Active Tracing and Monitoring of Contacts Associated With the First Cluster of Ebola in the United States

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Abstract
Background: Following hospitalization of the first patient with Ebola diagnosed in the United States on 28 September 2014, contact tracing methods for Ebola were implemented. Objective: To identify, risk-stratify, and monitor contacts of patients with Ebola. Design: Descriptive investigation. Setting: Dallas County, Texas, September to November 2014 Participants: Contacts of symptomatic patients with Ebola. Measurements: Contact identification, exposure risk classification, symptom development, and Ebola. Results: 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. Limitations: Data cannot be used to infer whether in-person direct active monitoring is superior to active monitoring alone for early detection of symptomatic contacts. Conclusion: 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 development of 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. Primary Funding Source: None.