According to Dr. Raphael Dolin in "Harrison's Principles of Internal Medicine," there are three types, or "genera," of influenza viruses: A, B and C. Epidemics are usually caused by influenza A viruses, in part because of their ability to rapidly evolve and change. As of Jan. 4, 2010, influenza A accounted for more than 99.5 percent of influenza infections in the United States. Influenza A treatment is centered on supportive care and, in some people, antiviral drugs.
Supportive Care
Supportive care for influenza A consists of rest, fluids and sometimes over-the-counter (OTC) medications. According to the CDC, you should stay home, except for visits to your health care provider and essential errands, if you can't find a friend or family member to assist you. Hydration is particularly important--choose clear fluids such as water, broth and sports drinks. Steer clear of alcohol and caffeine-containing beverages such as cola, coffee, and black or green tea.
Fever
According to the American College of Family Physicians (ACFP), several over-the-counter medications can be used to treat fever, including acetaminophen (Tylenol), ibuprofen (Advil, Motrin) and naproxen (Aleve). These medications are also effective against aches and pains. One thing you shouldn't give someone with flu is aspirin or aspirin-containing products. Aspirin can cause a serious condition known as Reye syndrome.
Cough
Influenza A is usually associated with a dry cough that causes chest pain and interrupts sleep. The CDC recommends a humidifier as a good option for all age groups. Adults and older children may also benefit from sucking on lozenges or hard candies. If these measures fail, consider an OTC cough suppressant, also called an antitussive. However, the ACFP warns, these products should never be used in children under 4.
Antiviral Medications
According to the CDC, antiviral medications are used to treat people who are hospitalized due to influenza A and those who are at high risk for influenza A-related complications. Examples of people at high risk include children under 2; adults 65 and older; pregnant women; women who are up to two weeks post-partum; people with chronic medical conditions such as asthma, heart failure and chronic lung disease; people with immune system problems such as HIV and diabetes; and people under age 19 who are taking aspirin on the advice of their physician. Sometimes, antiviral drugs are also prescribed for those in close contact with high-risk people in the hopes of preventing the disease from spreading altogether.
Neuraminidase Inhibitors
Oseltamivir and zanamivir are neuraminidase inhibitors which block the neuraminidase receptor that the influenza virus uses to enter human cells. Oseltamivir is FDA-approved for seasonal flu in people 1 and up and H1N1 flu in people of any age. Zanamivir is FDA-approved for seasonal flu in people 7 and up and H1N1 flu in people 5 and up. According to the CDC, neuraminidase inhibitors can reduce the duration of symptoms by one to two days and decrease the likelihood of influenza A-related complications such as pneumonia.
Adamantanes
Amantadine and rimantidine are adamantanes that work by preventing the uncoating process, which is a critical first step in viral replication. If begun within 48 hours of the onset of influenza A symptoms, adamantanes reduce the duration of systemic and respiratory symptoms of influenza by approximately 50 percent, according to "Harrison's Principles of internal Medicine." Unfortunately, the adamantanes have fallen out of favor since the 2005-2006 flu season, when resistance was reported in more than 90 percent of circulating influenza A strains.
References
- "Harrison's Principles of Internal Medicine"; A.S. Fauci, E. Braunwald, D.L. Kasper, S.L. Hauser, D.L. Longo, J.L. Jameson, J. Loscalzo (eds.); 2009
- CDC: Morbidity and Mortality Weekly Report; Jan 4. 2010
- American Academy of Family Physician: Colds and Flu
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