The Uncommon Cold

Pathogens & People: Do these 4 things and you might avoid the common cold EDWARD McSWEEGAN, For The Capital Published December 07, 2008

The cold and flu season is almost upon us. We worry about the flu and many of us will take the annual vaccine and try to avoid people who may have the flu. Colds, on the other hand, are viewed as mild irritants. Colds are just a few days of scratchy throats, running noses, coughs and maybe some mild fever. There's not much to do about a cold and not much to worry about either. Or is there? Last year, the Centers for Disease Control and Prevention reported 140 cases of an unusually severe type of cold. Five percent of the patients died. The "common cold" is caused by hundreds of common viruses. Most colds are caused by a group of viruses called rhinoviruses. Coronaviruses, parainfluenza viruses, adenoviruses, enteroviruses and some influenza viruses also can cause colds. There are about 50 types of adenoviruses that infect people. The adenoviruses are very hardy and can survive outside a human host long enough to be picked up by another unlucky victim. Some of these adenoviruses are able to cause persistent, but asymptomatic, infections of the tonsils and intestines. Still others are able to cause bronchitis, pneumonia and a sometimes fatal respiratory illness. One of these 50 adenovirus types is called Ad14 or serotype 14. This is the killer cold virus that was identified by CDC as the cause of outbreaks in four states in 2007. Ad14 was first seen among military recruits in 1955, but since then has rarely been seen in the U.S. So the 2007 outbreaks may represent the emergence

of a new and virulent strain of Ad14. Newborns, the elderly and people with compromised immune systems would be the most susceptible to a new and virulent cold virus. The cells of the nose and throat seem to be the primary targets of viral invasion. The virus triggers local inflammation and the production of immune regulators such as interferon. These immune response molecules in turn trigger most of the unpleasant symptoms of a cold: headache, malaise, fatigue, nausea, congestion and painful sinuses. Overthe-counter medications don't seem to help much, and antiviral drugs such as ribavirin and cidofovir don't seem to be very effective against adenoviruses. The emergence of a new and more virulent Ad14 virus could be especially bad news for the military. New recruits - crowded together in barracks and under the 24 / 7 stress of boot camp - are ideal candidates for acquiring and spreading adenovirus infections. The lost training time and medical costs from adenovirus infections encouraged the Defense Department to fund work on vaccines against two of the more common culprits, Ad7 and Ad4. An effective combination vaccine was produced and given to millions of new recruits, but disputes with the manufacturer led to the end of the military vaccination program in 1999. The following year, the Institute of Medicine recommended the immediate reestablishment of an adenovirus vaccine supply. Now, eight years later, Barr Labs in Virginia soon may be in a position to begin offering a new oral vaccine against Ad4 and Ad7 adenoviruses. There is no vaccine for Ad14. The common cold, and some of the uncommon causes of those colds, present unique challenges to both patients and physicians. There are too many viruses, too little understanding of how they spread and cause disease, too few effective medicines and even fewer available vaccines. Worse yet, your mother may have been right all along. Remember her telling you to put on a sweater or jacket "so you don't catch a cold''? In response, you may have wisely insisted that you couldn't get a cold from being cold. Well, maybe you

do. According to an article in New Scientist, researchers in the United Kingdom found more people developed colds after they became chilled. Cool temperatures prompt the body to redirect blood flow inward, including away from the nasal passages. The change in blood flow and nasal temperature may make it easier for viruses to enter via the nose. So mom may have been right again. I can already hear the "I told you so's." In the end, the best way to avoid a cold - and Ad14 - may be to keep your nose warm, wash your hands regularly, avoid small children and … listen to your mother. --Dr. Edward McSweegan has a Ph.D. in microbiology and lives in Crofton. He works on and writes about infectious disease issues. He may be contacted at [email protected].