Wendy M. Chung, MD; Jessica C. Smith, MPH; Lauren M. Weil, PhD, MPH; Sonya M. Hughes, MPH; Sibeso N. Joyner, MPH; Emily M. Hall, MPH; Julia Ritch; Divya Srinath, JD, MPH; Edward Goodman, MD; Michelle S. Chevalier, MD, MPH; Lauren Epstein, MD, MSc; Jennifer C. Hunter, DrPH; Alexander J. Kallen, MD, MPH; Mateusz P. Karwowski, MD, MPH; David T. Kuhar, MD; Charnetta Smith, MD; Lyle R. Petersen, MD, MPH; Barbara E. Mahon, MD, MPH; David L. Lakey, MD; Stephanie J. Schrag, DPhil
Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Acknowledgment: The authors are indebted to the staff of the following agencies for their respective contributions to contact tracing and monitoring during this response: Texas Health Resources Human Resources and Infection Prevention Departments, Dallas County Sheriff's Department, Dallas Police Department, and City of Dallas Fire–Rescue Department for their assistance identifying and locating contacts; CDC Ebola Response Team (Kristina M. Angelo, DO, MPH-TM; Sasha McGee, PhD, MPH; Aimee Summers, PhD; and Kerton R. Victory, PhD, MSc) for assistance with interviewing and monitoring contacts; Collin County Health Care Services, Dallas County Health and Human Services (DCHHS), Denton County Health Department, Tarrant County Health Department, and the Texas Department of State Health Services (DSHS) Region 2/3 Office, for additional assistance with monitoring contacts; CDC Ebola Response Team (Matthew Biggerstaff, MPH; Aaron Curns, MPH; Ethan Fechter-Leggett, DVM, MPVM; Edith N. Nyangoma, MD, MPH; Sarah Rhea, DVM, MPH, PhD; and Melissa A.R. Rolfes, PhD, MPH) and Texas DSHS TB/HIV/STD Epidemiology Branch (Dylan McAfee, MPH, and Anna Klioueva, MPH) for data management; City of Dallas, Dallas County Office of the County Judge and Office of Emergency Management, DCHHS Public Health Preparedness Division, Texas DSHS (David Gruber, MS) and CDC Ebola Response Team (Dikia Anderson, David Daigle, MA; Lyn Finelli, DrPH, MS; Thomas George, MPH; Maleeka Glover, ScD, MPH; Gayle Langley, MD; Rosa Lira, MPH; Megan O'Sullivan, MPH; Scott Santibañez, MD, DMin; and Amy Stewart, MPH) for technical assistance and logistical support and coordination for contact monitoring activities; Dallas City Attorney's office, Dallas County District Attorney's office, and Texas DSHS Legal Section for on-site legal support to field teams; faith-based and community organizations, charitable foundations, Dallas County Independent School Districts, Dallas County Medical Society, Texas Health Resources, and all other agencies volunteering support for contacts; Texas Health Resources Dallas physicians (Glen Owen, MD; Mark Till, MD; and Allison Liddell, MD) and CDC Ebola Response Team (Matthew R. Moore MD, MPH) for clinical evaluation of contacts; and DCHHS LRN Laboratory (Edward Bannister, PhD; Samira Peyrovi, BS; Daniel Serinaldi, mbASCP; and Joey Stringer), Texas DSHS Biothreat Laboratory Team, CDC Ebola Response Laboratory Team, and the Texas Health Resources Dallas Laboratory for testing of contacts for Ebola. The authors particularly thank all the contacts for graciously allowing entry into their homes and lives, and for their extraordinary patience and understanding.
Disclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M15-0968.
Editors' Disclosures: Christine Laine, MD, MPH, Editor in Chief, reports that she has no financial relationships or interests to disclose. Darren B. Taichman, MD, PhD, Executive Deputy Editor, reports that he has no financial relationships or interests to disclose. Cynthia D. Mulrow, MD, MSc, Senior Deputy Editor, reports that she has no relationships or interests to disclose. Deborah Cotton, MD, MPH, Deputy Editor, reports that she has no financial relationships or interest to disclose. Jaya K. Rao, MD, MHS, Deputy Editor, reports that she has stock holdings/options in Eli Lilly and Pfizer. Sankey V. Williams, MD, Deputy Editor, reports that he has no financial relationships or interests to disclose. Catharine B. Stack, PhD, MS, Deputy Editor for Statistics, reports that she has stock holdings in Pfizer.
