domingo, 25 de enero de 2015

A Plan for Community Event-Based Surveillance to Reduce Ebola Transmission — Sierra Leone, 2014–2015

A Plan for Community Event-Based Surveillance to Reduce Ebola Transmission — Sierra Leone, 2014–2015



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MMWR Early Release
Vol. 64, Early Release
January 23, 2015


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A Plan for Community Event-Based Surveillance to Reduce Ebola Transmission — Sierra Leone, 2014–2015
Sam Crowe, PhD, Darren Hertz, MEd, Matt Maenner, PhD, et al.
MMWR Morb Mortal Wkly Rep 2015;64(Early Release):1-4


Ebola was first detected in Sierra Leone in May 2014 and was likely
introduced into the eastern part of the country from Guinea. The disease
spread westward, eventually affecting Freetown, Sierra Leone’s densely
populated capital. In October 2014, members of the International Rescue
Committee, Sierra Leone’s Bo District Health Management Team, and
CDC developed the Community Event-Based Surveillance system to help
strengthen the country’s Ebola surveillance and response capabilities.
This report summarizes the plan.


A Plan for Community Event-Based Surveillance to Reduce Ebola Transmission — Sierra Leone, 2014–2015

Early Release

January 23, 2015 / 64(Early Release);1-4


Sam Crowe, PhD1,2Darren Hertz, MEd3Matt Maenner, PhD1,2Ruwan Ratnayake, MHS3Pieter Baker, MPH3, R. Ryan Lash, MA2John Klena, PhD2Seung Hee Lee-Kwan, PhD1,2Candice Williams, MD1,2Gabriel T. Jonnie3Yelena Gorina, MS2Alicia Anderson, DVM2Gbessay Saffa4Dana Carr, MSc5Jude Tuma, PhD5,Laura Miller, MPH3Alhajie Turay, MD4Ermias Belay, MD2 (Author affiliations at end of text)
Ebola virus disease (Ebola) was first detected in Sierra Leone in May 2014 and was likely introduced into the eastern part of the country from Guinea (1). The disease spread westward, eventually affecting Freetown, Sierra Leone's densely populated capital. By December 2014, Sierra Leone had more Ebola cases than Guinea and Liberia, the other two West African countries that have experienced widespread transmission (2). As the epidemic intensified through the summer and fall, an increasing number of infected persons were not being detected by the county's surveillance system until they had died (Figures 1 and 2). Instead of being found early in the disease course and quickly isolated, these persons remained in their communities throughout their illness, likely spreading the disease.
In October 2014, members of the International Rescue Committee (IRC), Sierra Leone's Bo District Health Management Team (DHMT), and CDC developed the Community Event-Based Surveillance (CEBS) system* to help strengthen the country's Ebola surveillance and response capabilities. It consists of community health monitors who are trained to detect trigger events (Box) thought to be associated with Ebola transmission to find possible cases early in the course of disease, and surveillance supervisors who investigate reported events and isolate and begin treating persons with suspected Ebola. It is not intended to replace the current system, but to supplement case-finding and contact tracing, the core of Ebola surveillance in the West African response (5,6). CEBS is being pilot tested in Sierra Leone's Bo District and recently has been adopted as part of Sierra Leone's national surveillance strategy in low- and medium-transmission districts.§ It will be deployed to other parts of the country soon. This report describes the CEBS system, plans for its evaluation, and some expected benefits and challenges.
Pilot Overview
In November 2014, the IRC implementation team chose two chiefdoms (Gbo and Selenga) in Bo District as pilot areas to assess the feasibility and acceptability ofCEBS. Local community health officers, who serve as clinical staff and health care facility administrators, consulted with the Gbo and Selenga paramount chiefs and chose community health monitors (e.g., teachers, farmers, or other community members who are knowledgeable about their village and its inhabitants) from participating villages.
Monitors are trained to detect and to report trigger events selected by the Bo District community health officers that might indicate introduction or presence of Ebola in a village, such as signs of illness among family members, friends, health care workers, funeral attendees, or travelers. Monitors function alongside the district contact tracers, but focus on detecting trigger events, which might involve previously unknown contacts. Monitors are provided with cellphones in a closed user group to facilitate communication, and receive a stipend to compensate for time spent away from their regular work.
When a monitor learns of a trigger event in the village, he or she reports the event to a local community surveillance supervisor. Supervisors are responsible for investigating trigger events and determining whether these indicate suspected Ebola cases. The supervisor must visit the affected village and conduct the investigation within 24 hours of the initial call. To ensure timely and consistent reporting, supervisors call monitors every week to check for missed alerts and to confirm that the monitors did not detect any Ebola trigger events. The supervisors document all calls with monitors, including those that do not result in detection of a suspected case.
If, after reviewing the monitor's notification and conducting an investigation, the supervisor suspects that there might be an Ebola case in a village, the supervisor contacts the local community health officer for guidance. Community health officers might visit affected villages to assist the monitor and supervisor in complicated or sensitive situations. When a supervisor finds a suspected Ebola case, he or she isolates the person at the periphery of the village, notifies the district Ebola surveillance office, and requests transportation for that person to a holding center, where staff collect blood specimens for Ebola virus testing. The supervisors carry sachets of oral rehydration salts to initiate early treatment, and packets of powdered bleach (with instructions for use) to provide to households with suspected cases to disinfect surfaces possibly contaminated with infected body fluids. With the assistance of the patient, the supervisor creates a line list of contacts and provides it to the district contact tracing team for follow-up.
Evaluation Plan
Preliminary assessments in December 2014 indicated that the pilot implementation in Bo District has had a high level of acceptance by key community leaders, villagers, and the case detection and response team members. Plans are being developed to expand CEBS to other chiefdoms in Bo District and other districts in Sierra Leone in the near future, making it possible to conduct an evaluation of its effectiveness in different parts of the country. The evaluation will include an assessment of the following system attributes: 1) the sensitivity and specificity of case detection (the number of cases detected by CEBS that were not found by contact tracers and did not generate alerts through the existing system, and the proportion of actual alerts); 2) the positive predictive value of the trigger events (the proportion of suspected cases detected by each trigger event that are confirmed to be actual cases); 3) the timeliness of reporting and response (the mean and median number of days from illness onset to specimen collection among detected cases before and after implementation of the system); and 4) the acceptability of the system, based on interviews of key informants in a sample of villages.
Expected Benefits and Challenges
Prompt detection and isolation of persons with Ebola is expected to lead to a number of key public health benefits. First, immediate isolation of infected persons and provision of bleach to affected households should reduce household contact with infectious body fluids and thereby limit disease spread (7). Second, decreasing the number of persons who die from Ebola in the community will also decrease the occurrence of burials by relatives, friends, and neighbors, which can address another route of Ebola virus transmission (8). Third, conducting investigations within 24 hours of case detection should help find patients at an earlier stage of illness and result in their arriving at an Ebola treatment unit much sooner. Fourth, initiating early oral rehydration therapy should help reduce dehydration, and might improve clinical outcomes (9). Fifth, training local Sierra Leoneans to monitor their villages for signs of disease spread can create a community-level surveillance infrastructure that can be used even after the epidemic in West Africa ends. This infrastructure, if established throughout the country, could help detect residual Ebola transmission and future Ebola outbreaks, and could even be used for other infectious diseases (3). In addition to these benefits, the system would likely increase community involvement and participation in the Ebola response, resulting in ownership of Ebola prevention activities and enhanced acceptance of key prevention messages.
Despite these benefits, challenges associated with implementation of CEBS will include recruiting and training staff, maintaining the communication and response network, monitoring participating villages for any concerns with CEBS operations, ensuring adequate transportation for the anticipated increased number of patients to the holding centers, and working with the holding centers to manage the expected increase in false-positive suspected cases. The implementation team will be monitoring these and other challenges throughout the pilot and as the system is expanded into other areas.
1Epidemic Intelligence Service, CDC; 2CDC Sierra Leone Ebola Response Team; 3International Rescue Committee; 4Bo District Health Management Team, Sierra Leone Ministry of Health and Sanitation; 5World Health Organization (Corresponding author: Sam Crowe, yeo2@cdc.gov, 404-639-0195)

