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Colds and the Flu - Diagnosis
(Page 3)
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 protection is incomplete, even with vaccination.
Ruling Out Other Causes of Sore Throat
In addition to common cold viruses, other, less frequent causes of sore throat include the following:
- Strep throat
- Sore throat related to the flu
- Foodborne and waterborne infections (Streptococcus C and G)
- An uncommon organism called Arcanobacterium haemolyticum (infection with this bacterium can mimic strep throat and may even cause a rash)
- Infectious mononucleosis ("mono")
- Herpesvirus 1
- Pneumonias caused by the atypical organisms mycoplasma or chlamydia
What is Strep Throat?
Group A Streptococcal bacteria is the most common bacterial cause of the severe sore throat known commonly as "strep throat." It occurs mostly in school age children, but people of all ages are susceptible. (Strep throat constitutes only about 12% of all sore throat cases seen by doctors.)
The symptoms of strep throat include the following:
- A sudden onset of severe sore throat
- Difficulty in swallowing
- Fever
- Headache
- Stomach pain
- Vomiting
Only about half of patients with strep throat have such clear-cut symptoms. Furthermore, half of people who have these symptoms do not actually have strep throat.
How Is Strep Throat Diagnosed?
Most cold-related sore throats are caused by viruses and require no treatment. They usually do not last more than a day. When the sore throat persists and is very painful the doctor will want to rule out or confirm the presence of the strep bacteria.
- The doctor will look for redness and pus-filled patches on the tonsils and back of the throat. Enlarged tonsils are less likely to indicate a strep throat.
- The doctor will feel the sides of the neck for swollen lymph nodes. If the lymph nodes are not swollen, it is less likely to be a strep throat.
- A cotton swab is used to take a sample of pus in the throat for a throat culture.
A throat culture is the most effective and least expensive test for confirming the presence of strep throat. It takes 24 - 48 hours to obtain a result.
Rapid Antigen-Detection Test for Strep Throat. A faster test called the rapid strep antigen test uses chemicals to detect the presence of bacteria in a few minutes. A positive result nearly always means that streptococcal bacteria is the cause of the infection. The test, however, fails to detect between 10 - 20% of cases, so a culture may still be necessary to catch any missed infections, particularly in children.
How Serious is Strep Throat?
The use of antibiotics has removed the threat of most complications from streptococcus infection in the throat (strep throat). However, untreated strep throat could lead to the following complications:
- Abscess in the tonsils
- Scarlet fever
- Rheumatic fever (rare in the U.S.)
How Is Strep Throat Treated?
Strep throat infections require antibiotics. The following are generally used:
- Penicillin is usually the antibiotic of choice unless the patient is allergic. A full 10 days may be necessary. Amoxicillin, a form of penicillin, is proving to be effective when taken in a single daily dose for 10 days.
- Macrolide antibiotics. Erythromycin is known as a macrolide antibiotic and is the first choice for patients with penicillin allergies. A 10-day regimen is needed. Another macrolide, azithromycin, can be given as a single daily dose and may be effective in 5 days. It is expensive, however, and bacterial resistance to macrolides is growing, so it should not be given as a first choice.
- Cephalosporins are a potent, but expensive, group of antibiotics that are very effective in eradicating the bacteria.
Antibiotics are very commonly inappropriately prescribed for non-Strep sore throats. One study reported that an estimated 6.7 million American adults visited their doctors because of sore throat between 1989 and 1999, with 73% of them receiving antibiotics. Studies indicate, however, that less than half of adults and far fewer children with even strong signs and symptoms for strep throat actually have strep infections.
Parents should be comforted that a delay in antibiotic treatment while waiting for lab results does not increase the risk that the child will develop serious long-term complications, including acute rheumatic fever. If a patient is severely ill, however, it is reasonable to begin administering antibiotics before the results are back. If the culture is negative (there is no evidence of bacteria), then the doctor should call the family to make certain they stop taking the antibiotics and discard any remaining pills.
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Review Date: 03/06/2007
Reviewed By: A.D.A.M. Editorial Team: Greg Juhn, M.T.P.W., David R. Eltz, Kelli
A. Stacy. Previously reviewed by Harvey Simon, MD, Associate
Professor of Medicine, Harvard Medical School; Physician,
Massachusetts General Hospital (12/4/2006).
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