Diagnosis
Differentiating between a cold and flu may be difficult. Cold symptoms are nearly always less severe than those of the flu.
Comparing Colds and Flus
Symptoms
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Cold
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Flu
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Fever
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Text Continues Below
Rare
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Common and high (102-104 degrees F); lasts 3-4 days
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Headache
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Rare
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Almost always present
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General aches and pains
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Mild, if they occur at all
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Often severe
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Fatigue, exhaustion, and weakness
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Mild, it they occur at all
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Extreme exhaustion is early and severe; can last 2 to 3 weeks
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Stuffy nose
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Nearly always
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Sometimes
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Sneezing
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Very common
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Sometimes
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Sore throat
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Common
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Sometimes
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Chest discomfort and cough
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Mild to moderate, hacking cough
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Common, can be severe
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Source: National Institute of Allergy and Infectious Disease
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Diagnosing the Flu
A number of tests are available to isolate and identify the viruses responsible for some respiratory infections. They are generally not needed, since most cases of the flu are self-evident. However, such tests can be very helpful in confirming or ruling out the flu. If a doctor believes a diagnosis would help, samples using a swab should be taken from the nasal passages or throat within 4 days of the first symptoms.
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| A nasopharyngeal culture is a test used to identify disease-causing organisms in nasal secretions. Nasopharyngeal cultures are useful in identifying Bordetella pertussis and Neisseria meningitidis (types of bacteria). The culture may help determine appropriate antibiotic therapy. |
A number of rapid tests for the flu are available that can produce results in less than 30 minutes, but vary on the specific strain or strains that they can detect. They are not as accurate as a viral culture, however, in which the virus is reproduced in the laboratory; culture results can take 3 to 10 days. Blood tests can also document the infection several weeks after symptoms appear.
Diagnosing Avian Influenza
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