An investigation into a cluster of five health care workers infected with Ebola virus while treating patients at a designated center in Monrovia, Liberia, has revealed no common source or chain of transmission, according to a report published by the Centers for Disease Control and Prevention.
Nonetheless, the investigators, led by the CDC’s Dr. Joseph D. Forrester, found several opportunities for transmission at the hospital and treatment center during an on-site evaluation conducted in late July 2014. All five infections occurred over a 2-week period ending July 29.
Potential means of transmission included exposure to patients with undetected Ebola infection in the emergency department (before they could be transferred to the hospital’s Ebola treatment unit); inadequate or inconsistent use of personal protective equipment, particularly during or after cleaning; and transmission of Ebola virus from one health care worker (HCW) to another, Dr. Forrester and his colleagues report in an early release of the Oct. 14 Morbidity and Mortality Weekly Report (MMWR 2014;63).
Two of the five health care workers who became ill died as a result of their infections.
Opportunities for transmission to the HCWs identified by Dr. Forrester and his colleagues included a patient with unrecognized Ebola who died in the emergency department, potentially exposing HCWs there. They also found that HCWs were not being monitored for fever or other symptoms, and that some had cleaned grossly contaminated surfaces without adequate protective equipment.
“None of the information collected suggested a mode of Ebola virus transmission that had not previously been described,” the investigators wrote in their analysis.
They noted as limitations of their study that interviews had not been conducted in a standardized format, and that one of the HCWs had died before investigators could conduct an interview, forcing them to rely on information provided by that individual’s colleagues.
In the same issue of MMWR, Dr. Satish K. Pillai of the CDC and his colleagues described an incident management system (IMS) implemented by Liberian health officials in consultation with the CDC. The system is designed to enhance the speed and effectiveness of the chain of command structure governing the Ebola response. It is modeled after IMSs that have been used by state and government agencies in the United States.
Changes to the Liberian system include the appointment of an incident manager in charge of setting the goals of the response. The system also creates additional staff positions to improve the logistical, financial, and administrative components of the response.
The Liberian Ministry of Health and Social Welfare will continue working with the CDC for the next 6-9 months to refine the Ebola response to IMS, Dr. Pillai and his colleagues noted. “The findings in this report might also be useful in other settings where IMS has not been used previously and is being considered for the first time,” they said.