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Surface contamination likely source of infection during South Korean MERS outbreak
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The frequent contamination of various surfaces and objects within health care centers could be a factor in the spread of Middle East respiratory syndrome coronavirus, or MERS-CoV, within hospital settings, according to recently published data.
Furthermore, virus isolates collected through respiratory secretions up to 25 days after symptom onset suggest that MERS-CoV patients may continue to be infectious after clinical symptoms have subsided, Yu Bin Seo, MD, of the microbiology department at Chungbuk National University, Cheongju, South Korea, and colleagues wrote.
“Following the first MERS-CoV outbreak in South Korea on May 20 in 2015, widespread contamination of the hospital environment was suspected as a cause of the rapid transmission, although direct evidence is limited,” the researchers wrote. “Although MERS-CoV is assumed to be transmitted through large droplets, contact and aerosols, the relative importance of aerosol transmission vs. spread by large droplets or contact is unknown. Therefore, there is an urgent need to investigate whether environmental contamination by droplets or other factors play a role in nosocomial transmission of the MERS-CoV.”
Seo and colleagues examined the treatment rooms of four MERS-CoV patients treated in two Korean hospitals from June 8, 2015 to July 3, 2015. They collected respiratory and environmental samples during the later stages of clinical disease, and continued environmental collection 24 to 120 hours after patient discharge. Researchers collected respiratory samples by either encouraging patients to expectorate sputum or using nasotracheal suction. Various environmental surfaces were swabbed and immediately transported for testing. Both clinical and environmental samples were tested for the presence of MERS-CoV using reverse transcription-PCR, and respiratory specimens also were cultured and isolated to confirm virus viability.
The median age of the four enrolled women was 68 years; all had pneumonia. One patient died 23 days after developing symptoms, and two of the patients shared a room for part of their hospital stay.
Clinical samples collected from three of the patients were positively isolated, despite the detection of MERS-CoV RNA in this fourth patient. Researchers observed virus in patient sputum as many as 25 days after symptom onset, and virus isolation persisted until 22 days after symptom onset in two of the patients.
Environmental contamination was detected in patients’ rooms as many as 120 hours after the residing patient’s last positive reverse transcriptase-PCR test. Numerous surfaces — bed rails, device and door buttons, floors, IV fluid hangers, and ceiling air inlets — were positive for specimens containing MERS-CoV RNA, including floors and desks in anterooms the patients were unable to reach themselves.
Taken together, these findings suggest that infection control, prevention and quarantine policies should extend past the acute phase of illness, the researchers wrote. Improper sanitation and health care workers also should be considered as potential factors during a MERS-CoV outbreak.
“Frequent and thorough environmental cleaning and disinfection are therefore critical to reduce spread of this highly contagious virus, especially in the hospital setting,” the researchers wrote. “In addition, detailed, pre-existing guidelines should be in place to disinfect the environment, protect health care workers from contaminated hospital surfaces, and isolate patients for a sufficient time period in order to limit virus spread.” – by Dave Muoio
Disclosure: The researchers report no relevant financial disclosures.
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