CHICAGO — Junior doctors quickly learn that exposure to patients’ germs is part of the job, but a study suggests many are returning the favor. More than half of doctors in training said in a survey that they’d shown up sick to work, and almost one-third said they’d done it more than once.

Misplaced dedication and fear of letting other doctors down are among reasons the researchers cited as possible explanations.

The researchers analyzed an anonymous survey of 537 medical residents at 12 hospitals around the country conducted last year by the Accreditation Council for Graduate Medical Education. The response rate was high; the hospitals were not identified.

The results appear in today’s Journal of the American Medical Association.