, killing 42 of them (see Fig. 2.1).

• Download Figure 2.1 Map showing countries affected by the current outbreak of A/H5N1 (PDF, 31K)

Two other avian flu viruses have recently caused illness in people but not on the same scale as that caused by A/H5N1: A/H7N7 emerged in the Netherlands in February 2003 causing mild illness in 83 people, and one death.

A/H9N2 also caused mild cases of flu in two children in Hong Kong in 1999 and one child in mid-December 2003.

Table 2.1: Reported cases of avian influenza in humans up to February 2005.

Have there been human cases of avian flu in the UK?

Have there been human cases of avian flu in the UK?

In England in 1996, a woman farmer acquired a typically avian flu virus (H7) and suffered conjunctivitis (eye infection) after cleaning out a poultry house.

There have been no human cases in this country associated with the current outbreak of A/H5N1. Controls are in place, but it remains a very remote possibility that A/H5N1 in its current form could be introduced to poultry or humans in the UK, either by the migration or illegal importation of wild birds carrying the virus or the importation of contaminated dead chickens for consumption. It is also possible the UK could import avian flu through someone entering the country having acquired the infection in an infected area.

2.1.3 How does avian flu spread?

Avian flu viruses spread through poultry flocks either via respiratory secretions or contact with contaminated faeces (droppings). A single gram of contaminated faeces can contain enough virus to infect one million birds. Droppings can also contaminate dust, soil, water, feed, equipment and clothing.

People are usually infected through close contact with infected birds or their faeces. Person-to-person spread, if it has occurred, has done so only with difficulty and has not so far resulted in onward transmission of the infection.

2.1.4 Symptoms

The symptoms of avian flu in people range from conjunctivitis to typical flu-like symptoms which can lead to pneumonia, acute respiratory distress, viral pneumonia, and other severe and life-threatening complications.