An Illinois resident tested positive for Middle East Respiratory Syndrome after being in contact with an infected patient, though he did not show signs of illness, health officials said on Saturday, the Associated Press reported.
The man likely contracted MERS from a man in Indiana who was hospitalized in late April with the first known U.S. case of the illness, the AP reported.
The Illinois resident's lack of symptoms may shed light on milder forms of the deadly virus, which emerged in the Middle East in 2012 and has infected more than 500 patients in Saudi Arabia alone. It kills about 30 percent of those who are infected, according to the AP.
Researchers at the forefront of the global MERS response said this week they were investigating whether people infected with MERS who have no symptoms could still pass the virus on to others, the AP reported.
CDC officials explained that the blood test is not sufficient to consider him a confirmed case of MERS because it detected only antibodies, not the live virus, according to the AP. Swerdlow said the agency would discuss with the World Health Organization its system of classifying MERS cases to account for milder cases.
On April 25, the Illinois man had a 40-minute face-to-face meeting with the Indiana patient, a business associate, Swerdlow said, the AP reported. The two men shook hands but the Indiana patient did not have a cough at the time.
Swerdlow said 50 people who came into contact with the Indiana patient have tested negative for MERS but are undergoing more tests, according to the AP. Health officials are now trying to identify and monitor close contacts of the Illinois resident.
"It's possible that as the investigation continues, others may also test positive for MERS-CoV infection but not get sick," Swerdlow said, the AP reported.
The first case of MERS was confirmed in Indiana in early May and the second, in Florida, on May 11, according to the AP.
The disease causes coughing, fever and sometimes fatal pneumonia and is moving out of the Arabian peninsula as infected individuals travel from the region, the AP reported.
