Recent data from outbreaks of schistosomiasis in immuno-logically naiv
e populations have refuelled the debate concerning the nature or exist
ence of protective, acquired immunity to schistosomiasis in humans. Da
ta from endemic communities provide some compelling evidence for an ab
rupt change in reinfection rates that coincides with puberty. We sugge
st that the hormonal changes of adrenarche may hold the key to underst
anding the relative resistance to infection found in adults.