Latent Tuberculosis Infection
Background. Few data are available describing treatment completion rates among recently infected contacts of tuberculosis (TB) cases, a group at high risk for development of active TB.
Methods. Health department records were reviewed for all contacts of 360 culture-positive pulmonary TB cases reported from five health departments in the United States in 1996.
Results. Of 2,267 contacts who completed screening, 630 (28%) had newly documented positive skin tests (121 with skin test conversion). Treatment of latent TB infection was documented to have been recommended for 447 (71%). Among these, treatment was documented to be initiated for 398 (89%). Of these, 203 (51%) were documented to have completed a 6-month course of treatment, and 78 (20%) received directly observed treatment. Treatment was recommended more often for contacts <15 years of age, skin test converters, close contacts, and contacts of smear-positive cases. Treatment completion rates were higher for skin test converters.
Conclusions. In this study, fewer than one third of all persons with newly documented positive skin tests detected during contact investigations were proven to have completed treatment. Achieving high rates of completion of therapy for latent TB infection in recently infected contacts of active cases of pulmonary TB is essential to maximize public health prevention efforts aimed at eliminating TB.
The activity of highest priority for TB control programs in the United States is the detection and cure of all active cases of TB, thereby stopping transmission of Mycobacterium tuberculosis. The next highest priority is the effective investigation of the contacts of infectious TB cases, who are themselves at increased risk of having active TB.
Tuberculin skin testing and clinical evaluation of contacts should be done promptly after a suspected case of infectious TB is reported, particularly when young children, immunocompromised persons, or others at greater risk for TB may have been exposed. Repeat skin testing is recommended 3 months after last exposure, since skin test conversion may occur up to 10 weeks after exposure. Health department staff conducting contact investigations assess the probability of recent transmission based on infection rates among persons with the most exposure to the case, as well as certain characteristics of the source case, the exposed contacts, and the environment in which exposure occurred.
The effectiveness of isoniazid therapy in preventing progression from TB infection to active disease is well established. Recent studies have also shown the effectiveness of several alternative regimens to treat latent TB infection in persons with human immunodeficiency virus (HIV) infection. As a result, treatment of latent TB infection is generally recommended for all contacts of active cases of pulmonary TB believed to have been recently infected. Despite the recognized importance of treatment of latent TB infection in TB control, few data describe the proportion of infected contacts who initiate and complete therapy, or how completion of therapy is monitored. This manuscript describes a retrospective evaluation of the initiation and completion of therapy for latent TB infection among contacts of active TB cases identified in 1996 by health departments in parts of five states. A description of contact investigation procedures and results of tuberculin skin test screening for these contacts has already been described.
Background. Few data are available describing treatment completion rates among recently infected contacts of tuberculosis (TB) cases, a group at high risk for development of active TB.
Methods. Health department records were reviewed for all contacts of 360 culture-positive pulmonary TB cases reported from five health departments in the United States in 1996.
Results. Of 2,267 contacts who completed screening, 630 (28%) had newly documented positive skin tests (121 with skin test conversion). Treatment of latent TB infection was documented to have been recommended for 447 (71%). Among these, treatment was documented to be initiated for 398 (89%). Of these, 203 (51%) were documented to have completed a 6-month course of treatment, and 78 (20%) received directly observed treatment. Treatment was recommended more often for contacts <15 years of age, skin test converters, close contacts, and contacts of smear-positive cases. Treatment completion rates were higher for skin test converters.
Conclusions. In this study, fewer than one third of all persons with newly documented positive skin tests detected during contact investigations were proven to have completed treatment. Achieving high rates of completion of therapy for latent TB infection in recently infected contacts of active cases of pulmonary TB is essential to maximize public health prevention efforts aimed at eliminating TB.
The activity of highest priority for TB control programs in the United States is the detection and cure of all active cases of TB, thereby stopping transmission of Mycobacterium tuberculosis. The next highest priority is the effective investigation of the contacts of infectious TB cases, who are themselves at increased risk of having active TB.
Tuberculin skin testing and clinical evaluation of contacts should be done promptly after a suspected case of infectious TB is reported, particularly when young children, immunocompromised persons, or others at greater risk for TB may have been exposed. Repeat skin testing is recommended 3 months after last exposure, since skin test conversion may occur up to 10 weeks after exposure. Health department staff conducting contact investigations assess the probability of recent transmission based on infection rates among persons with the most exposure to the case, as well as certain characteristics of the source case, the exposed contacts, and the environment in which exposure occurred.
The effectiveness of isoniazid therapy in preventing progression from TB infection to active disease is well established. Recent studies have also shown the effectiveness of several alternative regimens to treat latent TB infection in persons with human immunodeficiency virus (HIV) infection. As a result, treatment of latent TB infection is generally recommended for all contacts of active cases of pulmonary TB believed to have been recently infected. Despite the recognized importance of treatment of latent TB infection in TB control, few data describe the proportion of infected contacts who initiate and complete therapy, or how completion of therapy is monitored. This manuscript describes a retrospective evaluation of the initiation and completion of therapy for latent TB infection among contacts of active TB cases identified in 1996 by health departments in parts of five states. A description of contact investigation procedures and results of tuberculin skin test screening for these contacts has already been described.