-IBIS-1.5.0-
tx
respiratory system
influenza
diagnoses

definition and etiology

definition:
An acute viral respiratory illness involving an influenza virus.

etiology:
The disease is mostly seen in the winter. Most of the outbreaks and epidemics of flu are caused by the Influenza A virus, although illness caused by other viruses (rhinovirus, echovirus) may cause identical presentations and be called "the flu" even if the influenza virus was not at fault. Pandemics have occurred every 10-15 years since the Great Pandemic of 1918-19.

signs and symptoms

signs and symptoms:
The incubation period is 48 hours. The onset is usually extremely abrupt.
• Headache.
• Fever.
• Malaise.
• Myalgias: especially the back and legs.
• Respiratory illness: characterized by sore throat and cough.
• Easy lacrimation.
• Weakness and fatigue.
• Hyperemic oropharynx though no exudate is present.

lab findings:
• WBCs usually normal or even low: if high, consider secondary bacterial infection.
• Viral serologic tests or virus isolation.

course and prognosis

Although the general patient's recovery from the flu is typically uneventful, the disease can be fatal to certain "high-risk" groups such as infants; the elderly; the debilitated; and patients with chronic pulmonary disease; heart valve problems; CHF; and pregnant women in the third trimester.
Complications include: pneumonia; hemorrhagic bronchitis; encephalitis; Reye's syndrome; and myocarditis. An conventional approach to influenza is through prophylaxis with yearly viral vaccines.

differential diagnosis

• Common cold.
• Strep throat.
• Mononucleosis.
• Bronchitis.
• Viral pneumonia.


footnotes