The Middle East respiratory syndrome (MERS) coronavirus has been making patients severely ill in the Arabian Peninsula for several years, but on May 20, the first laboratory-confirmed infection was reported in Korea, eventually leading to the largest outbreak of MERS-CoV in another part of the world.
The Centers for Disease Control and Prevention (CDC) issued an advisory in June giving U.S. physicians updated criteria for when to suspect that a patient might have MERS, particularly focused on patients who had traveled from the Arabian Peninsula or Korea. U.S. hospitalists need to learn about and prepare for the possibility of MERS as they have with other emerging infections, such as Ebola or Lassa, advised Frederick G. Hayden, MD, FACP, infectious diseases specialist at the University of Virginia in Charlottesville.
“You do not know who is going to appear in the emergency room on any given day, and you need to be ready to ask the right questions to sort things out,” he said.
U.S. surveillance for MERS began in 2012. As of June 5, 45 states had submitted specimens to the CDC or conducted their own testing for the virus. Of the 584 people tested in the U.S., 2 were positive in May 2014. Both cases were tied to travel to Saudi Arabia.
The 2 patients were safely cared for by U.S. hospitals, according to Jeff Hageman, MHS, of the Prevention and Response Branch in the CDC's Division of Healthcare Quality Promotion. The CDC sent teams to help state public health authorities assess health care workers and household members who had close contact with the patients.
None of the workers or household contacts became infected with MERS, but the CDC recognizes the potential for this virus to spread further and cause more cases in the United States and globally, Mr. Hageman said. “CDC and public health organizations continue to monitor the MERS situation closely, and we are taking actions to prepare for possible cases.”
The virus has been introduced from the Arabian Peninsula to more than 2 dozen countries, including China, Thailand, and the Philippines in May and June, noted Dr. Hayden.
“Given the fact that there still are new cases occurring in Saudi Arabia and some of the other countries in the Arabian Peninsula, I think there is going to be the continued threat of introductions into other countries, and certainly into the United States, because there is a fair bit of travel back and forth,” he said.
Between September 2012 and September 2015, the World Health Organization (WHO) counted 1,542 laboratory-confirmed cases of MERS, including at least 544 deaths.
One of the challenges of MERS is that it presents in a nonspecific fashion. “Fever, cough, shortness of breath, chills, aches, and pains can all be part of initial presentation. Early MERS can be influenza-like illness, but this is nonspecific. There are a lot of conventional pathogens, including influenza virus itself, which can cause similar symptoms, and dual infections with MERS-CoV and other pathogens have also occurred,” Dr. Hayden said.
The additional signs and symptoms offered by the CDC's website are also nonspecific: headache, sore throat, coryza, nausea and vomiting, dizziness, sputum production, diarrhea, and abdominal pain. The agency noted that limited clinical data for MERS patients are available, as most published clinical information is from critically ill patients.
As the disease progresses, it can lead to pneumonia, acute lung injury, acute respiratory distress syndrome, and failure of the kidneys and other organs, Dr. Hayden said. Patients who are most likely to require intensive care often have a history of a febrile upper respiratory tract illness with rapid progression to pneumonia within a week of illness onset, according to the CDC.
The presence of at least 1 comorbid condition (e.g., immunocompromised state, malignancies, obesity, diabetes, cardiac disease, renal disease, and lung disease) has been reported in 76% of cases and is associated with a higher risk of death, according to the WHO.
According to the CDC, about 3 or 4 out of every 10 confirmed MERS patients have died.
Stopping the spread
Although it is hard to identify MERS early, it is important to, since the majority of MERS cases are secondary and have resulted from human-to-human transmission, most often in health care settings, related to breaches in infection prevention and control practices, according to a WHO report.
“One of the features of the MERS-CoV outbreak is that once patients have been introduced into hospitals in affected countries, and Korea is an excellent example of this, there was amplification of the outbreak in health care facilities. We saw this with SARS [severe acute respiratory syndrome] historically, but here again, part of this is inadequate initial recognition, and of course, inadequate application of infection control procedures,” said Dr. Hayden.
He was among the experts who helped prepare “Clinical management of severe acute respiratory infection when Middle East respiratory syndrome coronavirus (MERS-CoV) infection is suspected,” a document the WHO released in July (available online). )
“The virus does not appear to transmit easily from person to person unless there is close contact, such as providing clinical care to an infected patient while not applying strict hygiene measures,” it said.
It is essential to promptly isolate any hospital patient who might have MERS, noted Mr. Hageman. “Infection control measures should be implemented at the first point of a patient's arrival in a health care setting while evaluation is under way,” he said.
He outlined several steps for hospitals to follow:
- Take a thorough travel and exposure history of patients with respiratory symptoms such as cough, runny nose, and fever.
- Be prepared to have potentially infectious individuals wear a mask and be quickly moved to a private room.
- Ensure hospital staff are trained on the proper use of personal protective equipment.
- Use signs and other cues to encourage people with symptoms of respiratory infections to identify themselves and wait in an area away from others.
- Provide patients and visitors with the supplies and instructions for proper hand hygiene and cough etiquette.
For patients with suspected or confirmed MERS, contact and airborne precautions should be employed, the CDC advises. (More information from the CDC is online.) It recommends collecting specimens from several sites for testing with the MERS real-time reverse transcription polymerase chain reaction assay, including a lower respiratory specimen, a nasopharyngeal/oropharyngeal swab, and serum.
Don't forget, however, that the same symptoms and travel history could appear with other infectious threats. “It's not just MERS-CoV; it could be an avian H5 case, or an H7N9 case of influenza coming from China or another affected country. The point is there are other respiratory pathogens you have to be concerned about, including the conventional ones,” said Dr. Hayden.
Although research into a vaccination or treatment is ongoing, current care of MERS focuses on supportive care, which can be intensive in serious cases. Some patients require intubation, placement on a ventilator, or even renal replacement therapy, said Dr. Hayden.
“There is no antiviral therapy of proven benefit right now, nor is there a vaccine available. However, there has been a lot of work, especially since SARS, on developing these interventions for novel coronaviruses and some progress has certainly been made,” he said, adding that studies of several neutralizing antibody-based products are expected to begin shortly.