Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 21, Number 7—July 2015
Letter

Estimating Ebola Treatment Needs, United States

Cite This Article

To the Editor: By December 31, 2014, the Ebola epidemic in West Africa had resulted in treatment of 10 Ebola case-patients in the United States; a maximum of 4 patients received treatment at any one time (1). Four of these 10 persons became clinically ill in the United States (2 infected outside the United States and 2 infected in the United States), and 6 were clinically ill persons medically evacuated from West Africa (Technical Appendix 1 Table 6).

To plan for possible future cases in the United States, policy makers requested we produce a tool to estimate future numbers of Ebola case-patients needing treatment at any one time in the United States. Gomes et al. previously estimated the potential size of outbreaks in the United States and other countries for 2 different dates in September 2014 (2). Another study considered the overall risk for exportation of Ebola from West Africa but did not estimate the number of potential cases in the United States at any one time (3).

We provide for practicing public health officials a spreadsheet-based tool, Beds for Ebola Disease (BED) (Technical Appendix 2) that can be used to estimate the number of Ebola patients expected to be treated simultaneously in the United States at any point in time. Users of BED can update estimates for changing conditions and improved quality of input data, such as incidence of disease. The BED tool extends the work of prior studies by dividing persons arriving from Liberia, Sierra Leone, and Guinea into the following 3 categories: 1) travelers who are not health care workers (HCWs), 2) HCWs, and 3) medical evacuees. This categorization helps public health officials assess the potential risk for Ebola virus infection in individual travelers and the subsequent need for post-arrival monitoring (4).

We used the BED tool to calculate the estimated number of Ebola cases at any one time in the United States by multiplying the rate of new infections in the United States by length of stay (LOS) in hospital (Table). The rate of new infections is the sum of the rate of infected persons in the 3 listed categories who enter the United States from Liberia, Sierra Leone, or Guinea. For the first 2 categories of travelers, low and high estimates of Ebola-infected persons arriving in the United States are calculated by using low and high estimates of both the incidence of disease in the 3 countries and the number of arrivals per month (Table). Calculating the incidence among arriving HCWs required estimating the number of HCWs treating Ebola patients in West Africa (Technical Appendix 1, Tables 2–4). For medical evacuations of persons already ill from Ebola, we calculated low and high estimates using unpublished data of such evacuations through the end of December 2014.

Although only 1 Ebola case has caused additional cases in the United States (7), we included the possibility that each Ebola case-patient who traveled into the United States would cause either 0 secondary cases (low estimate) or 2 secondary cases (high estimate) (Table). Such transmission might occur before a clinically ill traveler is hospitalized or between a patient and HCWs treating the patient (7). To account for the possibility that infected travelers may arrive in clusters, we assumed that persons requiring treatment would be distributed according to a Poisson probability distribution. Using this distribution enables us to calculate, using the BED tool, 95% CIs around the average estimate of arriving case-patients. The treatment length used in both the low and high estimate calculations was 14.8 days, calculated as a weighted average of the LOS of hospitalized case-patients treated in West Africa through September 2014 (Technical Appendix 1 Table 5) (8). We conducted a sensitivity analysis using LOS and reduced case-fatality rate of patients treated in the United States (Technical Appendix 1 Table 6).

For late 2014, the low estimate of the average number of beds needed to treat patients with Ebola at any point in time was 1 (95% CI 0–3). The high estimate was 7 (95% CI 2–13).

In late 2014, the United States had to plan and prepare to treat additional Ebola case-patients. By mid-January 2015, the capacity of Ebola treatment centers in the United States (49 hospitals with 71 total beds [9]) was sufficient to care for our highest estimated number of Ebola patients. Policymakers already have used the BED model to evaluate responses to the risk for arrival of Ebola virus–infected travelers, and it can be used in future infectious disease outbreaks of international origin to plan for persons requiring treatment within the United States.

Top

Acknowledgment

We thank Caresse Campbell and Bishwa Adhikari for compiling various data and the Centers for Disease Control and Prevention’s Ebola Response Global Migration Task Force for data on HCW arrivals.

