title: Presence of Middle East respiratory syndrome coronavirus antibodies in Saudi Arabia: a nationwide, cross-sectional, serological study.
abstract: BACKGROUND
  Scientific evidence suggests that dromedary camels are the intermediary host for the Middle East respiratory syndrome coronavirus (MERS-CoV). However, the actual number of infections in people who have had contact with camels is unknown and most index patients cannot recall any such contact. We aimed to do a nationwide serosurvey in Saudi Arabia to establish the prevalence of MERS-CoV antibodies, both in the general population and in populations of individuals who have maximum exposure to camels.
  
  
  METHODS
  In the cross-sectional serosurvey, we tested human serum samples obtained from healthy individuals older than 15 years who attended primary health-care centres or participated in a national burden-of-disease study in all 13 provinces of Saudi Arabia. Additionally, we tested serum samples from shepherds and abattoir workers with occupational exposure to camels. Samples were screened by recombinant ELISA and MERS-CoV seropositivity was confirmed by recombinant immunofluorescence and plaque reduction neutralisation tests. We used two-tailed Mann Whitney U exact tests, χ(2), and Fisher's exact tests to analyse the data.
  
  
  RESULTS
  Between Dec 1, 2012, and Dec 1, 2013, we obtained individual serum samples from 10,009 individuals. Anti-MERS-CoV antibodies were confirmed in 15 (0·15%; 95% CI 0·09-0·24) of 10,009 people in six of the 13 provinces. The mean age of seropositive individuals was significantly younger than that of patients with reported, laboratory-confirmed, primary Middle Eastern respiratory syndrome (43·5 years [SD 17·3] vs 53·8 years [17·5]; p=0·008). Men had a higher antibody prevalence than did women (11 [0·25%] of 4341 vs two [0·05%] of 4378; p=0·028) and antibody prevalence was significantly higher in central versus coastal provinces (14 [0·26%] of 5479 vs one [0·02%] of 4529; p=0·003). Compared with the general population, seroprevalence of MERS-CoV antibodies was significantly increased by 15 times in shepherds (two [2·3%] of 87, p=0·0004) and by 23 times in slaughterhouse workers (five [3·6%] of 140; p<0·0001).
  
  
  CONCLUSIONS
  Seroprevalence of MERS-CoV antibodies was significantly higher in camel-exposed individuals than in the general population. By simple multiplication, a projected 44,951 (95% CI 26,971-71,922) individuals older than 15 years might be seropositive for MERS-CoV in Saudi Arabia. These individuals might be the source of infection for patients with confirmed MERS who had no previous exposure to camels.
  
  
  BACKGROUND
  European Union, German Centre for Infection Research, Federal Ministry of Education and Research, German Research Council, and Ministry of Health of Saudi Arabia.
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.
authors: Marcel A
authors: MA
authors: Müller
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.
authors: Benjamin
authors: B
authors: Meyer
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany; German Centre for Infection Research, Partner Site Bonn-Cologne, Bonn, Germany.
authors: Victor M
authors: VM
authors: Corman
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia.
authors: Malak
authors: M
authors: Al-Masri
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia; Makkah Regional Health Affairs, Ministry of Health, Makkah, Saudi Arabia.
authors: Abdulhafeez
authors: A
authors: Turkestani
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.
authors: Daniel
authors: D
authors: Ritz
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.
authors: Andrea
authors: A
authors: Sieberg
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany.
authors: Souhaib
authors: S
authors: Aldabbagh
authors: Department of Infectious Diseases and Immunology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands.
authors: Berend-J
authors: BJ
authors: Bosch
authors: Euroimmun AG, Lübeck, Germany.
authors: Erik
authors: E
authors: Lattwein
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia.
authors: Raafat F
authors: RF
authors: Alhakeem
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia.
authors: Abdullah M
authors: AM
authors: Assiri
authors: Saudi Center for Disease Control, Riyadh, Saudi Arabia.
authors: Ali M
authors: AM
authors: Albarrak
authors: National Health Laboratory, Riyadh, Saudi Arabia.
authors: Ali M
authors: AM
authors: Al-Shangiti
authors: Johns Hopkins Aramco Healthcare, Dhahran, Saudi Arabia; Indiana University School of Medicine, Indianapolis, IN, USA.
authors: Jaffar A
authors: JA
authors: Al-Tawfiq
authors: Institute of Evolutionary Biology, University of Edinburgh, Centre for Infection, Immunity and Evolution, Edinburgh, UK.
authors: Paul
authors: P
authors: Wikramaratna
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia.
authors: Abdullah A
authors: AA
authors: Alrabeeah
authors: Institute of Virology, University of Bonn Medical Centre, Bonn, Germany; German Centre for Infection Research, Partner Site Bonn-Cologne, Bonn, Germany. Electronic address: drosten@virology-bonn.de.
authors: Christian
authors: C
authors: Drosten
authors: King Abdulaziz Medical City & Advisor Royal Court, Riyadh, Saudi Arabia; Alfaisal University, Riyadh, Saudi Arabia. Electronic address: zmemish@yahoo.com.
authors: Ziad A
authors: ZA
authors: Memish
mesh_terms: D000003:Abattoirs; D000293:Adolescent; D000328:Adult; D000368:Aged; D000822:Animal Husbandry; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002162:Camelus / Q000821:virology*; D018352:Coronavirus Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D065207:Middle East Respiratory Syndrome Coronavirus / Q000276:immunology*; D009790:Occupations; D015995:Prevalence; D012529:Saudi Arabia / Q000453:epidemiology; D016036:Seroepidemiologic Studies
chemical_list: D000914:Antibodies, Viral