MERS-CoV in Upper Respiratory Tract and Lungs of Dromedary Camels, Saudi Arabia, 2013-2014

Abstract

To assess the temporal dynamics of Middle East respiratory syndrome coronavirus (MERS-CoV) infection in dromedary camels, specimens were collected at 1-2 month intervals from 2 independent groups of animals during April 2013-May 2014 in Al-Ahsa Province, Saudi Arabia, and tested for MERS-CoV RNA by reverse transcription PCR. Of 96 live camels, 28 (29.2%) nasal swab samples were positive; of 91 camel carcasses, 56 (61.5%) lung tissue samples were positive. Positive samples were more commonly found among young animals (<4 years of age) than adults (>4 years of age). The proportions of positive samples varied by month for both groups; detection peaked during November 2013 and January 2014 and declined in March and May 2014. These findings further our understanding of MERS-CoV infection in dromedary camels and may help inform intervention strategies to reduce zoonotic infections.

Keywords: MERS-CoV; Middle East Respiratory syndrome; Saudi Arabia; abattoir; coronavirus; dromedary camels; viruses; zoonoses.

Figure 1

Mucopurulent nasal discharge and lacrymation in 8-month-old dromedary camel naturally infected with Middle East respiratory syndrome coronavirus, Ahsa, Saudi Arabia, December 2013.

Figure 2

Midpoint-rooted phylogenetic tree of Middle East respiratory syndrome coronavirus spike gene open reading frame sequences of this virus obtained from camels and select humans (sequences available from GenBank). The estimated neighbor-joining tree was constructed from nucleotide alignments by using MEGA version 6.06 (http://www.megasoftware.net). Sequence names are derived from GenBank accession number | virus strain name | month-year of collection. Numbers in parentheses denote number of additional available identical spike gene sequences obtained from same identified region of the representative strains. Bootstrap support values (1,000 replicates) >70% are plotted at the indicated internal branch nodes. Scale bars indicate number of nucleotide substitutions per site. Sequences obtained from camels are designated by an icon; sequences obtained from camels in Al-Ahsa Province, Saudi Arabia, 2013–2014, are designated by an asterisk (*).