CONCORD — David Kwiatkowski, 33, the traveling hospital technician believed responsible for dozens of cases of hepatitis C among patients at Exeter Hospital's cardiac-catheterization unit, made his initial appearance in U.S. District Court Tuesday.

Kwiatkowski, who had been undergoing treatment in a Massachusetts hospital, was transported to court by the U.S. Marshal's Service.

U.S. Attorney John Kacavas said Kwiatkowski was advised of his rights and the charges against him, and he waived both a preliminary hearing and a detention hearing.

Kacavas said that following the brief hearing, Kwiatkowski was remanded to the custody of the marshals and was transported to the Strafford County Jail.

Kacavas said Kwiatkowski was initially informed of two federal offenses he is alleged to have committed during his employment, first as a traveling technician working as a temporary and later as a hospital employee between April 1, 2011, and May 25, 2012.

So far, 30 patients who were treated at the cardiac-catheterization unit while Kwiatkowski worked at the hospital have been diagnosed with the same strain of hepatitis C as Kwiatkowski's.

State public health officials earlier said they believed a hospital worker, now identified as Kwiatkowski, abused drugs and used syringes with anesthetics intended for patients and then replaced the contents of the contaminated needles with another liquid that was used on patients, resulting in infections.

Kacavas said the number of charges against Kwiatkowski will increase when information is presented to the grand jury. “We'll let the evidence dictate what the charges are,” said Kacavas. He declined to say when that grand jury will sit.