The patient, a healthcare worker who lives in Saudi Arabia and is in the U.S. visiting family, flew to Chicago on April 24 and took a bus from Illinois to Indiana. About 100 airline and 10 bus passengers were exposed to the patient, the CDC said. Most have been tested and none so far are found to be positive for MERS.
About 50 employees of Community Hospital in Munster, Ind., were exposed to the patient, who arrived in the hospital's emergency room on April 28. Those employees have also tested negative for MERS, but will remain at home throughout the incubation period.
The patient is currently breathing independently and recovering well, officials said. He may be released from the hospital soon, but an expected date and whether or not he will be released into home isolation or return immediately to Saudi Arabia, is still being determined.
Like SARS, the viral respiratory illness that appeared in 2003, MERS is caused by a coronavirus and spreads through sustained close contact with an infected individual. MERS has been most virulent among the elderly and people with other underlying conditions, leading to death in about a third of those cases.
Most patients develop flu-like symptoms within about five days after exposure to the virus, though for some it can be as little as two days and others as many as 14. Though no travelers or hospital employees exposed to the patient have tested positive, each will be monitored for 14 days after the last contact with the patient and retested.
“We're not surprised that MERS has come to the U.S.,” said Dr. Daniel Feikin, the CDC medical epidemiologist who is leading the investigation. “We know infectious diseases do not respect international boundaries.”
In anticipation of the virus, the CDC has been working for over a year with local and state health departments to enhance surveillance and provide information on testing. They are also working closely with agents at U.S. ports of entry, but there are no active screenings for people entering the U.S. from the Middle East.
More than 400 people in 12 countries have been reported with the condition since it was first identified 2012. There have been 93 deaths, according to the CDC. All reported cases have originated in six countries in the Arabian Peninsula.
Follow Sabriya Rice on Twitter: @MHsrice