More people had measles infections in the first seven months of this year than during any comparable period since 1996, and public health officials blamed growing numbers of parents who refuse to vaccinate their children.

Many of these parents say they believe vaccines cause autism, even though multiple studies have found no reputable evidence to support such a claim. In Britain, Switzerland, Israel and Italy, measles outbreaks have soared, sickening thousands and causing at least two deaths.

From January through July, 131 measles cases were reported to the Centers for Disease Control and Prevention from 15 states and the District of Columbia. Fifteen people, including four infants, were hospitalized. There were no deaths. Nearly all the cases resulted when people traveling abroad or visiting from a foreign country spread the illness to others. In Illinois, 30 people were sickened in one outbreak.

Most of those who were sickened were unvaccinated or had an unknown vaccination status. Sixteen were younger than a year old, too young to have been vaccinated. But two-thirds of the rest  or 63 people  were unvaccinated because of their or their parents’ philosophical or religious beliefs.