Clinicians may need to keep a sharper eye out for measles and mumps, now that more cases of the illnesses are being reported. Many of the patients stricken so far have been adults.
Between January 1 and April 25 of this year, the CDC confirmed 64 cases of measles—the highest number reported for the same period since 2001. Outbreaks occurred in Arizona, Michigan, New York, and Wisconsin, and 21 patients were aged 20-50. Only one patient had defnitely been vaccinated; the rest either hadn’t been or didn’t know their vaccination status.
Whereas failure to vaccinate is mainly to blame for the measles outbreak, failure of inoculation is behind the mumps resurgence. The 6,584 cases reported in 2006 represent the largest mumps outbreak in 20 years, according to researchers led by the CDC’s Gustavo H. Dayan, MD (N Engl J Med. 2008; 358:1580-1589).
Most cases (76%) occurred between March and May, and 85% were in eight contiguous Midwestern and Plains states. The illnesses were characterized by a two-dose vaccine failure, “particularly among Midwestern college-age adults (aged 18-24) who probably received the second dose as schoolchildren,” according to the researchers.
Guidelines call for administering the first dose of mumps vaccine when a child is 12-15 months of age, with a second dose between four and six years of age. Experts say that recent outbreaks raise the possibility that the vaccine’s effectiveness wanes about 10 years after the second dose.