References

  1. World Health Organization. Sierra Leone: a traditional healer and a funeral. Geneva, Switzerland: World Health Organization; 2014. Available athttp://www.who.int/csr/disease/ebola/ebola-6-months/sierra-leone/enExternal Web Site Icon.
  2. World Health Organization. Ebola response roadmap situation report, 7 January 2015. Geneva, Switzerland: World Health Organization; 2014. Available athttp://apps.who.int/iris/bitstream/10665/147112/1/roadmapsitrep_7Jan2015_eng.pdf?ua=1&ua=1External Web Site Icon.
  3. Lamunu M, Lutwama JJ, Kamugisha J, et al. Containing a haemorrhagic fever epidemic: the Ebola experience in Uganda (October 2000–January 2001). Int J Infect Dis 2004;8:27–37.
  4. Mbonye AK, Wamala JF, Nanyunja M, Opio A, Makumbi I, Aceng JR. Ebola viral hemorrhagic disease outbreak in West Africa—lessons from Uganda. Afr Health Sci 2014;14:495–501.
  5. Frieden TR, Damon I, Bell BP, Kenyon T, Nichol S. Ebola 2014—new challenges, new global response and responsibility. N Engl J Med 2014; 371:1177–80.
  6. 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;371:1481–95.
  7. Baron RC, McCormick JB, Zubeir OA. Ebola virus disease in southern Sudan: hospital dissemination and intrafamilial spread. Bull World Health Organ 1983;61:997–1003.
  8. Pandey A, Atkins K, Medlock J, et al. Strategies for containing Ebola in West Africa. Science 2014;346:991–5.
  9. Chertow DS, Kleine C, Edwards JK, Scaini R, Giuliani R, Sprecher A. Ebola virus disease in West Africa—clinical manifestations and management. N Engl J Med 2014; 371:2054–7.


