Factors associated with prevalent Mycobacterium tuberculosis infection and disease among adolescents and adults exposed to rifampin-resistant tuberculosis in the household

BACKGROUND

Understanding factors associated with prevalent Mycobacterium tuberculosis infection and prevalent TB disease in household contacts of patients with drug-resistant tuberculosis (TB) may be useful for TB program staff conducting contact investigations.

METHODS

Using data from a cross-sectional study that enrolled index participants with rifampin-resistant pulmonary TB and their household contacts (HHCs), we evaluated HHCs age ≥15 years for factors associated with two outcomes: Mycobacterium tuberculosis infection and TB disease. Among HHCs who were not already diagnosed with current active TB disease by the TB program, Mycobacterium tuberculosis infection was determined by interferon-gamma release assay (IGRA). TB disease was adjudicated centrally. We fitted logistic regression models using generalized estimating equations.

RESULTS

Seven hundred twelve HHCs age ≥15 years enrolled from 279 households in eight high-TB burden countries were a median age of 34 years, 63% female, 22% current smokers and 8% previous smokers, 8% HIV-positive, and 11% previously treated for TB. Of 686 with determinate IGRA results, 471 tested IGRA positive (prevalence 68.8% (95% Confidence Interval: 64.6%, 72.8%)). Multivariable modeling showed IGRA positivity was more common in HHCs aged 25-49 years; reporting prior TB treatment; reporting incarceration, substance use, and/or a period of daily alcohol use in the past 12 months; sharing a sleeping room or more evenings spent with the index participant; living with smokers; or living in a home of materials typical of low socioeconomic status. Forty-six (6.5% (95% Confidence Interval: 4.6%, 9.0%)) HHCs age ≥15 years had prevalent TB disease. Multivariable modeling showed higher prevalence of TB disease among HHCs aged ≥50 years; reporting current or previous smoking; reporting a period of daily alcohol use in the past 12 months; and reporting prior TB treatment.

CONCLUSION

We identified overlapping and distinct characteristics associated with Mycobacterium tuberculosis infection and TB disease that may be useful for those conducting household TB investigations.

Vitamin D Status in Botswana Children Under 2 Years Old With and Without Active Tuberculosis

Additional strategies are needed to prevent and treat tuberculosis (TB). Although vitamin D may have antimycobacterial effects, it is unknown whether low vitamin D status confers a risk for active TB in African children. This case-control study assessed serum 25-hydroxyvitamin D (25(OH)D) concentration in children with and without active TB in Gaborone, Botswana. A total of 80 children under 2 years old with and without active TB, seen at hospitals and clinics in the greater Gaborone area between September 2010 and November 2012, were enrolled. Of these, 39 cases did not differ from the 41 controls in median 25(OH)D levels (P = 0.84). The 25(OH)D was < 20 ng/mL in 8/39 (21%) cases and 7/41 (17%) controls (P = 0.69, χ(2)). Univariate analyses of subject clinical characteristics (other than 25(OH)D levels) showed that any degree of weight loss was associated with a diagnosis of TB (P = 0.047). Other clinical characteristics, including age (P = 0.08) or weight below third percentile (P = 0.58), showed no association with TB. There was no significant difference in vitamin D status between children under 2 years old with and without active TB. Lower vitamin D status did not appear to be a risk factor for TB in this small Gaborone cohort.