A health consultant to the Marshall Islands says a mumps outbreak in Arkansas State last year could be linked to the current outbreak in the Marshalls.
Arkansas has a large Marshallese community, and they accounted for more than half of cases during a mumps outbreak there late last year.
The Marshall Islands was now battling at least a thousand cases of mumps, which was first discovered in March.
Jill McCready, who works for the Pacific Island Health Officers' Association, said travel advice was issued to Marshallese living in Arkansas in October, but this wasn't enough to keep the outbreak contained.
She said the Arkansas outbreak raised concerns in the Marshall Islands, which was conveyed to the Attorney General.
"It was an absolute concern that we would import it from Arkansas and despite all of our efforts it happened because you know you absolutely cannot tell someone they cannot get on an airplane, that's what the Attorney General told us."
"We had no ability to stop someone from travelling," she said.