Preparing for the Bird Flu and Other Killer Viruses
By Michael T. Murray, N.D.
The "bird flu" is the common name given to avian influenza - an infectious disease of birds caused by type A strains of the influenza virus. There are many different subtypes of type A influenza viruses. The subtype that is the most significant to humans right now is H5N1. Although this strain has been around for some time, a significantly deadly outbreak of influenza H5N1 occurred among poultry in Hong Kong in 1997 and throughout Asia during late 2003 and early 2004. During that time, more than 100 million birds in the affected countries either died from the disease or were killed in order to try to control the outbreak. In 1997, the entire poultry population of Honk Kong (estimated to be 1.5 million birds) were wiped out in an attempt to block the spread of the disease. Obviously, this effort failed.
So, what is the big deal about birds dying from a virus. Well, although the H5N1 virus does not usually infect humans if it does make the leap it produces severe and often fatal consequences. The first documented infection of humans with an avian influenza virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans, of whom 6 died. Since the more recent outbreak of H5N1 in Asian poultry, fatal human infections of H5N1 have now been reported in Cambodia, Indonesia, Thailand, and Vietnam.
Of the 15 avian influenza virus subtypes, H5N1 is of particular concern for several reasons. First, it mutates rapidly and has a documented propensity to acquire genes from other viruses that would allow it to infect humans. Secondly, it is an extremely deadly virus compared to other subtypes.
Published information about the clinical course of human infection with H5N1 is limited. In the 1997 Hong Kong outbreak, patients developed symptoms of fever, sore throat, cough and, in several of the fatal cases, severe respiratory distress secondary to viral pneumonia.
Right now it appears that human infection with H5N1 most often occurs from contact with infected poultry or contaminated surfaces; however, it is thought that in a few cases human-to-human spread of H5N1 have occurred, but spread of the virus has not continued beyond one person. However, because all influenza viruses have the ability to change, scientists are concerned that the H5N1 virus one day could be able to infect humans and spread easily from one person to another. Because these viruses do not commonly infect humans, there is little or no built in immune protection against them in humans. If the H5N1 virus were able to infect people and spread easily from person to person, an influenza pandemic (worldwide outbreak of disease) could begin.
The warning of a major bird flu pandemic coming from various health experts and recently echoed by President Bush are based on historical patterns. Throughout history influenza pandemics have occurred. In the 20th century, the following pandemics occurred:
1918-19 – The "Spanish flu" caused the highest number of known influenza deaths. More than 500,000 people died in the United States and up to 50 million people died worldwide. Many people died within the first few days after infection, and others died of secondary complications.
1957-58, "Asian flu," [A (H2N2)], caused about 70,000 deaths in the United States . First identified in China in late February 1957, the Asian flu spread to the United States by June 1957.
1968-69, " Hong Kong flu," [A (H3N2)], caused about 34,000 deaths in the United States . This