A novel coronavirus (MERS-CoV) is causing severe disease in the Middle East. In this report on a hospital outbreak of MERS-CoV infection, 23 confirmed cases and evidence of person-to-person transmission were identified. The median incubation period was 5.2 days.
Respiratory viruses are an emerging threat to global health security and have led to worldwide epidemics with substantial morbidity, mortality, and economic consequences.
• What is Middle East respiratory syndrome coronavirus (MERS-CoV)?
In September 2012, the World Health Organization (WHO) reported two cases of severe community-acquired pneumonia caused by a novel human (beta)-coronavirus, subsequently named MERS-CoV. Since then, MERS-CoV has been identified as the cause of pneumonia in patients in Saudi Arabia, Qatar, Jordan, the United Kingdom, Germany, France, and Tunisia. Phylogenetic analysis shows that the MERS-CoV defines a novel lineage C, making this coronavirus the first
• What were the demographic and clinical features associated with the outbreak described by the authors in this week’s issue of the Journal?
Most of the case patients were men, and the median age was 56 years. The most common signs and symptoms were fever (in 87% of the patients) and cough (in 89%), and 35% presented with vomiting or diarrhea. Among patients in whom the illness progressed, the median time from the onset of symptoms to ICU admission was 5 days (range, 1 to 10), the median time to the need for mechanical ventilation was 7 days (range, 3 to 11), and the median time to death was 11 days (range, 5 to 27). Three of four patients (75%) whose cases were detected by active surveillance during the outbreak, as compared with 3 of 19 (16%) whose cases were identified clinically, have recovered (P=0.04). The authors describe a 65% case fatality rate in this outbreak.
Morning Report Questions
Q: What was the incubation period of confirmed cases and mode of transmission?
A: The incubation period of confirmed cases was 5.2 days (95% confidence interval [CI], 1.9 to 14.7); distributions that were fit to observed data indicated that 95% of infected patients would have an onset of symptoms by day 12.4 (95% CI of 95th percentile, 7.3 to 17.5), whereas 5% would have an onset of symptoms by day 2.2 (95% CI of 5th percentile, 1.2 to 3.1). Epidemiologic and phylogenetic analyses support person-to-person transmission. It could not be determined whether person-to-person transmission occurred through respiratory droplets or through direct or indirect contact and whether the virus was transmitted when the contact was more than one meter away from the case patient.
Q: What is the optimal laboratory testing for diagnosis of MERS-CoV infection?
A: Laboratory testing for MERS-CoV remains a challenge. Validated serologic assays are not yet available. In the reported cluster, results of throat swabs were occasionally negative and the testing needed to be repeated. It is not clear whether sputum or nasopharyngeal samples might be superior to throat samples or whether virus is shed more abundantly later in the course of the illness or in more severe illness, as it is in Severe Acute Respiratory Syndrome (SARS). The authors conclude that one cannot reliably rule out MERS-CoV disease on the basis of a single negative test when a patient presents with the appropriate clinical syndrome and epidemiologic exposure. They indicate that repeat testing or tests on sputum or bronchoalveolar-lavage fluid may be of value in improving diagnostic accuracy.