* This type of surveillance has been used in previous Ebola outbreaks in Uganda (3,4) in addition to outbreaks of other infectious diseases, such as polio and influenza, throughout the world.
In Sierra Leone, there are three ways to meet the suspected case definition: 1) a person must have a temperature >100.4°F (>38.0°C) and three or more symptoms associated with Ebola, such as vomiting, diarrhea, abdominal pain, headache, joint pain, fatigue, or unusual bleeding; 2) a person must have a fever and have been in contact with a confirmed case in the preceding 3 weeks; or 3) a person must be bleeding for an unexplained reason.
§ Sierra Leone has 14 districts, which comprise 149 chiefdoms. Each chiefdom is further divided into sections and then into villages. Bo District consists of 15 chiefdoms and approximately 1,000 villages and has both rural and urban areas. The second largest city in the country, Bo Town, is located in Bo District. Bo District has one Ebola holding center, one Ebola treatment unit, and a CDC laboratory that tests for Ebola.
There are 43 villages in Gbo and 32 in Selenga, with a combined estimated population in the two chiefdoms of approximately 13,000. All 75 villages in Gbo and Selenga are participating in the pilot.


FIGURE 1. Number of confirmed cases of Ebola virus disease, by epidemiologic week and status at time of case report — Sierra Leone, May–December 2014
The figure above is a histogram showing an epidemic curve with the number of confirmed cases of Ebola virus disease, by epidemiologic week and status at time of case report in Sierra Leone during May-December 2014.
Source: Sierra Leone's Epi Info Viral Hemorrhagic Fever database.
Alternate Text: The figure above is a histogram showing an epidemic curve with the number of confirmed cases of Ebola virus disease, by epidemiologic week and status at time of case report in Sierra Leone during May-December 2014.


FIGURE 2. Proportion of persons with confirmed cases of Ebola virus disease who were already dead at time of case report, by epidemiologic week — Sierra Leone, May–December 2014
The figure above is a line graph showing the proportion of persons with confirmed cases of Ebola virus disease who were already dead at time of case report, by epidemiologic week in Sierra Leone during May-December 2014.
Source: Sierra Leone's Epi Info Viral Hemorrhagic Fever database.
Alternate Text: The figure above is a line graph showing the proportion of persons with confirmed cases of Ebola virus disease who were already dead at time of case report, by epidemiologic week in Sierra Leone during May-December 2014.


BOX. Ebola trigger events for community health monitors — Community Event-Based Surveillance system, Sierra Leone, 2014–2015
  • Two or more ill or dead family members, household members, or friends.
  • One ill or dead traveler in the village (the traveler could be someone from the village who left and returned or someone who is not from the village).
  • One ill or dead health care worker in the village.
  • One ill or dead person who was a contact of a suspected Ebola case and was not known to be tracked by a contact tracing team.
  • One ill or dead person who attended a funeral within the preceding 3 weeks.
  • Any traditional burial that took place in the village or surrounding community (this event trigger will not generate a suspected case investigation, but will alert the surveillance and response team that there might be multiple cases in the near future).

Effectiveness of Ebola Treatment Units and Community Care Centers — Liberia, September 23–October 31, 2014

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Effectiveness of Ebola Treatment Units and Community Care Centers — Liberia, September 23–October 31, 2014



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MMWR Early Release
Vol. 64, Early Release
January 23, 2015
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Effectiveness of Ebola Treatment Units and Community Care Centers — Liberia, September 23–October 31, 2014
Michael L. Washington, PhD, Martin L. Meltzer, PhD
MMWR Morb Mortal Wkly Rep 2015;64(Early Release):1-4


Previous reports have shown an Ebola outbreak can be slowed, and eventually
stopped, by placing patients into settings where there is reduced risk for onward
Ebola transmission, such as Ebola treatment units (ETUs) and community care
centers (CCCs) or equivalent community settings. To estimate the effectiveness
of ETUs and CCCs or equivalent community settings in preventing greater Ebola
transmission, CDC applied the EbolaResponse model to the period September
23–October 31, 2014, in Liberia. This report summarizes the results of that modeling.

