What indicates a positive result of a tuberculin test?

A positive result of a tuberculin test, also known as the Mantoux test, is indicated by the presence of induration (swelling) at the injection site, typically measured 48 to 72 hours after administration. The size of the induration varies based on individual risk factors; for example, a reaction of 15 mm or more is generally considered positive in healthy individuals, while smaller reactions may be significant in those with higher risk factors, such as recent exposure to tuberculosis or immunocompromised status.