Medical Health Encyclopedia

Acute Bronchitis. Acute bronchitis is usually caused by a virus and in most cases is self-limiting. The cough it causes typically lasts for about 7  to 10 days, but in about half of patients, coughing can last for up to three weeks, and 25% of patients continue to cough for over 1 month.

Atypical Pneumonia. Pneumonia caused by atypical organisms (e.g., Mycoplasma pneumonia, Legionella) can cause symptoms similiar to the flu. Only laboratory tests can diagnose the difference. [For more information see In-Depth Report # 64 Pneumonia.]

Ruling out More Serious Viral Infections. Respiratory syncytial virus (RSV) and, possibly human parainfluenza viruses (HPV), are proving to be important causes of serious respiratory infections in infants, the elderly, and people with damaged immune systems. (Both also cause mild conditions.) RSV may be a much more common cause of flu-like symptoms than previously thought. In one British study of patients with flu symptoms, RSV was responsible for 22% of the cases and influenza for 32%. And among children under age five, RSV was responsible for more flu-like cases than the flu virus itself.

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Pertussis. Pertussis (whooping cough) was a very common childhood illness throughout the first half of the century. Although immunizations caused a decline in cases to only 1,700 in the U.S. in 1980, the incidence has risen recently, with almost 30,000 cases reported between 1997 and 2000 (17 infants died of the disease in 2000). Many more cases are reported worldwide.

Nearly half of pertussis cases now occur in people 10 years of age or older, perhaps due to waning immunity in adolescents and adults. Such cases may be greatly underreported. One study suggested that as many as 25% of adults who see a doctor for persistent cough may actually have pertussis. It may go undiagnosed, however, because symptoms are usually mild and adults are unlikely to have the classic "whooping" cough. This is of some concern because such adults may unknowingly infect unvaccinated children. The younger the patient, the higher the risk for severe complications, including pneumonia, seizures, and even death. Children younger than 6 months are at particular risk because even with vaccination, protection is incomplete.

Ruling Out Other Causes of Sore Throat