Rubella Almost Eradicated In The United States.

2002 FEB 7 - (NewsRx.com & NewsRx.net) -- A study of the incidence and characteristics of rubella (also known as German measles) cases reported in the United States from 1990 through 1999 shows record low levels of the disease. However, the characteristics of cases have changed significantly.

Susan E. Reef, MD, and colleagues from the National Immunization Program, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, studied the incidence and characteristics of rubella and congenital rubella syndrome (CRS, which is a cluster of symptoms in infants who are infected with rubella through maternal transmission during pregnancy) reported to the National Notifiable Diseases Surveillance System (NNDSS) from 1990 to 1999. For each rubella case, the authors collected information regarding age, sex, race/ethnicity, relationship to an outbreak and molecular typing of virus isolates.

"The incidence of rubella decreased dramatically, from 0.45 per 100,000 in 1990 to 0.1 per 100,000 in 1999," the authors reported in the January 23/30, 2002, issue of the Journal of the American Medical Association (2002;287:464-472). "In 1969, when the vaccination program began, 57,600 rubella cases were reported in the United States. However, annually from 1990 through 1999, the median number of reported rubella cases was 232. Since 1992, fewer than half of the states reported cases of rubella, with four or fewer states annually reporting a majority of the cases."

Since the beginning of the 1990s, the demographics of the rubella and CRS cases and the characteristics of the outbreaks have changed significantly. Rubella now occurs mainly among foreign-born Hispanic adults who are either unvaccinated or whose vaccination status is unknown with very limited spread and circulation among the U.S. resident population. Also, during the early 1990s, most of the CRS cases occurred in infants whose mothers had been exposed to rubella in the United States. By the end of the decade nearly half of the cases were imported."

The authors add that their results indicate that the United States is on the verge of elimination of indigenous rubella and CRS, but that the threat of CRS remains, particularly among women of childbearing age born outside the United States.

The authors also found that both U.S.-born and foreign-born individuals with rubella were more likely to be unvaccinated or had unknown vaccination status. Molecular typing, which provides information on the origin of viruses, identified three different groups of rubella viruses responsible for illness in the 1990s. All three groups exhibited little internal diversity, suggesting a single source was responsible for each cluster or outbreak.

The authors also found that during the 1990s the incidence of rubella in children younger than 15 years decreased and the incidence in adults ages 15 to 44 years increased. Since the mid 1990s, fewer cases were reported among women than among men. However, every year since 1992, more than 50% of the cases among women occurred among those of childbearing ...