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Original Research |

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

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; and Stephanie J. Schrag, DPhil
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This article was published online first at www.annals.org on 26 May 2015.


From Dallas County Department of Health and Human Services and Texas Health Resources, Dallas, Texas; Centers for Disease Control and Atlanta, Georgia; and Texas Department of State Health Services, Austin, Texas.

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, wendy.chung@dallascounty.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.


Ann Intern Med. 2015;163(3):164-173. doi:10.7326/M15-0968
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Background: 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.

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.

Limitation: 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 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.

Context

  • After confirmation of the first case of Ebola virus disease diagnosed in the United States, contact tracing and monitoring were instituted.

Contribution

  • 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.

Implication

  • 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.


Tracing and monitoring contacts exposed to patients with Ebola virus disease in past epidemics in Africa have been central to effective outbreak control by ensuring that persons at higher risk for infection are identified, isolated, and evaluated as soon as possible after symptom onset (13). Such contact tracing was challenging during the 2014 western Africa Ebola epidemic, particularly after the disease extended into dense urban areas of Guinea, Liberia, and Sierra Leone (45). However, contact tracing and active monitoring were critical components of containment of Ebola importations into urban Nigeria and Senegal during the summer of 2014 (67).

Before 25 September 2014, 4 patients with Ebola had been treated in the United States; all of them were diagnosed in western Africa and evacuated to biocontainment facilities in the United States for care (8). On 25 September, a 45-year-old man (patient 1), who had arrived in the United States from Liberia 5 days earlier, presented to a Dallas, Texas, emergency department (ED) with a 1-day history of fever, abdominal pain, and headache (9). He was prescribed antibiotics for possible sinusitis and discharged a few hours later. On 28 September, he returned to the hospital by ambulance with persistent fever, abdominal pain, and intervening onset of diarrhea. Ebola was suspected, and he was placed in a private room under standard, droplet, and contact precautions. He was transferred to the hospital's medical intensive care unit on 29 September. Ebola was confirmed on 30 September, and the patient died on 8 October. On 11 October and 15 October, 2 health care personnel (HCP) (patients 2 and 3, respectively) who had cared for patient 1 were confirmed to have Ebola (10). This domestic cluster of Ebola provided the opportunity to assess implementation of contact tracing and monitoring approaches for this high-consequence disease in both community and health care settings for the first time in the United States.

Case and Contact Identification

The case and contact definitions used at the outset of this investigation were the extant definitions from the Centers for Disease Control and Prevention (CDC), operational as of 28 September 2014; they have since been revised (11). Possible Ebola case-patients were persons with both potential Ebola epidemiologic risk factors and consistent symptoms. Potential Ebola exposure risk factors included contact with a patient who had laboratory-confirmed Ebola or who had traveled from countries affected by the Ebola outbreak. The extant symptom criteria included temperature of 101.5°F or greater (≥38.6°C); 1 or more of the following symptoms: severe headache, sore throat, malaise, muscle pain, diarrhea, vomiting, rash, or unexplained bleeding within 21 days after exposure or travel; and no alternative diagnosis. Confirmed patients had Ebola virus detected in a blood sample by real-time reverse-transcription polymerase chain reaction performed at the CDC (12).

Contact tracing was initiated for possible and confirmed Ebola cases. A contact was defined as any person, irrespective of use of personal protective equipment, who touched the skin, blood, or other body fluid of a symptomatic patient with confirmed Ebola; had been within 3 feet of a symptomatic patient with Ebola for more than 15 minutes; or who interacted with a possibly contaminated health care environment.

Contacts whose Ebola exposures occurred outside of health care settings were designated as community contacts. Community contacts who interacted with the patient between symptom onset and admission were identified by interviewing patients with Ebola, their household members, and other reported potential contacts. Identification and monitoring of additional possible community contacts of patient 3 from a visit to Ohio are described elsewhere (1314).

Contacts whose Ebola exposures occurred during ambulance transport or at the hospital were designated as health care contacts. Ambulance transport contacts were identified through emergency medical services. The HCP contacts were identified through the hospital's human resources department from a combination of information provided by department managers, records of staff movement from location-tracking badge tags, security sign-in sheets, and prospective logs used to document HCP participating in the care of the patients with Ebola.

Risk Classification and Monitoring of Contacts

Standardized questionnaires on the nature and duration of potential exposures were administered to contacts to stratify them into exposure risk groups termed “high risk,” “some risk,” or “no known exposure” (Table 1). These groups were defined according to the extant CDC classification criteria, which have since been revised (15). The “no known exposure” category encompassed contacts without recognized unprotected exposures to Ebola, including HCP who used recommended personal protective equipment when caring for patients with Ebola. After confirmation of patient 2's Ebola diagnosis, additional subclassifications (“higher risk,” “lower risk,” and “least risk”) were created to further stratify risk levels within the “no known exposure” group and help guide heightened monitoring and movement restrictions (Table 1).

Table Jump PlaceholderTable 1. Ebola Exposure Categories to Determine Public Health Actions—Dallas, Texas, 2014 

All contacts received instruction about symptom monitoring and procedures to follow in the event of illness onset. Monitoring entailed twice-daily oral temperature measurement and checking for symptoms compatible with Ebola for 21 days from the date of last exposure. Contacts in the “high risk” and “some risk” groups underwent direct active monitoring, with at least 1 of their twice-daily symptom checks directly observed by a member of the investigation team at their place of lodging, and the second reported by phone.

In accordance with the extant national guidance, twice-daily self-monitoring for fever and symptoms was initially recommended to the contacts in the “no known exposure” risk group. After patient 2's Ebola diagnosis, all HCP contacts in the “no known exposure” category were transitioned to direct active monitoring, with at least 1 in-person check daily onsite at the hospital. From 1 to 7 November, the last week of monitoring in Dallas County, alternatives, such as video chat, were used when in-person checks were not feasible.

Data from EPI-Info 7 (CDC) was reentered into Microsoft Access 2010 (Microsoft Corp.) and later into Maven (Consilience Software) databases and analyzed using SAS software, version 9.3 (SAS Institute). Because this investigation was part of a public health response, it was determined to be nonresearch by the CDC and therefore was not subject to CDC institutional review board review.

Movement Restrictions

Movement restrictions were recommended to prevent possible spread should a contact become symptomatic. Contacts with “high risk” and “some risk” exposure levels were instructed to avoid travel by commercial conveyances and public transportation during their monitoring period (15). According to the extant CDC guidance for monitoring and movement of persons with Ebola exposures, contacts in the “no known exposure” risk category were not initially subject to movement restrictions; however, after patient 2's Ebola diagnosis, directives for controlled movement were also applied to this risk group. On 16 October, all contacts in the “no known exposure” category who had ever entered the index patient's room were additionally restricted from direct care activities of other patients and from public gatherings. Public health control orders for quarantine were implemented whenever voluntary adherence to active monitoring or controlled movement directives could not be ensured.

Investigation of Symptomatic Contacts

Contacts of the 3 patients with Ebola reporting a temperature of 100.4 °F (38 °C) or greater, or compatible symptoms (severe headache, sore throat, malaise, muscle pain, diarrhea, vomiting, rash, or unexplained bleeding) were referred to the ED, isolated, and assessed to determine whether Ebola testing was warranted. If the result of an initial reverse-transcription polymerase chain reaction test for Ebola was negative, contacts with persistent symptoms and without an alternative diagnosis underwent additional Ebola testing 72 hours or more after symptom onset. Patients were eligible for discharge after improvement or resolution of symptoms for 24 hours or a negative Ebola test result obtained 72 hours or more after symptom onset.

From 28 September to 16 October, more than 280 reported potential contacts of the 3 Ebola case-patients were investigated, of whom 179 were confirmed as contacts and monitored (Figure). Patient 1 had 139 contacts (17 community contacts and 122 health care contacts, 2 of whom became patients 2 and 3). Patients 2 and 3 had 73 contacts (3 community and 70 HCP contacts); 33 of their HCP contacts were also contacts of patient 1. Among the 3 patients who were part of this investigation, patient 1 had the longest period of symptoms before hospital admission (5 days; 24–28 September) and the longest hospital stay (11 days; 28 September–8 October). Patients 2 and 3 were each symptomatic for less than 24 hours in the Dallas community before admission, and their Dallas hospital stays were also shorter (7 days and 1 day, respectively) because of their transfers to hospitals with dedicated biocontainment units.

