Viral Upper Respiratory Infections

• ANATOMY OR SYSTEM AFFECTED: Ears, lungs, muscles, nose, throat, upper respiratory tract
• ALSO KNOWN AS: Cold, common cold, influenza, the flu

Definition

Viral upper respiratory infection comprises the common cold and influenza. A common cold is a viral infection that irritates the upper respiratory tract (nose and throat). Colds are commonly mistaken for influenza, a more severe viral disease that affects the respiratory system and includes a high fever and extreme fatigue, among other symptoms.

Causes

The common cold is caused by any of about two hundred viruses, including rhinovirus, coronavirus, adenovirus, coxsackie virus, paramyxovirus, parainfluenza virus, and respiratory syncytial virus. There are two significant types of influenza viruses: A and B (influenza virus type C causes minor infections).

The vast majority of the population in any given area may get colds or influenza during the course of a year. The average rate for adults in the United States is three or four infections per person per year. Children get even more.

Risk Factors

Risk factors for getting a cold include being near someone who has a cold; touching one’s nose, mouth, or eyes with contaminated fingers; having allergies (which lengthens the duration of the cold); smoking or being near cigarette smoke (because of decreased resistance); and stress (because of decreased resistance). Another risk factor for the common cold (and influenza) is living in crowded conditions.

For the seasonal flu, people younger than age five years or older than age sixty-five years are most at risk for contracting the flu, as are healthcare workers. Several groups of people are at high risk for complications from the flu. According to the Centers for Disease Control and Prevention (CDC), high-risk groups include pregnant women, people with certain chronic medical conditions (such as heart disease or diabetes), people whose immune system is weakened or suppressed (such as persons with human immunodeficiency virus (HIV) infection), young children, and people older than age fifty years.

Symptoms

Common cold symptoms, which usually resolve on their own within one to two weeks, include a sore throat or scratchy throat; stuffy nose (hard to breathe through the nose); runny nose; sneezing; itchy, stuffed sensation in the ears; watery eyes; slight cough; headache; aches and pains; low energy and malaise; and low-grade fever.

The classic symptoms of the flu, which can take up to four days (in adults) from the time of infection to appear, are high fever and chills, sore throat, dry cough, runny nose, watery eyes, severe muscle aches, severe fatigue and malaise, decreased appetite, and headache. The headache can be severe enough to cause sensitivity to light. Muscle aches are most common in the legs, though they can appear anywhere in the body.

Nausea, vomiting, and diarrhea can occur in people with the flu and are especially common in children. Most flu symptoms disappear in five to six days, though full recovery takes longer; the fatigue may last several weeks.

Most people are familiar with cold and flu symptoms; however, one should be aware of a few specifics. Having a runny nose, the discharge of which is yellow or green, combined with a fever, sore face or teeth, and persistent symptoms, may signal the onset of a sinus infection. Blood in the mucus or phlegm and a headache are even more likely to be the result of a sinus infection.

A dry cough is much less problematic than a wet cough. Colored sputum, be it yellow, green, or bloody, could be a sign of bronchitis or pneumonia; in such cases, one should contact a doctor, especially if the infected person is a smoker.

If the glands near the throat are swollen or if the throat is bright red or covered with yellow or white discharge, the infected person may have strep throat. Strep throat should be treated with penicillin (to prevent rheumatic fever).

Screening and Diagnosis

The purpose of screening is early diagnosis and treatment. Screening tests are usually administered to people without current symptoms, but who may be at high risk for certain diseases or conditions. There are no screening tests for colds and influenza. Diagnosis and treatment begin with the onset of symptoms.

Based on symptoms and a physical examination, a doctor can diagnose a cold or influenza. In some situations, tests, such as a throat culture or blood count, may be ordered to characterize the severity of the condition and identify other related problems. At-home influenza and COVID tests are available.

Identification of the specific virus causing the symptoms was considered unimportant in the twenty-first century until the COVID-19 pandemic because treatments did not greatly differ between virus types. Influenza A was the exception to this because, based on the time of year and community public health reports, persons at high risk for infection could be treated specifically for that virus. Beginning in 2020, it became important to rule out COVID-19 as the cause of symptoms.

Diagnosis may include the following: taking one’s temperature every six to eight hours to help define the severity of the illness; a urinalysis to check for conditions (such as diabetes) that may make an acute case of cold or influenza worse (this is not usually done for colds or flu unless there is another reason to suspect urinary infection); a blood count to assess general health and the ability to fight the illness (also not done routinely in colds or flu); a throat culture if there are signs or symptoms of sore throat (to rule out strep throat); and a chest x-ray if the doctor suspects that the infection has spread to the lungs (which could indicate pneumonia).

Treatment and Therapy

The treatment and management of colds and influenza mainly involves alleviating symptoms, though the symptoms ordinarily resolve on their own. Persons with a chronic health condition, particularly diabetes and chronic heart and lung diseases, could see their condition worsen during a cold or flu. Occasionally, viral upper respiratory infections develop into complications such as ear or sinus infections or pneumonia.

