New Hampshire ? A New Hampshire woman diagnosed with a rare gastrointestinal anthrax case may have swallowed spores propelled into the air by vigorous drumming, a state health expert said.

Officials haven’t confirmed how she contracted the disease but are focusing on a drum circle gathering she attended Dec. 4 at the United Campus Ministry center in Durham shortly before becoming ill. Anthrax spores were found on two drums.

Dr. Elizabeth Talbot, an adviser to the state’s public health division, said one theory is that the woman ingested airborne spores from a drum’s animal-hide covering.