D5

Diana M., Gavin W.,

Mary C., James F., Lindsay

Professor Underwood

November 26, 2007

SMIN Group Five

What is Avian Influenza? The Health Protection Agency defines Avian Influenza as “a disease of birds caused by influenza viruses closely related to human influenza viruses.” The article entitled, “Q&A: Bird flu.” from BBC News on November 12, 2007 and the New England Journal of Medicines article entitled, “Avian Influenza A (H5N1) Infection in Humans” help to describe the bird flu in more detail about the transmission of the disease; prevention; and the effects of the disease on humans.

The bird flu or Avian Influenza is effecting birds through different strains. The most contagious strains are the H5 and H7 which cause fatalities in birds. The really contagious H5 has nine different types, which take different forms. This causes some of the H5 to be highly pathogenic while others may be harmless. The type causing the most concern is the Asian strain of the H5N1 virus which is highly pathogenic.

Causing more concern is the discovery that scientists have made of four different subtypes of H5N1. These cause disease and death in birds and may also have the same effect on humans. But the disease primarily only affects birds. Most of the humans affected were poultry workers whom handle the birds on a daily basis.

Humans catch the Avian Influenza through contact with live birds who are carrying the disease. The birds pass on the disease through the excretion of their faeces. As the faeces dry and become pulverized while containing the disease, then this allows humans to inhale the disease. As the bird flu is passed on this increases the risk that humans may intercept the influenza. There are also assumptions that the disease may be transmitted through the plucking and preparing of diseased birds; handling fighting cocks; playing with poultry, particularly asymptomatic infected ducks; and consumption of duck's blood or possibly undercooked poultry. The disease may not be passed though human to human contact easily.

Avian Influenza may even be passed onto humans from the environment. These transmissions are theoretically possible because the ability of the disease to survive in natural environments. One way the disease may be transmitted is through oral ingestion of contaminated water during swimming and direct intranasal or conjunctival immunization during exposure to water, such as the “contamination of hands from infected fomites and subsequent self-inoculation.” (New England Journal of Medicine, 2007) Another environmental risk is the use of untreated poultry feces as fertilizer.

Increasing this risk are the migratory wildfowl and the wild ducks who may naturally carry the disease but most likely will not develop an infection. This increases the risk that they survive and thus pass Avian Influenza onto the domestic birds which are more susceptible to the virus.

While these birds may be natural carriers and may pass on the disease there is no failsafe way to prevent the spread of the disease. Experts suggest that proper poultry control should be put in place. One suggestion is to prevent wild birds from getting into the poultry houses. They also say that the migratory patterns of the wild birds should be monitored. This will provide early alerts of the arrival of infected flocks, so that the birds may be stopped as soon as they get there.

These precautions should be put in place because the disease is spreading. I three year old boy in Hong Kong became the first human victim in May 1997. Then the disease was detected a second time in Hong Kong, taking a father and son victim in February 2003. They were diagnosed with the H5N1 strain.

Precautions are being put into place to contain the virus in the counties that are already affected. Millions of birds on farms have been culled and millions others have been vaccinated and confined indoors. Areas where the disease was found have been isolated and others are banning imports of live birds and poultry products. In January 2006 international donors pledged $1.9bn in the fight against the Avian Influenza and the World Health Organization has put in place a rapid-response plan to detect and stop a global influenza pandemic.

Although the precautions of mass culls, exclusion zones, and other measures it has continued to travel. This strain has spread westward through Asia, the Middle East, Europe, and Africa. In 2005 a dead swan was found in Scotland carrying the strand. Once again in February 2006 in only a week the first cases were reported for Italy, Greece, Bulgaria, Germany, Austria, France, Slovenia, India, Iran, and Egypt.

Although the disease is being passed throughout the world there is no evidence of a possible pandemic of person to person transmission. Most people have contracted the disease from contact with sick birds but there are a few examples of human to human transmission. In Thailand there was a case of probable transmission from a girl with Avian Influenza to her mother, both died. The girls aunt was infected as well, but survived.

Another case occurred in 2004 when humans in close contact with one another were infected. Two sisters in Vietnam died from the disease after possibly contracting it from their brother who died from an unidentified respiratory disease. Previous to this case was one that occurred in 1997 when a doctor similarly could have caught the disease from a patient with the Avian flu virus in Hong Kong but this was never decisively proved. Professor John Oxford, a United Kingdom virology said these cases mean that the basic virus could be passed among humans and predicted that in the future similar small clusters of incidents would occur once again.

If a mass outbreak were to occur among humans then the consequences would be catastrophic. Experts predict that worldwide anything between two million and fifty million deaths could occur. But they say the mortality rate is presently at 50% of confirmed cases could decline as it mutates.