Helminth infection, fecundity, and age of first pregnancy in women

Abstract

Parasitic worms influence human fecundity Parasitic worms infect 2 billion people globally. Mostly, such infections are symptomless and individual worm burdens are low. Blackwell et al. monitored the fecundity of Tsimane women in Bolivia. These women have on average of 10 children in their lifetimes. However, if they had successive hookworm infections, lifetime births dropped to 7. Surprisingly, if the women were chronically infested with roundworm, they had as many as 12 children. These effects may relate to the balance of immune responses that the different worms induce, rather than to the physiological costs of parasitism. Science , this issue p. 970