CDC Releases New Reports on Ebola Cases in Liberia and the United States

Progress in some Liberian counties but multiple outbreaks continue throughout country

Press Release

For Immediate Release: Friday, November 14
Contact: Media Relations
(404) 639-3286

The effort to contain the Ebola epidemic in Liberia is showing preliminary signs of progress in some counties, but maintaining and extending these trends will require sustained efforts, according to three early-release articles in CDC’s Morbidity and Mortality Weekly Report (MMWR) on November 14. The three reports are among six MMWR articles on Ebola released by CDC today.

One of the six reports provides an overview of the complex and rapidly changing situation in Liberia. There is widespread distribution of disease in urban and rural settings. Containing the epidemic will require more intensive efforts to identify new cases and perform contact tracing in the densely populated capital city of Monrovia while rapidly containing outbreaks in hard-to-reach and newly affected areas.

Two other reports document a significant decrease in new Ebola cases in two of Liberia’s 15 counties. Nevertheless, new cases continue to occur in these areas. United States, Liberian and international partners are now responding to new outbreaks in remote parts of the country as opposed to the larger outbreaks primarily occurring in more accessible areas. In recent weeks, there has been approximately one new outbreak or cluster per day. For comparison, during the past four decades, CDC has responded to approximately one Ebola outbreak every one to two years.

The Ebola epidemic in Liberia poses new challenges for response containment efforts. Because small outbreaks will expand if they are not contained quickly, response efforts are being adapted to manage smaller outbreaks in widely scattered, remote areas.

Declines in cases in two counties may also be a sign that medical and humanitarian support provided by the U.S. government and its partners – augmented by efforts from local communities and the Liberian government – is helping to slow the epidemic.

“The recent decrease in cases suggested by these reports shows how important it is to continue to intensify our Ebola response,” said CDC Director Tom Frieden, M.D., M.P.H. “We have to keep our guard up. In Guinea, cases have increased and decreased in waves; we can’t stop until we stop the last chain of transmission.”

Half of Liberia’s Ebola cases have been in Montserrado County, which is home to the capital city of Monrovia with its population of about 1.5 million. Since mid-September there has been a 73 percent decline in admissions to Ebola Treatment Units (ETUs), a 58 percent decline in blood samples testing positive for Ebola, and a 53 percent decline in body collections. Expansion of ETUs, safe burials, and public education and community action appear to be important factors in this improvement.

The report warns that Ebola has not been eliminated from Montserrado County. New cases continue to occur, and a reversal of this recent positive trend remains possible.

Another report documenting a decrease in Ebola cases in Liberia comes from Lofa County, where Liberia’s Ebola epidemic began. The weekly number of newly reported cases in Lofa decreased from a peak of 153 new cases in the week ending on August 16 to four new cases in the week ending November 1. Weekly admissions to the county’s ETU dropped from a peak of 133 in the week ending August 16 to one new admission in the week ending November 1. Results for testing of deceased persons for Ebola were 95% positive from June 8 to August 16 but declined to 25 percent positive during August 24 to November 1.

The Ebola containment strategy in Lofa County had several key elements:

  • Encouraging community behavior change, including safe burial practices.
  • Establishing an ETU
  • Setting up a local Ebola hotline and outreach teams that quickly transported people with Ebola symptoms to the ETU
  • Initiating active case finding, which means rigorously identifying and following up with contacts of patients with Ebola
  • Training community volunteers to monitor patient contacts for Ebola symptoms

The strategy recently implemented in Lofa County might serve as a model for reducing transmission of Ebola, but the report warns that new Ebola cases continue to be reported in Lofa County, and continued vigilance is needed there and in other affected areas, including Guinea and Sierra Leone.

Ebola among Health Care Workers Not Working in Ebola Treatment Units– Liberia

A separate MMWR article released today explores how health care workers in West Africa were at increased risk of Ebola infection if they were not working in ETUs. This report, which covers events before mid-August, highlights the importance of recent key efforts of the international Ebola response in West Africa, such as establishing more ETUs and strengthening infection control in all healthcare facilities.

