Guide to the Application of Genotyping to Tuberculosis Prevention and Control

Tuberculosis Genotyping Case Studies: How TB Programs Have Used Genotyping

Using Genotyping to Evaluate the Impact of a Screening Program

The staff of Denver Metro TB Clinic, Denver Public Health Department used genotyping results to evaluate their skin test and symptom screening program among the homeless (Kong 2002). Previous genotyping results had demonstrated an association between recent TB transmission and homelessness. In response, the Clinic developed a screening program for homeless persons, which required annual TSTs and chest radiography for tuberculin reactors or those with symptoms of tuberculosis. This intervention boosted estimated skin-testing coverage from 27% to 67% among the homeless from 1995 through 1998. Latent TB infection treatment completion increased minimally from 19% to 37% in the same time period.

The Clinic’s screening program was associated with a decrease in the TB rate from 510 per 100,000 homeless persons in 1995 to 121 in 1998. The estimated proportion of TB cases resulting from recent transmission within the homeless population, defined as cases that were clustered within the previous 2 years, decreased from 49% (1988–1994) to 14% (1995–1998).