Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) 
in 2012, there have been a number of clusters of human-to-human transmission. 
These cases of human-to-human transmission involve close contact and have 
occurred primarily in healthcare settings, and they are suspected to result from 
repeated zoonotic introductions. In this study, we sequenced whole MERS-CoV 
genomes directly from respiratory samples collected from 23 confirmed MERS cases 
in the United Arab Emirates (UAE). These samples included cases from three 
nosocomial and three household clusters. The sequences were analysed for changes 
and relatedness with regard to the collected epidemiological data and other 
available MERS-CoV genomic data. Sequence analysis supports the epidemiological 
data within the clusters, and further, suggests that these clusters emerged 
independently. To understand how and when these clusters emerged, respiratory 
samples were taken from dromedary camels, a known host of MERS-CoV, in the same 
geographic regions as the human clusters. Middle East respiratory syndrome 
coronavirus genomes from six virus-positive animals were sequenced, and these 
genomes were nearly identical to those found in human patients from 
corresponding regions. These data demonstrate a genetic link for each of these 
clusters to a camel and support the hypothesis that human MERS-CoV diversity 
results from multiple zoonotic introductions.