Be wary of MERS introductions

Super-spread pattern occurs in hospitals

Could a SARS-like outbreak be on the horizon? MERS-CoV (Middle Eastern respiratory syndrome coronavirus) has had limited transmission, but hospital-based outbreaks — and illnesses among Saudi Arabian health care workers — are reminiscent of the outbreaks of Severe Acute Respiratory Syndrome (SARS) that occurred 10 years ago.

One patient in a dialysis unit in Saudi Arabia, for example, spread MERS-CoV to seven other patients, which led to 12 other cases, including the infection of a health care worker.1

That pattern is "like the super-spreading events during SARS," says Allison McGeer, director of infection control at Mount Sinai Hospital in Toronto and an expert on SARS who has traveled to Saudi Arabia to help investigate MERS-CoV. She added, "It’s not as dramatic as some of the super-spreading during SARS."

SARS culminated in 8,100 cases and 774 deaths, for a case fatality rate of about 10%. About a year after MERS-CoV was first detected in September 2012, there were 130 lab-confirmed cases and 58 deaths, or a case fatality rate of 45%. While urging greater surveillance and infection control, in September a World Health Organization panel of experts declined to call MERS-CoV a "Public Health Emergency of International Concern," a designation that leads to specific actions.

Still, hospitals in North America should be alert to MERS-CoV symptoms among patients with recent travel to the Middle East or contact with others who traveled there, she says. The symptoms include fever, cough, shortness of breath, and breathing difficulties, and could include gastrointestinal symptoms such as diarrhea. Patients have had pneumonia and some have had kidney failure, the World Health Organization reports.

Although no cases have yet been reported in North America, "these cases have been exported. We are at risk," says McGeer.

The greatest challenge may be in detecting MERS-CoV in a contact or family member of someone who traveled to the Middle East, McGeer cautions. "What happens if it’s the traveler’s wife or the traveler’s boyfriend or the traveler’s mother? That’s where we’re more likely to get into trouble," she says. "That’s where we got into trouble with SARS."

Echoes of SARS

An outbreak in the Al-Hasa region of Saudi Arabia, with 23 confirmed cases and 11 probable cases in four health care facilities reveals the SARS-like potential of MERS-CoV.

Patient A was admitted to the hospital with dizziness and profuse sweating. Four days later, he had developed a fever and pneumonia-like symptoms. He wasn’t tested for MERS-CoV, but his son would later have a confirmed case.

Meanwhile, Patient C in the adjacent room developed fever three days later. Six new cases of MERS-CoV were linked to contact with him in the hemodialysis unit including among three patients who were in adjacent beds. There was further secondary spread, including to two health care workers. (Patient C also was linked to a case in the intensive care unit.)

Most concerning, six new cases of confirmed or probable MERS-CoV occurred after heightened infection control. Those precautions included: "monitoring hand hygiene, implementing droplet and contact precautions for febrile patients, testing patients with fever for MERS-CoV, putting masks on all patients undergoing hemodialysis, not allowing patients with suspected MERS-CoV infection into the dialysis unit, enhancing environmental cleaning, and excluding visitors and nonessential staff."1

CDC: Use airborne precautions

Much is still not known about MERS-CoV — including how it is spread. In the report of the investigation of a hospital outbreak, the authors noted:
"[W]e are unable to determine whether person-to-person transmission occurred through respiratory droplets or through direct or indirect contact and whether the virus was transmitted when the contact was more than 1 meter away from the case patient. Because some patients presented with gastrointestinal symptoms, and transmission appeared to occur between rooms on the ward, the current WHO recommendations for surveillance and control should be regarded as the minimum standards."

The Centers for Disease Control and Prevention recommends airborne infection isolation rooms for patients and N95s, gloves, gowns and goggles or face shields for health care workers entering a patient room. (www.cdc.gov/coronavirus/mers/infection-prevention-control.html) (The World Health Organization recommends the use of a surgical mask except during aerosol-generating procedures, which then call for an N95.)

Some cases of MERS-CoV are likely still occurring due to an animal vector, perhaps linked to camels, but as of September, researchers had not established the source.

In September, the World Health Organization reported four additional lab-confirmed cases of MERS-CoV. One, a 41-year-old female health care worker from Riyadh, Saudi Arabia, had no known exposure to a MERS patient or to animals likely to carry MERS. She died within a couple of weeks of onset of her illness.

A 30-year-old male health care worker at the same hospital became ill with severe pneumonia and was in critical condition. Two other Saudis who had family members with MERS also became ill; one died and the other was in critical condition.

MERS-CoV cases have been detected in France, Germany, Italy, Jordan, Qatar, Saudi Arabia, Tunisia, the United Arab Emirates, and the United Kingdom. All cases either involved people who lived in or traveled to the Middle East or who had contact with people who had probable or lab-confirmed MERS-CoV.