Credit Saudi MOH
In its relatively short (known) history of infecting humans, large nosocomial outbreaks have played a large part in the spread of MERS-CoV. The first identified outbreak took place in April of 2012 at a Jordanian hospital, infecting perhaps a dozen. Since then we’ve seen this pattern of hospital spread repeat, and expand in size, in places like Jeddah, Taif, Riyadh, Hofuf, and even South Korea.
According to the Saudi MOH (see graphic above), nearly half (45%) of their 1250+ MERS cases were acquired in a healthcare facility.
South Korea, which saw 185 cases spanning multiple hospitals starting last May, is yet another example. And while smaller, outbreaks in Jordan and the UAE have also revolved around hospitals. Despite attempts at improving hospital infection control, we continue to see large, difficult to contain outbreaks of the virus.
A failure to quickly identify and isolate MERS infected patients has obviously been a major contributor to these outbreaks. But even weeks after hospital outbreaks have become apparent - some patients, visitors, and HCWs have continued to become infected - suggesting a much deeper infection control challenge.
While the MERS outbreaks in the Middle East haven't suggested a `classically airborne' virus like influenza or measles, droplet spread over short distances through the air is assumed and limited airborne transmission seems possible (see mBio: Airborne Fragments Of MERS-CoV Detected In Saudi Camel Barn).
Certain medical procedures - like the use of nebulizers and intubation (see CDC IC guidelines) – have been linked to short-distance airborne spread of the virus, and six week ago (see NIOSH Video: Adventures In Toilet Plume Research) we looked at another `plausible’ mechanical cause of virus aerosolization.
Of course, unidentified asymptomatic or `mild’ cases among patients, visitors, or staff may also help perpetuate these outbreaks.
While all of these are likely factors contributing to these hospital outbreaks, time and again we seem to go back to fomites – contaminated environmental surfaces – as potential drivers of these outbreaks (see MERS: A Focus On Fomites?).
In 2013, a study called Stability of Middle East respiratory syndrome coronavirus (MERS-CoV) under different environmental conditions by N van Doremalen1, T Bushmaker1, V J Munster found, under favorable temperature and humidity conditions (such as you might find in an air conditioned hospital), the MERS virus survives quite well on surfaces, and in the air.
While strongly suspected, the evidence for fomites sparking these large outbreaks is largely circumstantial. The WHO Joint Mission to Korea last June found:
The mission was unable to conclude whether environmental contamination, inadequate ventilation or other factors played a role in the transmission of the virus in the outbreak, but made a number of recommendations to improve health facilities in the country to reduce the possibility of the virus being spread by these means in the future.
Related or not, within three weeks the spread of the virus was halted in Korean hospitals (the last patient was confirmed infected on July 4th).
All of this leads us to a presentation at last week’s IDSA IDWeek held in San Diego, by Korean researchers, that found extensive and persistent environmental contamination by the MERS virus in, and even adjacent to, isolation rooms, highlighting the need for strict environmental infection control.
A link to, and some excerpts, from the Abstract (follow the link to read it in its entirety).
Session: Oral Abstract Session: Featured Oral Abstract
Saturday, October 10, 2015: 4:45 PM
Result: Environmental surfaces of MERS patient’s room including many points frequently touched by patients or healthcare workers were contaminated by MERS-CoV. Also in anterooms, medical devices and air-ventilating equipment, the MERS-CoV RNA was detected. In addition, we could isolate the MERS-CoV in bedsheets, bedrails, IV fluid hangers and X-ray devices. During the late clinical phase of MERS, viable virus could be isolated in 3 of the 4 enrolled patients on day 18 to day 27 after symptom onset. In environmental specimens (bed controller and thermometer), PCR positivity persisted until the 5th day from the last positive PCR of patient’s respiratory specimen.
Conclusion: Most of touchable environments in MERS units were contaminated by patients and health care workers and the viable virus could shed through respiratory secretion of patients who clinically fully recovered with conventional PCR-negative. Therefore, our results emphasize strict environment surface hygiene practices and detailed and premeditative proceeding/guideline to disinfect the health care workers.
Hye Won Jeong, M.D. Ph.D.1, Jung Yeon Heo, MD2, Hyung-Woo Kim, MD2, Young Ki Choi, Ph.D.3, Min-Sok Song, Ph.D.3, Yu Bin Seo, M.D.4 and Jacob Lee, M.D.4, (1)Department of Internal Medicine, Chungbuk National University College of Medicine, Cheongju, South Korea, (2)Division of Infectious Diseases, Department of Internal Medicine, Chungbuk National University Hospital, Cheongju, South Korea, (3)Department of Microbiology, Chungbuk National University College of Medicine, Cheongju, South Korea, (4)Department of Internal Medicine, Hallym University Medical Center, Seoul, South Korea
Although their MERS outbreak is still not yet officially declared over, it is heartening to see we are already getting some valuable data from South Korea’ experience – either through venues like IDWeek – or published in scientific journals (see EID Journal: Serologic Responses to MERS in Humans - South Korea).