Objectives

Basic understanding of BCG

Impacts of BCG on interpretation of tests for LTBI

Awareness of BCG Atlas website as a resource

Question 10 year old boy was referred for a TST that showed induration = 12 mm. Born in Switzerland in 2006 and moved to

U.S. at age 4 Moved to Morocco 3 years ago to live with

his maternal family Returned to U.S. 1 year ago

Does he have LTBI? Does he need an IGRA?

Terminology / Acronyms • Bacille Calmette-Guerin (BCG) Vaccine

BCG Vaccine - Efficacy • Protection against meningeal/miliary: RR = 0.15 • Variable efficacy vs pulmonary TB – overall 50% reduction

• Greatest in neonates (RR 0.41) and school age kids who were TST negative (RR=0.26)

• Adults RR = 0.8, although confidence intervals include 1

• Greater protection the farther you move from the Equator

• Most heterogeneity explained by location, age at vaccination, TST strategy, age of participants.

Mangtani, CID 2014

BCG Vaccine around the world

Zwerling, PLoS Med 2011

BCG Atlas - http://www.bcgatlas.org/ -10 yo boy (born 1996) -Never rec’d BCG vaccination Likely LTBI Treat for LTBI

How about….

-40 yo man born in Switzerland -Lived in Morocco for past 10 years -TST = 15 mm Treat? Re-test with IGRA?

How does BCG impact TST result? • PPD > 200 antigens BCG cause of false positive TST

Farhat IJTLD 2006

Summary

• Impact on TST based, in part, on age at vaccination and years since vaccination

• BCG Atlas is a nifty reference

• Rare indications for its use in USA

BCG Vaccine – U.S.A. • BCG never universally recommended • CDC: Consider BCG only in very select persons who meet

criteria & in consultation with expert • Children. Consider if negative TST &:

• Continual exposure and cannot be separated from adults who are untreated or ineffectively treated for TB (if the child cannot be given long-term treatment for infection); or

• Have TB caused by strains resistant to isoniazid and rifampin • Health Care Workers (HCW) - Consider on individual basis IF:

• A high percentage of TB patients are infected with MDR-TB • Infection likely due to ongoing MDR TB transmission to HCWs • Comprehensive TB infection-control precautions have been

implemented, but have not been successful.

References

• Farhat M. False-positive tuberculin skin tests: what is the absolute effect of BCG and non-tuberculous mycobacteria? IJTLD 2006; 10(11): 1192-1204

• Mangtani P. Protection by BCG vaccine against tuberculosis: a systematic review of randomized controlled trials. Clin Infec Dis 2014;58(4):470-80

• Zwerling A. The BCG world atlas: a database of global BCG vaccination policies and practices. PLoS Med 2011