Modern vaccines date back to British doctor Edward Jenner's 1796 work immunizing children using pus from cowpox blisters.

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At the winter break I stayed on cam pus, one of the few.

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Within a day or two, many of these lesions turn into small blisters filled with clear fluid, which then turns into pus.

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Most MRSA infections acquired in community settings present themselves as sores or boils and often appear red, swollen, painful or with drainage such as pus, the CDC says.

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An abscess, which occurs when pus collects in the pouch.

CNN: Diverticulitis

Some of them were tipped with cream-colored pus.

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At the time Jorge Bergoglio was a teenager, most lung surgery was done for infections, especially tuberculosis (TB) and empyema, a condition related to pneumonia where pus accumulates between the lung and the chest wall.

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In 1802, after Edward Jenner published his first results claiming that scratching cowpox pus into the arms of healthy children could protect them against smallpox, a political cartoon appeared showing newly vaccinated people with hooves and horns.

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"If you have somebody who has an infection -- he has a draining infection -- and he gets some of his pus on a bench, that staph's going to be there for hours or days before it dries out, " he said.

CNN: NFL stars no match for bacteria