The 130th Annual Meeting of APHA

4030.0: Tuesday, November 12, 2002 - 9:35 AM

Abstract #51909

Extensive M. Tuberculosis Transmission In A Low Incidence Area: August 2001 - April 2002

McKenzie Andre, MD, Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Mailstop E-10, Atlanta, GA 30333, 404-639-2429, mia8@cdc.gov

Background: The potential remains for tuberculosis (TB) outbreaks to occur even in low incidence areas. Since August 2001, a large cluster of TB cases has been investigated in three contiguous rural counties in a southwestern State that, combined, reported only four cases per year in the previous three years. Methods: Hospital, health department and city jail records were reviewed and TB case-patients interviewed. Contacts were evaluated for latent TB infection (LTBI) and active disease. Tuberculin skin testing (TST) results were analyzed by level of exposrue to the index patient. Network analysis was performed using InFlow software. Results: The index case-patient was ill with fever and cough for eight months before diagnosis. 284 contacts were identified around his home, place of employment, city jail and 3 hospitals. Close contacts had a higher risk of positive TST (RR 2.0, 95% CI 1.3 to 2.9) compared to his other contacts. Through May 2002, a total of 29 cases have been identified, including eight pediatric case-patients. Eleven patients had HIV testing performed and all were negative. Overall, the index case-patient and eight culture-confirmed pulmonary case-patients identified 494 contacts (median=28, range 4 to 264) and 95 (19%) were candidates for treatment of LTBI. Network analysis revealed the critical importance of the index case in generating this outbreak. Conclusions: One infectious TB case was associated with a five-fold increase in TB cases in three rural counties. Delays in diagnosis of active TB threaten to reverse recent advances in other low incidence areas. Network analysis may enhance routine contact investigations and help characterize the relative importance of various persons within an outbreak.

Learning Objectives:

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.

Social Networks and Alternative Approaches to TB Contact Investigations

The 130th Annual Meeting of APHA