Upper Respiratory Tract Infection
Upper respiratory infection facts
- Upper respiratory infections are one of the most common reasons for doctor visits.
- Upper respiratory infections are the most common illness resulting in missed work or school.
- Upper respiratory infections can happen at any time, but are most common in the fall and winter.
- The vast majority of upper respiratory infections are caused by viruses and are self-limited.
- Symptoms of upper respiratory infection include
- nasal discharge,
- nasal congestion,
- runny nose,
- scratchy or sore throat, and
- nasal breathing.
- Antibiotics are rarely needed to treat upper respiratory infections and generally should be avoided, unless the doctor suspects a bacterial infection.
- Simple techniques, such as, proper hand washing and covering face while coughing or sneezing, may reduce the spread of upper respiratory infections.
- General outlook for upper respiratory infections is favorable, although, sometimes complication can occur.
What is an upper respiratory infection?
The upper respiratory tract includes the sinuses, nasal passages, pharynx, and larynx. These structures direct the air we breathe from the outside to the trachea and eventually to the lungs for respiration to take place.
An upper respiratory tract infection, or upper respiratory infection, is an infectious process of any of the components of the upper airway.
Infection of the specific areas of the upper respiratory tract can be named specifically. Examples of these may include rhinitis (inflammation of the nasal cavity), sinus infection (sinusitis or rhinosinusitis) – inflammation of the sinuses located around the nose, common cold (nasopharyngitis) – inflammation of the nares, pharynx, hypopharynx, uvula, and tonsils, pharyngitis (inflammation of the pharynx, uvula, and tonsils), epiglottitis (inflammation of the upper portion of the larynx or the epiglottis laryngitis (inflammation of the larynx), laryngotracheitis (inflammation of the larynx and the trachea), and tracheitis (inflammation of the trachea).
Upper respiratory infections are one of the most frequent causes for a doctor visit with varying symptoms ranging from runny nose, sore throat, cough, to breathing difficulty, and lethargy. In the United States, upper respiratory infections are the most common illness leading to missing school or work.
Although upper respiratory infections can happen at any time, they are most common in the fall and winter months, from September until March. This may be explained because these are the usual school months when children and adolescents spend a lot of time in groups and inside closed doors. Furthermore, many viruses of upper respiratory infection thrive in the low humidity of the winter.
Is an upper respiratory infection contagious?
A majority of upper respiratory infections are due to self-limited viral infections. Occasionally, bacterial infections may cause upper respiratory infections. Most often, upper respiratory infection is contagious and can spread from person to person by inhaling respiratory droplets from coughing or sneezing. The transmission can also occur by touching the nose or mouth by hand or other object exposed to the virus.
What are the causes of upper respiratory infection?
An upper respiratory tract infection is generally caused by the direct invasion of the inner lining (mucosa or mucus membrane) of the upper airway by the culprit virus or bacteria. In order for the pathogens (viruses and bacteria) to invade the mucus membrane of the upper airways, they have to fight through several physical and immunologic barriers.
The hair in the lining of the nose acts as physical barrier and can potentially trap the invading organisms. Additionally, the wet mucus inside the nasal cavity can engulf the viruses and bacteria that enter the upper airways. There are also small hair-like structures (cilia) that line the trachea which constantly move any foreign invaders up towards the pharynx to be eventually swallowed into the digestive tract and into the stomach.
In addition to these intense physical barriers in the upper respiratory tract, the immune system also does its part to fight the invasion of the pathogens or microbes entering the upper airway. Adenoids and tonsils located in the upper respiratory tract are a part of the immune system that help fight infections. Through the actions of the specialized cells, antibodies, and chemicals within these lymph nodes, invading microbes are engulfed within them and are eventually destroyed.
Despite these defense processes, invading viruses and bacteria adapt various mechanisms to resist destruction. They can sometimes produce toxins to impair the body’s defense system or change their shape or outer structural proteins to disguise from being recognized by the immune systems (change of antigenicity). Some bacteria may produce adhesion factors that allow them to stick to the mucus membrane and hinder their destruction.
It is also important to note that different pathogens have varying ability to overcome the body’s defense system and cause infections.
What are the symptoms of upper respiratory infection?
Generally, the symptoms of upper respiratory infection result from the toxins released by the pathogens as well as the inflammatory response mounted by the immune system to fight the infection.
Common symptoms of upper respiratory infection generally include:
- nasal congestion,
- runny nose (rhinorrhea),
- nasal discharge (may change from clear to white to green)
- nasal breathing,
- sore or scratchy throat,
- painful swallowing (odynophagia),
- cough (from laryngeal swelling and post nasal drip),
- malaise, and
- fever (more common in children).
Other less common symptoms may include
- foul breath,
- reduced ability to smell (hyposmia),
- shortness of breath,
- sinus pain,
- itchy and watery eye (conjunctivitis),
- diarrhea, and
- body aches.