Grahic Jump Location
Figure.

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.

Grahic Jump Location
Community Contacts

Community contacts (n = 20) (Table 2) ranged in age from 2 to 58 years; 53% were female. Seven were household contacts of patients with Ebola; the remaining 13 visited patient 1's household after his first ED visit. Four contacts met criteria for “high-risk” exposure (Table 3): Patient 1's domestic partner, who served as his primary caregiver from symptom onset until his hospital admission (including after the onset of diarrhea on 27 September); 2 community members who had direct skin-to-skin contact with patient 1; and 1 contact who had direct skin-to-skin contact with patient 2. Three contacts shared a bed with a symptomatic patient with Ebola. Most (80%) community contacts were in the “some risk” category, primarily from having spent an hour or more in the same room as a symptomatic patient with Ebola.

Table Jump PlaceholderTable 2. Exposures of Community Contacts of Patients With Ebola—Dallas, Texas, 2014* 
Table Jump PlaceholderTable 3. Contacts of Patients With Ebola, by Exposure Risk Classification and Setting—Dallas, Texas, 2014 

Because all identified community contacts had exposures of “high risk” or “some risk” levels, all were restricted from travel by commercial conveyances (Table 4). After initiation of direct active monitoring, 2 community contacts missed an in-person symptom check during their monitoring period. Five community contacts were quarantined to ensure adherence to direct active monitoring and movement restrictions.

Table Jump PlaceholderTable 4. Movement and Work Restrictions for Contacts of Patients With Ebola 
Health Care Contacts

No patients in the ED were contacts of patient 1 during his first or second ED visit. Because not all medical equipment in the ambulance that transported patient 1 to his second ED visit had undergone complete disinfection, 10 patients transported in the ambulance after him were classified in the “some risk” group; 2 of these were quarantined.

The HCP contacts from all 3 patients (n = 149) included staff from ambulance (n = 3) and hospital settings (n = 146) (Table 3). The HCP contacts most frequently worked in the medical intensive care unit (43%), the ED (27%), and laboratory (19%). Twenty percent (22 of 112) of HCP contacts of the index case had known unprotected exposures classified as “high risk” (n = 7) or “some risk” (n = 15). All of these exposures occurred during patient 1's first ED visit or during emergency medical service transport. At the first ED visit and during ambulance transport to the second visit, the patient experienced no episodes of diarrhea or vomiting. No known unprotected exposures of HCP occurred among contacts of patients 2 or 3.

Among the 125 HCP without recognized unprotected exposures who had been classified in the “no known exposure” group (Tables 1 and 3), 41 (33%) were differentiated as being in the “high-risk” group because they had entered the room of a patient with Ebola on more than 1 day or had substantial interaction with the patient or contaminated items or surfaces. This group comprised mostly medical intensive care unit personnel (93%). Another subset of 44 (35%) HCP within the “no known exposure” group were differentiated as having “least risk” because of activities outside of active patient care areas, such as laboratory and environmental services personnel (Tables 1 and 3).

Movement restrictions for HCP contacts were expanded after 12 October (Table 4), prohibiting all but the “least risk” subgroup of the “no known exposure” group from traveling by commercial conveyances. On 16 October, the Texas Department of State Health Services also issued directives restricting use of public transportation and attendance at public gatherings for all contacts who had ever been in patient 1's room. More than 30 HCP voluntarily undertook self-quarantine, which entailed staying in a home alone or in a designated facility; none required public health orders for quarantine. The hospital provided food and accommodation in the hospital's hotel wing for 11 HCP contacts who chose to self-quarantine at this location, as well as wage compensation for HCP placed on administrative leave.

Among the 62% (91 of 147) of health care contacts residing in Dallas, none had more than 1 day elapse without in-person or telephone monitoring while under direct active surveillance. Complete monitoring records were not available for the 38% of health care contacts residing outside of Dallas. Adherence to direct active monitoring checks conducted at contacts' places of lodging was high, with no missed in-person checks for the “high risk” or “some risk” health care contacts residing in Dallas. Lower completion rates for in-person checks were noted among the “no known exposure” HCP contacts for whom direct active monitoring was conducted on-site at the hospital. For HCP who were requested to drive themselves to the hospital for their daily checks, 34% (24 of 70) missed at least one in-person check during their active monitoring period. Adherence to phone monitoring was higher; 6% (4 of 70) of HCP missed 1 or more phone checks.

Evaluation of Symptomatic Contacts

Fourteen contacts were hospitalized for Ebola evaluation during their monitoring period, including 11 contacts of patient 1 (including patients 2 and 3), 2 contacts of patient 2, and 1 contact of patient 3 (Table 5). Most (n = 11) were HCP, 2 were ambulance patient contacts, and 1 was a community contact. Fever with temperature of greater than 100.4 °F (38 °C) was documented in 7 of the 14 contacts; symptoms of headache, abdominal pain, nausea, vomiting, or diarrhea were reported in the 7 who did not have fever. Eleven of these 14 contacts recognized and reported their symptoms promptly. The 3 with delays were HCP. One contact who experienced fever while self-monitoring did not report symptoms until 4 days after onset because of attributing the fever to a recent dental procedure. Another contact experienced several days of fatigue and low appetite before admission; these symptoms occurred during the transition period from self-monitoring to active monitoring and were not among the specified symptoms for which contacts were self-monitoring at the time. A third contact under direct active monitoring, who was admitted for documented fever at an in-person check, disclosed that a self-measured fever had been unreported and a scheduled telephone check had been missed because of oversleeping the prior evening. The median duration of hospitalization for contacts who tested negative for Ebola virus was 2.5 days (range, 1–5 days). Patients 2 and 3 were the only contacts who tested positive for Ebola virus, each within their first day of hospitalization.

Table Jump PlaceholderTable 5. Clinical Characteristics and Exposure Risks of Symptomatic Contacts Evaluated for Ebola Virus Disease—Dallas, Texas, 2014 

This report identifies key experiences from our implementation of contact tracing and monitoring that may assist ongoing preparedness efforts for Ebola. Although contact tracing is a well-established cornerstone of communicable disease control in public health, the intensity and scale of particular aspects of contact tracing for Ebola were unprecedented in the United States for any acute communicable disease. The need to comprehensively identify possibly exposed persons emphasized that hospital preparedness for such highly infectious and lethal pathogens must include systems for identifying and expeditiously reaching all HCP who had contact with a patient who had Ebola. A particular challenge for Ebola hospitalizations is the establishment of accurate prospective tracking mechanisms and data management for the duration of accrual and monitoring of HCP contacts (16). Preparedness activities should also predesignate a limited cadre of health care staff to interact with possible Ebola patients to minimize the total number of HCP contacts. The ED and ambulance health care contacts of the index patient also emphasize the importance of plans that include emergency medical service and ED preparedness—particularly for patients who are not under active monitoring and may not report a history of possible Ebola exposure (17).

Our experience also illustrates the challenges of applying specific monitoring approaches and movement restrictions when these measures are predicated upon assignment of exposure risk categories; as new risks are recognized, reevaluation of risk assignment criteria becomes essential. Although the specific exposure mechanisms that led to the Ebola infections of the 2 HCP remain unknown (Kuhar DT, Chung W, Kallen AJ, Hunter JC, Epstein L, Schrag S, et al. Transmission of Ebola virus in a U.S. hospital—Dallas, Texas. Unpublished data), these transmissions to HCP within the “no known exposure” category prompted revision of the risk classifications of HCP in this exposure group. Rapid expansion of associated monitoring and movement recommendations based on new evidence was found necessary during this response, and further adaptations may be required in future investigations. On 29 October, the CDC updated guidance on Ebola movement and monitoring to reflect our experience that Ebola may develop in HCP with unrecognized exposures during patient care in the United States (15). Of note, health care contacts in the United States without known unprotected exposure should be categorized as low (but not zero) risk for Ebola and actively monitored.

