Avian Bird Flu in Birds

The Avian Bird Flu is caused by the Influenza A virus which mainly affects bird species. There are numerous strands of the Bird Flu, these include 16 H subtypes and 9 N subtypes. The most fatal in birds are strains H5 and H7. The strand that has gained much media attention is the H5N1 virus. This is one of the most lethal strains and is highly contagious in birds. The virus mainly infects birds, but human infections occur rarely.

H5N1 in Humans

Of all the bird flu strands, it has been found that the H5N1 virus has caused the most deaths in humans. The virus is transmitted to humans when they come into close proximity with infected birds or infected surfaces, and human-to-human transmission has also been recorded. The affected people however, have mostly been people that live in close proximity or work with poultry.

Viruses have the ability to change very rapidly. And it is a worldwide concern that the bird flu viruses could gain the ability to infect humans more effectively. Because the virus does not normally infect humans, the human body has no immune defence against it, thus a flu pandemic is possible.

Avian Bird Flu Symptoms

• Viral Pneumonia
• Multiple organ failure

Research has also found that cells of infected humans release high levels of cytokines such as tumor necrosis factor alpha which is a protein that causes tissue destruction. This release of cytokines also causes symptoms such as fever, headaches and vomiting. The release of cytokines works with a positive feedback system, meaning that releasing the cytokines causes the release of more cytokines. This results in more tissue destruction and eventually, death.

Avian Bird Flu Treatments

There are two drugs that have been recommended in the event of an Avian Bird Flu pandemic. Tami Flu and Relenza. These drugs are neuraminidase inhibitors. They have been found to work at maximum effect, the earlier they are administered. The virus’ resistance to the drug has already been reported, but further research is needed to confirm it. The process of manufacturing Tamiflu is complex and time-consuming. It is said that it will take 10 years to manufacture enough Tamiflu to treat 20% of the world. Another downside is the high cost of the drugs.

Another class of drug name M2 inhibitors have been trialled in the treatment of the virus, but it seems that many strains of the virus are already resistant to the drugs.

The Genetics of the Avian Bird Flu

The H5N1 virus is extremely virulent. It continues to mutate, and reassortement occurs, allowing it to form different combinations of genes. These different combinations allow the virus to survive in different conditions, and are what gave it its ability to move from infecting birds alone, to also infecting humans. These mutations also increase the virus’ ability to cause disease.

During reassortment, the viral RNA “exchanges” segments of genetic material with it’s hosts. And this is how it acquires some of it’s new genes.

An Avian Bird Flu pandemic may occur in the near future. Drugs have been developed to fight the H5N1 virus. However, the time consuming process of manufacturing means that even after 10 years of manufacturing the drug there won’t be enough to cure more than 20 % of the population.