Reproducible Research Statement:Study protocol, data set, and statistical code: Not applicable.
Requests for Single Reprints: Wendy M. Chung, MD, Epidemiology and Acute Communicable Disease Division, Dallas County Health and Human Services, 2377 North Stemmons Freeway, Suite 502, Dallas, TX 75207; e-mail, firstname.lastname@example.org.
Current Author Addresses: Dr. Chung: Epidemiology and Acute Communicable Disease Division, Dallas County Health and Human Services, 2377 North Stemmons Freeway, Suite 502, Dallas, TX 75207.
Ms. Smith, Dr. Weil, Ms. Hall, Ms. Hughes, Ms. Joyner, Ms. Ritch, and Ms. Srinath: Epidemiology and Acute Communicable Disease Division, Dallas County Health and Human Services, 2377 North Stemmons Freeway, Suite 502, Dallas, TX 75207.
Dr. Goodman: Texas Health Presbyterian Hospital Dallas, 8200 Walnut Hill Lane, Dallas, TX 75231.
Drs. Chevalier, Karkowski, and Smith: Epidemic Intelligence Service, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333.
Drs. Epstein, Hunter, Kallen, and Kuhar: Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333.
Dr. Petersen: Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521.
Dr. Mahon: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333.
Dr. Lakey: Texas Department of State Health Services, 1100 West 49th Street, Austin, TX 78756.
Dr. Schrag: Division of Bacterial Diseases, Centers for Disease Control and Prevention, MS C23, 1600 Clifton Road NE, Atlanta, GA 30333.
Author Contributions: Conception and design: W.M. Chung, S.M. Hughes, J.C. Hunter, A.J. Kallen, D. Kuhar, D. Lakey, B.E. Mahon, L.R. Petersen, S. Schrag, J.C. Smith
Analysis and interpretation of the data: M.S. Chevalier, W.M. Chung, L. Epstein, E.L. Goodman, E. Hall, S.M. Hughes, J.C. Hunter, S.N. Joyner, A.J. Kallen, M.P. Karwowski, D. Kuhar, B.E. Mahon, L.R. Petersen, J. Ritch, S. Schrag, J.C. Smith, C.L. Smith, L. Weil.
Drafting of the article: W.M. Chung, S.M. Hughes, J.C. Hunter, L.R. Petersen, S. Schrag, J.C. Smith.
Critical revision for important intellectual content: W.M. Chung, L. Epstein, E.L. Goodman, E. Hall, S.M. Hughes, J.C. Hunter, S.N. Joyner, A.J. Kallen, M.P. Karwowski, D. Kuhar, B.E. Mahon, J. Ritch, S. Schrag, J.C. Smith, C.L. Smith, D.Srinath, L. Weil.
Final approval of the article M.S. Chevalier, W.M. Chung, L. Epstein, E.L. Goodman, E. Hall, S.M. Hughes, J.C. Hunter, S.N. Joyner, A.J. Kallen, M.P. Karwowski, D. Lakey, Barbara E. Mahon, L.R. Petersen, J. Ritch, S. Schrag, J.C. Smith, C.L. Smith, D. Srinath, L. Weil.
Provision of study materials or patients: D. Lakey.
Statistical expertise: E. Hall, S.M. Hughes, S.N. Joyner, D. Srinath, L. Weil.
Administrative, technical, or logistic support: W.M. Chung, E. Hall, S.M. Hughes, J.C. Hunter, S.N. Joyner, A.J. Kallen, D. Kuhar, D. Lakey, L.R. Petersen, J. Ritch, S. Schrag, J.C. Smith, C.L. Smith, D. Srinath, L. Weil.