Effectiveness of Ebola Treatment Units and Community Care Centers — Liberia, September 23–October 31, 2014

Early Release

January 23, 2015 / 64(Early Release);1-4


Michael L. Washington, PhD1Martin L. Meltzer, PhD(Author affiliations at end of text)
Previous reports have shown that an Ebola outbreak can be slowed, and eventually stopped, by placing Ebola patients into settings where there is reduced risk for onward Ebola transmission, such as Ebola treatment units (ETUs) and community care centers (CCCs) or equivalent community settings that encourage changes in human behaviors to reduce transmission risk, such as making burials safe and reducing contact with Ebola patients (1,2). Using cumulative case count data from Liberia up to August 28, 2014, the EbolaResponse model (3) previously estimated that without any additional interventions or further changes in human behavior, there would have been approximately 23,000 reported Ebola cases by October 31, 2014. In actuality, there were 6,525 reported cases by that date. To estimate the effectiveness of ETUs and CCCs or equivalent community settings in preventing greater Ebola transmission, CDC applied the EbolaResponse model (3) to the period September 23–October 31, 2014, in Liberia. The results showed that admitting Ebola patients to ETUs alone prevented an estimated 2,244 Ebola cases. Having patients receive care in CCCs or equivalent community settings with a reduced risk for Ebola transmission prevented an estimated 4,487 cases. Having patients receive care in either ETUs or CCCs or in equivalent community settings, prevented an estimated 9,100 cases, apparently as the result of a synergistic effect in which the impact of the combined interventions was greater than the sum of the two interventions. Caring for patients in ETUs, CCCs, or in equivalent community settings with reduced risk for transmission can be important components of a successful public health response to an Ebola epidemic.
One component of the national strategy in Liberia for responding to the ongoing Ebola epidemic is to isolate persons with suspected, probable, or confirmed Ebola in ETUs or, when ETUs are full or otherwise not available, in community-based settings such as CCCs, where there also is a reduced risk for Ebola transmission (4). The EbolaResponse model was used to estimate how many Ebola cases were averted in Liberia during September 23–October 31, 2014, because of the use of ETUs, CCCs, and equivalent community settings. This period was selected for study because there was a notable increase in interventions during that period that correlated with a decrease in cases (4,5).
The spreadsheet-based EbolaResponse modeling tool tracks patients through the following states of Ebola virus infection and disease: susceptible to disease, infected, incubating, infectious, and recovered. Data from reports of previous Ebola outbreaks were used to model the daily change of patients' status between the disease states. For example, a probability distribution to characterize the likelihood of incubating a given number of days was built using previously published data (3). Patients in the modeled population were distributed into three categories: 1) hospitalized in an ETU; 2) placed into a CCC or a home in a community setting where there was a reduced risk for disease transmission and an emphasis on changing human behaviors with regard to safe burials and reducing contact with patients; and 3) left at home with no effective isolation or safe burials. Both the risk for onward disease transmission by patient category and the percentage of patients in each category were calculated by altering these values until the estimates of cumulative cases over time produced by the model (the model "fit" [3]) closely matched those of the actual data.
An initial estimate of cumulative cases was made by fitting the EbolaResponse model to cumulative Liberian case count data (i.e., confirmed, probable, and suspected cases) from March 27 to November 15, 2014 (6). A good fit of the estimated cases to actual cases was obtained when patients were distributed, for the period September 23–October 31, 2014, into the three categories as follows: 20% of Ebola cases in ETUs, 35% in CCCs or equivalent community settings with a reduced risk for Ebola transmission , and 45% at home without effective isolation or safe burials. Three scenarios were then built to estimate the impact of ETUs and CCCs during the study period.
Three Estimation Scenarios
In scenario 1, to estimate the impact of placing Ebola patients in ETUs, for the period September 23–October 31, 2014, the 20% of all Ebola patients calculated to be in ETUs were moved to the category of patients who were at home without effective isolation or safe burials. The 35% of patients calculated to be in CCCs or equivalent community settings with reduced risk were unchanged. The model was refitted to produce estimates of cases that would have occurred without any patients in ETUs.
