Some examples of the disruption: Arizona has diagnosed only seven cases of measles, but those infected people have exposed as many as 1,000 others, including babies too young to have had their first measles shot, according to the Arizona Department of Health Services. Doctors recommend that unvaccinated people exposed to measles be quarantined for three weeks, the measles incubation period.
The CDC recommends that children receive a first measles shot around age 1 and a second at ages 4 to 6 before beginning kindergarten.
The Arizona measles cases began with one unvaccinated family of four from Pinal County that went to Disneyland, according to state health officials. Back at home, one of the children went to two urgent-care centers for medical attention, exposing 18 children, 13 of whom were unvaccinated. That family also exposed a woman from Maricopa County, who then exposed as many as 195 children at a child care center. A man who caught measles from the family then exposed others.
Although the routine spread of measles was eliminated in the USA in 2000, a low rate of vaccination in some communities has allowed the virus —
one of the most contagious — to make a comeback, says Walter Orenstein, a professor and associate director of the Emory Vaccine Center in Atlanta. Measles vaccination rates range from a low of 81% of kindergarten students in Colorado to a high of nearly 100% in Mississippi.
The current generation of parents has no experience with measles, Orenstein points out. A growing number have skipped or delayed children's vaccines because of debunked myths about vaccines causing autism, Orenstein says.
"People don't see these diseases, they don't fear these diseases, and they don't know how serious these diseases can be," he says.