Abstract & Commentary
U.S. MERS cases worked in Saudi hospitals
By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University, Hospital Epidemiologist, Sequoia Hospital, Redwood City, CA, Editor of Infectious Disease Alert
CDC. Middle East Respiratory Syndrome (MERS). http://www.cdc.gov/features/novelcoronavirus/
The first U.S. case of MERS-CoV infection diagnosed in the U.S. has been identified in an individual traveling from Saudi Arabia.
An American health care worker flew from Riyadh, Saudi Arabia, to Chicago on a connecting flight from London on April 24, 2014. This was followed by an approximately 30-mile bus ride to Munster, Indiana. Three days later, on April 27, he developed fever, cough, and breathlessness and he presented to the Emergency Department of the 427--bed Community Hospital in Munster on the evening of the following day and was admitted as an inpatient. Middle East respiratory syndrome coronavirus (MERS-CoV) infection was suspected. As a consequence, the patient was managed with appropriate isolation precautions and specimens were sent to the CDC, which confirmed the diagnosis on May 2nd.
In order to detect possible secondary cases, family members and health care workers with significant contact with the patient underwent daily monitoring for 14 days, which is considered the outer limit of the incubation period of the infection. CDC began contacting the patient’s airplane and bus co-passengers on May 3rd. (For an update of this story with details on the second U.S. MERS case see p. 105.)
COMMENTARY
As of May 12th, CDC reported a total of 538 confirmed MERS-CoV cases that include 145 deaths. The fact that 200 new cases were reported by Saudi Arabia and the United Arab Emirates in the single month of April 2014 has appropriately raised concerns that viral mutations had led to enhanced adaptation to human hosts.1
The available evidence, however, has not, to date, confirmed this fear. Rather, it has been suggested that at least part of the reason has been increased recognition of the disease. Another suspected factor is the mass birthing of dromedary camels (the one-humped type) that occurs every winter in breeding facilities.
The virus, like the SARS coronavirus, has been found in bats. The role of these mammals in the transmission of MERS-CoV is uncertain, but dromedary camels are an important reservoir of the virus. For instance, a country-wide survey in Oman led to its detection in conjunctival and nasal secretions in high concentration in 5 of 76 of the ungulates tested and the finding that the viruses were closely related to MERS-CoV of human origin detected in the same geographic area.2 In a few cases, closely related MERS-CoV has been identified in humans and camels with which they had had contact. Thus, it has been suggested that human infections may result from contact with the camels, eating camel meat, and the common practice of eating unpasteurized camel milk. Human-to-human transmission also occurs, with cases occurring in those with close contact with cases, including family members and health care workers. Fortunately, sustained transmission has not been observed.
Autochthonous cases of infection have occurred in 6 countries in or near the Arabian Peninsula: Saudi Arabia (where the bulk of cases have occurred), Oman, Kuwait, United Arab Emirates, Qatar, and Jordan. The U.S. is the 12th country to which the virus has been exported and, in our globally connected world, it will not be the last.
Fatal cases, in particular, mostly occurred in those with significant comorbidities such as chronic renal insufficiency and diabetes mellitus. Treatment of rhesus macaques experimentally infected with MERS-CoV with ribavirin and interferon-α2b, which are active against the virus in vitro, was associated with somewhat improved outcomes.3 Monoclonal antibodies with neutralizing activity have also been developed.
One last thing — congratulations to the alert clinicians at Community Hospital in Munster for rapidly recognizing the possibility of MERS-CoV infection in their patient!
References
- Kupferschmidt K. Soaring MERS cases in Saudi Arabia raise alarms. Science. 2014; 344:457-458.
- Nowotny N, et al. Middle East respiratory syndrome coronavirus (MERS-CoV) in dromedary camels, Oman, 2013. Eurosurveillance, Volume 19, Issue 16, 24 April 2014.
- Falzarano D, et al. Treatment with interferon-α2b and ribavirin improves outcome in MERS-CoV-infected rhesus macaques. Nat Med 2013; 19:1313-7.
