The origin of MERS (Middle East Respiratory Syndrome) is unknown. Centers for Disease Control and Prevention

Update 8:12 p.m. EDT: U.S. health officials confirmed the country's second case of MERS Monday, and said the patient was in good condition in an Orlando, Florida, hospital, Reuters reported.

The 44-year-old man is a health care worker who lives and works in Saudi Arabia and traveled to the United States to visit relatives. He was admitted to the Dr. P. Phillips Hospital in Orlando on Friday.

The first case was confirmed late last month in Indiana, raising fears about the global spread of the virus that has no treatment and kills about one-third of infected patients. The two cases are not related, said Dr. Anne Schuchat, director of the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention.

The new patient traveled on May 1 from Jeddah to London on Saudi Airlines Flight 113, then changed planes at Heathrow airport and flew from London to Boston, British public health officials said. From Boston, the patient took a flight to Atlanta, and then flew to Orlando. The CDC did not release U.S. flight numbers.

Schuchat said the patient was feeling ill on the flight from Jeddah, but did not feel sick enough to seek treatment until last Friday. The CDC confirmed the presence of MERS virus on Sunday.

The CDC said it is not clear whether the person was infectious on the plane, but it is now contacting some 500 people who traveled on the same U.S. flights as the health worker "out of an abundance of caution," CDC Director Dr. Thomas Frieden told reporters.

Original story:

A second case of the mysterious virus known as MERS (Middle East Respiratory Syndrome) has been reported in the United States, with health officials set to hold a news conference on Monday to discuss details about the latest confirmed case.

Middle East Respiratory Syndrome is caused by a beta coronavirus, a common virus that causes mild to moderate respiratory illness in those whom it effects. The full name of MERS is MERS-CoV, or Middle East Respiratory System Coronavirus. Most people who suffer from the MERS-CoV infection go on to develop severe acute respiratory illnesses, the symptoms of which include fever, coughing and shortness of breath, according to the Centers for Disease Control. About 30 percent of people infected with MERS have died.

The virus first showed up in Saudi Arabia in 2012. All original cases of the syndrome had been reported on the Arabian peninsula, with Saudi Arabia, the United Arab Emirates, Qatar, Oman, Jordan, Kuwait, Yemen and Lebanon all reporting cases. Travel-associated cases of MERS were later reported in the United Kingdom, France, Tunisia, Italy, Malaysia, Turkey and the United States, where the first case was announced on May 2, according to the CDC. That case involved an Indiana man who traveled to Saudi Arabia as a health care worker at a Riyadh hospital, the Associated Press reported. His condition improved, and he was released from a hospital last week.

The origins of MERS is unknown, although it’s believed to have come from an animal source. Besides humans, MERS has been found in camels and bats. “More information is needed to identify the possible role that camels, bats and other animals may play in the transmission of MERS-CoV,” the CDC said on its frequently asked questions page about MERS.

The virus currently spreads from human to human when people infected with MERS come in close contact with a caregiver. The MERS cases are not causing the CDC to place any travel restrictions on anyone planning to visit the Arabian Peninsula or Middle East.

“The CDC does not recommend that anyone change their travel plans because of MERS,” the agency said. “The current CDC travel notice is an Alert (Level 2), which provides special precautions for travelers. Because spread of MERS has occurred in healthcare settings, the alert advises travelers going to countries in or near the Arabian Peninsula to provide health care services to practice CDC’s recommendations for infection control of confirmed or suspected cases and to monitor their health closely. Travelers who are going to the area for other reasons are advised to follow standard precautions, such as hand washing and avoiding contact with people who are ill.”