( CNN ) -- This year is on track to be the worst for measles in more than a decade , according to new numbers released Thursday by the U.S. Centers for Disease Control and Prevention . And people who refuse to vaccinate their children are behind the increasing number of outbreaks , health officials say . There were 159 cases of measles in the United States from January 1 through August 24 , according to the CDC . If that trend continues , there will be more cases in 2013 than in any year since 1996 , when some 500 cases were reported . The number would also surpass that of 2011 , when there were 222 cases . Measles cases in the United States numbered in the hundreds of thousands before the advent of vaccination , and dropped dramatically throughout the 1960s . The disease was thought to have been eradicated in 2000 , but the numbers have recently crept back up , largely because of visitors from countries where measles is common and because of vaccine objectors within the United States . Nearly two-thirds of the reported cases happened in three outbreaks in communities where many people do n't vaccinate their children for religious or philosophical reasons . `` This is very bad . This is horrible , '' said Dr . Buddy Creech , a pediatric infectious disease expert at Vanderbilt University who was on a telephone briefing with the CDC Thursday morning . `` The complications of measles are not to be toyed with , and they 're not altogether rare . '' According to the CDC , one to three out of every 1,000 children in the United States who get measles will die from the disease , even with the best of care . Even if complications such as pneumonia and encephalitis are n't deadly , they can make children very sick ; in 2011 , nearly 40 % of children under the age of 5 who got measles had to be treated in the hospital . Measles usually starts with a fever , which can get very high , followed by a cough , runny nose and red eyes . Soon a rash of tiny , red spots will start at the head and spread to the rest of the body . The rash can last a week and coughing can last for up to 10 days . Creech said he 's concerned younger physicians might not be quick to recognize the signs of measles , since there have been only pockets of the disease since 2000 . `` Many young pediatricians might not know what measles looks like , '' he said . Among those who have been stricken with measles this year , 92 % were not vaccinated or had unknown vaccination status . The largest outbreak was in New York , where 58 people contracted measles in a community where many refuse to be vaccinated for religious reasons . Those who choose not to vaccinate put other people 's babies at risk , since babies can not be vaccinated until their first birthday , and are therefore vulnerable to the disease . `` I hope that those who are vaccine hesitant or vaccine avoidant realize there are consequences to their actions , '' Creech said . `` None of us lives in isolation . '' Ex-staffer : Church counseled faith , not shots , for measles .
159 cases of measles in the United States from January 1 through August 24 . Last highest year was 2011 , when there were 222 cases . Nearly two-thirds of cases happened in communities where many people do n't vaccinate . Nearly 40 % of children under the age of five who get measles have to be hospitalized .