Molecular Evolution of MERS Coronavirus: Dromedaries as a Recent Intermediate Host or Long-Time Animal Reservoir?

Lau, Susanna K. P.; Wong, Antonio C. P.; Lau, Terrence C. K.; Woo, Patrick C. Y.

In addition to understanding the evolutionary histories of the corresponding viruses, genome analysis has provided important insights to the approach of controlling the clinical diseases of SARS and MERS. The major SARS outbreak in humans in early 2003 originated from a single or very few civet-to-human interspecies jumping events in Southern China, which explains the monophyletic evolution of strains involved in this outbreak. As a result, the epidemic was successfully controlled when the animal source was segregated from humans after closure of wild life wet markets in Southern China. On the other hand, MERS-CoV had been endemic in dromedary population in the Middle East during the outbreak in 2012 with many independent, sporadic camel-to-human transmission events in Saudi Arabia and the neighboring countries. Since MERS-CoV is found in dromedary calves in most countries in the Middle East and Africa, it would be impossible to control the disease by closure of a limited number of facilities in a restricted geographical region. For visitors to the Middle East, it is important to improve education so that they will avoid contacts with dromedaries, particularly dromedary calves. For residents of the Middle East, more viable options may be through the development of rapid laboratory diagnostics, antivirals, and vaccines for treatment and prevention of MERS.