MERS-CoV: The back-burner, front-burner shuffle

Issue: September 2015

ByDonald Kaye, MD, MACP

ByMarjorie P. Pollack, MD

It has now been 3 years since the Middle East respiratory syndrome, or MERS, coronavirus was identified in a Saudi male with a clinical presentation consisting of severe respiratory illness and renal failure. During this 3-year period, we have watched the poorly orchestrated front-burner, back-burner shuffle, as transmission of the virus heats up and then cools down, only to heat up again ... and cool down again, not unrelated to the perceived threat of MERS to the industrialized world.

To jog our memories, MERS coronavirus (MERS-CoV) was identified in a patient that was fatally ill in Saudi Arabia in June 2012. The report of the discovery of a new “SARS-like” virus (remember 2003) was first released on ProMED-mail (promedmail.org) on Sept. 20, 2012, and published in an early release of the New England Journal of Medicine on Oct. 17, 2012. A second case was reported several days later in a Qatari under medical care in the United Kingdom. A retrospective look at an ICU-related outbreak that occurred in Jordan in April 2012 was also confirmed to be due to MERS-CoV. During the early months, there were sporadic cases reported, all related to exposure in the Middle East or contacts with individuals who had exposure in the Middle East. As a new organism/disease, reminiscent of SARS, and with the upcoming hajj during Oct. 24-29, 2012, it was a hot issue moved to the front burner, regarded as a potential international threat. After a collective sigh of relief when the annual pilgrimage passed without a major outbreak, the disease somewhat shifted to a back burner, except for those specifically interested in publications about MERS.

In the spring of 2013, there was an outbreak reported in the Eastern Province of Saudi Arabia associated with transmission in the health care environment involving several health care facilities — back to the front burner. Cases continued to occur, including importations to countries outside of the Middle East, but secondary cases from the importations were few, and there was no third-generation spread. So ... to the back burner. However, with the upcoming hajj (Oct. 13-18, 2013), MERS-CoV moved to the front burner again. Again, the hajj passed without a major outbreak, and this time publications appeared demonstrating that other respiratory viruses were brought back to countries post-hajj, but not MERS-CoV, so back to the back burner again as there was “no international threat.” However, another major outbreak occurred, again in Saudi Arabia, again in the springtime, this time in 2014, so back to the front burner. And to keep things hot and on the front burner, there were numerous importations to countries outside of the Arabian Peninsula. By now, the dromedary camel (DC), a familiar sight in the Middle East used for transport, racing and nutrition (camel meat, raw milk and camel urine are all consumed on the Arabian Peninsula), had become the suspected zoonotic host, leading to many studies on prevalence of MERS-CoV in the DCs and in cases with known contact with DCs. Seasonality prevailed with the summer of 2014 passing fairly quietly, and importations once again did not result in more than a few second-generation cases among close contacts, so back to the back burner it went. Keeping it solidly on the back burner was the very hot, major outbreak of Ebola virus disease (EVD) in West Africa.

Proving the seasonality of MERS-CoV, the situation heated up again in the fall of 2014 with increases in cases reported in Saudi Arabia, and several imported cases related to returning pilgrims having made the lesser pilgrimage to Saudi Arabia known as the umrah. With the hajj scheduled for Oct. 1-6, 2014, once again it was on the front burner, although it was the smaller of the two front burners, with the larger burner taken up by EVD activity. As in previous years, the hajj passed without imported cases in returning pilgrims, and transmission on the Arabian Peninsula slowed down again. Back to the back burner.

When the expected springtime increase in cases occurred, the flame was turned up a little. A major retrospective study on seroprevalence of MERS-CoV in the Saudi population was published in the New England Journal of Medicine, estimating that almost 45,000 Saudis had evidence of antibodies against MERS-CoV, and that those individuals with exposure to camels had significantly higher seroprevalence than those without camel exposure. The study period was from Dec. 1, 2013, to Dec. 1, 2014, during which time there had been approximately 700 cases of MERS-CoV infection confirmed in Saudi Arabia. So it stayed on the back burner.

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But, May 2015 pushed MERS-CoV to the front burner in a major way when a Korean businessman returned to South Korea from the Arabian Peninsula (Bahrain, Saudi Arabia and Qatar), and after visiting four different health care facilities, he was finally diagnosed with having MERS-CoV infection. What was very different here was that during the 9-day period after onset of his illness — before MERS-CoV infection was confirmed and the patient was isolated — he spent several days admitted to an open ward in a hospital. There, an additional 31 individuals were infected as second-generation cases. Infected individuals included his wife, his ward “roommate,” other patients on the ward and their family members and care takers and health care personnel.

