Immunity to rubella: a serological-epidemiological survey in female hospital employees, S. Paulo State, Brazil

Abstract

Antibody titers to rubella were determined by the hemagglutination inhibition test in sera of 1,886 female employees of the Hospital das Clínicas, of the School of Medicine, Ribeirão Preto, University of S. Paulo, in 1982-1983, and related to age, color, hospital unit, position and place of work, period of employment, and history of rubella or contagion when pregnant or not otherwise. In 1,617 of the 1,886 sera (85.7%), titers (reciprocal) were >; 20, and in 269 (14.3%) ;³; 20, distributed as follows: in 9.6% < 10; 1.22%-10; 3.5%-20; 5.8%-40; 10.6%-80; 20.7%-160; 27.8%-320; 12.6%-640; 7.3%-1,280 and 0.8%- 2,560. There was a weak association between titer and all other parameters (P ;@; 0); 87.1% of the employees denied a history of rubella and 73.9% of them had >; 20 titers; 57.5% denied communicant status, all also having >; 20 titers; in 1.1% of 11.1% who reported a history of rubella, titers were ;£; 20; 97% denied contact with rubella during pregnancy. There was one case of congenital malformation after rubella during the 1st trimester of pregnancy. Specific IgM was detected in 9.4% or 351 employees with ;³; 640 titers. No significant titer fluctuation was observed in different samples of one and the same employee. It follows that most employees are immune to rubella (>; 20 titer) regardless of the other parameters considered. The specific IgM may indicate subclinical disease or IgM persistence. The survey was considered useful for medical guidance of pregnant employees when they contacted a patient with suspected or confirmed rubella, and phrophylaxis for non-pregnant employees known to be non immune.