|COLDS & FLU|
Avian Flu in America
It sounded like the plot of a made-for-television movie. In the remote corner of China, a group of villagers develop a severe, rapidly fatal respiratory infection. The source of the illness is traced to a virus that normally affects birds. Officials are relieved to see that it only affects villagers exposed to sick birds and did not spread from person to person. They feel comfortable that they have contained the outbreak by destroying flocks of infected birds. Then the same disease appears in other regions in China and then jumps to Indonesia. Health care officials realize that migrating birds are spreading the virus across Southeast Asia — and soon would carry the infection throughout the world.
In recent years, it has ben hard to pick up a newspaper or turn on the TV without yet another story of bird or avian flu. Since it first appeared in China in 1997, avian flu has infected birds in 48 countries in Asian, Africa and Europe. It has caused devastating illness in people in seven countries in Southeast Asia, as well as in Egypt and Turkey. Over 200 children and adults have been stricken and more than 100 have died — a mortality rate of more than 50 percent.
Adding to the concern is the discovery that the infamous influenza epidemic of 1918 was caused by a form of avian flu. Health officials around the world have put into place increased viral surveillance as well as established public health strategies to contain an outbreak if it should develop in a country. When the Bush Administration issued an executive order that allowed officials to declare a state of quarantine should it be needed, it was a sobering reminder of just how seriously experts regarded the threat.
Are we really on the verge of an avian flu pandemic? Many of the critical signs are certainly there. An animal virus suddenly becomes lethal to man. Pandemics come in cycles and we are definitely overdue for this type of worldwide outbreak. On the other hand, there have only been 200 cases in humans. Is the anxiety the result of an overactive imagination on a slow news day? The truth lies somewhere in between.
Avian Flu 101
Most cases of avian flu are seen in people who had direct contact with infected poultry. It is believed that the bird flu is spread by contact with sick poultry. Farmers and those who work in poultry processing plants are currently at highest risk of contracting the disease. There have been less than a dozen cases where the disease has been spread from person to person. In the spring of 2006, a family of seven died from avian flu. Doctors were especially concerned because it was the first time that the infection had spread to others twice removed from contact with a sick bird.
In fact, one of the most puzzling aspect of avian flu is its low level of contagion between people. Researchers at the University of Washington suggest that the difficulty in people to people transmission virus is linked the the fact that the virus likes to grow in cells that are found in the lower lungs. The deep seated infection means that it is less likely to spread by sneezing or kissing, slowing the spread of viral particles. However, the viral growth in the lower airways also is one of the reasons tha avian flu is such a severe illness.
While this is somewhat reassuring, scientists know that the influenza viruses are relentlessly changing. There is a deep concern that with a few small changes in the genetic code, the avian flu virus will start to flourish in the upper airways. With this type of development, infection could be easily spread by sneezing and coughing. Even a used tissue could be the source of millions of infectious viral particles.
Symptoms of Avian Flu
The Good News about Avian Flu
So far this approach of suveillance and containment has been working. In Thailand and Vietnam, there has not been a single human death this year from avian flu. In Africa, where the lack of health care resources and infra-structure were felt to be a weak link, there has not been an explosion of disease among domestic flocks that are so essential for the African economy.
Preventing and Treating Avian Flu
The threat of a deadly epidemic has actually focused long-needed attention on vaccine development and production. One of the most interesting developments is the addition of compounds to the vaccine that improve its performance. Called adjuvents, they can raise the efficiency of a vaccine so that lower doses can be used and more people can be protected. Another exciting area of research is the development of a universal influenza vaccine. Currently flu viruses change enough each year to require a new forumulation, and each year there is an anxious scramble to produce sufficient quantities of an effective vaccine. A universal vacine will be able to protect against the genetic make-up of the viruses. Without the need to remake the vaccine from scratch each year, the flu vaccine shortages will no longer be an issue.
Fear of an avian flu pandemic has also stimulated new diagnostic technology. We now have an effective test for avian flu that provides results in several hours. Not satisfied with the wait, virologists are working on a test that will show results in a matter of minutes. The new techniques that are being developed for this test will then be used to help us diagnose other new infections as they arise.
There have been equally impressive developments in the search for effective antiviral treatments. Doctors are aware that Tamiflu has shown an ability to reduce the spread of avian flu virus. It can be used to protect people exposed to the flu virus as well as to treat those who are already infected. Governments throughout the world have rushed to stockpile Tamiflu, but the drug is expensive and in extremely short supply. The patent is held by just one company and manufacture of this drug is time-consuming, complicated and even has a step that can explode. Tamiflu starts with a spice called star anise that is in relatively limited supply. Star anise is a licorice tasting seed, grown only in China and harvested only from March to May. It is the only source of shikimic acid, the first essential ingredient in the production of Tamiflu.
It has been truly exciting to watch scientists investigate and come up with new ways to produce Tamiflu. A researcher at the University of Michigan has been able toproduce shikimic acid via fermentation of gentically engineered bacteria. At Harvard, a scientist starts with two very inexpensive and common ingredients that actually avoids dangerous and explosive steps in Tamiflu production.
As we look at the disturbing, grainy photographs of the 1918 influenza epidemic, it is important to recognize that the current worldwide, early warning systems now in place certainly have dampened the natural course of epidemic disease. In 1918, we did not even know that influenza was caused by a virus. There were no vaccines, no antibiotics, nor diagnostic tests. Advances in surveillance and communications have interrupted the spread and mortality characteristic of past epidemics. They may not have elminiated or even contained avian flu, but these strategies have brough us valuable time to develop better vaccines and treatments and organize public health measures if and when the avian flu becomes pandemic.
The Danger at our Doorstep
We are absolutely right to be concerned about the possibility of a deadly avian flu pandemic. We should be at least as concerned about protection for the annual influenza outbreaks that we know will appear in our community each fall. If you take just one idea away from this article, let it be the need for an annual flu shot for the whole family.