Pediatr Infect Dis J, 2003;22:323–9 Vol. 22, No. 4 Copyright © 2003 by Lippincott Williams & Wilkins, Inc. Printed in U.S.A. Burden of congenital rubella syndrome after a community-wide rubella outbreak, Rio Branco, Acre, Brazil, 2000 to 2001 TATIANA M. LANZIERI, MD, T. CRISTINA SEGATTO, RN, MARILDA M. SIQUEIRA, PHD, ELIZABETH C. DE OLIVEIRA SANTOS, MD, LI JIN, PHD AND D. REBECCA PREVOTS, PHD, MPH* Background. During 1999 and 2000 rubella out- breaks were reported in 20 of 27 states in Brazil, many among young adults. We investigated a large rubella outbreak in Rio Branco, Acre, in northwestern Brazil, where rubella vaccination targeting children 1 to 11 years old had been introduced in April 2000. Surveillance for con- genital rubella syndrome (CRS) was initiated after the outbreak. Methods. Suspected rubella cases were de- tected through active and passive surveillance. Confirmed rubella cases were patients with fe- ver, rash and rubella-specific IgM antibodies. Suspected CRS cases were infants born with CRS-compatible defects or born to mothers with a history of rubella during pregnancy. Con- firmed cases were infants with CRS-compatible defects and rubella-specific IgM antibodies. Results. From April 1 to December 31, 2000, 391 confirmed rubella cases were reported. The inci- dence among persons ages 12 to 19 years (3.3 per 1000 population) was increased 3.7-fold relative to children ages 1 to 4 years (95% confidence interval, 2.4 to 5.8). Of 21 infants with suspected CRS cases, 17 (91%) were tested for rubella- specific antibodies, of whom 7 were IgM-positive and 5 had confirmed CRS. The peak incidence of confirmed CRS (4.3 per 1000) was in March 2001, 7 months after the outbreak peak, with an annu- alized incidence of 0.6 per 1000. Conclusions. Vaccination among school age children was insufficient to prevent a rubella outbreak among young adults that resulted in the occurrence of at least 5 cases of CRS. To prevent further cases of CRS, outbreak vaccina- tion of young adults was conducted in November 2000 and among women ages 12 to 39 years in 2001 as part of a national campaign, with a cov- erage of 98% statewide. INTRODUCTION To better define the burden of congenital rubella syndrome and evaluate rubella vaccination strategies, WHO has recommended investigation of rubella out- breaks followed by active congenital rubella syndrome (CRS) surveillance. 1 During 1999 to 2000 Brazil expe- rienced widespread rubella transmission with out- breaks reported in most of the country. 2 Affected states had varying degrees of implementation of routine childhood rubella vaccination. In this report we de- scribe an outbreak investigation in a state that had initiated routine childhood rubella vaccination in the same year as the outbreak and assess the CRS burden after the outbreak. In 1992 routine childhood rubella vaccination was adopted in Brazil in a phased manner by state, begin- ning in Sao Paulo State. By 2000 all Brazilian states had introduced rubella vaccine into the routine sched- ule through use of the combined measles, mumps and rubella (MMR) vaccine. Initial “catch-up” campaigns took advantage of existing measles elimination efforts and targeted children ages 1 to 11 years. After these catch-up campaigns, states initiated routine rubella vaccination through use of MMR, with a dose sched- uled at 12 to 15 months. Rubella surveillance began in 1992, by testing all blood samples negative for measles- specific IgM antibody for rubella. Integrated measles- rubella surveillance was introduced in 1997, although implementation varied by state. As part of the regional goal for measles elimination in the Americas by the year 2000, measles-rubella surveillance was intensi- Accepted for publication Dec. 6, 2002. From the National Epidemiology Center, National Health Foundation, Ministry of Health (TML, CS), and the Pan Ameri- can Health Organization (RP), Brası ´lia, Brazil; Department of Virology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil (MMS); Evandro Chagas Institute, Ministry of Health, Bele ´m, Brazil (ECdOS); and Central Public Health Laboratory, London, UK (LJ). *Current address: Centers for Disease Control and Prevention, National Immunization Program, 1600 Clifton Rd., MS E-05, Atlanta, GA 30333. Key words: Rubella, outbreaks, vaccination, congenital rubella syndrome. Address for reprints: D. Rebecca Prevots, M.D., Centers for Disease Control and Prevention, National Immunization Pro- gram, 1600 Clifton Rd., MS E-05, Atlanta, GA 30333. Fax 404-639-8573; E-mail rprevots@cdc.gov. 323