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MERS spreads in UAE health care facilities before diagnoses
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Cases of Middle East respiratory syndrome, or MERS, coronavirus infection spread in health care facilities in Abu Dhabi, United Arab Emirates, often before the disease was diagnosed, according to an analysis of three clusters conducted by the CDC and local researchers.
The findings underscore the need for infection control measures at first points of entry in health care facilities and increased awareness of MERS coronavirus (MERS-CoV), according to Jennifer C. Hunter, DrPH, MPH, epidemiologist at the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, and colleagues.
“Because health care settings have the potential to contribute substantially to the spread of MERS-CoV infections, improving our understanding of infection risk and transmission patterns remains an urgent priority,” they wrote in Emerging Infectious Diseases.
Review of cases
Hunter and colleagues reviewed laboratory-confirmed cases of MERS-CoV reported to local health officials in Abu Dhabi from Jan. 1, 2013 to May 9, 2014, and found that 42% of the 65 patients (n = 27) had health care-associated cases — including 19 health care workers (HCWs).
The researchers determined health care exposure as any patient who worked at, was admitted to or visited a health care facility during the 14 days before symptom onset and had exposure to a known MERS-CoV patient exclusively in this setting. Patients were determined by the researchers to have had confirmed exposure to the virus if they were within 2 meters of a symptomatic case. They were said to likely be exposed if they were in the same hospital unit for more than 1 hour, had a common HCW, or had moved into a bed or dialysis station vacated by a symptomatic patient, or if they were continuously hospitalized and experienced symptoms more than 14 days after admission.
Epidemiologic and genetic sequencing suggested there were three health care clusters during this time, including one that resulted in 20 infected patients in a single hospital between March and April 2014, Hunter and colleagues reported. The source patient in that cluster was an expatriate man, aged 45 years, who had no apparent exposure to MERS-CoV before showing symptoms. He was assessed in an ED three times in early April for fever, cough, shortness of breath and pneumonia, before being admitted to a general medical unit.
During examination in an ED room with a curtain divider, the man was given a surgical mask and oxygen, which staff said he repeatedly removed because of difficulty breathing, according to the researchers.
The man died that month after he had been moved to the ICU and 1 day after his MERS-CoV diagnosis was confirmed. There were 12 secondary, six tertiary and two quaternary cases of MERS-CoV associated with the man’s introduction to the hospital.
Overall, two of the three source-case patients in the clusters died. There was one death among three infected hospital patients and no deaths among HCWs, Hunter and colleagues reported.
Infections occur before diagnosis
Of the 19 HCWs infected by MERS-CoV in the three clusters, 14 had provided care for a source case of the virus, the researchers found. Among them, 13 were exposed to the virus before the patient was diagnosed, and one was exposed after not adhering to ICU prevention measures.
Hunter and colleagues estimated a 16% attack rate among HCWs in EDs — about four times higher than that of household transmission estimates, they said.
“We found that health care-associated transmission occurred predominantly when HCWs, patients and visitors were exposed to an infected person before recognition of MERS-CoV and implementation of appropriate infection prevention measures,” they wrote. “These findings underscore the importance of early detection and intervention to limit the spread of disease.”
When combined with previous reports on more extensive transmission of MERS-CoV in health care facilities in South Korea, Saudi Arabia and Jordan, Hunter and colleagues said their analysis further showed that health care settings may be particularly efficient at transmitting the virus in the absence of appropriate infection prevention measures.
Reasons for a delay in diagnosis varied among clusters, Hunter and colleagues reported. In the largest cluster, however, the source-case patient was placed under standard precautions rather than contact and airborne precautions, likely because he had no known risk factors, they said.
“This cluster underscores the importance of maintaining vigilance and adherence to infection prevention policy, particularly in regions where known MERS-CoV infections exist,” the investigators wrote. – by Gerard Gallagher
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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David Thomas, MD, MPH
The virus that causes MERS can be transmitted from person to person, including within health care facilities and to health care personnel. These data add to those collected elsewhere, underscoring the importance of vigilance, rapid diagnosis and infection control practices to prevent spread.
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