First reported in Saudi Arabia in 2012, every case of MERS — so far, 571 confirmed in 18 countries, but the numbers are rapidly changing — was likely contracted on the Arabian Peninsula. The number of laboratory-confirmed MERS cases spiked since mid-March, mostly in Saudi Arabia and the United Arab Emirates, according to the World Health Organization.
The disease is caused by a coronavirus (known to produce mild-to-severe upper-respiratory-tract illnesses) called MERS-CoV. Confirmed cases of MERS have included fever, cough, and shortness of breath. No one knows for sure how this specific virus originated, but recent research found sub-strains of MERS in single-humped camels located in Saudi Arabia (read more here). Health officials are still investigating how people contract the virus, since most MERS patients had no established contact with camels. As of right now, the Centers for Disease Control says 30% of cases have resulted in death.
On May 2, the first U.S. case of MERS was confirmed in Indiana in an American health worker who had been on the job in Saudi Arabia. The CDC reports the patient is now fully recovered. Nine days later, a second U.S. case of MERS was confirmed in Orlando, Florida — also a health care professional who lives and works in Saudi Arabia.
Right now, the CDC says the two U.S. cases pose a very low risk to the general public, and does not recommend anyone change their current travel plans — though anyone who does travel to countries on or near the Arabian Peninsula should inform their doctor. Unfortunately, many questions remain unanswered about MERS. For example, we don't know how it spreads, how to treat it specifically, or how to take preventive measures (currently, there’s no available vaccine). As of Wednesday morning, WHO has not declared a global emergency.