Positive ppd reading if red?

Ppd reading red?: No redness does not mean it is positive.You feel the induration in mms to interpret it after 48 to 72 hours.5mm or more is positive in HIV posotive person, in someone with recent exposure to tb, with nodular or fibrotic changes on xray consistant with healed TB and patients with organ transplant and immunocompromised 10mm or more +in recent arrivals from high prevalace ares nursing homes 15mm + in.