Multifacility Outbreak of Middle East Respiratory Syndrome in Taif, Saudi Arabia

Abstract

Middle East respiratory syndrome (MERS) coronavirus (MERS-CoV) is a novel respiratory pathogen first reported in 2012. During September 2014-January 2015, an outbreak of 38 cases of MERS was reported from 4 healthcare facilities in Taif, Saudi Arabia; 21 of the 38 case-patients died. Clinical and public health records showed that 13 patients were healthcare personnel (HCP). Fifteen patients, including 4 HCP, were associated with 1 dialysis unit. Three additional HCP in this dialysis unit had serologic evidence of MERS-CoV infection. Viral RNA was amplified from acute-phase serum specimens of 15 patients, and full spike gene-coding sequencing was obtained from 10 patients who formed a discrete cluster; sequences from specimens of 9 patients were closely related. Similar gene sequences among patients unlinked by time or location suggest unrecognized viral transmission. Circulation persisted in multiple healthcare settings over an extended period, underscoring the importance of strengthening MERS-CoV surveillance and infection-control practices.

Keywords: MERS; MERS-CoV; Middle East respiratory syndrome; Saudi Arabia; coronavirus; epidemiology; genetic sequencing; respiratory infections; serum; viruses.

Figure 1

Middle East respiratory syndrome coronavirus (MERS-CoV) case-patients reported in Taif, Saudi Arabia, during September 2014–January 2015. Indicated are time of symptom onset or first positive laboratory testing. Healthcare setting where transmission likely occurred is shown by color. Circles indicate healthcare personnel (HCP), squares non-HCP; black outlines indicate that patient died. Asterisks (*) indicate that sequencing was performed on the patient’s serum sample.

Figure 2

Midpoint-rooted phylogenetic tree inferred from multiple-sequence alignment of 10 new cases of Middle East respiratory syndrome coronavirus (MERS-CoV) spike open reading frame sequences (4,062 nt) from Taif, Saudi Arabia (brackets). Colored circles identify healthcare facilities; numbers indicate individual patients. Taif sequences are shown in context with the closest related sequences that comprise the Hafr-Al-Batin_1 clade, as originally defined by Cotton et al. (17), and with sequences related to the 2015 outbreak event in South Korea. For clarity, the remaining published sequences are collapsed into triangles. Published sequences are designated by GenBank accession number, strain name, and month and year of sample collection. The estimated neighbor-joining tree was constructed from nucleotide alignments by using MEGA version 6.06 (http://www.megasoftware.net). Bootstrap support values (1,000 replicates) ≥70% are plotted at the indicated internal branch nodes. Scale bar shows the genetic distance as the number of nucleotide substitutions per site. KSA, Kingdom of Saudi Arabia.