Isolating infected patients is essential for preventing transmission. Historically, this has been accomplished by caring for infected persons in specialized ETUs with strict isolation and infection control protocols, including guidelines for patient movement, physical layout, disinfection, and use of personal protective equipment (PPE) designed to protect health care workers and patients.

CDC disease detectives and Liberia’s Ministry of Health investigated 62 Ebola cases before mid-August 2014 among health care workers not working in ETUs. The cases fell into 10 clusters, seven of which were primarily associated with hospitals.

“Health care workers in West Africa are on the front lines of the fight against Ebola. Protecting these workers will help stop the Ebola epidemic in West Africa at it source,” says CDC Director Tom Frieden, M.D., M.P.H. “Recent investments in infection control training and equipment in West Africa can reduce risk, protect workers and patients, help stop Ebola at the source, and reduce risks of spread of Ebola globally.”

The investigation found that in four of the 10 clusters, health care workers contracted Ebola from patients who had been admitted to a hospital and were suspected to have Ebola but did not yet have a confirmed diagnosis. In another four clusters, health care workers contracted Ebola from patients who were initially thought to have another diagnosis but eventually tested positive for Ebola. In one cluster, health care workers contracted Ebola from a patient who initially tested negative for Ebola but was tested later and came back positive.

During past Ebola outbreaks, up to 25 percent of cases have been among health care workers.

Factors in health-care-worker infections in Liberia included:

  • inconsistent recognition/triage of Ebola patients;
  • overcrowding of hospitals/clinics;
  • limitations in physical layout of hospitals;
  • lack of training in PPE and inadequate supply of PPE; and,
  • limited supervision of and adherence to infection control.

The report notes that the immediate consequences of Ebola among health care workers in West Africa are closure of health facilities, loss of routine services, grief and fear among healthcare workers, and public mistrust of healthcare workers and health facilities. All undermine the overall Ebola response effort.

Since August 2014, the U.S. government and a consortium of partners have worked with the Liberian Ministry of Health to strengthen the infection control infrastructure and training in non-ETU health facilities. Infection control specialists will be embedded in non-ETU facilities.

In addition, U.S. Public Health Service medical staff have opened the Monrovia Medical Unit which is a 25-bed facility dedicated to treating medical care workers in Liberia who contract the Ebola virus.

First Ebola Virus Disease Cluster in the United States—Dallas County, Texas, 2014

In late September 2014, a patient at a Dallas hospital showed symptoms of Ebola and later tested positive for the disease. This was followed by the first two domestically acquired Ebola cases in the United States as two of the nurses caring for the patient became infected.

The patient died on October 8. Initial contact tracing identified a total of 103 individuals, of whom 48 were close unprotected contacts of the initial patient. All 48 contacts underwent direct active monitoring, which means that public health authorities contacted them directly to check on the presence of symptoms. After the two nurses became infected, health officials identified three additional Dallas community contacts; all three lived within the households of the two nurses. One hundred forty-seven health care workers who cared for the initial patient or the two nurses, irrespective of PPE use, were actively monitored. As of November 7, all contacts of the three patients had finished active monitoring and none of the contacts besides the two nurses themselves had developed Ebola.

Response to Importation of a Case of Ebola Virus Disease – Ohio, October 2014

In October, two of the nurses who treated a Dallas patient with Ebola disease became infected with the virus. Before learning that either she or her colleague were infected, one of the nurses traveled to Cleveland, Ohio and returned to Dallas via a commercial airline.

During her time in Ohio, the nurse had contact with 164 people including: two household members, 10 friends and family members, and 60 persons at one store; seventeen airline and airport personnel and 76 airline passengers were also monitored in Ohio because of contact with the nurse (other passengers were followed by health departments in other states). Some contacts were brief, while others lasted several hours and included direct skin-to-skin exposure. All of these contacts completed daily monitoring for fever or Ebola symptoms. As of November 3, the end of the incubation period and final day of monitoring, none of the contacts had developed Ebola infection.


Page last reviewed: November 14, 2014