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With the approaching seasonal flu season complicated by possible introductions of an emerging novel corona virus, the Centers for Disease Control and Prevention has updated guidance for MERS-CoV.
In the previous guidance the CDC did not recommend MERS-CoV testing for people whose illness could be explained by another etiology. The new guidance states that, in patients who meet certain clinical and epidemiologic criteria, testing for MERS-CoV and other respiratory pathogens can be done simultaneously and that positive results for another respiratory pathogen should not necessarily preclude testing for MERS-CoV.
The CDC recommends collecting multiple specimens from different sites at different times after symptom onset. Lower respiratory specimens are preferred, but collecting nasopharyngeal and oropharyngeal (NP/OP) specimens, as well as stool and serum, are strongly recommended. This will increase the likelihood of detecting MERS-CoV infection. For more information, see CDC’s Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens. Many state health department laboratories are approved for MERS-CoV testing using the CDC rRT-PCR assay. (Contact your state health department to notify them of people who should be evaluated for MERS-CoV and to request MERS-CoV testing. If your state health department is not able to test, contact the CDC at 770-488-7100.)
The new guidance also clarifies recommendations for investigating clusters of severe acute respiratory illness when there is not an apparent link to a MERS-CoV case. Clusters of patients with severe acute respiratory illness (e.g., fever and pneumonia requiring hospitalization) should be evaluated for common respiratory pathogens and reported to local and state health departments. If the illnesses remain unexplained, testing for MERS-CoV should be considered, in consultation with state and local health departments.
No cases of MERS-CoV have been reported in the United States, but the CDC is urging vigilance in what could be a chaotic season for respiratory infections. In addition to MERS-CoV and seasonal flu, patients with similar respiratory symptoms with a history of recent travel to China will raise the specter of emerging novel influenza H7N9. No cases of H7N9 have been reported in the U.S. For now, the greater threat to hospitalized patients appears to be MERS-CoV, which can cause high mortality rates in patients with underlying medical conditions and has shown the ability to spread to patients and health care workers in hospital outbreaks in the Middle East.
As of August 12, 2013, 94 laboratory-confirmed cases of MERS have been reported. Of those cases, 46 (49%) were fatal. All diagnosed cases were among people who resided in or traveled from four countries (Kingdom of Saudi Arabia, United Arab Emirates, Qatar, or Jordan) within 14 days of their symptom onset, or who had close contact with people who resided in or traveled from those countries. Cases with a history of travel from these countries or contact with travelers from these countries have been identified in residents of France, the United Kingdom, Tunisia, and Italy.
The CDC has not changed the case definition of a confirmed MERS case, but the criteria for laboratory confirmation have been clarified. CDC has changed its definition of a probable case so that identification of another etiology does not exclude someone from being classified as a “probable case.” For CDC’s updated case definitions, see http://www.cdc.gov/coronavirus/mers/case-def.html