Tuberculosis (TB) Screening: Method of screening, who should be investigated, what is positive Mantoux tuberculin skin test (TST)

Tuberculosis (TB) Screening

•• Routine screening for TB is no longer recommended.

Method of screening

•• The intradermal Mantoux tuberculin skin test (TST) is the most reliable diagnostic for TB.

•• The test consists of 0.1 mL of purified protein derivative (PPD) injected intradermally on the volar aspect of the forearm.

•• Forming a 6- to 10-mm wheal.

•• The area is inspected at 48–72 h; induration, not erythema.

•• It is measured transversely to the long axis of the forearm and the results recorded in millimeters.

•• The test is considered to be positive at specific sizes of the area of induration, depending on associated features.

Indication for initial TB screening

•• If active disease is suspected

•• Contacts of individuals who have confirmed or suspected active TB

•• Children who have clinical or radiographic findings suggestive of TB

•• Children emigrating from countries where TB is endemic, who visit these countries frequently, or who have frequent visitors from these countries

•• All children who will begin immunosuppressive therapy

•• Children infected with HIV

•• Incarcerated adolescents

•• Positive TST interpretation depends on the size of induration and associated risk factors (see infectious disease

chapter)

Critical to know

•• Positive TST result in a child or adolescent should be regarded as a marker for active disease within that community and should serve as a call to investigate contacts and to find and treat cases of latent TB.