Incidence of Congenital Rubella Syndrome at a Hospital Serving a Predominantly Hispanic Population, El Paso, Texas

Abstract

Objective. The current epidemiology of rubella reveals an increase in the number of cases among adult Hispanics and an increase in the number of congenital rubella syndrome (CRS) cases among infants of Hispanic mothers. Recent rubella outbreaks have occurred primarily among adult Hispanics, many of whom are foreign-born natives of countries where rubella vaccination is not routine or has only recently been implemented. The objective of this study was to estimate the incidence of CRS in a hospital serving a predominantly Hispanic population. Methods. Hospital charts of infants <1 year old discharged between January 1, 1994 and December 31, 1996 withInternational Classification of Diseases, Ninth Revision(ICD-9) discharge codes consistent with CRS were reviewed; we looked for cataracts, deafness, congenital heart defects, dermal erythropoiesis, microcephaly, meningoencephalitis, and other defects associated with CRS. We abstracted data on maternal and infant ethnicity, maternal age, gestational age, infants' birth weight, infants' clinical characteristics, and laboratory evaluation. Cases were categorized according to the Council of State and Territorial Epidemiologists' case classification for CRS. Results. Of the 182 infants with 1 or more ICD-9 codes consistent with CRS, 6 (3.3%) met either the confirmed or probable case definition for CRS. Two infants met the definition for confirmed CRS. Although laboratory tests for rubella immunoglobulin M antibodies were positive for both of these infants, only 1 of the cases had been reported to the state health department. Four other infants had clinical presentations that met the definition for a probable case. One of these had been tested for rubella immunoglobulin M antibodies, and the test was negative. The other 3 had not been tested. The rate of infants meeting the definition of confirmed and probable CRS was 3.1 per 10 000 hospital births. All confirmed and probable cases were among infants born to Hispanic mothers. Maternal country of origin was Mexico for the 2 confirmed cases and 1 of the probable cases, and unknown for the remaining 3 probable cases. Conclusions. The rate of confirmed and probable CRS among infants in this predominantly Hispanic population is higher than the reported rate in the United States in the vaccine era, which has been reported to range from approximately 0.01–0.08 per 10 000 live births. These findings indicate a need for heightened awareness of CRS among physicians who serve populations at risk for rubella. Physicians should report all confirmed and probable CRS cases to the state health department. The lack of appropriate laboratory testing in 3 infants with probable CRS indicates that physicians should consider a diagnosis of CRS in infants with some signs consistent with CRS, particularly in areas serving high numbers of individuals at risk for rubella.