Submitted Photo - - Most cases of childhood measles documented in the United States trace from unvaccinated patients, citing religious or philosophical reasons.

ATLANTA (AP) — Measles cases in the U.S. are at the highest level in more than a decade, with nearly half of those involving children whose parents rejected vaccination, health officials announced in a report released last week. Worried doctors are troubled by the trend fueled by unfounded fears that vaccines may cause autism. The number of cases is still small, just 131, but that’s only for the first seven months of the year. There were only 42 cases for all of last year. ‘‘We’re seeing a lot more spread. That is concerning to us,’’ said Dr. Jane Seward, of the Centers for Disease Control and Prevention. Pediatricians are frustrated, saying they are having to spend more time convincing parents the shot is safe. ‘‘This year, we certainly have had parents asking more questions,’’ said Dr. Ari Brown, an Austin, Texas, physician who is a spokeswoman for the American Academy of Pediatrics.