Guide for Primary Health Care Providers: Targeted
Tuberculin Testing and Treatment of Latent Tuberculosis Infection
Latent tuberculosis infection (LTBI) is infection
with Mycobacterium tuberculosis organisms (tubercle bacilli)
without signs and symptoms nor radiographic or bacteriologic evidence
of tuberculosis (TB) disease. When small droplet nuclei containing
the tubercle bacilli reach the alveoli, they are engulfed by macrophages
and usually destroyed. However, when a number survive and multiply,
they can cause LTBI.
Approximately one third of the world’s population
is infected with M. tuberculosis.
In the United States,
it is estimated that 9–14
million people have LTBI. Without treatment, approximately 5–10% will progress to TB disease at
some point in their lifetime. Identifying and treating those at
highest risk for TB disease will help us move toward elimination
of the disease. Primary care providers play a key role in achieving
the goal of TB elimination because of their access to high-risk
The Centers for Disease Control and Prevention
(CDC) and the American Thoracic Society (ATS) published guidelines
in the June 9, 2000 issue of Morbidity and Mortality Weekly Report (MMWR), entitled Targeted Tuberculin Testing and Treatment of
Latent Tuberculosis Infection. In addition, updates to the 2000 guidelines have been published. Major changes from prior recommendations
fall into three categories: testing for LTBI, treatment of LTBI,
and clinical monitoring (see Table 1).
Terminology used in the guidelines also reflects
a change. The commonly used terms “preventive therapy” and “chemoprophylaxis”
have been replaced with “treatment of latent TB infection (LTBI).”
This more accurately describes the use of a treatment
regimen to prevent the development of TB disease in persons with
LTBI (see Table 2).
is not meant to be used as a substitute for the guidelines, but
rather as a ready and useful reference that highlights the main
points of those guidelines.