Atlas of pathophysiology, 2 Edition

Part II - Disorders

Respiratory Disorders

Upper Respiratory Tract Infection

Upper respiratory tract infection (also known as the common cold or acute coryza) is an acute, usually afebrile viral infection that causes inflammation of the upper respiratory tract. It's the most common infectious disease. Although a cold is benign and self-limiting, it can lead to secondary bacterial infections.

Causes

About 90% of colds stem from a viral infection of the upper respiratory passages and consequent mucous membrane inflammation; occasionally, colds result from a mycoplasmal infection. Over 100 viruses can cause the common cold. Major offenders include:

·   rhinoviruses

·   coronaviruses

·   myxoviruses

·   adenoviruses

·   coxsackieviruses

·   echoviruses.

Pathophysiology

Infection occurs when the offending organism gains entry into the upper respiratory tract, proliferates, and begins an inflammatory reaction. Acute inflammation of the upper airway structures, including the sinuses, nasopharynx, pharynx, larynx, and trachea, are seen. The presence of the pathogen triggers infiltration of the mucous membranes by inflammatory and infection-fighting cells. Mucosal swelling and secretion of a serous or mucopurulent exudate result.

Signs and symptoms

After a 1- to 4-day incubation period, the common cold produces:

·   pharyngitis

·   nasal congestion

·   coryza

·   sneezing

·   headache

·   burning, watery eyes.

Additional effects may include:

·   fever

·   chills

·   myalgia

·   arthralgia

·   malaise

·   lethargy

·   hacking, nonproductive, or nocturnal cough.

As the cold progresses, clinical features develop more fully. After a day, symptoms include a feeling of fullness with a copious nasal discharge that commonly irritates the nose, adding to discomfort.

Diagnostic test results

No explicit diagnostic test exists to isolate the specific organism responsible for the common cold. Consequently, diagnosis rests on the typically mild, localized, and afebrile upper respiratory symptoms. Diagnosis must rule out allergic rhinitis, measles, rubella, and other disorders that produce similar early symptoms.

Treatment

The primary treatments—aspirin or acetaminophen, fluids, and rest—are purely symptomatic because the common cold has no cure.

Other treatments may include:

·   decongestants

·   throat lozenges

·   steam.

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COMPLICATIONS OF THE COMMON COLD

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