The first case of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) transmitted to the U.S. has been found in an Illinois man.

The unidentified man from the U.S. was in close contact with the Illinois patient. According to CNN, the Indiana man had an "extended face-to-face contact" with the patient after travelling to Saudi Arabia.

CDC and state health departments began conducting large-scale investigations after confirmation of two MERS cases. The Indiana man was the first to be diagnosed with the Middle East Respiratory Syndrome Coronavirus, while the second was reported from Florida May 11.

The Indiana man was admitted to hospital April 28 and was diagnosed with the infection May 2. The patient has now been released.

Blood test has confirmed May 16 that the Illinois man had MERS infection. He suffered from mild cold-like symptoms and did not seek medical attention, CNN reported.

"This latest development does not change CDC's current recommendations to prevent the spread of MERS," said David Swerdlow, M.D., who is leading CDC's MERS-CoV response, according to a news release. "It's possible that as the investigation continues others may also test positive for MERS-CoV infection but not get sick. Along with state and local health experts, CDC will investigate those initial cases and if new information is learned that requires us to change our prevention recommendations, we can do so."

According to CDC, the virus has spread from person to person, but there is no report of a sustained outbreak of the disease. Most cases of MERS COV have been reported from countries in or near the Arabian Peninsula.

CDC hasn't issued any health warning to the travelers, but has said that people visiting Arabian countries to pay close attention to their health