In scenario 2, to estimate the impact of the 35% of Ebola patients calculated to be in CCCs or equivalent community settings with reduced risk for Ebola, the 35% were moved to the category of patients who were at home without effective isolation or safe burials. The 20% of patients in ETUs were unchanged, and the model was refitted to provide estimates of cases that would have occurred without any patients in CCCs or equivalent community settings.
In scenario 3, to measure the impact of placing patients in either ETUs or CCCs, the 55% of patients calculated to be in either ETUs or CCCs or equivalent community settings were moved to the category of patients who were at home without effective isolation or safe burials. The model was then refitted to provide estimates of cases without any patients in either ETUs or CCCs (Table 1).
Number of Ebola Cases Averted
The cumulative number of estimated cases during March 27–October 31, 2014, based on model assumptions, was 6,218, compared with 6,525 cumulative cases reported in Liberia (6). If no patients had been hospitalized in ETUs starting on September 23, 2014, (scenario 1), there would have been an estimated additional 2,244 cases by October 31, 2014 (Figure,Table 2). If no patients had been placed into CCCs or equivalent community settings with reduced risk for transmission, there would have been an estimated additional 4,487 cases by October 31, 2014. If no patients were placed into either ETUs or CCCs or the equivalent settings with reduced risk for Ebola transmission (scenario 3), there would have been an estimated additional 9,097 cases by October 31, 2014 (Figure).
Also estimated were the number of Ebola cases that would be averted for the period September 23–October 31, 2014, by placing only 1% of patients in either an ETU or a CCC or both. This calculation assumed that that the number of cases averted per 1% of patients placed into ETUs or CCCs did not change as the total percentage of patients in these care settings increased (i.e., a linear correlation was assumed between cases averted and percentage of patients in the care settings).
During September 23–October 31, 2014, for every 1% of patients placed into ETUs, an estimated 112 cases would have been averted (Table 2). Similarly, for every 1% of patients placed into CCCs or equivalent settings with reduced risk for transmission, an estimated 128 cases would have been averted. For every 1% increase in patients placed into ETUs or CCCs or equivalent settings, an estimated 165 cases would have been averted (Table 2).
Also calculated were the numbers of days required in each scenario for the number of cases to double (doubling time). For the study period, under scenario 1 (no ETUs operating) and scenario 2 (no CCCs or equivalent settings), cases doubled in 23 and 20 days, respectively. Under scenario 3 (neither ETUs nor CCCs operating), cases doubled in 18 days.
Discussion
During September 23–October 31, 2014, placing Ebola patients into ETUs or CCCs or equivalent settings with reduced transmission risk prevented an estimated 9,097 cases of Ebola in Liberia. The findings in this report support those from an earlier report on Lofa County, Liberia, that found ETUs played a major role in reducing the number of cases in October (5).
Of note is the finding that scenario 3 (combined effect of ETUs and CCCs) resulted in more cases averted than the sum of the estimated cases averted from scenario 1 (patients in ETUs) and scenario 2 (patients in CCCs and equivalent community settings). This apparent synergistic effect from having both ETUs and CCCs operating in a community during an Ebola epidemic might have resulted from the alteration of the doubling time.
The findings in this report are subject to at least two limitations. First, the findings are limited by the previously described limitations associated with using the EbolaResponse model (3). Second, the study is limited by the implicit assumption of a constant relationship (i.e., linear correlation) between patients in ETUs or CCCs and cases averted. In reality, such relationships most likely vary with changes in the number of total cases and the number of patients in ETUs or CCCs. Thus, caution should be exercised when using these results to estimate the potential impact of ETUs and CCCs in other settings.
The results of this study demonstrate the importance of effective isolation of Ebola patients in ETUs and CCCs in controlling an Ebola outbreak. At the peak of an Ebola outbreak in a community, there might be insufficient ETU capacity to accommodate all Ebola patients (4). Under such circumstances, provision of CCCs and community-based programs that encourage safe burials and reduced contact with Ebola patients should be established at least as interim measures until adequate treatment capacity is available. These data indicate that the rapid initiation of a multifaceted response to a large Ebola outbreak in Liberia was warranted.
1Division of Preparedness and Emerging Infections, National Center for Emerging and Zoonotic Infectious Diseases, CDC (Corresponding author: Michael L. Washington, mwashington@cdc.gov)