Unfortunately, South Korea represented the perfect storm. First, the index case (the importation from the Arabian Peninsula) was a superspreader, clearly releasing high viral loads into his environment. Second, medical care practices in South Korea involve hospital shopping (if patients are not satisfied with care from one hospital, they can easily go to another without financial penalty). In addition, there is overcrowding of major referral hospital ERs (as patients wait for beds to open up on the wards). And, once hospitalized, six bedded rooms are the norm, and family members and caretakers stay with their ill relations, so the hospital floors and rooms are overcrowded as well. Enter a superspreader and the rest is history. And to make things worse, two of the second-generation cases also were superspreaders, one of whom spent several days in the ER of a major tertiary care hospital in Seoul. The net outcome of this perfect storm was 186 cases, including 36 deaths (case fatality rate, 19.4%), reported from South Korea as of Aug. 27. Needless to say, this outbreak returned MERS-CoV to the larger front burner.

While the health care system with hospital overcrowding and questionable infection control practices allowed the South Korean epidemic to occur, the public health response with intense contact tracing and isolation and improvement of infection control seems to have ended it. During this outbreak, South Korea identified and monitored almost 16,700 contacts of patients with MERS-CoV. During the time covering the outbreak in South Korea, there was an importation into China (related to the South Korean outbreak), an importation into Thailand (from Oman), and one into the Philippines, without secondary cases. So, MERS-CoV seemed to be slipping back to the back burner again in July. However, cases started being reported in an escalating pattern from a major tertiary hospital in Riyadh, Saudi Arabia, beginning around July 21. As of Aug. 28, there have been a total of 1,173 cases of MERS-CoV infection, including 502 deaths (case fatality rate, 42.8%), reported by Saudi Arabia since June 2012, and the outbreak continues, pushing MERS-CoV to a front burner.

The 2015 hajj is most likely going to fall between Sept. 21 and Sept. 26, coincident with the fall seasonal increase in MERS-CoV activity in the Arabian Peninsula. So the key question is: If the outbreak in Riyadh is brought under control before mid-September, will the world be approaching the upcoming hajj with MERS-CoV on a back burner, or on a front burner? And will it return to a back burner once again after the hajj?

As parting notes, according to statistics maintained by the European CDC, as of Aug. 27, there have been a total of 1,511 cases of MERS-CoV, including 574 deaths (38% mortality rate), that have been reported by health authorities worldwide. In contrast, in less than 1 year, SARS came and went, with a total of 8,096 cases, including 774 deaths (case fatality rate, 9.6%). Yet SARS stayed on the front burner until it was long gone. As an observation, and as recommended, every U.S. doctor’s office, hospital and major airport asks about travel in West Africa. In addition, with nonexistent recommendations, none that we have encountered asks about travel to MERS-CoV areas. One MERS-CoV superspreader in the wrong place at the wrong time could result in a repetition of the South Korean experience.

References:
Al-Abdallat MM, et al. Clin Infect Dis. 2014;doi:10.1093/cid/ciu359.
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ProMED-mail. Novel coronavirus - Eastern Mediterranean: WHO, Jordan, conf., RFI. Archive Number: 20121130.1432498. http://promedmail.org/direct.php?id=1432498. Accessed July 19, 2015.
WHO. Middle East respiratory syndrome coronavirus (MERS-CoV) – Republic of Korea. May 24, 2015. http://www.who.int/csr/don/24-may-2015-mers-korea/en/. Accessed July 19, 2015.
WHO, Summary of probable SARS cases with onset of illness from 1 November 2002 to 31 July 2003. http://www.who.int/csr/sars/country/table2004_04_21/en/. Accessed August 18, 2015.
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For more information:
Donald Kaye, MD, is a professor of medicine at Drexel University College of Medicine, associate editor of ProMED-mail, section editor of news for Clinical Infectious Diseases and an Infectious Disease News Editorial Board member.
Marjorie P. Pollack, MD, is deputy editor of ProMED-mail and an independent consultant medical epidemiologist with a focus on developing world issues following CDC training. She is based in New York.

Disclosure: Kaye and Pollack report no relevant financial disclosures.