He said it would pick up similar symptoms found at hospitals in the same area, where a doctor finding a patient with a rash and fever might not immediately think of smallpox.

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The paper's authors, Richard Zegers, Andreas Weigl and Andrew Steptoe, reached their conclusion by comparing historical accounts of the maestro's illness - fever, rash, limb pain and swelling - with illnesses prevalent at the time of his death.

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The most common symptoms people called in with on Boxing Day were vomiting, fever, cough, diarrhoea and rash.

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