The Chief of Pediatrics at the LBJ Hospital in American Samoa, Fuata Dr Iatala, says there is concern about the increase in the cases of mumps.
This comes after reports of a spread of measles but Dr Iatala says there has been no outbreak this year.
However, he says there has been an unusually large number of older children who have come down with mumps.
These include those who have already had measles, mumps and rubella shots.
Dr Iatala says what they are afraid of is a new strain of mumps developing.