[Seroprevalence of rubella in urban and rural populations, Guaratinguetá]

To investigate seroprevalence of rubella antibodies in a 15 to 39 year old population in the municipal district of Guaratinguetá.

The 996 samples studied were collected in urban and rural zones, after informed and elucidated consent from men and women stratified by age (15 -39 years). Rubella IgG antibodies were detected by ELISA using the commercial kit Rubenostika IgGII (Organon Teknika THE, Holland). Age groups were stratified in 3 categories: 15-19; 20-29 and 30-39 years of age. Statistical analyses were accomplished with the software MINITAB version 14.0 (Minitab Inc, USA).

The proportion of seropositives for antibodies of the IgG class were: 92.7.% positive for 15-19 years; 82.4% for 20 to 29 years and 90.7% for 30-39 years, with a significant difference in the seropositive proportions by age group (p <0.001). Variation of intensity of antibody response was calculated and results show a significant difference (p = 0.002) between means of the 3 age groups studied. In relation to rural and urban zone average of the ratio DO/CO for each age group, a significant tendency towards a lower average was observed in the rural zone. The same was true when the seropositive proportions were calculated.

Results showed that the percentage and individuals with antibodies of the IgG class against rubella in the 20-29 year age group was lower than that in the younger and older age groups. Furthermore, the difference between seropositivity in the urban and rural zones discloses susceptibility with a potential for continued circulation of the virus in this zone.