<prompt> A positive tuberculin test is indicated by an area of induration of5mm in diameter6-9mm in diameter10mm in diameterNo induration  <response>: In this test 0.1 ml of PPD containing 5 TU is injected intradermally on the flexor aspect of the forearm with a tuberculin syringe, raising a wheal. The site is examined48-72 hrs later and the induration of: 10mm: positive 6-9mm : equivocal doubtful 5mm : negative Ref: Textbook of microbiology; Ananthanarayan and panikers; 10th edition; Pg: 360 