Virus That Causes Influenza

The Greeks of old told the myth of Pandora's Box, an ancient contraption that the curious Pandora opened, unleashing all the world's sickness and disease. Although medical science has disproved the myth and uncovered the tiny microbes that infect host organisms, the battle against disease continues. The flu, a common disease that affects millions worldwide every year, can be fatal to a small percentage of the population.

Types

• The virus that causes influenza, or the flu as it is commonly known, is divided into three separate classes: A, B or C. Flu viruses are RNA based, meaning they have ribonucleic acid as their genetic base. These viruses cause a host of complications in both human and animal organisms, and the illness they cause is highly contagious. Vaccinations are the main defense against flu, but because the viruses mutate easily and rapidly, vaccination doesn't guarantee complete immunity.

The A Virus

• Influenza A is the type that typically makes headlines. It is the culprit behind the infamous flu outbreaks of 1918 and 2009, two incidents of a pandemic that killed thousands. Type A, considered the most dangerous of all the flu viruses, is divided into ten different classes (called serotypes), with H1N1 being the notorious "swine flu." Its cousin H5N1 ("avian flu" or "bird flu") has been monitored closely by the World Health Organization as a potential pandemic threat.

The B Virus

• Not as prevalent as type A virus, type B causes disease mostly in human hosts, although scientists have found seals and ferrets are susceptible as well. Type B cannot mutate as fast as Type A, leaving it only one known serotype. Because of the virus's inherent weakness and inability to mutate to overcome a host's natural defenses, immunity is attained at a very early age, although the immunity is not lasting. Because of the serotype and common immunity, pandemics of type B influenza virus are nearly impossible.

The C Virus

• Influenza C is similar to B in that it only has one serotype, which makes it less common than A, but more common than B. It can infect humans and animals such as dogs and pigs, and can cause localized epidemics that are relatively easy to contain, but infections are usually mild and sometimes confused with colds.

Treatments

• Typical flu symptoms include fever, headache, fatigue, cough, sore throat, runny or stuffy nose, body aches, diarrhea and vomiting. Over-the-counter medications can alleviate some of the symptoms; however, medications are ineffective at ridding the body of a virus. Vaccination and simple precautions like hand washing and basic sanitary procedures are on first-line defense against infection. Antibiotics have no effect against flu. Two classes of drugs (neuraminidase inhibitors and M2 protein inhibitors) have had some success against flu, but resistance is prevalent, especially in rapidly mutating flu strains.