Treatment includes pain relievers for body aches and headaches and medicine to reduce fever. Many over-the-counter, multi-symptom flu treatments are available. They treat the worst cold symptoms and can bring relief, though they will not cure the flu. Treatments for the common cold include pain relievers (for aches and pains and fever) such as acetaminophen (Tylenol), ibuprofen (Motrin), and aspirin. Another treatment for the cold is the use of nasal sprays, which can shrink nasal passages and decrease mucous production. Nasal sprays should be used for two to three days only.

Medications against the flu virus are called antiviral medications. Two classes of antivirals are available against the flu virus: Neuraminidase inhibitors are effective against influenza A and B. They interfere with the release of the virus from infected cells. Two drugs are available in this class: oseltamivir (Tamiflu) and zanamivir (Relenza). Amantadines are effective only against some influenza A viruses, and viral resistance to this class of antivirals is high. Two drugs are available in this class: amantadine (Symmetrel) and rimantadine (Flumadine).

Prevention and Outcomes

The most important way to keep from getting or spreading a cold is by washing one’s hands, and to do so well and often. Other ways to keep from getting a cold include keeping hands away from one’s nose, mouth, and eyes, and avoiding people who have a cold.

The best protection against the flu is vaccination. Because the flu viruses that circulate in the population change every year, it is important to get the flu vaccine each year. Vaccination is especially important in people who are at high risk for serious complications from influenza. It is also important that people who care for or live with a person in any of the risk groups be vaccinated to prevent giving the disease to the person at high risk. Healthcare workers should receive the vaccine every year.

The primary way of spreading both colds and influenza is person-to-person contact. Handwashing is the most neglected, yet most effective, method of disease containment. Using alcohol-based hand gels when washing is not possible is another effective method. Persons at high risk of catching a cold or influenza or are at risk for developing complications from these infections should avoid crowded areas and avoid contact with sick people during the influenza season.

Each year, the World Health Organization (WHO) tries to determine what strains of the influenza virus will be most dangerous in the upcoming influenza season. Vaccines are developed for these seasonal strains.

The seasonal flu vaccine has been associated with fewer hospitalizations and deaths from influenza or pneumonia among the elderly living in community settings (such as nursing homes or residential care). There are two types of seasonal flu vaccines. One is the flu shot, which is approved for use in people older than six months of age. The shot is made from an inactivated, killed virus. It is given by injection, usually into the arm. Another type of seasonal flu vaccine is the nasal spray flu vaccine, which is approved for healthy people between the ages of two and forty-nine years (and who are not pregnant). It is made from live, weakened flu viruses.

A possible side effect of the vaccines is a mild flu-like reaction, including fever, aches, and fatigue. Up to 5 percent of people experience these symptoms after getting the seasonal influenza vaccine.

Bibliography

Beigel, John, and Mike Bray. "Current and Future Antiviral Therapy of Severe Seasonal and Avian Influenza." Antiviral Research, vol. 78, 2008, pp. 91-102, doi.org/10.1016/j.antiviral.2008.01.003. Accessed 5 Nov. 2024.

Belshe, R. B., et al. "Live Attenuated Versus Inactivated Influenza Vaccine in Infants and Young Children." New England Journal of Medicine, vol. 356, no. 7, 2007, pp. 685-96, doi.org/10.1056/NEJMoa065368. Accessed 5 Nov. 2024.

Cowling, B. J., et al. "Facemasks and Hand Hygiene to Prevent Influenza Transmission in Households." Annals of Internal Medicine, vol. 151, no. 7, 2009, pp. 437-46, doi.org/10.7326/0003-4819-151-7-200910060-00142. Accessed 5 Nov. 2024.

Eccles, Ronald, and Olaf Weber, editors. Common Cold. Birkhäuser, 2009.

Pappas, D. E., et al. "Symptom Profile of Common Colds in School-Aged Children." Pediatric Infectious Disease Journal, vol. 27, 2008, pp. 8-11, doi.org/10.1097/INF.0b013e31814847d9. Accessed 5 Mar. 2023.

Schaffer, Kirsten, et al. "Respiratory Viruses." Cohen and Powderly Infectious Diseases, edited by Jonathan Cohen et al., 3rd ed., Mosby, 2010, pp. 1928-42.

Strauss, James, and Ellen Strauss. Viruses and Human Disease. 2nd ed., Elsevier, 2008.

2011 PDR for Nonprescription Drugs, Dietary Supplements, and Herbs. Thomson Health Care, 2010.

"Understanding a Common Cold Virus." National Institute of Allergy and Infectious Diseases, www.nih.gov/news-events/nih-research-matters/understanding-common-cold-virus. Accessed 5 Mar. 2023.