The symptoms of upper respiratory infection usually last between 3-14 days; if symptoms last longer than 14 days, an alternative diagnosis can be considered such as, sinusitis, allergy, pneumonia, or bronchitis.
Bacterial pharyngitis (strep throat due to group A Streptococcus) may be considered if symptoms continue to worsen after the first week in the absence of runny nose, cough, or conjunctivitis. Prompt testing and initiation of appropriate antibiotics is important due to the risk of developing rheumatic fever, especially in children.
Epiglottitis is an upper respiratory infection in children that may have a more sudden onset of sore throat, feeling of a lump in the throat, muffled voice, dry cough, very painful swallowing, and drooling.
Upper respiratory infections in the lower part of the upper respiratory tract, such as, laryngotracheitis, are more commonly featured with dry cough and hoarseness or loss of voice. Barking or whooping cough, gagging, rib pain (from severe cough) are other symptoms and signs.
What are the risk factors for upper respiratory infection?
Some common risk factors for upper respiratory infection are:
- physical or close contact with someone with a upper respiratory infection;
- poor hand washing after contact with an individual with upper respiratory infection;
- close contact with children in a group setting, schools or daycare centers;
- contact with groups of individuals in a closed setting, such as, traveling, tours, cruises;
- smoking or second-hand smoking (may impair mucosal resistance and destroy the cilia);
- health care facilities, hospitals, nursing homes;
- immunocompromised state (compromised immune system) such as, HIV, organ transplant, congenital immune defects, long term steroid use; and
- anatomical abnormalities as in facial trauma, upper airway trauma, nasal polyps
What is the treatment for upper respiratory infection?
As described above, most cases of upper respiratory infection are caused by viruses and therefore, require no specific treatment and are self-limited. People with upper respiratory infections typically diagnose themselves and treat their symptoms at home without requiring doctor’s visit or prescription medications.
Rest is an important step in treating upper respiratory infections. Usual activities, such as, working and light exercising may be continued as much as tolerated.
Increased intake of oral fluids is also generally advised to keep up with the fluid loss from runny nose, fevers, and poor appetite associated with upper respiratory infections.
Treatment of the symptoms of upper respiratory infection is usually continued until the infection has resolved.
Antibiotics are sometimes used to treat upper respiratory infections if a bacterial infection is suspected or diagnosed. These conditions may include strep throat, bacterial sinusitis, or epiglottitis. Antivirals may occasionally be recommended by doctors in patients who are immunocompromised (poor immune system). The treating doctor can determine which antibiotic would be the best option for a particular infection.Because antibiotics are associated with many side effects and can promote bacterial resistance and secondary infections, they need to be used very cautiously and only under the direction of a treating physician.
Inhaled epinephrine is sometimes used in children with severe spasm of the airways (bronchospasm) and in croup to reduce spasm.
Rarely, surgical procedures may be necessary in cases of complicated sinus infections, compromised airway with difficulty breathing, formation of abscesses behind the throat, or abscess formation of the tonsils (peritonsillar abscess).
What are the complications of an upper respiratory infection?
Some of the common complications of upper respiratory infections are the following:
- respiratory compromise from epiglottitis;
- secondary infection by bacteria (viral infection can cause impairment of the physical barrier in the respiratory airways making it easier for bacteria to invade) resulting in bacterial sinusitis, bronchitis, pneumonia;
- formation of abscesses in the tonsils;
- rheumatic fever from strep throat;
- spread of infection from sinuses to the brain (meningitis);
- involvement of the ears resulting in middle ear infections (otitis media);
- worsening of underlying chronic lung disease (asthma, COPD);
- spread of infection to the heart (pericarditis, myocarditis);
- spread of the infection to the brain or the fluid around the brain causing encephalitis or meningitis; and
- muscular pain and rib fractures from forceful coughing.
Can an upper respiratory infection be prevented?
There are several measures that can reduce the risk of infections in general. Smoking cessation, reducing stress, adequate and balanced diet, and regular exercise are all measures that can improve the immune system and reduce the overall risk of infections. Breastfeeding also helps strengthen the immune system of infants by transferring the protective antibodies from the mother’s milk to the baby.
Other preventive measures to diminish the risk of spread of upper respiratory infections are:
- hand washing is especially encouraged during the cold seasons (fall and winter) or handling others with the infection;
- reducing contact with people who may have the infection (people may carry and spread the virus a few days before they have symptoms and a few days after their symptoms have resolved);
- proper cleaning of common objects that are touched by individuals who may be infectious such as, telephones, refrigerator door, computers, stair railings, door handles, etc.;
- covering mouth and noise when coughing or sneezing; and
- vaccination with flu vaccine as recommended for certain people (elderly, people with chronic medical conditions, health care workers, etc.).