Monday, April 24, 2006
Slate.com has a good overview of the recent outbreak of mumps in the midwest and discusses one potential cause of the outbreak -
No vaccine is perfect, however. The worst mumps epidemic in 17 years is currently sweeping through a heavily vaccinated population in the Midwest. Nearly 1,000 cases have been reported in Iowa since March, and hundreds more in seven other states. A single dose of mumps vaccine—the recommended dosage in Iowa before 1991—protects about 80 percent of those who get it; two doses, the norm today, confers 90 percent immunity. The Iowa outbreak is concentrated in college students, about one-third of whom had not gotten two doses of vaccine as children. Mumps is more serious in older kids and adults—about a fifth of infected men get swollen testicles, as well as the disease's trademark symptom of a swollen neck; women get sore breasts. Outbreaks in vaccinated populations tend to be less serious, though, and only about 20 people have so far been hospitalized, according to Julie Gerberding, director of the Centers for Disease Control.
The CDC is investigating the origins of the Midwest outbreak. The agency has no clear answers yet, but it may be that these mumps cases are linked to an earlier vaccine scare in Britain. In 1998, gastroenterologist Andrew Wakefield published a report in the medical journal Lancet in which he suggested that the MMR vaccine (called that because mumps protection is nearly always packaged together with vaccines for measles and rubella) caused autism. The article has since been withdrawn and the link between the vaccine and autism disproved. But vaccination rates plunged in the United Kingdom for a few years, resulting in a mumps epidemic of 100,000 cases since 2004. The mumps virus circulating in the Midwest is the same type as the British epidemic strain, though it is too common a variant for scientists to be certain, at this point, of a definitive link.