Collection and assembly of data: M.S. Chevalier, W.M. Chung, L. Epstein, E. Hall, S.M. Hughes, J.C. Hunter, S.N. Joyner, A.J. Kallen, M.P. Karwowski, D. Kuhar, L.R. Petersen, J. Ritch, S. Schrag, J.C. Smith, C.L. Smith, D. Srinath, L. Weil.
Following hospitalization of the first patient with Ebola virus disease diagnosed in the United States on 28 September 2014, contact tracing methods for Ebola were implemented.
To identify, risk-stratify, and monitor contacts of patients with Ebola.
Dallas County, Texas, September to November 2014.
Contacts of symptomatic patients with Ebola.
Contact identification, exposure risk classification, symptom development, and Ebola.
The investigation identified 179 contacts, 139 of whom were contacts of the index patient. Of 112 health care personnel (HCP) contacts of the index case, 22 (20%) had known unprotected exposures and 37 (30%) did not have known unprotected exposures but interacted with a patient or contaminated environment on multiple days. Transmission was confirmed in 2 HCP who had substantial interaction with the patient while wearing personal protective equipment. These HCP had 40 additional contacts. Of 20 community contacts of the index patient or the 2 HCP, 4 had high-risk exposures. Movement restrictions were extended to all 179 contacts; 7 contacts were quarantined. Seven percent (14 of 179) of contacts (1 community contact and 13 health care contacts) were evaluated for Ebola during the monitoring period.
Data cannot be used to infer whether in-person direct active monitoring is superior to active monitoring alone for early detection of symptomatic contacts.
Contact tracing and monitoring approaches for Ebola were adapted to account for the evolving understanding of risks for unrecognized HCP transmission. HCP contacts in the United States without known unprotected exposures should be considered as having a low (but not zero) risk for Ebola and should be actively monitored for symptoms. Core challenges of contact tracing for high-consequence communicable diseases included rapid comprehensive contact identification, large-scale direct active monitoring of contacts, large-scale application of movement restrictions, and necessity of humanitarian support services to meet nonclinical needs of contacts.
After confirmation of the first case of Ebola virus disease diagnosed in the United States, contact tracing and monitoring were instituted.
Challenges included the need for rapid response in a setting of evolving knowledge, institution of direct active monitoring and movement restriction for a large number of contacts, and provision of mental health and other supports. Quarantine was necessary in only a few cases.
Contact tracing of the first case of U.S.-diagnosed case of Ebola was unprecedented in complexity. This experience may be useful in future instances of exposure to highly communicable diseases.
Table 1. Ebola Exposure Categories to Determine Public Health Actions—Dallas, Texas, 2014
Number of community and health care contacts of 3 patients with Ebola virus disease undergoing active monitoring—Dallas, Texas, 2014.
Contacts whose Ebola exposures occurred outside of health care settings were designated as community contacts. Active monitoring required that contacts report twice-daily oral temperature measurements and presence of possible Ebola symptoms to public health teams. All contacts in the “high risk” or “some risk” exposure groups underwent direct active monitoring, with at least 1 in-person check daily. Twice-daily self-monitoring for fever and symptoms was initially recommended for all contacts in the “no known exposure” risk group; however, after patient 2's Ebola diagnosis, all contacts in the “no known exposure” category were transitioned to direct active monitoring.
Table 2. Exposures of Community Contacts of Patients With Ebola—Dallas, Texas, 2014*
Table 3. Contacts of Patients With Ebola, by Exposure Risk Classification and Setting—Dallas, Texas, 2014
Table 4. Movement and Work Restrictions for Contacts of Patients With Ebola
Table 5. Clinical Characteristics and Exposure Risks of Symptomatic Contacts Evaluated for Ebola Virus Disease—Dallas, Texas, 2014
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Chung WM, Smith JC, Weil LM, Hughes SM, Joyner SN, Hall EM, et al. Active Tracing and Monitoring of Contacts Associated With the First Cluster of Ebola in the United States. Ann Intern Med. 2015;163:164-173. doi: 10.7326/M15-0968
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Published: Ann Intern Med. 2015;163(3):164-173.
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