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Issue: July 2016
ByDonald Kaye, MD, MACP
ByMarjorie P. Pollack, MD
July 22, 2016
6 min read
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MERS-CoV: Waiting for the other shoe to drop

Issue: July 2016
ByDonald Kaye, MD, MACP
ByMarjorie P. Pollack, MD
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It is time for another update on the Middle East respiratory syndrome coronavirus situation globally. To refresh memories, MERS-CoV has been circulating in the Arabian Peninsula for some time now. The virus was first identified in September 2012, after a fatal severe acute respiratory illness, or SARI, with renal failure presentation in a Saudi Arabian male. Within a few days of publication of a report on this case in ProMED-mail, physicians in the United Kingdom identified another case of SARI and renal failure in a Qatari citizen who had been medevaced to the U.K. for treatment. Retrospective studies on specimens from fatalities due to SARI in an April 2012 outbreak at a Jordanian hospital ICU also identified MERS-CoV as the etiologic agent.

We now have almost 4 years of experience with MERS-CoV. During those 4 years, we have learned that MERS-CoV, while phylogenetically closest to a bat beta coronavirus, has been circulating among camels in the Arabian Peninsula and Africa for more than 10 years. We also have learned that routes of transmission include close contact with camels, close contact with infected individuals in the household and nosocomial transmission both among patients and their visitors and between patients and health care workers.

We still have the enigma of explaining “primary cases” in those MERS-CoV–infected individuals with no history of contact with camels, the health care environment, or other known MERS-CoV–infected individuals in the 14 days preceding onset of illness (the longest assumed incubation period). Saudi Arabia has been classifying cases by probable source of infection. According to the Saudi Ministry of Health, since January 2015, 42% of cases were classified as primary cases, 30% as health care-acquired in patients, 13% in household contacts, 12% as health care-acquired in health care workers, and 4% remained unclassified. Primary cases included individuals with a history of contact with camels, those with no history of contact with camels and those where a camel contact history was unknown. Putting this into perspective, among 558 cases reported by Saudi Arabia from Jan. 1, 2015 through June 5, 2016, 64 (11.5%) had a history of contact with camels in the 14 days preceding onset of illness, 189 (33.9%) had no history of contact with camels in the 14 days preceding onset of illness, and the remainder were either under investigation or no information was provided. Hence, while 42% of cases were classified as primary cases, only 11.5% were reported officially to have had a history of contact with camels in the 14 days before onset of illness.

Figure 1. MERS-CoV has been circulating among camels in the Arabian Peninsula and Africa for more than 10 years.

Source:Shutterstock.com

Click the image to enlarge.

At the time of our last update, South Korea was in the final days of a major outbreak of MERS-CoV, which resulted in 186 cases. All of the cases traced back to an index case who had traveled to the Arabian Peninsula on business, returned home and developed a febrile illness that escaped diagnosis during multiple visits to multiple health care facilities. To further complicate matters, a number of the secondary and tertiary cases ended up being “superspreaders,” infecting numerous individuals in the health care environment. Lessons learned through this experience included the importance of ascertainment of clear travel histories when a patient presents with a febrile illness, the need to consider isolation of patients with an undiagnosed severe febrile respiratory illness, and the need to reduce the crowding of EDs and hospital rooms with visiting family members and caretakers who are untrained in infection control procedures.

August 2015 brought an early start to the expected autumn seasonal increase, with 127 cases occurring in Saudi Arabia, including 120 in Riyadh. In late August, there was a case reported from Jordan with a history of travel to Saudi Arabia. This case led to nosocomial transmission in Jordan with 16 cases reported by the middle of October. Nosocomial transmission in Saudi Arabia continued during September and October, and then trickled down during November and December, thereby assuring that MERS-CoV would be lost from the news as Zika virus’ impact on the developing fetus dominated headlines.

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January was a slow month for MERS-CoV transmission in Saudi Arabia, with only seven cases reported, although there were cases reported from Oman (n = 1); Kuwait (n = 1); Abu Dhabi, the United Arab Emirates (n = 2); and Thailand (in an Omani medical tourist traveling to Thailand).

Click the image to enlarge.

Transmission in Saudi Arabia picked up again in February, March and April, with 20, 55 and 14 cases reported each month, respectively. During this same period there were cases reported from Qatar (one case with a history of travel to his camel farm in Saudi Arabia during the incubation period and a second case with a history of travel in Saudi Arabia for 2 months preceding the onset of his illness), and Bahrain (one case in a Saudi traveling to Bahrain for cardiac surgery).

May was a very slow transmission month with only four cases reported from Saudi Arabia and a single case in a Qatari camel worker with no history of travel before the onset of his illness.

Aside from the obvious slowdown in transmission of MERS-CoV, including a possible reduction in nosocomial transmission risk through improved infection control procedures in health care facilities in Saudi Arabia, there are other concrete signs that MERS-CoV has been relegated to forgotten news. These include the facts that: 1) the most recent epidemiologic review of MERS-CoV published by the European Centre for Disease Control was on Sept. 2, 2015, having been supplanted by a plethora of epidemiologic reviews on Zika virus and associated congenital neurologic disorders as well as Guillain-Barré syndrome, and 2) although largely ignored by the media, the major yellow fever activity this year in multiple countries in Africa and South America and a shortage of vaccine supplies has received increasing attention from the global public health community. Noticeably, the most recent WHO Disease Outbreak News updates on MERS-CoV activity were published on May 16.

So where are we now? We have a severe disease, clearly related to transmission on the Arabian Peninsula, with Saudi Arabia reporting 80% (1,384 out of 1,735) of all cases reported to WHO. We have continued sporadic transmission of the virus on the Arabian Peninsula with an estimated 2 million to 3 million pilgrims traveling to Saudi Arabia for the hajj on an annual basis, and another 2 million to 3 million pilgrims traveling to Saudi Arabia for the umrah, the lesser pilgrimage, on an annual basis. Many of these pilgrims return to countries where diagnostic and infection control capabilities are suboptimal. There have been 628 deaths from MERS vs. 774 deaths from the 2002-2003 severe acute respiratory syndrome (SARS) outbreak, which caused international panic. We know there is the potential of superspreaders with MERS just as with SARS. Are we ready to just keep MERS-CoV as yesterday’s news, waiting for indications to make it front page news? Should we erroneously assume we no longer have to worry since there have been 4 years with zero identified transmission to attendees of the hajj’s pilgrims and minimal (though not zero) transmission to pilgrims making their umrah journey? Will MERS come back to bite us while we are concentrating virtually all efforts on Zika and yellow fever?

Only time will tell ...

  • For more information:
  • Donald Kaye, MD, MACP, 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 after CDC training. She is based in New York.

Disclosures: Kaye and Pollack report no relevant financial disclosures.

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