While camels are strongly suspected to be the primary zoonotic source of human MERS infection, according to an interview by Dr. Tariq Ahmed Madani last week, only about 3% of human MERS cases actually acquire the virus directly from an animal source.
Limited, and thus far inefficient, human-to-human transmissions – mostly in healthcare settings – are responsible for the rest.
While zoonotic transmission represents only a small percentage of the total, these animal exposures are important because they continually reseed the virus back into the community, and provide the virus with additional opportunities to adapt to human hosts.
Hence the repeated warnings (see Back To The Camel `Shed’) regarding unprotected exposure to camels.
Today, the Saudi MOH has announced another MERS case – this time with `animal exposure’ listed as a possible route of infection, in Rafha.