Community contacts, particularly those whose contact occurred during the first days of illness, may have a lower risk for infection than HCP caring for hospitalized patients with Ebola. None of patient 1's community contacts became infected, despite some “high-risk” exposures. One of his contacts served as his primary caregiver, an identified risk factor in African Ebola outbreaks (1819). This is consistent with studies in Africa indicating that Ebola is not necessarily highly transmissible in the first days of symptom onset and that HCP can be at increased risk for Ebola compared with community contacts (2023). Studies of household Ebola transmission in Africa have reported transmission rates of 10% to 20% among household contacts, with lower risk among children and higher risk among those with physical contact late in the clinical course (1819). Although our investigation included only 7 household contacts, the lack of observed transmission may be consistent with these rates. Other differences between Africa and the United States, such as almost universal access to running water and flush toilets in the United States, may reduce the risk for transmission to U.S. community contacts.

Maintaining a direct active surveillance program for large numbers of contacts provided an additional measure of assurance that contacts with possible symptoms of Ebola would be recognized and referred for evaluation promptly, rather than relying predominantly on contacts to self-monitor and report symptoms. The public health burden of in-person active monitoring was substantial for this Dallas cluster, however, and required additional surge support resources that should be considered in planning for future responses. Our experience did not allow for assessment of whether in-person direct active monitoring is superior to active monitoring by telephone for early detection of symptomatic contacts. Overall adherence to active monitoring was high among our contacts, some of whom voluntarily self-quarantined. Public health control orders were implemented for only a small subset of contacts.

Our experience with large-scale application of movement restrictions illustrates the critical importance of meeting social and economic needs of contacts under active monitoring in order to facilitate their adherence to monitoring stipulations and movement restrictions (2425). Many contacts were excluded from the workplace by their employers (Table 4); school-age contacts were excluded from schools; decontamination of patients' residences left household contacts without a place of residence; some contacts could not meet daily living needs; and most contacts experienced anxiety, stigma, or social isolation because of their possible Ebola exposures. Public health emergency preparedness for Ebola should therefore include engagement with community, charity, and faith-based organizations and mental health resources in planning to provide for nonclinical needs, such as housing, transportation, education, food, and household supplies.

Because some contacts under monitoring (7% during our experience) can be expected to develop symptoms possibly consistent with Ebola, public health agencies must ensure capacity to support frontline clinicians in decisions about when to admit and test contacts. Facilities with domestically diagnosed patients with Ebola should prepare for referrals of potentially large numbers of exposed health care and community contacts who may develop symptoms requiring medical evaluation. Clearly established protocols should be communicated to contacts to minimize further transmission in case they become ill, including procedures to notify public health agencies and designated health care facilities before presenting for care, along with transportation protocols using designated emergency medical services.

Additional Ebola introductions into the United States will remain possible while the epidemic in western Africa continues. Maintaining flexibility in adapting principles of contact tracing and monitoring to the introduction of Ebola in new settings (in our case, a metropolitan setting in the United States) and to account for the evolving understanding of risks of unrecognized HCP transmissions may help to limit the size of any future clusters.

As a high-consequence communicable disease new to the United States, Ebola propelled to the forefront core challenges associated with effective contact tracing for such diseases, including heightened urgency of comprehensive contact identification and interview, implementation of direct active monitoring of large numbers of contacts, large-scale application and enforcement of movement restrictions, and mobilization of humanitarian services to meet nonclinical needs and to protect the dignity and privacy of contacts under monitoring and quarantine (24). Planning for such anticipated challenges will strengthen collective preparedness for emerging diseases, such as Ebola, and for resurgences of more familiar diseases, such as measles and tuberculosis.

World Health Organization.  Contact tracing during an outbreak of Ebola virus disease. Brazzaville, Republic of the Congo: WHO Regional Office for Africa; September 2014. Accessed at www.who.int/csr/resources/publications/ebola/contact-tracing-during-outbreak-of-ebola.pdf on 20 March 2015.
 
