Prevalence of diphtheria and tetanus antibodies and circulation of Corynebacterium diphtheriae in São Paulo, Brazil

The introduction of routine vaccination against tetanus and diphtheria in Brazil has decreased the incidence and changed the epidemiology of both diseases. We then investigated the prevalence of Corynebacterium diphtheriae carrier status and diphtheria and tetanus immunity in São Paulo, Brazil. From November 2001 to March 2003, 374 individuals were tested for the presence of C. diphtheriae in the naso-oropharynx and of serum diphtheria and tetanus antibodies. Participants were all healthy individuals without acute or chronic pathologies and they were stratified by age as follows: 0-12 months and 1-4, 5-9, 10-14, 15-24, 25-39, 40-59, and ³60 years. Antibodies were assessed using a double-antigen ELISA. C. diphtheriae species were identified by biochemical analysis and toxigenicity was assessed by the Elek test. For diphtheria, full protection (antibodies ³0.1 IU/mL) was present in 84 percent of the individuals, 15 percent had basic protection (antibodies ³0.01 and <0.1 IU/mL) and 1 percent were susceptible (antibodies <0.01 IU/mL). Full tetanus protection (antibodies ³0.1 IU/mL) was present in 79 percent of the participants, 18 percent had basic protection (antibodies ³0.01 and <0.1 IU/mL) and 3 percent were susceptible (antibodies <0.01 IU/mL). The geometric mean of diphtheria and tetanus antibodies reached the highest values at 5-9 years and decreased until the 40-59-year age range, increasing again in individuals over 60 years. Three participants (0.8 percent) were carriers of C. diphtheriae, all non-toxigenic strains. The present results demonstrate the clear need of periodic booster for tetanus and diphtheria vaccine in adolescents and adults after primary immunization in childhood.

Tetanus and diphtheria immunity in adolescents from São Paulo, Brazil

Tetanus and diphtheria vaccines are of special concern in adolescents because boosters are necessary for adequate maintenance of protection and are often omitted. We assessed serum levels of tetanus and diphtheria antibodies in adolescents and their association with vaccination status. From May to October 2001, we evaluated the vaccination records of 208 adolescents aged 10 to 20 years in São Paulo, Brazil. Antibodies to tetanus and diphtheria were detected using double-antigen ELISA and vaccination records were analyzed according to the guidelines of the Brazilian National Immunization Program. All adolescents had received complete primary vaccinations against tetanus and diphtheria, but 23.1 percent of them had not received a booster dose in the last 10 years. All adolescents were immune to tetanus and 88.9 percent were fully protected (antibodies ³0.1 IU/mL). One individual (0.5 percent) was non-immune to diphtheria and 86 percent were fully protected against the disease. Adolescents with up-to-date vaccination records had higher antibody levels than those with not up-to-date records for tetanus (0.763 vs 0.239 IU/mL, t-test: P < 0.0001) and diphtheria (0.366 vs 0.233 IU/mL, t-test: P = 0.014). Full immunity against tetanus (antibodies ³0.1 IU/mL) was higher among individuals with up-to-date vaccination (93.1 percent) when compared to those with not up-to-date records (75 percent, Fisher's exact test: P = 0.001). All adolescents had received basic immunization in childhood and were protected against tetanus and diphtheria. However, these data indicate that more emphasis should be placed on the tetanus-diphtheria booster in order to avoid a decay in antibody levels.