Proteinuria is associated with persistence of antibody to streptococcal M protein in Aboriginal Australians

Aboriginal communities in Northern Australia with high rates of group A str eptococcal (GAS) skin infection in childhood also have high rates of renal failure in adult life. In a cross-sectional study of one such high risk com munity, albuminuria was used as a marker of renal disease. The prevalence o f albuminuria increased from 0/52 in subjects aged 10-19 years to 10/29 (32 .9 %) in those aged 50 or more (P < 0.001). Antibodies to streptococcal M p rotein, markers of past GAS infection, were present in 48/52 (92 %) at ages 10-19 years, 16/32 (50 %) at ages 30=39, and 20/29 (69 %) in those aged 50 or more. After allowing for the age-dependencies of albuminuria and of M p rotein antibodies (P < 0.081) albuminuria was significantly associated with M protein antibodies (P < 0.01). Thus, 72 % of adults aged 30 or more with M protein antibodies also had albuminuria, compared with only 21% of those who were seronegative. More detailed modelling suggested that although mos t Aboriginal people in this community developed M protein antibodies follow ing GAS infection in childhood, the development of proteinuria was associat ed with the persistence of such seropositivity into adult life. The models predicted that proteinuria developed at a mean age of 30 years in seroposit ive persons, at 45 years in seronegative persons who were overweight, and a t 62 years in seronegative persons of normal weight. We demonstrated a clea r association between evidence of childhood GAS infection and individual ri sk of proteinuria in adult life. This study provided a strong rationale for prevention of renal disease through the more effective control of GAS skin infections in childhood and through the prevention of obesity in adult lif e.