Feldmann H, Geisbert TW. Ebola haemorrhagic fever. Lancet. 2011; 377:849-62.
PubMed
CrossRef
 
Nkoghe D, Kone ML, Yada A, Leroy E. A limited outbreak of Ebola haemorrhagic fever in Etoumbi, Republic of Congo, 2005. Trans R Soc Trop Med Hyg. 2011; 105:466-72.
PubMed
CrossRef
 
Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola virus disease in Guinea. N Engl J Med. 2014; 371:1418-25.
PubMed
CrossRef
 
WHO Ebola Response Team. Ebola virus disease in West Africa—the first 9 months of the epidemic and forward projections. N Engl J Med. 2014; 371:1481-95.
PubMed
CrossRef
 
Mirkovic K, Thwing J, Diack PA, Centers for Disease Control and Prevention (CDC). Importation and containment of Ebola virus disease—Senegal, August-September 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:873-4.
PubMed
 
Shuaib F, Gunnala R, Musa EO, Mahoney FJ, Oguntimehin O, Nguku PM, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease outbreak—Nigeria, July-September 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:867-72.
PubMed
 
Lyon GM, Mehta AK, Varkey JB, Brantly K, Plyler L, McElroy AK, et al, Emory Serious Communicable Diseases Unit. Clinical care of two patients with Ebola virus disease in the United States. N Engl J Med. 2014; 371:2402-9.
PubMed
CrossRef
 
Chevalier MS, Chung W, Smith J, Weil LM, Hughes SM, Joyner SN, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease cluster in the United States—Dallas County, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1087-8.
PubMed
 
Liddell AM, Davey Jr. RT, Mehta AK, Varkey JB, Kraft CS, Tseggay GK, et al. Characteristics and clinical management of a cluster of 3 patients with Ebola virus disease, including the first domestically acquired cases in the United States. Ann Intern Med. 2015; 163:81-90.
CrossRef
 
Centers for Disease Control and Prevention.  Case definition for Ebola virus disease (EVD). Updated 16 November 2014. Accessed at www.cdc.gov/vhf/ebola/healthcare-us/evaluating-patients/case-definition.html on 11 March 2015.
 
Towner JS, Sealy TK, Ksiazek TG, Nichol ST. High-throughput molecular detection of hemorrhagic fever virus threats with applications for outbreak settings. J Infect Dis. 2007; 196 Suppl 2:S205-12.
PubMed
CrossRef
 
McCarty CL, Basler C, Karwowski M, Erme M, Nixon G, Kippes C, et al, Centers for Disease Control and Prevention (CDC). Response to importation of a case of Ebola virus disease—Ohio, October 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1089-91.
PubMed
 
Regan JJ, Jungerman R, Montiel SH, Newsome K, Objio T, Washburn F, et al, Centers for Disease Control and Prevention (CDC). Public health response to commercial airline travel of a person with Ebola virus infection—United States, 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:63-6.
PubMed
 
Centers for Disease Control and Prevention.  Interim U.S. guidance for monitoring and movement of persons with potential Ebola virus exposure. Updated 24 December 2014. Accessed at www.cdc.gov/vhf/ebola/exposure/monitoring-and-movement-of-persons-with-exposure.html on 11 March 2015.
 
Yacisin K, Balter S, Fine A, Weiss D, Ackelsberg J, Prezant D, et al. Ebola virus disease in a humanitarian aid worker—New York City, October 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:321-3.
PubMed
 
Centers for Disease Control and Prevention.  Interim guidance for emergency medical services (EMS) systems and 9-1-1 public safety answering points (PSAPs) for management of patients under investigation (PUIs) for Ebola virus disease (EVD) in the United States. Updated 2 January 2015. Accessed at www.cdc.gov/vhf/ebola/healthcare-us/emergency-services/ems-systems.html on 11 March 2015.
 
Dowell SF, Mukunu R, Ksiazek TG, Khan AS, Rollin PE, Peters CJ. Transmission of Ebola hemorrhagic fever: a study of risk factors in family members, Kikwit, Democratic Republic of the Congo, 1995. Commission de Lutte contre les Epidémies à Kikwit. J Infect Dis. 1999; 179 Suppl 1:S87-91.
PubMed
CrossRef
 
Francesconi P, Yoti Z, Declich S, Onek PA, Fabiani M, Olango J, et al. Ebola hemorrhagic fever transmission and risk factors of contacts, Uganda. Emerg Infect Dis. 2003; 9:1430-7.
PubMed
CrossRef
 
World Health Organization.  Situation Assessment: unprecedented number of medical staff infected with Ebola. 25 August 2014. Accessed at www.who.int/mediacentre/news/ebola/25-august-2014/en/ on 11 March 2015.
 
