Most of us are familiar with seasonal influenza or the “flu,” a viral infection that, despite annual vaccinations, results in approximately 36,000 deaths in the United States, including 2,000 in Illinois, and 200,000 hospitalizations annually. Intermittently over the centuries, changes in the genetic makeup of influenza virus result in a new strain to which people have never been exposed. These novel strains have the potential to cause a pandemic or worldwide outbreak of influenza, with potentially catastrophic consequences. In Illinois alone, a pandemic of even modest severity could result in thousands of deaths and the sickening of millions, even among those previously healthy. A new strain of influenza virus, H5N1, has been found in birds in Asia and Europe, and has shown it can infect humans. If the avian virus undergoes further change and becomes transmissible between humans, it could very well be the source of a new pandemic. It is impossible to know whether the currently circulating H5N1 strain will cause a human pandemic, but history and science suggest that the world will face one or more pandemics this century.
How are seasonal, avian and pandemic flu different?
Seasonal (common) flu is a respiratory illness that can be transmitted person-to-person. Most people have some immunity, and a vaccine is available.
Avian (or bird) flu is caused by influenza viruses that occur naturally among wild birds. The H5N1 variant is deadly to domestic fowl and can be transmitted from birds to humans. There is no human immunity and no vaccine is available.
Pandemic flu is a virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person-to-person. Currently, there is no pandemic flu.