Top

Gabriel Rainisch1Comments to Author , Jason Asher1, Dylan George1, Matt Clay, Theresa L. Smith, Christine Kosmos, Manjunath B. Shankar, Michael L. Washington, Manoj Gambhir, Charisma Atkins, Richard Hatchett, Tim Lant2, and Martin I. Meltzer2

Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (G. Rainisch, T.L. Smith, K. Cosmos, M. Shankar, M. Washington, C. Atkins, M.I. Meltzer); Leidos, Reston, Virginia, USA (J. Asher, M. Clay); Biomedical Advanced Research and Development Authority, Washington, DC, USA (D. George, R. Hatchett, T. Lant); Monash University, Melbourne, Victoria, Australia (M. Gambhir)

Top

References

  1. Ashkenas  J, Buchanan  L, Burgess  J, Fairfield  H, Grady  D, Keller  J, How many Ebola patients have been treated outside of Africa?: New York Times; 01/26/2015 [cited 2015 Feb 13]. http://www.nytimes.com/interactive/2014/07/31/world/africa/ebola-virus-outbreak-qa.html
  2. Gomes  MFC, Piontti  AP, Rossi  L, Chao  D, Longini  I, Halloran  ME, Assessing the international spreading risk associated with the 2014 West African Ebola outbreak. PLoS Curr. 2014;6. pii: ecurrents.outbreaks.cd818f63d40e24aef769dda7df9e0da5. PubMed
  3. Bogoch  II, Creatore  MI, Cetron  MS, Brownstein  JS, Pesik  N, Miniota  J, Assessment of the potential for international dissemination of Ebola virus via commercial air travel during the 2014 west African outbreak. Lancet. 2015;385:2935 . DOIPubMed
  4. Brown  CM, Aranas  AE, Benenson  GA, Brunette  G, Cetron  M, Chen  TH, Airport exit and entry screening for Ebola—August–November 10, 2014. MMWR Morb Mortal Wkly Rep. 2014;63:11637 .PubMed
  5. World Health Organization. Global Alert and Response (GAR). Situation reports with epidemiological data: archive. Situation report update—October 22, 2014. Ebola response roadmap situation report [cited 2014 Dec 24 ]. http://www.who.int/csr/disease/ebola/situation-reports/archive/en/
  6. Centers for Disease Control and Prevention. Interim US guidance for monitoring and movement of persons with potential Ebola virus exposure. December 24, 2014 [cited 2014 Dec 24]. http://www.cdc.gov/vhf/ebola/exposure/monitoring-and-movement-of-persons-with-exposure.html
  7. Chevalier  MS, Chung  W, Smith  J, Weil  LM, Hughes  SM, Joyner  SN, Ebola virus disease cluster in the United States—Dallas County, Texas, 2014. MMWR Morb Mortal Wkly Rep. 2014;63:10878 .PubMed
  8. World Health Organization Ebola Response Team. Ebola virus disease in West Africa—the first 9 months of the epidemic and forward projections. N Engl J Med. 2014;371:148195. Epub 2014 Sep 22. DOIPubMed
  9. Centers for Disease Control and Prevention. Current Ebola treatment centers. 12/31/2014 [cited 2014 Jan 5]. http://www.cdc.gov/vhf/ebola/healthcare-us/preparing/current-treatment-centers.html

Top

Table

Top

Cite This Article

DOI: 10.3201/eid2107.150286

1These first authors contributed equally to this article.

2These senior authors contributed equally to this article.

Related Links

Top

Table of Contents – Volume 21, Number 7—July 2015

Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Gabriel Rainisch, Centers for Disease Control and Prevention, 1600 Clifton Rd NE, Mailstop C18, Atlanta, GA 30333, USA

Send To

character(s) remaining.

Comment submitted successfully, thank you for your feedback.

Top

Page created: June 16, 2015
Page updated: June 16, 2015
Page reviewed: June 16, 2015
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external