Fear of bird flu pandemic grows as more humans infected

Main Category: Bird Flu / Avian Flu
Also Included In: Flu / Cold / SARS
Article Date: 13 Mar 2005 - 10:00 PDT


Health officials around the world look on anxiously as Vietnamese officials confirm another person has come down with bird (avian) flu - this time a nurse who had been attending a bird flu patient. This is the second nurse in less than a week.

Experts worry that the virus could mutate, become transmissible from human to human - resulting in a worldwide pandemic.

Countries are already beginning to build up national stocks of antivirals - the UK has 14m of them in the form of Tamiflu (an antiviral drug).

About two thirds to three quarters of bird flu patients die.

What is Bird Flu?

Bird flu or avian influenza is an infectious disease of birds ranging from mild to severe form of illness. All birds are thought to be susceptible to bird flu, though some species are more resistant to infection than others. Some forms of bird flu can cause illness to humans.

What causes bird flu?

Bird flu is caused by different subtypes of influenza A virus affecting chickens, ducks and other birds Viruses which cause mild disease can mutate into viruses that can cause serious disease (highly pathogenic).

To date, all outbreaks of the highly pathogenic form have been caused by Influenza A /H5N1 virus, the only subtype that cause severe disease in humans.

How is bird flu transmitted in chickens and other birds?

-- Direct contact with discharges from infected birds, especially feces and respiratory secretions

-- Contaminated feed, water, cages equipment, vehicles and clothing

-- Clinically normal waterfowl and sea birds my introduce the virus into flocks

-- Eggs from infected hens can break and contaminate incubators

Birds that survive infection excrete virus for at least 10 days, orally and in feces. Highly pathogenic viruses can survive for long periods in tissue, water and the environment, especially when temperatures are low.

How do outbreaks of bird flu spread within the country?

1. Domestic birds can get the infection when they:

-- roam freely

-- share water supply with wild birds

-- use a water supply that might be contaminated by infected droppings

2. Contaminated equipment, vehicles, feeds, cages, or clothing, especially shoes can carry the virus from farm to farm

3. Wet markets where live chickens and other birds are sold under crowded and sometimes unsanitary conditions

How is bird flu transmitted to humans?

Bird flu is transmitted to humans from direct or indirect contact with infected wild ducks and chickens through infected aerosols, discharges and surfaces.

A person handling or taking care infected chickens or came near or inside a poultry or market where there are sick chickens can inhale the particles from dried discharges or feces with the bird flu virus.

Discharges can get in contact with the nose or eyes of a person handling infected chickens.

There is no reported case of bird flu in humans after handling dressed chicken. Since the virus is easily inactivated by heat, one does not get bird flu from thoroughly cooked chicken meat.

To date, there is no evidence of human-to-human transmission.

Written by Christian Nordqvist, Editor, Medical News Today

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