Reports on HIV/AIDS: 1990

MAY 18, 1990, MMWR, Vol. 39, RR-8: [inclusive page numbers]
RECOMMENDATIONS
The main purpose of preventive therapy is to prevent latent (asymptomatic)
infection from progressing to clinical disease (9). Such therapy also is used to
prevent initial infection and to prevent recurrence of past disease.
Although the number of persons in the United States who are asymptomatically
infected with Mycobacterium tuberculosis is not known, projections based on
previous data range from 10 million to 15 million (CDC, unpublished data). Estimates
are that >90% of current tuberculosis cases occur from this large pool of previously
infected persons. Unless preventive therapy is more effectively applied to reduce this
reservoir of infection, hundreds of thousands of new tuberculosis cases and tens of
thousands of deaths can be expected over the next few decades.
High-Risk Groups
Certain groups within the infected population are at greater risk than others and
should receive high priority for preventive therapy. In the United States, persons with
any of the following six risk factors should be considered candidates for preventive
therapy, regardless of age, if they have not previously been treated:
* Persons with human immunodeficiency virus (HIV) infection (>5 mm)* and
persons with risk factors for HIV infection whose HIV infection status is unknown
but who are suspected of having HIV infection.
* Close contacts of persons with newly diagnosed infectious tuberculosis
(>5 mm). In addition, tuberculin-negative (<5 mm) children and adolescents
who have been close contacts of infectious persons within the past 3 months are
candidates for preventive therapy until a repeat tuberculin skin test is done 12
weeks after contact with the infectious source.
* Recent converters, as indicated by a tuberculin skin test (>10 mm increase
within a 2-year period for those <_35 years old; >15 mm increase for those > 35
years of age).
* Persons with abnormal chest radiographs that show fibrotic lesions likely to
represent old healed tuberculosis (>5 mm).
* Intravenous drug users known to be HIV-seronegative (>10 mm).
* Persons with medical conditions that have been reported to increase the risk of
tuberculosis (>10 mm).
In addition, in the absence of any of the above risk factors, persons <35 years of
age in the following high-incidence groups are appropriate candidates for preventive
therapy if their reaction to a tuberculin skin test is >10 mm:
* Foreign-born persons from high-prevalence countries.
* Medically underserved low-income populations, including high-risk racial or
ethnic minority populations, especially blacks, Hispanics, and Native Americans.
*The criterion for a positive reaction to a skin test (in millimeters of induration) for each group
is given in parentheses and is based on data cited in references 11-13.

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