The seroprevalence of Bordetella pertussis antibodies in adolescents in the Western Cape

Pertussis is a highly contagious respiratory disease that can occur in all age groups. Over the past 15 years, an increase in the incidence of reported cases has been observed globally. Local surveillance data have also shown an increase in the number of laboratory-confirmed cases. This raises concerns about waning immunity in adolescents and adults. The aim of this study was to screen for seropositivity against pertussis infection by measuring immunoglobulin G (IgG) antibody titers of Bordetella pertussis in an adolescent population in the Western Cape, South Africa. Serum samples were collected from 182 adolescents aged 15-18 years from different racial groups. The SERION ELISA ® classic B. pertussis IgG assay was used to detect human antibodies in serum. Twenty-seven subjects (15%) were seronegative and 135 (74%) seropositive for IgG antibodies. Racial breakdown showed that 84% of the black, 74% of the coloured, and 69% of the white subjects were seropositive, while the largest percentage (24%) of sero-negative individuals was in the white population group. This study demonstrated a high percentage of individuals in the adolescent age group with sero-positive antibody levels. However, it is unknown if these antibody levels are functionally protective. A more rigourous surveillance system would assist in defining and understanding the epidemiology of pertussis in South Africa, and could provide evidence of the need for booster vaccinations in adolescence and adulthood.