( CNN ) California health officials said Wednesday there are 79 confirmed measles cases in the state , as federal health authorities reported that the number of U.S. cases in 2014 more than tripled any total in recent years . According to the California Department of Public Health website , 52 of those cases are linked to an outbreak at Disneyland . There are four confirmed cases in Riverside County , where the Desert Sands Unified School District told 66 students -- who have either not been vaccinated for measles or ca n't show proof -- that they need to stay home . CNN affiliate KESQ reported that one student at Palm Desert High School is suspected of having had measles . The student has been cleared to return to class but health officials are still trying to determine if the student actually had measles . For now , the others will have to study at their homes . `` They are going to be asked to stay home until the incubation period for contagion is complete , '' a spokeswoman for the school district , Mary Perry , said of the students who were released . The earliest a student can return without proof of vaccination is February 9 , the station reported . Of the 79 California cases , 15 are in Los Angeles County , and all victims were unvaccinated for measles , said Dr. Jeffrey Gunzenhauser , the county 's interim health officer . Of those 15 county cases , 14 are linked to Disneyland , Gunzenhauser said . `` In L.A. County , we 're , fortunately , highly vaccinated . Five percent or less are unvaccinated , '' Gunzenhauser said . There are 16 cases linked to Disneyland outside California ( seven in Arizona , three in Utah , two in Washington , one in Colorado , one in Oregon , one in Nebraska and one in Mexico ) . Arizona officials said they have identified 1,000 contacts of the seven cases in their states . They 're asking anyone within that group to isolate themselves for 21 days if he or she is n't vaccinated . The disease outbreak became apparent when visitors reported coming down with measles after visiting the park from December 15 to December 20 . At least five Disney employees have been diagnosed with measles , Disney said . Mom angry at vaccination opponents . Also , the families of 195 children in Mesa , Arizona , have been contacted because they were in an urgent care clinic with someone who has measles . Midway across the country , at the University of Minnesota , a student who had traveled abroad is self-isolating after contracting the disease , the school said in a statement . The university is working to find everyone who may have been exposed to the student , who attended class four days last week . Though students have largely been immunized because of enrollment requirements , the university warned anyone who had not been vaccinated to be vigilant . Minnesota is one of 27 states that reported measles cases last year , according to the Centers for Disease Control and Prevention . The 644 cases reported in 2014 mark a stark spike compared with recent years . Since 2001 , the number of cases has topped 100 only five times , and 2011 was the only year in which cases topped 200 . Measles is a highly communicable respiratory disease caused by a virus and spread through the air . Measles starts with a fever , runny nose , cough , red eyes and sore throat , the CDC says . 5 things to know about measles . CNN 's Debra Goldschmidt , Eliott C. McLaughlin , Michael Martinez and John Newsome contributed to this report .
All 15 measles cases in Los Angeles County involve unvaccinated people . CDC reports cases topped 600 in 2014 , a significant spike over recent years . Comment: