Concerns about Misinterpretation of Recent Scientific Data Implicating Dromedary Camels in Epidemiology of Middle East Respiratory Syndrome (MERS)

Samara, Emad M.; Abdoun, Khalid A.

As for camel-to-human MERS-CoV transmission, several points can be raised that contradict these authors' findings as to whether this form of transmission can or cannot happen. In fact, the reported outcomes by the authors, together with no more than two cases of infection in humans reported over the past 2 years to have been in close proximity to DCs (10, 11) , indicate at most that a virus that is "closely related" to MERS-CoV has been circulating in DCs for the last 2 decades in Saudi Arabia. Additionally, it might be possible that MERS-CoV cannot be transmitted from DCs to humans, as happened previously between cats and humans during the SARS-CoV epidemic (12) . Of course, we understand that identification of the route of transmission from DCs to human beings (if any) would be of utmost importance and (if confirmed) could lead directly to implementation of prevention and intervention strategies. Unfortunately, however, the transmission capability of MERS-CoV from DCs to humans cannot yet be ascertained. Thus, claiming that DCs harbor the infectious form of MERS-CoV does not support the conclusion that they are the source of transmission to humans. It must be confirmed that this form of transmission can actually occur. We suggest addressing this conundrum by the viral culture of MERS-CoV, during which it is imperative to first isolate the virus (preferably the three genotypic variants) from DCs, then to infect epithelial cells of human airway tissues derived from nasal or tracheobronchial regions with the isolated virus, and thereafter, to note the cytopathological changes in the infected cells. This will also provide a useful in vitro model of human lung origin to study the characteristics of MERS-CoV replication and pathogenesis (such as identifying specific cell surface receptors for MERS-CoV). Therefore, an explicit assessment of the epidemiological role of DCs has yet to be made.