Giardia intestinalis infection as a risk factor for Cyclospora cayetanensis and Cryptosporidium infections in Peruvian children

This study examined whether Giardia intestinalis infection alters the risk of subsequent Cyclospora cayetanensis or Cryptosporidium infection in Peruvian children. Using data from a five‑year prospective cohort of 477 children, we assessed infection frequency, symptom patterns, treatment rates, and risk factors. One‑third of children had Giardia within 60 days of enrollment, and nearly 80% experienced infection during the study. Cox proportional hazards analysis showed that Giardia infection significantly increased the risk of later Cryptosporidium infection, and also increased the risk of Cyclospora infection, with stronger effects in households lacking toilets. Treatment of Giardia did not change these risks. Findings suggest Giardia may predispose children to subsequent protozoal infections, underscoring the need for further investigation of environmental and socioeconomic risk factors.