Diagnosis is difficult, because early symptoms of fever, muscle aches and fatigue often are confused with the flu.

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Once a person contracts the flu virus, he or she is contagious approximately 12 to 24 hours before the peak onset of symptoms, and is often contagious up to 24 hours after resolution of fever.

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While not dangerous, and often symptomless in more healthy patients, in the elderly, weak or immuno-suppressed, MRSA can cause fever and pneumonia.

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Symptoms typically develop within three to seven days of exposure and can include stiff neck, fever, headache, nausea, vomiting, increased sensitivity to light and an altered mental state, often confusion.

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