References

  1. Legrand J, Grais RF, Boelle PY, Valleron AJ, Flahault A. Understanding the dynamics of Ebola epidemics. Epidemiol Infect 2007;135:610–21.
  2. Borchert M, Mutyaba I, Van Kerkhove MD, et al. Ebola haemorrhagic fever outbreak in Masindi District, Uganda: outbreak description and lessons learned. BMC Infect Dis 2011;11:357.
  3. Meltzer MI, Atkins CY, Santibanez S, et al. Estimating the future number of cases in the Ebola epidemic—Liberia and Sierra Leone, 2014–2015. MMWR Surveill Summ 2014;63(Suppl no. 3).
  4. Nyenswah T, Fahnbulleh M, Massaquoi M, et al. Ebola epidemic—Liberia, March–October 2014. MMWR Morb Mortal Wkly Rep 2014;63:1082–6.
  5. Sharma A, Heijenberg N, Peter C, et al. Evidence for a decrease in transmission of Ebola virus—Lofa County, Liberia, June 8–November 1, 2014. MMWR Morb Mortal Wkly Rep 2014;63:1067–71.
  6. World Health Organization. Ebola response roadmap—situation report. Available at: http://www.who.int/csr/disease/ebola/situation-reports/enExternal Web Site Icon.
FIGURE. Estimates of the cumulative number of Ebola cases with and without Ebola treatment units (ETUs) and community care centers (CCCs)* — Liberia, September 23–October 31, 2014
The figure above is a bar chart showing estimates of the cumulative number of Ebola cases with and without Ebola treatment units and community care centers in Liberia during September 23-October 31, 2014.
* CCCs or equivalent community settings with a reduced risk for Ebola transmission (including safe burial and community-based programs to change human behavior to reduce contact with patients).
The initial estimate was calculated by fitting the EbolaResponse model to cumulative cases in Liberia for the period March 27–November 15, 2014. From this fit, 6,218 cumulative cases were estimated to have occurred by October 31, 2014. During September 23–October 31, 2014, it was calculated that 20% of Ebola patients were in ETUs, 35% were in CCCs or equivalent community settings with a reduced risk for Ebola transmission (including safe burial), and, 45% were at home without effective isolation, resulting in an increased risk for Ebola transmission (including unsafe burials).
§ The impact if there were no ETUs was calculated by moving the 20% of Ebola patients in ETUs in the initial estimate to the category of patients who were at home without effective isolation (including unsafe burials).
The impact if there were no CCCs, safe burials, and other community-based interventions to reduce the risk for transmission was calculated by moving the 35% of patients in CCCs or equivalent community settings to the category of patients who were at home without effective isolation (including unsafe burials).
** The combined impact if there were no ETUs and CCCs, safe burials and other community-based interventions to reduce the risk for transmission was calculated by moving both the 20% of patients in ETUs and 35% of patients in CCCs or equivalent community settings to the category of patients who were at home without effective isolation (including unsafe burials).
Alternate Text: The figure above is a bar chart showing estimates of the cumulative number of Ebola cases with and without Ebola treatment units and community care centers in Liberia during September 23-October 31, 2014.

