The most recent issue of the describes a highly detailed and thorough investigation into the hospital-associated outbreak of MERS that occurred in Saudi Arabia in earlier this year, between April and May.
While some have accused Saudi Arabia of suppressing information -- yes, the country remains an absolute monarchy -- the transparency of information to date is to be commended.
Consider this: a WHO-led international team, including a Canadian infectious diseases expert, was invited to participate in the investigations, and participated in the authorship of the NEJM paper. Saudi Arabia鈥檚 Deputy Minister of Health, Dr. Ziad Memish, is a Canadian-trained Infectious Diseases specialist and the paper鈥檚 final author.
While MERS 鈥� referred to earlier as simply a 鈥渃oronavirus鈥� 鈥� has been heavily covered in the news from over the past few months, here鈥檚 what we know about the virus based on the review of 23 cases, outlined in the NEJM:
MERS is caused by a different type (鈥淟ineage C鈥�) of coronavirus from the one that caused SARS. The cause of MERS was promptly identified early in late 2012, well before this outbreak began. (SARS was a called a 鈥榤ystery illness鈥� before the cause was known. Also, a lack of a cause meant a lack of diagnostic tests for many weeks. Outbreak investigators were shooting in the dark, so to speak.)
MERS has spread internationally, but transmission in other countries has not been sustained. (SARS spread for weeks within China and to other countries well before the outbreak was recognized and addressed.)
Most patients with a severe form of the illness have underlying disease. End-stage renal disease (dialysis patients) and diabetes figure prominently. Older men (more than 50 years of age) represent 75 per cent of the 23 cases described in the NEJM paper. (SARS afflicted healthy patients and healthcare workers alike.)
While most MERS patients have fever and cough, some have diarrhea. This was also seen with SARS, and the question now is whether diarrhea contributes to the spread. (Like SARS.)
The period between exposure and the development of symptoms 鈥� also called the incubation period -- is two to 10 days (Like SARS)
Of the 23 cases, about 80 per cent of patients ended up on a breathing machine, and 65 per cent of the cases were fatal. (Like SARS)
Multiple chains of person-to-person transmission have occurred in a hospital setting. (Like SARS)
Health-care providers and family members may be coincidentally infected as well, and while they do not seem to propagate spread of the virus to other health-care providers, patients or additional family members. (SARS spread more easily in these groups, and between hospitals via infected health-care providers.)
It appears that patients with symptoms are more likely to spread the disease than those with mild disease or those infected who don鈥檛 yet show symptoms. (Like SARS)
Spread between hospitals occurs when a patient is moving from one institution to another. (Like SARS)
The outbreak was brought under control using measures similar to those used to control SARS outbreaks.
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Some questions about MERS remain unanswered 鈥� in particular the source of the infections acquired in the community. After all, the hospital outbreak originated from an initial case that was acquired in the community.
Is contact with an animal source required for infection? How is it spread within households or between patients: through coughing and sneezing, or does diarrhea lead to contamination of the hospital and/or household environment? Exactly how long are patients contagious? Finally, how much milder, perhaps unrecognized illness is out in the community?
Despite the uncertainties mentioned above, time is the best measure of risk. Since late 2012, multiple months of intense international surveillance -- including what we do in hospitals in Canada -- have not identified cases without a link to the Arabian Peninsula.
Reassuring indeed; perhaps we are looking at 鈥淪ARS Lite.鈥�
