smallpox

a highly infectious viral disease that has nonetheless been eradicated. INFECTION results, after about two weeks, in a high fever, head and body aches and vomiting. Eventually red spots appear, which change to water and then pus-filled vesicles that, on drying out, leave scars. The person stays infectious until all scabs are shed. Fever often returns, with DELIRIUM , and although recovery is usual, complications often ensue, e.g. PNEUMONIA .