THURSDAY, Aug. 21, 2008 (HealthDay News) -- Some parents' refusal to vaccinate children seems to be behind the highest rate of measles cases reported since 1996, federal officials said Thursday.
Between Jan. 1 and July 31 of this year, 131 measles cases have been reported in the United States, many of them among children whose parents have philosophical or religious objections to the vaccine, according to the U.S. Centers for Disease Control and Prevention.
At least 15 patients, including four children 15 months or younger, were hospitalized. No deaths have been reported.
By comparison, 55 cases of measles were reported in 2006, 66 in 2005, 37 in 2004, 56 in 2003 and 44 in 2002, for an average of about 64 per year.
"Every year, we experience importation of measles from other countries and from those going abroad, but this year is different. Once measles is imported here, we're seeing it spread to many more people," Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, said during a Thursday teleconference. "Many cases are in children who are eligible for vaccination but who have not been immunized because of parents' decisions."
Before the measles vaccine became available in the mid-1960s, the disease caused an estimated 450 deaths and 4,000 cases of measles encephalitis annually, some 1,000 of which resulted in chronic disability. In the decade before the vaccination was introduced, an estimated 3 million to 4 million people were infected each year.
The disease was declared eliminated from the United States in 2000, but sporadic cases are imported from other countries. Some 20 million cases still occur globally, said Dr. Jane Seward, deputy director of the National Center for Immunization and Respiratory Diseases' division of viral diseases.
Measles is highly contagious and requires high vaccination rates. In a room of 100 people, only one of whom actually has measles, another 90 to 95 people will become infected, Seward said. "We need very high levels of population immunity, approximately 95 percent," she said.
The first cases in the current outbreak appeared in April in Washington state. Eight children in one household fell ill, four of them after attending a church conference, which may have been the source of the outbreak. In all, 19 people contracted measles, 11 of them home-schooled children who were not required to be vaccinated. The particular strain identified had been circulating in Japan and Europe, officials said.
In May, four girls aged 10 to 14 contracted measles in Illinois. All had attended at least one event together; the events were also attended by a teenager who had just returned from Italy and reportedly had fever and rash. Officials were unable to get more information on the traveler, but the strain identified this time had been circulating in Italy. Through July, a total of 32 cases were identified in Illinois, 25 of them in home-schooled children.
Other cases have been identified in New York (27), Arizona (14), California (14), Wisconsin (seven), Michigan (four), Hawaii (five), Arkansas (two), and Washington, D.C., and Georgia, Louisiana, Missouri, New Mexico, Pennsylvania and Virginia (one each), officials said.
Of the 131 people throughout the United States who contracted measles this year, 112 were unvaccinated or their vaccination status was unknown. Sixteen were under 1 year of age and too young to be vaccinated.
Ninety-five patients were eligible for the vaccination, but 63 were not vaccinated because of their parents' beliefs, officials said.
Seventeen of the total cases were "importations" -- three each from Switzerland and Italy; two each from Israel, Belgium and India; one each from Germany, China, Pakistan, Russia and the Philippines. Israel, Switzerland, Austria, Italy and Great Britain are all reporting outbreaks among individuals who have refused vaccination. Britain and Italy are reporting endemic measles, officials said.
Officials emphasized the importance of keeping children's vaccinations current.
"We have been lucky to have low levels of measles and other vaccine-preventable diseases, but children can still get measles and can still spread measles, including to those too young to be immunized and those who can't be vaccinated because of medical reasons," Schuchat said.
Seward added: "It's important in this country to maintain high levels of vaccination that have been so successful in limiting measles to relatively low numbers over the last decade. We would like to remind parents, as their children go back to school, whether or not they attend in schools or are home-schooled or attend day care, this is a good time to be considering their vaccination status for measles to protect them from acquiring this disease."
The CDC has more on measles.