Upper Respiratory Infection

What is going on in the body?

The term upper respiratory infection (URI) includes the common cold, sore throats, and flu. URIs are usually caused by a virus but may also be due to bacteria or other organisms. An upper respiratory infection is rarely serious but often causes bothersome symptoms.

What are the causes and risks of the infection

There are many different types of upper respiratory infections, including:

the common cold, usually due to a virus

the flu, or influenza virus infection, which causes more severe symptoms than a cold

acute sinusitis or chronic sinusitis, which involve the nasal sinuses

otitis externa, or infection of the outer ear

acute otitis media, or infection of the middle ear behind the eardrum

pharyngitis, or sore throat

acute bronchitis, an infection in the lower windpipes

croup, which is a viral infection of the main windpipe that is usually only seen in children

epiglottitis, a bacterial infection of the main windpipe that is more commonly seen in children

Other types of URI may also occur, but they are less common.  

What are the signs and symptoms of the infection?
Many of the signs and symptoms depend on the type of upper respiratory infection. Common symptoms of URIs include:

a runny nose or stuffy nose

sore throat

fever

headache

cough

malaise, or vague feeling of illness

muscle aches

loss of appetite

ear pain          

How is the infection diagnosed?

The healthcare provider diagnoses most URIs after a history and physical exam.
In some cases, further tests may be ordered. For example, the back of the throat may be swabbed if strep throat is suspected. This swab test, called a throat culture, can check for the bacteria that cause this infection. A blood test called an antibody titer may be done if certain infections are suspected. A chest X-ray may be ordered to make sure pneumonia, a more serious infection deep in the lungs, is not present. Other tests may be ordered in certain cases.

What can be done to prevent the infection?

Many cases of upper respiratory infection cannot be prevented. Almost all URIs are contagious, so avoiding sick people can help prevent some cases. Frequent hand washing can also help reduce the spread of many URIs. Vaccines are used to help prevent some cases. For example, the flu shot can be given to high-risk individuals every fall to help prevent the flu.

What are the long-term effects of the infection?

Most URIs are mild and go away with or without treatment. However, some URIs can be more serious and may have long-term effects. For example, untreated strep throat can lead to kidney damage or rheumatic fever, which can damage the heart. Acute otitis media can result in hearing loss. Severe croup and epiglottitis may be life-threatening. URIs can also put people at risk of getting pneumonia, which may be life-threatening, especially in the elderly and very young.

What are the risks to others?

Most upper respiratory infections are highly contagious. They are transmitted through respiratory secretions. Sneezing and coughing can spread these droplets. The germ can also be passed on when an individual with an upper respiratory infection touches his or her nose and then handles an object that another person later touches. The second person can then pick up the germ from the object and transfer it into his or her own respiratory tract by touching the face



Reference 
Harrison's Principles of Internal Medicine, 1998, Fauci et al.
Rudolph's Fundamentals of Pediatrics, 1998, Rudolph et al