Centers for Disease Control and Prevention.  Review of human-to-human transmission of Ebola virus. Updated 29 October 2014. Accessed at www.cdc.gov/vhf/ebola/transmission/human-transmission.html on 20 March 2015.
 
Kilmarx PH, Clarke KR, Dietz PM, Hamel MJ, Husain F, McFadden JD, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease in health care workers—Sierra Leone, 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1168-71.
PubMed
 
Bausch DG, Towner JS, Dowell SF, Kaducu F, Lukwiya M, Sanchez A, et al. Assessment of the risk of Ebola virus transmission from bodily fluids and fomites. J Infect Dis. 2007; 196 Suppl 2:S142-7.
PubMed
CrossRef
 
Smith CL, Hughes SM, Karwowski MP, Chevalier MS, Hall E, Joyner SN, et al, Centers for Disease Control and Prevention (CDC). Addressing needs of contacts of Ebola patients during an investigation of an Ebola cluster in the United States—Dallas, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:121-3.
PubMed
 
Santibañez S, Siegel V, O'Sullivan M, Lacson R, Jorstad C. Health communications and community mobilization during an Ebola response: partnerships with community and faith-based organizations. Public Health Rep. 2015; 130:1-6.
PubMed
 

Figures

Grahic Jump Location
Figure.

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.

Grahic Jump Location

Tables

Table Jump PlaceholderTable 1. Ebola Exposure Categories to Determine Public Health Actions—Dallas, Texas, 2014 
Table Jump PlaceholderTable 2. Exposures of Community Contacts of Patients With Ebola—Dallas, Texas, 2014* 
Table Jump PlaceholderTable 3. Contacts of Patients With Ebola, by Exposure Risk Classification and Setting—Dallas, Texas, 2014 
Table Jump PlaceholderTable 4. Movement and Work Restrictions for Contacts of Patients With Ebola 
Table Jump PlaceholderTable 5. Clinical Characteristics and Exposure Risks of Symptomatic Contacts Evaluated for Ebola Virus Disease—Dallas, Texas, 2014 

References

World Health Organization.  Contact tracing during an outbreak of Ebola virus disease. Brazzaville, Republic of the Congo: WHO Regional Office for Africa; September 2014. Accessed at www.who.int/csr/resources/publications/ebola/contact-tracing-during-outbreak-of-ebola.pdf on 20 March 2015.
 
Feldmann H, Geisbert TW. Ebola haemorrhagic fever. Lancet. 2011; 377:849-62.
PubMed
CrossRef
 
Nkoghe D, Kone ML, Yada A, Leroy E. A limited outbreak of Ebola haemorrhagic fever in Etoumbi, Republic of Congo, 2005. Trans R Soc Trop Med Hyg. 2011; 105:466-72.
PubMed
CrossRef
 
Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola virus disease in Guinea. N Engl J Med. 2014; 371:1418-25.
PubMed
CrossRef
 
WHO Ebola Response Team. Ebola virus disease in West Africa—the first 9 months of the epidemic and forward projections. N Engl J Med. 2014; 371:1481-95.
PubMed
CrossRef
 
Mirkovic K, Thwing J, Diack PA, Centers for Disease Control and Prevention (CDC). Importation and containment of Ebola virus disease—Senegal, August-September 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:873-4.
PubMed
 
Shuaib F, Gunnala R, Musa EO, Mahoney FJ, Oguntimehin O, Nguku PM, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease outbreak—Nigeria, July-September 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:867-72.
PubMed
 
Lyon GM, Mehta AK, Varkey JB, Brantly K, Plyler L, McElroy AK, et al, Emory Serious Communicable Diseases Unit. Clinical care of two patients with Ebola virus disease in the United States. N Engl J Med. 2014; 371:2402-9.
PubMed
CrossRef
 
Chevalier MS, Chung W, Smith J, Weil LM, Hughes SM, Joyner SN, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease cluster in the United States—Dallas County, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1087-8.
PubMed
 
Liddell AM, Davey Jr. RT, Mehta AK, Varkey JB, Kraft CS, Tseggay GK, et al. Characteristics and clinical management of a cluster of 3 patients with Ebola virus disease, including the first domestically acquired cases in the United States. Ann Intern Med. 2015; 163:81-90.
CrossRef
 
Centers for Disease Control and Prevention.  Case definition for Ebola virus disease (EVD). Updated 16 November 2014. Accessed at www.cdc.gov/vhf/ebola/healthcare-us/evaluating-patients/case-definition.html on 11 March 2015.
 
