Risk Factors for Primary Middle East Respiratory Syndrome Coronavirus Illness in Humans, Saudi Arabia, 2014

Alraddadi, Basem M.; Watson, John T.; Almarashi, Abdulatif; Abedi, Glen R.; Turkistani, Amal; Sadran, Musallam; Housa, Abeer; Almazroa, Mohammad A.; Alraihan, Naif; Banjar, Ayman; Albalawi, Eman; Alhindi, Hanan; Choudhry, Abdul Jamil; Meiman, Jonathan G.; Paczkowski, Magdalena; Curns, Aaron; Mounts, Anthony; Feikin, Daniel R.; Marano, Nina; Swerdlow, David L.; Gerber, Susan I.; Hajjeh, Rana; Madani, Tariq A.

Risk factors for primary Middle East respiratory syndrome coronavirus (MERS-CoV) illness in humans are incompletely understood. We identified all primary MERS-CoV cases reported in Saudi Arabia during March–November 2014 by excluding those with history of exposure to other cases of MERS-CoV or acute respiratory illness of unknown cause or exposure to healthcare settings within 14 days before illness onset. Using a case–control design, we assessed differences in underlying medical conditions and environmental exposures among primary case-patients and 2–4 controls matched by age, sex, and neighborhood. Using multivariable analysis, we found that direct exposure to dromedary camels during the 2 weeks before illness onset, as well as diabetes mellitus, heart disease, and smoking, were each independently associated with MERS-CoV illness. Further investigation is needed to better understand animal-to-human transmission of MERS-CoV.