Predictors of primary multiple drug resistant tuberculosis (MDR-TB) transmission in Lima, Peru

Article Outline

• Copyright

Background: The emergence of MDR-TB strains is considered among the greatest threats to global TB control. Despite a well-established national directly observed therapy (DOTS) TB control program with high treatment compliance rates and a low burden of HIV co-infection among cases, Peru has among the highest MDR-TB incidence rates in the Americas. Understanding primary MDR-TB transmission is essential for developing effective control strategies and preventing further emergence.

Methods: Using a semi-structured questionnaire, we conducted a case-control study of risk factors for primary MDR-TB in San Juan de Lurigancho (SJL), a Lima district with the highest TB rates in Peru. Consecutive, consenting TB cases (drug sensitive (DS) and primary MDR-TB cases) followed in SJL clinics and randomly selected healthy community controls were enrolled. Questionnaire data were analyzed using Chi-square tests and logistic regression comparing primary MDR-TB cases with DS-TB and healthy community controls.

Results: Sixty MDR-TB cases, 80 DS-TB and 80 community controls enrolled. MDR-TB cases were significantly more likely to have a household contact diagnosed with TB compared with DSTB cases (OR 3.20 p=0.003) and community controls (OR 16.0 p<0.0001) in the 3 years prior to their own diagnosis. While MDR-TB cases and DS-TB cases were equally likely to have had a TB diagnosis in their workplace, 40% of MDR-TB cases reported being unsure if there was a TB diagnosis at work in comparison to 20% of drug sensitive TB cases (OR. 3.18 p=0.006). Spending time in hospitals or clinics, methods of transportation, visiting the prison and geographic location within SJL were not statistically associated with MDR-TB. Further analyses are required to confirm the strength of the effect after considering potential confounders, however preliminary multivariate models show that household and workplace contact with TB remain significant predictors of primary MDR-TB.

Conclusion: These results support ongoing community transmission of primary MDR-TB in SJL. Though a basic contact tracing program is in place for household contacts aged % 15 years old and others are encouraged to present for care if they develop symptoms, control measures in addition to DOTS are likely needed to stem community transmission of primary MDR-TB.