Influenza; Strep throat; Bird flu; Avian influenza
The very young and the very old are at higher risk for upper respiratory tract infections and their associated complications.
Children. Young children are prone to colds and may have 8 to 12 of them every year. Millions of cases of influenza develop in American children and adolescents each year.
Before the immune system matures, all infants are susceptible to upper respiratory infections, with a possible frequency of one cold every 1 - 2 months. Smaller nasal and sinus passages also make younger children more vulnerable to colds than older children and adults. Upper respiratory infections gradually diminish as children grow, until at school age their rate of such infections is about the same as an adult's. There is almost never cause for concern when a child has frequent colds, unless the colds become unusually severe or more frequent than usual.
The Elderly. The elderly have diminished cough and gag reflexes, and their immune systems are often weaker. They are therefore at greater risk for serious respiratory infections than the young and middle-aged adults.
The risk of respiratory infections is increased by exposure to cigarette smoke, which can injure airways and damage the cilia (tiny hair-like structures that help keep the airways clear). Toxic fumes, industrial smoke, and other air pollutants are also risk factors. Parental smoking increases the risk of respiratory infections in their children.
People with AIDS and other medical conditions that damage the immune system are extremely susceptible to serious infections.
Cancers, especially leukemia and Hodgkin's disease, put patients at risk. Patients who are on corticosteroid (steroid) treatments, chemotherapy, or other medications that suppress the immune system are also prone to infection.
People with diabetes are at a higher risk for the flu.
Certain genetic disorders predispose people to respiratory infections. They include sickle-cell disease, cystic fibrosis, and Kartagener syndrome (which results in malfunctioning cilia).
A number of studies suggest that stress increases one's susceptibility to a cold. Stress appears to increase the risk for a cold regardless of lifestyle or other health habits. And once a person catches a cold or flu, stress can make symptoms worse.
It is not clear why these events occur. Some experts believe that stress alters specific immune factors, which cause inflammation in the airways.
In people who already have colds, exercise has no effect on the illness' severity or duration of the infection. Some highly trained athletes, for instance, report being susceptible to colds after strenuous events. People should avoid strenuous physical activity when they have high fevers or widespread viral illnesses.
Colds and flus occur predominantly in the winter. Flu season typically starts in October and lasts into mid March.
The reasons for this seasonal bias are not due to the cold itself, but to other factors. Certainly, flus and colds are more likely to be transmitted in winter because people spend more time indoors and are exposed to higher concentrations of airborne viruses. Dry winter weather also dries up nasal passages, making them more susceptible to viruses. Some experts theorize that the high rates of viral infections in winter may be due to certain immune factors, which react to light and dark and affect a person's susceptibility to viruses.
Traveling in close contact with people, whether on trains, planes, or buses, can increase the risk for respiratory infections.
Children who attend day care may have an increased risk of colds. However, they may have lower cold rates in their first years of regular school. The colds they catch in day care, then, may bestow some immunity to future colds for a few years. By age 13, such protection has worn off. There is also some evidence that frequent colds in young children may help protect against future allergies and asthma.
American Academy of Pediatrics Committee on Infectious Diseases. Recommended childhood and adolescent immunization schedule: United States, 2005. Pediatrics. 2005 Jan;115(1):182.
Caruso TJ, Prober CG, Gwaltney JM Jr. Treatment of naturally acquired common colds with zinc: a structured review. Clin Infect Dis. 2007;45(5):569-74.
Centers for Disease Control and Prevention. Key Facts About Seasonal Influenza (Flu). Available online.
Centers for Disease Control and Prevention. 2007-08 Influenza Prevention & Control Recommendations: Vaccination of Specific Populations. Available online.
Centers for Disease Control and Prevention. Acute Respiratory Disease Associated with Adenovirus Serotype 14 -- Four States, 2006-2007. MMWR. 2007;56(45):1181-84.
Centers for Disease Control and Prevention. FDA Approves New Laboratory Test To Detect Human Infections With Avian Influenza A/H5 Viruses. February 3, 2006.
Harper SA, Fukuda K, Uyeki TM, Cox NJ, Bridges CB. Prevention and Control of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2005 Jul 29;54(RR-8):1-40.
Hayden GF, Turner RB. Acute Pharyngitis. In: Behrman RE, Kliegman RM, Jenson HB, eds. Behrman: Nelson Textbook of Pediatrics, 17th ed. Philadelphia, Pa: Saunders; 2004.
Interagency Task Force on Antimicrobial Resistance. Executive Summary: 2006 Annual Report on Progress on "A Public Health Action Plan to Combat Antimicrobial Resistance." Draft release, June 2007. Available online.
Jefferson T, Demichelli V, Rivetti D, Jones M, Di Pietrantonj C, Rivetti A. Antivirals for influenza in healthy adults: systematic review. Lancet 2006 Jan 28;367(9507):303-13.
Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2008. MMWR. July 17, 2008/57(Early Release);1-60.
Reveiz L, Cardona AF, Ospina EG. Antibiotics for acute laryngitis in adults. Cochrane Database Syst Rev. 2007 Apr 18;(2):CD004783.
Sasazuki S, Sasaki S, Tsubono Y, Okubo S, Hayashi M, Tsugane S. Effect of vitamin C on common cold: randomized controlled trial. Eur J Clin Nutr. 2006;60(1):9 - 17.
Shah SA, Sander S, White CM, Rinaldi M, Coleman CI. Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis. Lancet Infect Dis. 2007;7(7):473-80.
Simasek M, Blandino DA. Treatment of the common cold. Am Fam Physician. 2007;75(4):515-20.
Taverner D, Latte J. Nasal decongestants for the common cold. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD001953.
U.S. Food and Drug Administration: Nonprescription Drugs and Pediatric Advisory Committee Meeting. Joint Meeting of the Nonprescription Drugs Advisory Committee and the Pediatric Advisory Committee October 18-19, 2007. Available online.
World Health Organization: Neuraminidase Inhibitor Susceptibility Network. Monitoring of neuraminidase inhibitor resistance among clinical influenza virus isolates in Japan during the 2003-2006 influenza seasons. Weekly epidemiological record. 2007;82(17):149-50.
World Health Organization. Cumulative Number of Confirmed Human Cases of Avian Influenza A/(H5N1) Reported to WHO. December 16, 2008. Available online.
© 2011 University of Maryland Medical Center (UMMC). All rights reserved.
UMMC is a member of the University of Maryland Medical System,
22 S. Greene Street, Baltimore, MD 21201. TDD: 1-800-735-2258 or 1.866.408.6885