The outbreak was responsible for more than half of the 66 measles cases that occurred in the United States that year.
According to AP reports, the study found that the Indiana girl became infected after visiting a Romanian orphanage while on a church-mission trip. The health investigators said that she in turn infected other people who attended a church gathering with her the day after she returned.
Dr. Philip Gould of the Centers for Disease Control and Prevention said, "Orphanages are known to be higher risk. The main point is to ensure that people do get vaccinated, especially prior to leaving the country, going to a place that physicians suspect that measles is a risk."
The hospital records show that33 people from Indiana and one from Illinois became infected. Three people were hospitalized, but no one died.
Only two of the 34 had been vaccinated against measles.
According to the CDC report, "The outbreak occurred because measles was imported into a population of children whose parents had chosen not to vaccinate their children because of safety concerns, despite evidence that measles-containing vaccine is safe and effective."
The records show that almost all of the 32 other U.S. cases in 2005 originated abroad, including 16 involving U.S. residents infected while traveling overseas.
The CDC says that the increasing number of measles vaccinations in the U.S. has decreased the occurrence of the disease, which is often characterized by a rash that begins on the face and spreads to other parts of the body.
The illness, which can cause ear infections, diarrhea and pneumonia, kills about one in 1,000 patients.