Towner JS, Sealy TK, Ksiazek TG, Nichol ST. High-throughput molecular detection of hemorrhagic fever virus threats with applications for outbreak settings. J Infect Dis. 2007; 196 Suppl 2:S205-12.
PubMed
CrossRef
 
McCarty CL, Basler C, Karwowski M, Erme M, Nixon G, Kippes C, et al, Centers for Disease Control and Prevention (CDC). Response to importation of a case of Ebola virus disease—Ohio, October 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1089-91.
PubMed
 
Regan JJ, Jungerman R, Montiel SH, Newsome K, Objio T, Washburn F, et al, Centers for Disease Control and Prevention (CDC). Public health response to commercial airline travel of a person with Ebola virus infection—United States, 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:63-6.
PubMed
 
Centers for Disease Control and Prevention.  Interim U.S. guidance for monitoring and movement of persons with potential Ebola virus exposure. Updated 24 December 2014. Accessed at www.cdc.gov/vhf/ebola/exposure/monitoring-and-movement-of-persons-with-exposure.html on 11 March 2015.
 
Yacisin K, Balter S, Fine A, Weiss D, Ackelsberg J, Prezant D, et al. Ebola virus disease in a humanitarian aid worker—New York City, October 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:321-3.
PubMed
 
Centers for Disease Control and Prevention.  Interim guidance for emergency medical services (EMS) systems and 9-1-1 public safety answering points (PSAPs) for management of patients under investigation (PUIs) for Ebola virus disease (EVD) in the United States. Updated 2 January 2015. Accessed at www.cdc.gov/vhf/ebola/healthcare-us/emergency-services/ems-systems.html on 11 March 2015.
 
Dowell SF, Mukunu R, Ksiazek TG, Khan AS, Rollin PE, Peters CJ. Transmission of Ebola hemorrhagic fever: a study of risk factors in family members, Kikwit, Democratic Republic of the Congo, 1995. Commission de Lutte contre les Epidémies à Kikwit. J Infect Dis. 1999; 179 Suppl 1:S87-91.
PubMed
CrossRef
 
Francesconi P, Yoti Z, Declich S, Onek PA, Fabiani M, Olango J, et al. Ebola hemorrhagic fever transmission and risk factors of contacts, Uganda. Emerg Infect Dis. 2003; 9:1430-7.
PubMed
CrossRef
 
World Health Organization.  Situation Assessment: unprecedented number of medical staff infected with Ebola. 25 August 2014. Accessed at www.who.int/mediacentre/news/ebola/25-august-2014/en/ on 11 March 2015.
 
Centers for Disease Control and Prevention.  Review of human-to-human transmission of Ebola virus. Updated 29 October 2014. Accessed at www.cdc.gov/vhf/ebola/transmission/human-transmission.html on 20 March 2015.
 
Kilmarx PH, Clarke KR, Dietz PM, Hamel MJ, Husain F, McFadden JD, et al, Centers for Disease Control and Prevention (CDC). Ebola virus disease in health care workers—Sierra Leone, 2014. MMWR Morb Mortal Wkly Rep. 2014; 63:1168-71.
PubMed
 
Bausch DG, Towner JS, Dowell SF, Kaducu F, Lukwiya M, Sanchez A, et al. Assessment of the risk of Ebola virus transmission from bodily fluids and fomites. J Infect Dis. 2007; 196 Suppl 2:S142-7.
PubMed
CrossRef
 
Smith CL, Hughes SM, Karwowski MP, Chevalier MS, Hall E, Joyner SN, et al, Centers for Disease Control and Prevention (CDC). Addressing needs of contacts of Ebola patients during an investigation of an Ebola cluster in the United States—Dallas, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2015; 64:121-3.
PubMed
 
Santibañez S, Siegel V, O'Sullivan M, Lacson R, Jorstad C. Health communications and community mobilization during an Ebola response: partnerships with community and faith-based organizations. Public Health Rep. 2015; 130:1-6.
PubMed
 

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