Prevalence of MERS-CoV in Healthy Adults in Western Saudi Arabia, 2011-2016; a Retrospective, Cross-Sectional Seroepidemiological Study

Abstract

Background: MERS-CoV is a newly recognized zoonotic coronavirus. Current evidence confirms the role of dromedaries in primary human cases but does not explain sporadic community cases. However, asymptomatic or subclinical cases could represent a possible source of infection in the community. Therefore, we investigated the seroprevalence of MERS-CoV in the general population of the western region of Saudi Arabia. Methods: Archived human sera (7,461) collected between 2011 and 2016 from healthy adult blood donors from 50 different nationalities in the western part of Saudi Arabia were obtained. Samples were tested for MERS-CoV S1-specific antibodies (Abs) by ELISA and confirmed by testing for neutralizing Abs (nAbs) using both pseudotyped and live virus neutralization assays. Findings: Out of 7,461 samples, 174 sera from individuals with 18 different nationalities were ELISA positive (2·3%, 95% CI 2·0-2·7). Presence of nAbs was confirmed in 17 samples (0·23%, 95% CI 0·1-0·4) of which one sample exhibited positivity in both neutralization assays. Confirmed seropositivity was identified in young (15-44 years) Middle Eastern men and women from Saudi Arabia, Egypt, Yemen, Pakistan, Palestine, Sudan, and India without significant preference. Interpretation: An increasing trend of unreported MERS-CoV seroprevalence was observed in the general population in western Saudi Arabia, suggesting that asymptomatic or mild infections might exist and act as an unrecognized source of infection. Seropositivity of individuals from different nationalities underscores the potential MERS exportation outside of the Arabian Peninsula. Thus, enhanced and continuous surveillance is highly warranted. Funding Statement: King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia (grant number 09-1). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: Ethical approval was obtained from the Unit of Biomedical Ethics in King Abdulaziz University Hospital. Before starting the study, all samples were anonymized using serial numbers.