CHAPTER 102 The Common Cold
ETIOLOGY
The common cold is a viral infection with prominent symptoms of rhinorrhea and nasal obstruction, absent or mild fever, and no systemic manifestations. It is often referred to as rhinitis but usually involves the sinus mucosa and is more correctly termed rhinosinusitis.
The viruses primarily associated with colds are rhinoviruses and, less commonly, coronaviruses. Other viruses that cause common cold symptoms include respiratory syncytial virus and, less commonly, influenza, parainfluenza, and adenoviruses. Viral infection of nasal epithelium causes an acute inflammatory response with mucosal infiltration by inflammatory cells and release of cytokines. The inflammatory response is partly responsible for many of the symptoms.
EPIDEMIOLOGY
Colds occur throughout the year with peak incidence from early fall through late spring, reflecting the seasonal prevalence of viral pathogens and confined habitation during colder months. Young children have an average of 6 to 7 colds each year, and 10% to 15% of children have at least 12 colds each year. The annual number of colds decreases with age, to 2 to 3 colds each year by adulthood. Children in out-of-home day care during the first year of life have 50% more colds than children cared for only at home. This difference diminishes during subsequent years in day care.
CLINICAL MANIFESTATIONS
Common cold symptoms typically develop 1 to 3 days after viral infection and include nasal obstruction, rhinorrhea, sore or scratchy throat, and occasional nonproductive cough. Colds usually persist about 1 week, although 10% last 2 weeks. There is often a change in the color or consistency of nasal secretions, which is not indicative of sinusitis or bacterial superinfection. Examination of the nasal mucosa may reveal swollen, erythematous nasal turbinates.
LABORATORY AND IMAGING STUDIES
Laboratory studies often are not helpful. A nasal smear for eosinophils may be useful in the evaluation for allergic rhinitis (see Chapter 79).
DIFFERENTIAL DIAGNOSIS
The differential diagnosis of the common cold includes allergic rhinitis, foreign body (especially with unilateral nasal discharge), sinusitis, pertussis, and streptococcal nasopharyngitis. Allergic rhinitis is characterized by absence of fever, eosinophils in the nasal discharge, and other manifestations, such as allergic shiners, nasal polyps, a transverse crease on the nasal bridge, and pale, edematous, nasal turbinate mucosa. Rare causes of rhinorrhea are choanal atresia or stenosis, cerebrospinal fluid fistula, diphtheria, tumor, congenital syphilis (with snuffles), nasopharyngeal malignancy, and Wegener granulomatosis.
TREATMENT
There is no specific therapy for the common cold. Antibacterial therapy is not beneficial. Management consists of symptomatic therapies. Antihistamines, decongestants, and combination antihistamine–decongestants are not recommended for children younger than 6 years of age because of adverse effects and lack of benefits. Fever infrequently is associated with an uncomplicated common cold and antipyretic treatment is usually unnecessary, although acetaminophen may reduce symptoms of sore throat. Cough suppressants and expectorants have not been shown to be beneficial. Vitamin C and inhalation of warm, humidified air are no more effective than placebo. The benefit of zinc lozenges or sprays has been inconsistent.
COMPLICATIONS AND PROGNOSIS
Otitis media is the most common complication and occurs in 5% to 20% of children with a cold (see Chapter 105). Other complications include bacterial sinusitis, which should be considered if rhinorrhea or daytime cough persists without improvement for at least 10 to 14 days or if severe signs of sinus involvement develop, such as fever, facial pain, or facial swelling (see Chapter 104). Colds may lead to exacerbation of asthma and may result in inappropriate antibiotic treatment.