Sixteen more measles cases were reported to the US Centers for Disease Control and Prevention (CDC) last week, lifting the national total to 170 cases so far this year, about three fourths of them part of a large ongoing multistate outbreak linked to Disneyland in California.
Though 17 states and the District of Columbia have reported measles cases this year, 89% of the cases are from four outbreaks, with California and its link to the Disney outbreak having the most cases. Three other states—Illinois, Nevada, and Washington—have outbreaks under way that aren't linked to the Disney outbreak.
Disneyland outbreak total grows
Seven more infections have been linked to the Disney outbreak, lifting that total to 140, the CDC said. However, 15 of those cases were reported from late December when the outbreak first began and aren't included in the 170 total cases for this year.
Most people who have been sickened by measles this year were unvaccinated, the CDC said. It said measles is still common in many parts of the world and that travelers with the disease continue to bring the virus into the United States.
The CDC has said the virus strain involved in the Disneyland outbreak is the same one that caused a large outbreak in the Philippines in 2014, but the same type has been identified in the past 6 months in 14 other countries and at least six US states not linked to the current outbreak.
Health officials said the outbreak was probably sparked by a travelers who was infected overseas, then visited the amusement park. No source has been identified, and CDC officials have said the virus spreads easily in pockets of undervaccinated people.
Though some measles cases in other states and other countries, including Canada and Mexico, have links to the Disneyland outbreak, 130 of the cases since December are from California, according to a Feb 27 update from the California Department of Public Health (CDPH). It said the outbreak involves the measles B3 strain, but new introductions of measles involving the D8 and D4 strains have also occurred. The CDPH added that 3 cases are known to have a different genotype from the outbreak strain.
Outbreaks in other states
Nevada's outbreak has been traced to an infected staff member at a Las Vegas restaurant, Emeril's Fish House. The Southern Nevada Health District (SNHD), which includes the city, said on Feb 27 that three more cases have been reported in the area, bringing the outbreak total to nine so far.
The three new case-patients include two staff members and a customer. The SNHD had previously said the source of the restaurant outbreak is an infant too young to be vaccinated who was thought to have passed the virus to the first restaurant worker, along with four other people.
The SNHD warned that one of the staff member was possible contagious while working between Feb 18 and Feb 21 and that one of the newly identified patients visited a local drug store and another restaurant on Feb 22. It urged people who were at the locations during those times to check their measles immunization status and contact a health provider if the develop rash with fever or other symptoms over the next 21 days.
Illinois has had 15 measles cases, 12 of them associate with a KinderCare in Palatine, according to updates from the Illinois Department of Public Health (IDPH) and the Cook County Department of Public Health. Of 14 cases reported so far in Cook County, 3 are in adults and 11 are in children. So far it's not clear if the cases are connected with the multistate outbreak linked to Disneyland.
In Washington State, two cases in unvaccinated Grays Harbor residents are believed to be linked to the Disneyland outbreak, but a cluster of four infections in Clallam County doesn't appear to be connected, according to health department statements.
Measles in Europe
In another measles development, the European Centre for Disease Prevention and Control (ECDC) issued a new report summarizing measles and rubella activity in 2014, which said countries reported 3,616 cases, with 58.6% of them in Germany and Italy.
Vaccination status was known for 89% of cases, which showed that 83% were unvaccinated. Of sick children ages 1 to 4 years old, the group targeted for routine vaccination, 75% were unvaccinated. No measles deaths were reported in 2014, but five cases involved acute measles encephalitis.
An outbreak in Slovenia in November was linked to exposure at an international event. A large measles outbreak in Berlin that began in October was initially limed to asylum seekers from Bosnia and Herzegovina and Serbia, but has now spread to the general population, according to the ECDC. It added that measles outbreaks are ongoing in those countries, plus Kyrgyzstan.
Mar 2 CDC measles update on 2015 cases
Feb 27 CDPH measles update
Feb 27 SNHD statement
Feb 25 IDPH measles update
Mar 2 Cook County measles update
Mar 2 Clallam County Department of Health and Human Services measles update
Feb 20 Washington State Department of Health measles update
March ECDC measles and rubella monitoring report