The source? Signs of the Middle East respiratory syndrome virus have been detected in camels on the Arabian Peninsula. But it's still a mystery how people catch the disease. Sean Gallup/Getty Images hide caption

itoggle caption Sean Gallup/Getty Images

A new coronavirus looks a lot like its cousin SARS under the microscope, but it appears they're quite different when it comes to contagiousness. NIAID/RML hide caption

itoggle caption NIAID/RML

Coronaviruses have a characteristic crown of tentacles when viewed under the electron microscope. BSIP/UIG via Getty Images hide caption

itoggle caption BSIP/UIG via Getty Images

Virologists discovered the new coronavirus after it killed a Saudi Arabian man last summer. Elizabeth R. Fischer/Rocky Mountain Labs/NIAID/NIH hide caption

itoggle caption Elizabeth R. Fischer/Rocky Mountain Labs/NIAID/NIH