Two-stage tuberculin skin testing in individuals with human immunodeficiency virus infection. Community Programs for Clinical Research on AIDS

Unrecognised transmission of tuberculosis in prisons

BACKGROUND

Tuberculosis (TB) is a public health concern in correctional facilities. High turnover of inmate populations may preclude timely diagnosis of TB, so that unrecognised transmission may be common.

OBJECTIVE

To determine the proportion of inmates with new skin test conversions who had identifiable exposure to diagnosed cases of TB in the correctional system, and to test the hypothesis that source cases of TB may be undiagnosed during incarceration.

SETTING

Maryland Division of Corrections, USA.

SUBJECTS

All inmates whose skin test converted from negative to positive at annual screening.

DESIGN

All cases of TB in inmates, diagnosed in the prisons during the relevant time period, were identified. Movements of skin test converters and potential source cases within the prisons were matched. We then matched all inmates discharged from the prison system with all new cases of tuberculosis notified to the Maryland Department of Health & Mental Hygiene tuberculosis registry in 1994.

RESULTS

The inmate turnover was 21% per year. Probable exposure to a diagnosed source case was found in 13% of converters, possible exposure in 10% and no exposure in 72%. In a further 5% exposure status could not be determined. We identified four cases of pulmonary tuberculosis notified to the state in 1994, within 3 months of discharge in released inmates, who were not known to have tuberculosis whilst incarcerated.

CONCLUSIONS

Significant transmission of TB due to undiagnosed index cases may occur in prisons due to high population turnover. New skin test conversions in inmates should be treated as new infection, even in the absence of identifiable exposure to TB.

Tuberculin testing in patients with human immunodeficiency virus/acquired immune deficiency syndrome

After declining for decades, the incidence of Mycobacterium tuberculosis is increasing. The Mantoux tuberculin skin test, which uses purified protein derivative (PPD) of tuberculin, has been used for years as a screening device to detect the presence of exposure and infection to tuberculosis. However, the advent of human immunodeficiency virus (HIV) has elicited many questions regarding the validity of traditional standards for PPD administration and interpretation. The uncertainties in interpreting tuberculin skin tests in immunocompromised individuals is part of the challenge that is being faced by the health-care profession in this 2nd decade of acquired immune deficiency syndrome. This article will help advanced practice nurses understand the relationship between the immune system, tuberculosis, and the PPD skin test; the problem of anergy with immunocompromised patients, particularly those who are HIV-infected; issues involved in placement and interpretation of the results of the PPD test; new Agency for Health Care Policy and Research (AHCPR) standards for PPD interpretation with HIV-infected persons; the "booster" effect and two-step PPD testing; concerns regarding bacille Calmette-Guérin vaccine; and the use of a critical pathway to aid in rapid identification and isolation of the patient with HIV admitted with a potential diagnosis of tuberculosis versus Pneumocystis carinii pneumonia.