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

The number of measles cases associated with an outbreak in Texas has increased to 159 -- an increase of 13 cases in the past five days, authorities said on Tuesday.

Harris County officials outlined a plan to boost vaccination rates for measles and trace any potential cases in Houston—as Robert F. Kennedy Jr. said the federal government plans to combat the outbreak by shipping doses of vitamin A to Gaines County.