Robert F. Kennedy Jr., the H.H.S. secretary, claimed that doctors had successfully treated children with unconventional remedies, including cod liver oil.

An outbreak of measles in northwest Texas grew to 159 cases on Tuesday, about a dozen more than health officials reported late last week. The latest update from the Texas Department of State Health Services shows the outbreak remains concentrated in school-aged children who have not received the vaccine that protects against measles,

As measles — a preventable disease the U.S. considered eliminated in 2000 — spreads through West Texas’ rural expanse, Klassen is sticking to an approach on vaccines that is a key tenet for Mennonites. Family leaders are the top decision-making authority — not outside recommendations, certainly not government mandates.