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Some HCWs in past Ebola outbreak may be able to ‘neutralize’ virus

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October 9, 2018

Health care workers, or HCWs, are on the front lines of patient care during Ebola virus outbreaks and at an increased risk for disease due to occupational exposures. According to findings from a recently published study, a significant proportion of HCWs from a prior Ebola outbreak in the Democratic Republic of the Congo were reactive to at least one Ebola virus protein despite never reporting infection and may be able to “neutralize” the virus, researchers said.

“Historically, HCWs have perpetuated the spread of amplification of [Ebola virus disease] and serve as axes of viral transmission often before Ebola virus is even recognized as the causative agent,” Nicole A. Hoff, PhD, MPH, epidemiologist in the University of California, Los Angeles’ UCLA-DRC Health Research and Training Program, and colleagues wrote. “Despite HCWs’ increased risk of acquiring and transmitting the disease, there is limited research assessing the total burden of Ebola virus among HCWs.”

Hoff and colleagues conducted a serosurvey of HCWs living in or near the Boende health zone, 750 miles northwest of the DRC capital of Kinshasa, from September to November in 2015 — about a year after an Ebola outbreak struck the region. HCWs chosen for the study had to be older than 18 years of age, be healthy, work in a health facility and report being active during the 2014 Boende outbreak response.

A total of 565 HCWs enrolled in the study. Hoff and colleagues collected blood samples and gave participants a sociodemographic and epidemiologic questionnaire.

Among the 565 HCWs, 50.1%, had direct contact with patients, 31.8% had indirect contact and 18.1% were unlikely to have had any contact, the researchers reported. They found that 28.1% of participants were seroreactive for anti-glycoprotein immunoglobulin G, 15.8% were seroreactive for anti-nucleoprotein IgG, 9.5% were positive for the Ebola virus matrix protein VP40, and 2.8% — 16 in total — demonstrated neutralization. Overall, 41.4% (n = 234) of all HCWs were seroreactive for at least one assay, Hoff and colleagues reported. They determined the greatest overlap of responses came among HCWs who were both nucleoprotein and glycoprotein seropositive. All neutralization-positive individuals also were reactive for at least one other viral protein, and half presented with both anti-nucleoprotein IgG and VP40 reactivity. Only three HCWs were seroreactive for every assay, they found.

According to the study findings, among the 16 HCWs who they said may be able to neutralize the virus, three were seroreactive on all tests.

“It is not known whether seroreactivity to assays is related to [Ebola virus] exposure during the 2014 outbreak — in particular because all HCWs included for this analysis participated in the outbreak response and reported varying levels of contact with EVD patients and biological specimens,” Hoff and colleagues wrote. “It may also be possible that variation in antigenic response and neutralization levels may be related to asymptomatic or minimally symptomatic infection, which would not have been necessarily detected as illness due to [Ebola virus]. It is possible that some seroreactive individuals could also have been exposed to a non-[Ebola virus] filovirus.”

They said the findings highlight the elevated risk that HCWs in the DRC face and their exposure to bloodborne pathogens in general.

“Providing adequate training of HCWs to infection control procedures and availability of personal protective equipment to reduce exposure to bodily fluids of patients they treat before an EVD outbreak occurs is ultimately one of the most important strategies to limit the spread of Ebola virus and other blood-borne pathogens of both high and low consequence,” they wrote. – by Caitlyn Stulpin

Disclosures: The authors report no relevant financial disclosures.