Public Health Response to Commercial Airline Travel of a Person with Ebola Virus Infection — United States, 2014

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Public Health Response to Commercial Airline Travel of a Person with Ebola Virus Infection — United States, 2014

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Public Health Response to Commercial Airline Travel of a Person with Ebola Virus Infection — United States, 2014
Joanna J. Regan, MD, Robynne Jungerman, MPH, Sonia H. Montiel, et al.
MMWR Morb Mortal Wkly Rep 2015;64(Early Release):1-4


In July 2014 two persons with confirmed Ebola virus infection who were infected
early in the Nigeria outbreak traveled by commercial airline while symptomatic,
involving a total of four flights (two international flights and two Nigeria domestic
flights). In October 2014, another airline passenger, a U.S. health care worker who
had traveled domestically on two commercial flights, was confirmed to have Ebola
virus infection. This report summarizes the investigations that followed.

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Vol. 64, Early Release 
January 23, 2015

Public Health Response to Commercial Airline Travel of a Person with Ebola Virus Infection — United States, 2014


Early Release

January 23, 2015 / 64(Early Release);1-4

Joanna J. Regan, MD1Robynne Jungerman, MPH1Sonia H. Montiel1Kimberly Newsome, MPH2Tina Objio, MSN1Faith Washburn, MPH1Efrosini Roland1Emily Petersen, MD3,4Evelyn Twentyman, MD3,4Oluwatosin Olaiya, MD3,4Mary Naughton, MD1Francisco Alvarado-Ramy, MD1Susan A. Lippold, MD1Laura Tabony, MPH5Carolyn L. McCarty, PhD3,6Cara Bicking Kinsey, PhD3,7Meghan Barnes, MSPH8Stephanie Black, MD9Ihsan Azzam, MD10Danielle Stanek, DVM11John Sweitzer, ScM12Anita Valiani, MPH13Katrin S. Kohl, MD1Clive Brown, MBBS1Nicki Pesik, MD(Author affiliations at end of text)
Before the current Ebola epidemic in West Africa, there were few documented cases of symptomatic Ebola patients traveling by commercial airline (1,2), and no evidence of transmission to passengers or crew members during airline travel. In July 2014 two persons with confirmed Ebola virus infection who were infected early in the Nigeria outbreak traveled by commercial airline while symptomatic, involving a total of four flights (two international flights and two Nigeria domestic flights). It is not clear what symptoms either of these two passengers experienced during flight; however, one collapsed in the airport shortly after landing, and the other was documented to have fever, vomiting, and diarrhea on the day the flight arrived. Neither infected passenger transmitted Ebola to other passengers or crew on these flights (3,4). In October 2014, another airline passenger, a U.S. health care worker who had traveled domestically on two commercial flights, was confirmed to have Ebola virus infection. Given that the time of onset of symptoms was uncertain, an Ebola airline contact investigation in the United States was conducted. In total, follow-up was conducted for 268 contacts in nine states, including all 247 passengers from both flights, 12 flight crew members, eight cleaning crew members, and one federal airport worker (81 of these contacts were documented in a report published previously [5]). All contacts were accounted for by state and local jurisdictions and followed until completion of their 21-day incubation periods. No secondary cases of Ebola were identified in this investigation, confirming that transmission of Ebola during commercial air travel did not occur.
Investigation Protocols
On October 14, 2014, the health care worker, who was among those who had cared for a patient with confirmed Ebola in the United States (6), experienced fever and rash and sought medical care. On October 15, Ebola virus infection was confirmed in this health care worker, who had traveled by commercial airline from Dallas, Texas, to Cleveland, Ohio, on October 10, 2014, and from Ohio to Texas on October 13, 2014 (Figure). The date of symptom onset was uncertain; however, based on medical history and clinical and laboratory findings, CDC determined that a contact investigation should be performed for persons aboard either flight (5).
The CDC public health response protocol for airline contact investigations involving viral hemorrhagic fevers such as Ebola involves using brief interviews about exposures and events on the flight to determine risk categories. Previously, the investigation was limited to the flight attendants and cleaning crew members who serviced the flight and to passengers seated for an extended time within 3 feet of the symptomatic passenger. This earlier protocol recommended that contacts self-monitor for fever or other symptoms for 21 days and check in weekly with the local health department, but did not recommend restrictions on travel or other activities for contacts who were asymptomatic.
Because of concern after transmission of Ebola to health care workers in Texas and recognition that data on transmission risk aboard aircraft were limited, all passengers and crew were investigated, and CDC issued additional recommendations for the investigation of the two flights between Texas and Ohio. Within 48 hours after onset of the investigation for each flight, all passengers and flight crew had been notified about the health care worker with Ebola and the ongoing investigation (Table 1). All cleaning crew members were contacted and interviewed by October 21.
Categorization of Contacts
At the beginning of the investigation, the recommendations from CDC to state and local health departments categorized all passengers seated within 3 feet of the traveler with confirmed Ebola (the 3-foot zone) as having "some risk" (Figure). Four public health actions were recommended for these passengers. First, interview these passengers using the standard interview form. Second, initiate active, twice-daily monitoring for symptoms and fever for the 21 days following the flight; passengers were required to take their own temperature twice daily and report it to the health department once a day. Third, place these passengers in quarantine; the specific terms of quarantine were left to the discretion of the state and local jurisdictions. Fourth, place these passengers on federal public health travel restrictions (the Do Not Board list) to ensure they could not travel commercially.
Travelers seated outside the 3-foot (approximately 1 meter) zone were considered at a lower risk of exposure and were categorized in the "uncertain risk" group. Flight attendants who reported they had no known direct contact with the Ebola patient also were categorized as uncertain risk. CDC recommended that state and local health departments initiate active, twice-daily monitoring for fever and symptoms for passengers in the uncertain risk group. If people in this risk group developed symptoms, health departments were asked to complete the standard passenger or flight crew interview and contact CDC. CDC did not recommend movement or travel restrictions for passengers in the uncertain risk group, and specific guidance was at the discretion of the health departments.
If it was determined that there was no environmental contamination of the aircraft related to the Ebola patient (e.g., diarrhea or vomiting), persons who had no contact with the Ebola patient and were not within the passenger cabin (i.e., were in the cockpit) would be categorized in the "no known risk" group. This would also include the cleaning crews if no additional potential exposures were reported. The no known risk group would not require active monitoring, occupational restrictions, or travel restrictions.
In this investigation, CDC recommended that all passengers and crew members, including persons in the no known risk and uncertain risk groups, be contacted by state or local public health authorities at the end of 21 days to ensure that 1) they had remained symptom-free throughout the incubation period, or 2) any symptoms experienced were properly reported, assessed, and determined not to be caused by Ebola.
