UPDATE 1-U.S. retains measles-elimination status despite worst outbreak in quarter-century

quarter-century@ (Adds background throughout)

Oct 4 (Reuters) - The United States has narrowly retained its World Health Organization measles elimination status, despite seeing 1,249 measles cases so far this year in the worst outbreak since 1992, federal health officials said on Friday.

The U.S. Centers for Disease Control said that 75% of cases of the highly contagious and sometimes deadly disease this year were associated with outbreaks in New York City and New York State, and blamed the spread on parents who had opted not to vaccinate their children.

"Both jurisdictions have since passed two incubation periods for measles with no additional reported cases associated with these outbreaks as of Oct. 1, 2019; however, continued vigilance is important to ensure that elimination is sustained," the report said.

An outbreak is typically considered over when there are no new measles cases reported for 42 days, which is double the incubation time for the disease.

The disease was declared eliminated in the United States in 2000, meaning there was no continuous transmission for a year, and the outbreak in New York this year narrowly avoided meeting that threshold. The last rash onset associated with a measles case in New York, where the outbreak initially centered on Orthodox Jewish communities, was recorded on Aug. 19.

Health officials have attributed the outbreak, which affected 31 states this year, to a vocal fringe of U.S. parents who refuse to vaccinate their children because they believe, contrary to scientific evidence, that ingredients in them can cause autism.

U.S. Health and Human Services Secretary Alex Azar in April said the outbreak was "completely avoidable" and that it was the unfortunate result of some people's choice to deny the proven safety of vaccines. (Reporting by Gabriella Borter in New York; Editing by Scott Malone and Bernadette Baum)