Tuberculosis, a bacterial infection rare on college campuses, may be at Yale.

Doctors at Yale HEALTH are treating an undergraduate student for suspected active tuberculosis, though they are still waiting for confirmation of the respiratory bacterial infection — a test which can take up to six weeks. The student is currently undergoing antibiotic therapy in an isolation room at the Yale Health Center at 55 Lock St., Director of Yale HEALTH Paul Genecin said in an e-mail to members of the Yale community Tuesday morning.

“This is a disease that is clinically compatible with TB and in which other tests (besides cultures) are positive,” Genecin said in an interview Sunday night. “Since we are treating the patient for active TB as well as identifying and testing his contacts, this patient’s culture result — positive or negative — is unlikely to have practical importance.”

Genecin reported that the student, who has not been identified for confidentiality reasons, is improving and will be able to resume normal activities after two weeks in the isolation unit.

Because people with active tuberculosis are able to spread bacteria to others, Yale HEALTH has requested that about 50 students and faculty who have been in close contact with the student take a tuberculosis test when they arrive back on campus after fall break.

“The risk of catching tuberculosis from an actively infected person depends on the proximity and intensity of contact,” Genecin said in an e-mail Thursday. “Unless someone spends significant amounts of time within 20 feet of the patient, the risk of transmission is very low.”

Only people with active tuberculosis are able to expose others to the bacteria, he said, and because people who are newly infected with tuberculosis do not cough up sputum — matter from the respiratory tract that contains the bacteria — Yale students have little to fear.

“Those who have had close contact with this student have NO potential to further spread tuberculosis at this time,” Genecin said.

He said that although many people at Yale regularly test positive for tuberculosis infection, their immune systems — in combination with appropriate drug treatment — are able to keep bacteria from causing illness in themselves and the people around them. Such cases are called latent TB infections, Genecin said.

Genecin said tuberculosis is an infection rarely seen on the Yale campus, with a case surfacing on average every couple of years.

Tuberculosis might not be a common disease at Yale, but the Centers for Disease Control report that the disease affects approximately one in three people worldwide. The Connecticut Department of Health reported 11 cases of tuberculosis in New Haven in 2009.