What Have We Learned About Middle East Respiratory Syndrome Coronavirus Emergence in Humans? A Systematic Literature Review

Dawson, Patrick; Malik, Mamunur Rahman; Parvez, Faruque; Morse, Stephen S.

However, there is relatively little information on asymptomatic individuals, most of whom are detected by contact tracing. In one study, an asymptomatic health care worker excreted MERS-CoV for over 5 weeks (Al-Gethamy et al. 2015) . In the spring 2014 outbreak in Saudi Arabia, an estimated 25.1% of laboratory-confirmed MERS-CoV was asymptomatic (Oboho et al. 2015 ). An analysis of 65 MERS-CoV patients in United Arab Emirates found that 35% were asymptomatic, and 1 individual yielded positive lower respiratory tract specimens for more than 2 weeks . Al Hammadi et al. reported two asymptomatic men who had contact with infected camels; infection was confirmed by PCR in both men, and in all eight camels in the group (Al Hammadi et al. 2015) . However, the actual frequency of asymptomatic individuals compared with symptomatic individuals is largely unknown.