A long-awaited report on a large and possibly still ongoing outbreak of MERS coronavirus in Saudi Arabia reveals the virus spreads easily within hospitals, at one point passing in a person-to-person chain that encompassed at least five generations of spread.
The study, co-written by Toronto SARS expert Dr. Allison McGeer, also hints there may have been a superspreader in this outbreak, with one person infecting at least seven others.
The study lays out what is known about an outbreak of MERS that erupted this spring in four hospitals in the Eastern Province of Saudi Arabia, in an area whose name translated into English can be spelled Al-Ahsa or Al-Hasa (the study uses the second version). It was reported online on Wednesday by the New England Journal of Medicine.
Superspreaders played a key role amplifying SARS cases during the 2003 outbreak. That, combined with the symptoms patients manifest when they become sick and the long and varied incubation period, paint a picture that is reminiscent of SARS for the authors, several of whom, like McGeer, worked in Toronto to contain that coronavirus.
“This virus is closer to SARS than anything else,” McGeer, an infection control expert at Toronto’s Mount Sinai Hospital, said in an interview from Cairo, where she was attending a World Health Organization meeting on MERS on Wednesday. She travelled to Al-Hasa to help investigate the outbreak in May and was on a WHO mission to Saudi Arabia earlier this month.
“If you want to think about how you’re going to prevent and manage hospital outbreaks, SARS is the place that all of us would start.”
The 2003 SARS outbreak infected more than 8,400 people in 31 countries, killing at least 916. In the main it was an outbreak of hospitals, wreaking its devastation on staff, patients and visitors of facilities in which it spread. MERS and SARS are members of the same viral family.
McGeer said there are some fortunate distinctions — few health-care workers appear to be getting infected with MERS — as well as some worrisome ones. The high attack rate among patients was “pretty unnerving,” she said, as is the fact that it appears people are infectious earlier in their illness than SARS patients were.
SARS cases were contagious mainly late in their illness, which gave health authorities a chance to diagnose and isolate patients before they could make others sick. If MERS is contagious earlier in the course of illness “that’s not good,” McGeer said. “If it’s true, it’s a real challenge because identifying cases early with either SARS or MERS is really difficult.”
Others too could see similarities to SARS based on the findings of the study.
“Clearly like with SARS the health-care environment is a significant risk factor for ongoing transmission,” Michael Osterholm, an infectious diseases expert who has been following MERS closely, said after reading the paper. He was not involved in the work.
“It means that unless the index of suspicion is very high and patients are immediately handled with the highest level of infection control, you could surely expect that you’re going to see additional episodes outside of the Middle East like are being seen in the Middle East.”