As measles cases in West Texas are still on the rise two months after the outbreak began, local public health officials say they expect the virus to keep spreading for at least several more months and that the official case number is likely an undercount.

(Reuters) -Measles cases in Texas and New Mexico rose to 351 on Friday, the health departments of the states said, an increase of 34 infections over the last three days as the United States deals with one of the largest measles outbreaks in the past decade.