Several studies have been conducted on the transmission of bacteria from human-to-human through sexual relations, she said. But, bacterial infections, at times, appear in people who have not engaged in sexual relations.

“What we don’t know is how these women — and men in this case — actually acquire the bacterium,” Manning said.

Human GBS infection has been suspected to originate in cows, but very little research has been conducted to confirm the suspicion. The researchers looked for a potential link between exposure to cows and the presence of the bacteria, said Dele Davies, the study’s lead researcher and MSU’s Department of Pediatrics and Human Development chairman.

“It’s trying to understand how bugs move from species to species — which one came first? The ones in the humans, the ones in the cows or vice versa,” Davies said.

The researchers collected stool samples from 68 southeastern Michigan families and their livestock, said Amber Million, a 2009 MSU graduate who was involved in the study. DNA was then taken from the samples and examined, she said.

One couple was found to carry the same strain as their cow, indicating there is a possibility the bacteria is transferred between the two species, Davies said.

“We don’t know which direction the transmission occurred,” he said. “Quite possibly, it could have come from human to cows.”

Davies said the research does not mean people should be fearful of exposure to cows. There is no risk factor for being in contact with cows, he said.

“It’s not saying that there’s any risk to drinking cow’s milk,” Davies said. “We just made an observation that just tells us maybe there’s some transmission that can go either way that for the vast majority is no problem.”

Million said more research into the bacteria’s potential transmission is needed.

“We don’t know a lot about (the bacteria), so by figuring out how it’s transmitted … can kind of help us pinpoint mutations and maybe help us lead to a vaccine,” she said.