The Centers for Disease Control and Prevention is urging passengers on a flight that left Atlanta for Paris earlier this month to check for possible tuberculosis exposure.

The CDC held a news conference Tuesday to warn air travelers that a passenger on those flights was probably ill with a highly drug resistant strain of TB.

The man with the suspected rare form of TB was aboard Air France flight 385 that departed from Hartsfield-Jackson International Airport on May 12, arriving in Paris May 13. He flew from Prague to Montreal on Czech Airlines flight 0104 on May 24 and entered the U.S. by car.

Dr. Julie Gerberding, head of the CDC, said travelers who sat near the ill passenger could become exposed, although the risk of transmission is low.

"The CDC is recommending those patients be notified and such persons have a test for tuberculosis," Gerberding said. "The potential for transmission is on the low side but we know it isn't zero."

She said the passenger was aware he had TB but had "compelling personal reasons" to travel. She did not identify him.

Gerberding said the patient is being kept in isolation during evaluation. This marks the first time since 1963 that the government issued a quarantine order. The last such order was to quarantine a patient with smallpox, according to the CDC.

Before this case, only 49 instances of extensively drug-resistant TB have been reported in the U.S. since 1993. But Gerberding called it "an emerging problem on a global basis."

TB germs are spread by coughing, sneezing and speaking, and can float in the air for several hours. Persons with TB can suffer sickness, weakness, weight loss, fever and night sweats. Coughing, chest pain and coughing up of blood also can occur.

Approximately 30 percent of individuals with extensively drug-resistant TB are cured, according to the CDC.

The ill passenger cooperated with authorities after learning he had an unusually dangerous form of TB. He voluntarily went to a hospital and is not facing prosecution, officials said.

The man is hospitalized in Atlanta in respiratory isolation, according to the World Health Organization.

The CDC recommends medical exams for cabin crew members on those two flights, as well as passengers sitting in the same rows or within two rows of the passenger.

Because of antibiotics and other measures, the TB rate in the United States has been falling for years. Last year, it hit an all-time low of 13,767 cases, or about 4.6 cases per 100,000 Americans.

Tuberculosis kills nearly 2 million people each year worldwide.