This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

(CNN) — Four cases of measles have been linked to a restaurant at the MGM Grand Hotel & Casino in Las Vegas, the Southern Nevada Health District reported Friday.

A patron and two staff members of Emeril’s New Orleans Fish House probably contracted measles from a contagious staff member, the health agency said Friday in a press release, bringing to nine the total number of people diagnosed with measles this year in Clark County, Nevada.

An infant too young to have received the immunization may have transmitted measles to the initial Emeril’s staff member, the health district said.

One-hundred fifty-four cases of measles were discovered in the United States from January 1 to February 20, the Centers for Disease Control and Prevention said on its website. The CDC said 118 cases were part of an ongoing, multistate outbreak linked to DisneyLand in California.

A record number of U.S. measles cases — 644 cases from 27 states — were reported in 2014. That’s the greatest number since measles elimination was documented in the United States in 2000.

The Southern Nevada Health District said no measles cases had been reported in its district since 2011.

Measles is a highly communicable respiratory disease caused by a virus and spread through the air, according to the CDC. Measles starts with a fever, runny nose, cough, red eyes and sore throat, the CDC said.

Emeril’s put out a press release Friday, saying, “One of our team members was potentially contagious while working shifts beginning at 4 p.m. on Wednesday, February 18, Thursday, February 19, Friday, February 20, and Saturday, February 21. The affected employee has not been on site since then. … In addition to the ongoing education of our staff, we are engaging in a cooperative effort with the health district to provide immunizations to all of our employees who believe they might be at risk.”

People who dined at the restaurant on those days, as well as people who dined after 4 p.m. on February 4-7, should review their immunization status and contact their doctors if they are not fully immunized or haven’t already had measles, the health district said.

The health district said a person with one of the newly identified cases visited two other Las Vegas businesses, a Walgreens and a Chili’s Grill & Bar, on February 22.

BART, the transit system in the San Francisco area, on Wednesday said some riders may have been exposed last week after a San Mateo County resident with measles commuted. BART said the risk of “contracting measles via BART is negligible.”