Credit CDC
# 8637
According to ACEP (the American College of Emergency Physicians), hospital emergency rooms provided treatment to more than 136 million Americans in 2009. Which means that every day across the United States hundreds of thousands of people present at emergency rooms, with a wide variety of problems.
Some cases will be critically ill or injured, while others will have relatively simple complaints like URIs, fever, gastrointestinal complaints – all exceedingly common - yet all potentially early signs of MERS coronavirus infection.
For doctors, nurses, and other medical personnel in the United States (and around the world) this adds the task of identifying and isolating what is currently a needle-in-a-haystack – that one patient out of a million who might be carrying the MERS coronavirus – while simultaneously dealing with the urgent demands of a busy emergency room.
Today the likelihood that anyone presenting at an emergency room in the US with `flu-like’ symptoms has the MERS coronavirus is exceedingly, almost astronomically, low. But that statistic is of little comfort to the staff and patients at the emergency rooms of Munster, Indiana or Orlando, Florida.
The odds of being struck by lightning or winning the lottery are miniscule as well, but it still happens.
One of the tenets of emergency medicine is that you start with the most likely diagnosis, rule that out, and progressively work through next most likely scenarios before exploring more exotic illnesses.
It’s a variation of Occam’s Razor, that the simplest explanation is often correct, and is often taught as an aphorism to medical students: `If you hear hoof beats, think horses, not zebras’.
While still literally a one-in-a-million shot that any given patient going to an North American ER today with `the flu’ has the MERS virus, if it continues to circulate unabated in the Middle East, the odds favor our seeing more `zebras’ showing up at local ERs over time.
Which is why the CDC has updated their MERS Interim Guidance for Health Professionals, to help identify, isolate, and test potential MERS carriers before they can further spread the virus. Some excerpts from this guidance follow:
Patients in the U.S. Who Should Be Evaluated for MERS-CoV Infection
Healthcare professionals should evaluate for MERS-CoV infection, patients in the U.S. who meet the following criteria:
- Fever and pneumonia or acute respiratory distress syndrome (based on clinical or radiologic evidence) AND EITHER:
OR
- history of travel from countries in or near the Arabian Peninsula1 within 14 days before symptom onset OR
- close contact2 with a symptomatic traveler who developed fever and acute respiratory illness (not necessarily pneumonia) within 14 days after traveling from countries in or near the Arabian Peninsula) OR
- is a member of a cluster of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) of unknown etiology in which MERS-CoV is being evaluated in consultation with state or local health department (more details below).
- Close contact2 of a confirmed or probable case of MERS (more details below).
See the Case Definitions for more information.
Patients with lower respiratory illness should also be evaluated for common causes of community-acquired pneumonia3, guided by clinical presentation and epidemiologic and surveillance information. For these patients, testing for MERS-CoV and other respiratory pathogens can be done simultaneously. Positive results for another respiratory pathogen (e.g., influenza) should not necessarily preclude testing for MERS-CoV because co-infection can occur.
The big unknown right now is how well this virus spreads – either mildly or asymptomatically – among the contacts of active MERS cases. And this is why there is so much focus on contact tracing, and testing of those who may have been exposed.
Right now we don’t know if Saturday’s revelation that a contact of the Indiana case has developed antibodies (see CDC: Contact Of Indiana MERS Case Tests Positive For The Virus) to the virus is a rare `exception to the rule’, or if it happens with some degree of regularity.
If anything `good’ can be said about the importation of the virus to the United States, it is that the CDC’s and local public health department’s investigations will probably tell us more about how this virus spreads to close contacts over the next couple of weeks than we’ve learned over the past two years.
The CDC’s guidelines for tracking and evaluating these contacts follows:
Evaluation and Management of Close Contacts
CLOSE CONTACTS OF A CONFIRMED OR PROBABLE CASE
Close contacts2 of a confirmed or probable case of MERS while the case was ill should be evaluated in consultation with state and local health departments. Other contacts of the ill person, such as community contacts or contacts on conveyances (e.g., airplane, bus), should also be evaluated in consultation with state and local health departments.
Close contacts2 of a confirmed or probable case, if not using recommended infection control precautions (e.g., appropriate use of personal protective equipment), are at increased risk and should be evaluated and monitored by healthcare professionals with a higher index of suspicion to detect MERS-CoV infection. The spectrum of illness due to MERS-CoV infection is incompletely defined. Although most reported cases have had severe acute lower respiratory illness, mild and asymptomatic infections have been reported and in some cases, diarrhea preceded respiratory symptoms. Testing nasopharyngeal and oropharygeal swabs by rRT-PCR to detect MERS-CoV should be considered on initial evaluation, regardless of the presence or nature of symptoms. Healthcare professionals should carefully monitor for the appearance of fever (T>100°F) or respiratory symptoms within 14 days following the close contact, as one of these signs would meet the criteria for a patient under investigation (PUI). Other early symptoms have included headache, chills, myalgia, nausea/vomiting and diarrhea. Symptomatic contacts should be evaluated and, depending on their clinical history and presentation, considered for more extensive MERS-CoV testing, including rRT-PCR testing of lower respiratory and serum specimens, and possibly MERS-CoV serology, especially if symptom onset was more than 14 days prior.
Close contacts2 who are ill and being evaluated for MERS-CoV infection and do not require hospitalization for medical reasons may be cared for and isolated in their home. (Isolation is defined as the separation or restriction of activities of an ill person with a contagious disease from those who are well). For asymptomatic close contacts2 who are being evaluated for MERS-CoV, the possible benefit of home quarantine or other measures, such as wearing masks, is uncertain due to lack of information about transmissibility from persons with asymptomatic infection. Asymptomatic contacts who test positive by PCR, especially in respiratory specimens or serum, likely pose a risk of transmission, although the magnitude and contributing factors are unknown. Providers should contact their state or local health department to discuss home isolation, home quarantine or other measures for close contacts, especially for patients who test positive, and to discuss criteria for discontinuing any such measures. Recommendations may be modified as more data become available. For more information, see CDC’s Interim Home Care and Isolation Guidance for MERS-CoV.
CLOSE CONTACTS OF A PUI
Evaluation and management of close contacts2 of a PUI should be discussed with state and local health departments. Close contacts of a PUI should monitor themselves for fever and respiratory illness and seek medical attention if they become ill within 14 days after contact. Healthcare providers should consider the possibility of MERS.
Clusters of Respiratory Illness in Which MERS-CoV Infection Should Be Considered
Clusters4 of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) without recognized links to a case of MERS-CoV infection or to travelers from countries in or near the Arabian Peninsula should be evaluated for common respiratory pathogens.3 If the illnesses remain unexplained, providers should consider testing for MERS-CoV, in consultation with state and local health departments.
The reality is (in the near term) that hundreds of people will probably be evaluated for, and cleared of, MERS for every case that proves positive. We know that so far, most contacts of known cases never develop illness. And that is likely to remain the case unless the virus changes in some way.
The current risk to the general community is very low. Outside of the Arabian Peninsula, MERS remains a very rare virus.
Our best hope of keeping it rare is to remain vigilant and exercise an abundance of caution when it comes to isolating suspected cases. But no matter how vigilant we remain - mild, asymptomatic, or atypical presentations of the virus – could easily thwart even the best of surveillance and containment plans.
Which means that until this virus can be contained and controlled at its source (the Arabian Peninsula), it is likely to pose a serious challenge to the entire world’s public health systems for some time to come.
