Transmission of Tuberculosis Among Illicit Drug Use Linkages

Overview

Tuberculosis (TB) is the leading infectious disease killer globally and leading cause of death in persons with HIV. The most effective way to reduce TB incidence and mortality is to interrupt transmission. This requires finding and treating individuals with TB disease early, including those with subclinical disease. Molecular epidemiologic studies and mathematical models have shown that the primary approach to case finding-household contact tracing-identifies only 8-19% of transmissions in high TB and TB/HIV burden settings. Thus there is a clear need to identify new groups and settings where TB transmission occurs. Spatial clustering of individuals with higher rates of progression from infection to disease, such as those with HIV and malnourishment, can also form transmission hotspots. Illicit drug (i.e., methamphetamines, crack/cocaine, opiates) users have higher TB infection prevalence and disease incidence compared to non-users, likely due to significant within-group transmission and/or clustered vulnerability. Increased transmission among people who use illicit drugs (PWUD) could result from creation of more efficient TB transmitters, increased close contact among transmitters, increased rates of primary progression from infection to disease among contacts, or a combination. Interrogation of illicit drug user networks for TB transmission, therefore, holds great potential as a target for early case identification and linkage to treatment, with potential benefit for halting transmission to the broader population.

A cross-sectional, observational study design using respondent driven sampling (RDS) will be used for this research study. In Aim 1, individuals will be recruited who currently use meth and/or Mandrax to assess TB exposure, incipient TB prevalence, and TB disease prevalence in the network. RDS will be used to seek out 750 meth/Mandrax users. Initial seeds (N=4) will be individuals from the investigator's current R01, the Tuberculosis treatment outcomes and alcohol use study (TRUST) cohort who have had active pulmonary TB disease in the prior 1-2 years and report current meth/Mandrax use. For Aim 2, individuals from Aim 1 identified to have possible TB disease will be screened and enrolled to estimate the proportion that reflect recent transmission via genotyping and social epidemiologic links. In Aim 3, the investigators will examine physiologic factors that may make PWUD more efficient TB transmitters. 50 PWUD participants from Aim 2 will be recruited who have active, untreated pulmonary TB and 50 individuals with active, untreated pulmonary TB who do not use meth/Mandrax, matched on age and gender will be recruited