What is avian influenza and how people can protect against this disease?

According to the World Health Organization (WHO) the UN or avian influenza is an infectious disease that affects birds and is caused by type A strains of influenza virus. This disease, which was first identified in Italy more than 100 years ago, occurs worldwide.

It is believed that all birds are susceptible to such infection, although certain species are more resistant than others. Infected birds may show different symptoms, from mild flu to a highly contagious disease and fulminant course resulting in severe epidemics.

The latter is known as “highly pathogenic avian influenza. This form is characterized by sudden onset, severe illness and rapid death, with a mortality that can approach 100%.

Migratory waterfowl – especially wild ducks – are the natural reservoir of avian influenza viruses, also being the most resistant to infection. The domestic poultry, including chickens and turkeys, are particularly vulnerable to epidemics of rapidly fatal influenza.

The direct or indirect contact of domestic flocks with wild migratory waterfowl has been mentioned as a frequent cause of such epidemics. Live bird markets have also played an important role in the spread of epidemics.

Why is the avian flu virus H5N1 is so dangerous?

Of the 15 subtypes of avian influenza virus, H5N1 is the most worrying because it mutates rapidly and has a documented propensity to acquire genes from viruses infecting other animal species.

Their ability to cause serious disease to humans has been documented on two occasions. In addition, laboratory studies have shown that the isolated viruses are highly pathogenic and can cause severe disease in humans.

Birds that survive infection excrete virus for at least 10 days, both orally further facilitating the spread in the markets for live poultry and through migratory birds.

The epidemic of highly pathogenic avian influenza caused by H5N1, which began in mid December 2003 in the Republic of Korea and currently affects other Asian countries is therefore of particular public health importance.

H5N1 variants demonstrated a capacity to directly infect humans in 1997, and has done so again in Vietnam in January 2004. The spread of infection among birds increases the potential for direct infection of humans.

If as time goes on growing the number of infected people will also increase the likelihood that humans, when concurrently infected with strains of human influenza and avian influenza, also serve as a “Shaker” for the emergence of a novel subtype with sufficient human genes to be passed easily from person to person. An act of such features mark the start of an influenza pandemic.

In the HongKong outbreak in 1997, patients had symptoms of fever, sore throat, cough and, in some fatal cases, severe respiratory distress secondary to viral pneumonia. Were affected previously healthy adults and children, and some people with chronic medical conditions.

Since then, the tests for all strains of flu virus that affects animals and humans are rapid and reliable. Many laboratories worldwide network of WHO flu have high security facilities and reagents as well as considerable experience, to carry out these tests.

It also offers Rapid bedside tests for the diagnosis of human influenza, although such tests lack the precision of the most comprehensive analysis currently required to understand the most recent cases and determine whether human infection is spreading, either directly from birds or from humans.

Antiviral drugs, some of which can be used both for the treatment and prevention, are clinically effective against virus strains in adults and children, otherwise healthy, but have some limitations. Some of these drugs are also expensive and supplies are limited.

The experience in the production of influenza vaccines is also considerable, especially considering that every year changes its composition to suit the changes in circulating virus due to antigenic drift. However, it takes at least four months to produce significant quantities of a new vaccine that protects against a new virus subtype.