PPD conversion

PPD conversion

Infectious disease The conversion from a state of nonreactivity to reactivity to immune challenge by PPD, presumptive evidence of active TB unless proven otherwise. See Tuberculosis. Cf Anergy.
References in periodicals archive ?
Supporting this perspective are studies associating zip code or area of residence with PPD conversion, rather than specific hospital occupation or specific exposure (9,10).
In some hospitals occupation is significantly associated with risk for PPD conversion.
The classification of risk is based on: 1) the profile of TB in the community, 2) the number of infectious TB patients admitted to the facility area, and 3) analysis of PPD conversion data for the facility's workers.
In these situations, the results of anergy testing may be useful for deciding which persons should be offered prolonged preventive therapy in settings in which a) exposure is likely but PPD conversion has not occurred, b) the consideration of primary prophylaxis may arise, and c) the most vulnerable persons in immunologic terms may have high priority for preventive therapy.