Public health actions varied by state and local jurisdiction. Many jurisdictions chose to have frequent follow-up with contacts, including those in the uncertain risk group, which in some cases included daily interaction with contacts. Other variations included requiring direct active monitoring of passengers in the 3-foot zone, which included twice-daily check-ins (once in person, and once by phone) (5,6). Although states could have issued quarantine orders for passengers in the "some risk group," they all chose the less restrictive option of issuing guidelines to these contacts for social distancing, which typically involved avoiding congregate settings and maintaining a 3-foot distance from others.
All 268 passengers and members of the flight and cleaning crews from the two flights were contacted, interviewed, and categorized into risk groups (Table 1). Mean age of the 268 contacts was 41.4 years (range = 6 months‒90 years). Of the 268 contacts, 21 (7.8%) passengers were classified as "some risk." These included 20 passengers seated in the 3-foot contact zone during the flight and one passenger who sat within the zone for 15 minutes before exiting the aircraft (Figure). CDC placed the 20 passengers who were seated in the 3-foot contact zone during the flight on the federal Do Not Board list, and a 21-day monitoring period was initiated by their respective state public health authorities. The passenger in the some risk group because of the 15-minute exposure was not placed on the Do Not Board list; however, this person did not travel and received the same monitoring by public health authorities as others in the group. On October 27 (day 17 of monitoring for the first flight, and day 14 for the second flight), CDC's categorization guidance was changed such that federal travel restrictions were no longer required for the passengers in the some risk group, and the 20 were removed from the Do Not Board list.
Findings
There were no reports from the Ebola patient, flight attendants, or passengers that the patient had vomited or had diarrhea during the two flights resulting in contamination of the plane. Of the 12 persons involved in serving or cleaning the cabin, six reported wearing gloves, and one reported using hand sanitizer after picking up a few items in the cabin without wearing gloves.
Of the 268 contacts, 32 (11.9%), including 28 passengers, three flight crew members, and one member of the cleaning crew, reported within 21 days of the flight one or more symptoms that can occur with Ebola (Table 2). One passenger in the uncertain risk category experienced a fever (defined as a temperature of ≥100.4°F [≥38°C]) on day 21 of monitoring and was hospitalized the same day. The fever was accompanied by respiratory symptoms and continued for several days without a confirmed alternative diagnosis, resulting in Ebola testing on days 1 and 3 of symptoms. Both tests were negative. There were 19 passengers who had temperatures of 99.0°F (37.2°C) or higher, but <100.4°F. Of these 19 with elevated temperatures, 13 had a single episode of elevated temperature, and six had multiple episodes. Although some passengers experienced symptoms that can occur with Ebola illness during their 21-day monitoring period, the monitoring period passed with no secondary cases of Ebola found.
Discussion
No secondary cases of Ebola were found in this investigation, and to date, no other airline contact investigations involving travelers with confirmed Ebola have found secondary cases among passengers or crew members (1–3,7). Guidelines for airline contact investigations for viral hemorrhagic fevers vary among countries and typically do not include notification of every passenger (7,8). When it was first learned that two U.S. health care workers using personal protective equipment had become infected with Ebola virus, CDC adopted a conservative approach for the airline contact investigation until additional information could be obtained. CDC expanded its existing airline contact investigation protocol to include all passengers, rather than limit the investigation to passengers who had been within 3 feet of the Ebola patient for a prolonged time. CDC guidance and contact investigation protocols were adapted to best protect the health of the public and address public concerns. As it became increasingly clear that Ebola transmission dynamics had not changed and transmission to passengers was not likely, the recommendations were modified to decrease restrictions on passengers within the 3-foot zone by no longer recommending that these passengers be issued quarantine orders or be added to the Do Not Board list.
Although no Ebola virus transmission occurred on these two domestic commercial flights, these findings might not be applicable to all airline contact investigations. For example, transmission during airline travel might be more likely if an exposure to body fluids from a passenger with more severe symptoms such as vomiting, diarrhea, or bleeding was to occur. In addition, both flights in this investigation were <4 hours in duration; longer flights might pose a greater risk for transmission. Previous airline contact investigations have not found evidence of Ebola transmission on commercial flights; however information about the symptoms experienced by Ebola patients aboard the aircraft in these few cases is limited (1–3,7).
This airline contact investigation provides additional evidence that the risk for Ebola transmission on commercial aircraft is likely very low when there is no evidence of blood or other body fluid exposure. Additional public health investigations and statistical modeling might be helpful to further define the possible risk for Ebola transmission on commercial flights. In future commercial flights involving Ebola-infected passengers, circumstances such as duration of exposure and degree of environmental contamination should be taken into consideration. Depending on these circumstances, limiting contact tracing to the flight crew and passengers seated within 3 feet of the Ebola patient might be appropriate.
1Division of Global Migration and Quarantine, National Center for Emerging and Zoonotic Infectious Diseases, CDC; 2Division of Birth Defects and Developmental Disabilities, National Center on Birth Defects and Developmental Disabilities, CDC; 3Epidemic Intelligence Service, CDC; 4Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, CDC; 5Texas Department of State Health Services; 6Ohio Department of Health; 7Pennsylvania Department of Health Bureau of Epidemiology; 8Colorado Department of Public Health and Environment; 9Chicago Department of Public Health; 10Nevada State Department of Health and Human Services; 11Florida Department of Health Division of Disease Control and Health Protection; 12Maryland Department of Health and Mental Hygiene; 13North Carolina Department of Health and Human Services Communicable Disease Branch (Corresponding author: Joanna J. Regan,jregan@cdc.gov, 404-639-4341)

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FIGURE. Seating charts for commercial airline flights 1142 and 1143 taken by a health care worker later diagnosed with Ebola, which became the focus of a public health response — United States, October 10 and 13, 2014
The figure above is a pair of seating charts for commercial airline flights 1142 and 1143 taken by a health care worker later diagnosed with Ebola, which became the focus of a public health response in the United States during October 10-13, 2014.
* One passenger on flight 1143 was in the 3-foot zone for only 15 minutes before exiting the plane before takeoff.
Alternate Text: The figure above is a pair of seating charts for commercial airline flights 1142 and 1143 taken by a health care worker later diagnosed with Ebola, which became the focus of a public health response in the United States during October 10-13, 2014.