The estimated cumulative incidence of confirmed Ebola among health care workers in Sierra Leone is more than 100-fold greater than in other adults, according to a report in MMWR.
“Cases of Ebola in HCWs are currently being investigated as sentinel public health events,” CDC investigators wrote. “An infection in an HCW might represent transmission from an Ebola patient in a health care facility, but might also be a signal for transmission to and from HCWs in the community, and for facility-based transmission from patient to patient and from HCWs to patients or to other HCWs.”
The investigators analyzed data from the national Viral Hemorrhagic Fever database. Previous data suggested that Sierra Leone had 2,402 people in the health care workforce, and this number was used as the denominator to estimate the incidence of Ebola in HCWs. The data include cases reported from May 23 to Oct. 31.
In Sierra Leone, there were 3,854 laboratory-confirmed cases of Ebola reported to the database in this time frame. Among those, 5.2% were in HCWs. The cumulative incidence of Ebola in HCWs was 8,285 per 100,000. By comparison, there were 2,806 confirmed cases in non-HCWs among a national population of 3.49 million persons aged 15 years and older, making the cumulative incidence of Ebola in this population 80.4 per 100,000. The incidence of Ebola among HCWs was 103-fold greater than in the general population.
Surveillance data collected from patients and their family members also were evaluated. There were 159 HCWs with data on funeral attendance, and 13.8% had attended a funeral, compared with 32.3% in non-HCWs. Data on contact with known or suspected Ebola patients were available for 148 of the HCWs, and among those, 18.2% had reported contact vs. 12.3% of non-HCWs.
Through site visits and interviews, the investigators identified a number of potential circumstances leading to HCWs becoming infected. These include: lack of protocols for infection prevention and control; staff shortages, limited availability of safe transport for patients and corpses; incorrect recognition of potential Ebola cases; delayed laboratory diagnosis; and lack of delineation between high- and low-risk Ebola zones.
“Given the high risk of nosocomial transmission of Ebolavirus, health authorities must be vigilant in implementation of strict infection prevention and control measures in all health care settings and alert to the possibility that less well-controlled settings might inadvertently act to propagate rather than interrupt transmission,” the researchers wrote. “Prevention of Ebola in HCWs is also critical to sustain the health workforce to address all causes of morbidity and mortality in Sierra Leone.”