Pirquet, Clemens, baron von

Pirquet, Clemens, baron von

(born May 12, 1874, Vienna, Austria—died Feb. 28, 1929, Vienna) Austrian physician. In 1906 he noticed that patients who received two injections of horse serum or smallpox vaccine usually had quicker, more severe reactions (which he called “allergies”) to the second injection. While studying cowpox vaccination symptoms, he also developed a new theory about infectious diseases' incubation times and about antibody formation. In the Pirquet test, a drop of tuberculin is scratched into the skin; a red, raised area developing at the site (Pirquet reaction) indicates tuberculosis.