MERS-CoV was first reported in Saudi Arabia in September 2012. In a press release issued May 2, 2014, the Centers for Disease Control and Prevention (CDC) identified 401 confirmed cases of MERS-CoV infection in 12 countries, with all reported cases originating in the Arabian Peninsula. Most patients developed severe acute respiratory illness, with fever, cough, and shortness of breath, and 93 patients have died. The case fatality rate in symptomatic patients is 30%.
On April 24, 2014, the World Health Organization (WHO) issued a statement indicating, "although camels are suspected to be the primary source of infection for humans, the exact routes of direct or indirect exposure remain unknown. Investigations to identify the source of infection and routes of exposure are still ongoing." (See also a recent article from Emerging Infectious Diseases, "Human Infection With MERS Coronavirus After Exposure to Infected Camels.")
The April 24, 2014, WHO statement pointed out that a full 75% of the recently reported cases appear to be secondary cases, meaning that the individuals acquired the infection from another infected person. "The majority of these secondary cases are mainly healthcare workers who have been infected within the healthcare setting, although several patients who were in the hospital for other reasons are also considered to have been infected with MERS‐CoV in the hospital. The majority of the infected healthcare workers presented with no or minor symptoms. Only 4 instances of transmission within households have been reported, and no large family cluster has been identified. When human‐to‐human transmission occurred, transmission was not sustained, and to date only 2 possible tertiary cases have been reported."
On May 2, 2014, the first confirmed case of MERS-CoV was reported in the United States: A healthcare worker who was working in Saudi Arabia and who traveled back to the United States on April 24 fell ill on April 27, went to an unidentified hospital emergency department in Indiana on April 28, and was admitted to the hospital that same day. On May 2, CDC testing confirmed that the patient had MERS-CoV, and he/she remains in the hospital, in isolation and in stable condition.
