Rubella in the United States is a disease that is mostly under control due to the practice of systematic, ongoing application of preventive measures applied to the general population. When sufficient levels of vaccinations are reached in the population, the number of protected persons is enough to break the chain of transmission of the disease when a case is brought into the community. However, there are sometimes specific groups in the community where this general level of protection is not found, because of having not been reached by such a prevention program. In North Carolina, we have witnessed this phenomenon in the past few years, with repeated outbreaks of rubella affecting mostly the recently established Hispanic community. Many were born in places where the vaccination program did not include rubella vaccine.
Rubella is a disease that is often mild in nature.
For example, the typical rash is absent in up to half of the cases. Reported cases are therefore not revealing the whole picture. Another difficulty may result from unrelated chains of transmission starting when new cases are arriving from outside the community. This may be the explanation for clusters of cases appearing at locations distant from an outbreak when no link is found with prior cases, or when so much time has elapsed between cases that a succession of undiagnosed cases is a less likely explanation. The nature of control efforts deployed in response to an outbreak is adapted to the specific circumstances.