infection control & hospital epidemiology october 2015, vol. 36, no. 10 commentary
Protecting Healthcare Personnel from Acquiring Ebola Virus Disease
David J. Weber, MD, MPH;1,2 William A. Fischer II, MD;3 David A. Wohl, MD;2 William A. Rutala, PhD, MPH1,2
The ongoing outbreak of Ebola virus disease (EVD) in West Africa, the largest in history, has devastated the affected countries and raised public health concerns throughout the world. The Centers for Disease Control and Prevention (CDC) in conjunction with the World Health Organization (WHO) has reported that as of July 8, 2015, there have been 16,913 total cases (suspected, probable and confirmed) in West Africa (of which 11,965 were laboratory confirmed) and 6,446 deaths.1 The CDC has estimated that there is potential underreporting by a factor of 2.5.2 For the first time ever, an Ebola outbreak has crossed international boundaries, initially moving among neighboring countries from Guinea to Liberia and Sierra Leone, and then spreading to non-contiguous countries including Nigeria, Senegal, Mali, Spain, the United Kingdom, and the United States.1 According to the WHO, as of July 5, 2015, a total of 875 confirmed healthcare personnel (HCP) infections had been reported from Guinea, Liberia, and Sierra Leone, with 509 deaths.3 As of March 12, 2015, 11 EVD-infected HCP had been transferred from West Africa to US hospitals.4 Secondary transmission from a patient with EVD to healthcare providers has also been reported in the United States and Spain.
ebola transmission
Epidemiological studies have suggested that the Ebola virus spreads primarily through direct contact with a symptomatic person or their body fluids, especially in the latter stages of clinical disease.5,6 The elevated risk of transmission in the latter stages of EVD is likely due to a combination of increased viral titers in body fluids and increased body fluid discharges (ie, vomitus, stool, and blood). Post-mortem contact is also associated with a high risk of Ebola virus transmission.5 Concern has been raised regarding the possibility of aerosol transmission “either via large droplets or small particles in the vicinity of source patients.”7 Although animal studies suggest that droplet/airborne transmission may occur when the virus is experimentally aerosolized, epidemiologic studies of
household contacts suggest that this rarely, if ever, occurs.5,6,8 However, there is concern that droplet or airborne transmission could occur in healthcare settings during aerosol-generating procedures such as intubation and induced sputum collection. The fact that Ebola has been demonstrated to survive and
remain infectious in liquid media at room temperature for at least 46 days raises concern about fomite transmission.9 Ebola inoculated onto glass carriers and maintained in the dark survived for hours to days (ie, 1-log10 decrease in 35.3 hours and 4-log10 decrease in 5.9 days).10 Some epidemiologic stu- dies have suggested the possibility of transmission from con- taminated environmental sources.6 Further, in the current outbreak, multiple environmental samples from an Ebola treatment unit were positive via polymerase chain reaction (PCR) testing.7 However, in a different study in which sampling was done following routine cleaning, all 31 envir- onmental samples were negative by reverse-transcriptase PCR (RT-PCR), suggesting that routine environmental cleaning and disinfection can decrease the potential for fomite transmission.11
preventing ebola acquisition by hcp
As noted above, a substantial number of HCP in West Africa have acquired EVD. Nosocomial transmission of Ebola and infection of HCP has been repeatedly documented in past outbreaks.12–14 The cluster of Ebola cases in Dallas is illus- trative of the 2 major risks for Ebola acquisition faced by US HCP.15,16 First, early recognition, triage, and isolation of all potential EVD cases are essential so adequate infection control measures can be applied and potential transmission of Ebola virus to HCP can be minimized. Second, the acquisition of EVD by 2 HCP who had substantial interaction with an Ebola patient while wearing protective equipment raised concern regarding the adequacy of protection afforded by personal protective equipment (PPE) or the training provided in its use. The basis for preventing the spread of infectious agents in healthcare facilities is the implementation of transmission-based
Affiliations: 1. Department of Hospital Epidemiology, University of North Carolina Health Care, Chapel Hill, North Carolina; 2. Division of Infectious
Diseases, UNC School of Medicine, Chapel Hill, North Carolina; 3. Division of Pulmonary and Critical Care Medicine, UNC School of Medicine, Chapel Hill, North Carolina.
© 2015 by The Society for Healthcare Epidemiology of America. 0899-823X/2015/3610-0014. DOI: 10.1017/ice.2015.205 Received July 18, 2015; accepted July 28, 2015
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