Every fall we worry about flu epidemics that may be coming. The true "flu" is influenza, a viral infection of the lungs. It can cause severe bronchitis and even pneumonia. It is often complicated by a later bacterial pneumonia, too. Flu epidemics are in the "A" family of viruses. "B" strains are also present, but they usually do not cause epidemics. Most influenza originates in Asia. Thus we have the "Hong Kong Flu", the "Chinese Flu", the "Australian Flu", etc. "A" type influenza viruses contain antigen markers labeled "H" and "N." The N is for neuroamidase, an enzyme necessary for the pathogenesis of influenza. These N antigens mutate most years. This is why last year's vaccine will usually not protect against a new mutant this year.
Influenza vaccine contains a complex of H and N antigens. This year we are particularly afraid of the "bird flu", which is designated H5N1. We don't have a vaccine for this one yet, and we hope that it does not cause an epidemic! This would be disastrous. Last year the Asian flu vaccine was in short supply because of manufacturing problems. This is being addressed this year and more vaccine will be available. The vaccine is also effective against B strains of influenza. But vaccination is only about 80% effective, and it tends to fail in older people and those with poor immune defenses.
There are also antivirus drugs that can prevent, or treat influenza if used when it just starts. Older drugs such as amantadine, and ranitidine, are not as effective as the new Tamiflu, and Relenza. Relenza is an inhaled drug and not good for asthmatics or those with COPD because of the irritation it causes. Tamiflu is a very good oral drug, and it may be a lifesaver if we get the bird flu, and in people who are not protected from any vaccine that is available. Tamiflu should be on hand for all at high risk, i.e., older people and babies, and those with severe organ system diseases such as heart, lung, kidney, liver or diabetes.
Influenza causes a well-recognized set of symptoms and signs. A sudden cough, fever, and severe muscle aches and pains are the tip off. If this happens suddenly, Tamiflu, two tablets a day, will usually abort the disease. It can be lifesaving. Tamiflu can also be used for prevention at one tablet a day, but it is probably best reserved for influenza when symptoms FIRST START!
Many other illness are called the "flu," such as the "stomach flu", the "24 hour flu", and so on. This is NOT influenza and should not be treated with Tamiflu. Also, the common cold is not treated or prevented by Tamiflu. Tamiflu should be kept in reserve for the true influenza.
If an epidemic hits, avoid crowds. Wash your hands frequently and take packaged hand wipes with you that contain a disinfectant. Be distant, even from your friends. Avoid kissing and hand shaking during a flu season. Just wave and smile. Influenza is a serious disease and we must be sensible about dealing with it. Keep healthy!
I'll be in touch next month!
Thomas Petty, MD