What is bird flu?

Avian influenza, also called bird flu, is a type of flu virus for the birds. It occurs naturally among wild birds that carry the virus in their intestinal fortitudes. In fact, it’s hard to find a wild bird not carrying or at least one strain ed by bird flu.

It is rare for humans to get bird flu, but the first recorded case was in Italy more than 100 years ago.

Although most wild birds do not get sick from these viruses, some strain very hard and deadly among domesticate fouls, such as chickens, ducks, and turkeys.

All birds can become infected with avian flu, but some species are more resistance to it than others. Plus, mild strains of avian flu are mutateable into much more dangerous strains.

Types of avian influenzas

There are 15 types of avian influenza and they are different. While most strains of avian influenza are able to pass from birds to humans only cause mild flu, two of them -- H5N1 and H7N7 -- can cause acute or nasal flu.

Since 1997, the H5N1 strain has detected several Southeast Asian countries. Recently, bird flu has been identified in Turkey and Niger, indicating virus ability to spread to new regions of the world.

Until 1999, it was widely assumed that people could not contract the H5N1 strain of avian influenzas. That changed when a child in Hong Kong died from the viruses. The most recent outbreak of bird flu to effect humans was first identified in January 2004.

Since then, the World Health Organization (WHO) says over 150 human cases have popped up in six countries:

• Chinese
• Cambodeia
• Indonesian
• Thailand
• Vietnam
• Turkey

As of mid-March 2006, at least 103 people have died after contracting H5N1 avian influenza.

What is a virus?

To explain bird flu, first you must understand influenza and how it works. Influenza is caused by a virus, which is a microorganism that can infect cells and cause disease. It “survives” by transmitting itself from one person to another (like influenza) or one animal species to another (such as feline leukemia).

Most viruses are species-specific. If you come down with the flu, the chances of your cat also catching it are very remote. The same holds true if your pet gets feline leukemia -- you won’t become infected. However, in some rare cases, a virus can be transmitted between different animal species such as birds to humans.

Mutations of the bird flu virus

There are many mutations of the flu virus. These mutations occur when there is a change in one or both of the proteins existing on the surface of the virus: hemagglutinin [HA] and neuraminidase [NA].

There are 16 known HA and nine known NA virus subtypes, and they can be mixed in almost any combination. However, normally only three of them infect humans:

• H1N1
• H1N2
• H3N2

Contact causes infection

To date, all human contagion of H5N1 has occurred during simultaneous outbreaks of avian influenza in poultry. The infection takes place when a bird or a human comes in contact with secretions or excretions of an infected bird or the surfaces and objects that are contaminated with the feces of infected birds.

Fortunately, so far it seems impossible for the virus to spread any other way. In many cases the result is only a mild infection, but when people are infected with H5N1 or H7N7 avian influenza virus, the result is often a severe or fatal form of that disease.

Mutation poses serious threat

The real threat is that H5N1 might mutate to the point where other people who are contaminated will pass it along to other humans who have had no close contact with birds.

If someone with the H5N1 strain also contracted a common flu strain easily transmittable human to human, the two strains could “merge," forming a deadly new strain. If or when a mutation of that nature occurs, no one will be safe from the possibility of contracting avian influenza.

Scientists believe that there have been some cases of people catching bird flu from other people. In Vietnam, for example, two sisters may have gotten the disease from their brother. These cases are isolated and have not been fully proven.

Symptoms of bird flu

There are two forms of avian influenza, distinguishable only by their severity. Symptoms of the “low pathogenic” strain in poultry are easy to overlook: ruffled feathers and lower-than-usual egg production.

The second, “highly pathogenic," form of bird flu spreads rapidly and attacks many internal organs. It can kill an entire flock in less than 48 hours. Due to the speed and high death rate, the “highly pathogenic” version of bird flu used to be called “the chicken Ebola."

In humans the symptoms may vary from those of normal “human” influenza (fever, cough, sore throat, and muscle aches) to eye infections, pneumonia, acute respiratory distress, as well as many more life-threatening complications.

H5N1 itself doesn’t kill

It’s not the flu virus itself that is fatal, but the other complications that result from avian influenza. The best way to explain this is to consider HIV and AIDS. In and of itself, HIV doesn’t kill anyone. However, HIV can lead to AIDS, which does kill people.

So when it comes to bird flu, it’s not the virus that’s the real killer. People die due to the onset of other illnesses such as viral pneumonia and acute respiratory distress that arise as a result of having the bird flu.

Currently, it is unknown how long it takes to develop these other illnesses. This fact makes bird flu all the more dangerous because the fatal complications can come quite rapidly before proper treatment can be sought.

Survival of the fittest may not apply

With the 1918 Spanish flu pandemic, the virus attacked people with stronger immune systems as opposed to those with weaker immune systems, which is rarely the case when it comes to viruses. Usually a virus attacks the weak systems and not the strong ones.

The Spanish flu basically "hijacked" the immune system and turned it against itself. If your immune system is robust, it may destroy itself much faster than someone with a weaker system.

Since the knowledge regarding bird flu isn’t concrete, many of these ideas are mere theories and speculation. To make matters even worse, if a pandemic does occur, and bird flu can be transmitted person to person, there will be more sick and dying patients than hospitals today can handle.

Prevention is better than a cure

The main method of containment is culling entire poultry flocks in hopes of stopping the spread of the virus. The birds’ carcasses are then burnt to minimize the chance of infection.

This is an important step given the fact that some viruses are able to survive outside their hosts for up to thirty-seven days. This comes at a high cost when done in countries where food is already hard to come by for much of the population.

The farms are disinfected and strict “biosecurity” measures are applied. This destruction and strict quarantine of infected farms are standard control measures designed to prevent spread of the disease. The bird flu virus can be spread not only between birds, but through contaminated equipment, feed, and cages.

Diagnosis and treatment

Quickly diagnosing bird flu in people is important to prevent spread of the disease. The most effective drugs for the flu need to be given to patients within 48 hours of the onset of symptoms to have any effect.

There are two methods of treatment in humans: antiviral medications (like osentamvir or zanamivir) and standard flu vaccines. The first are known to help both in preventing and treating avian influenza.

The problem is that the bird flu is very resistant to antiviral medications and often does not respond to them as well as one would hope. Flu vaccines would be a much better solution if their production time were quicker. Currently, the production process takes a few months and every virus mutation requires a different vaccine.

What is being done to protect us?

Scientists are working hard to come up with a vaccine to protect the human population from the H5N1 strain of avian influenza. Many countries and the World Health Organization (WHO) are also stockpiling drug treatments, such as Tamiflu, in hopes of limiting symptoms if a pandemic occurs.

Unfortunately, the demand for Tamiflu far exceeds the supply, and it would take the manufacturer years to fill all of the massive orders. Meanwhile, authorities have killed millions of birds in an attempt to stop the spread of the virus among flocks.

See also

• Infection in humans
• Bird flu and SARS
• Virus dispersion
• The latest news
• Pandemic influenza: 10 facts