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To determine whether clinical manifestations are associated with genotypes or subtypes of Cryptosporidium spp., we studied a 4-year longitudinal birth cohort of 533 children in Peru. A total of 156 infection episodes were found in 109 children. Data from first infections showed that C. hominis was associated with diarrhea, nausea, vomiting, general malaise, and increased oocyst shedding intensity and duration. In contrast, C. parvum, C. meleagridis, C. canis, and C. felis were associated with diarrhea only. C. hominis subtype families were identified (Ia, Ib, Id, and Ie); all were associated with diarrhea. Ib was also associated with nausea, vomiting, and general malaise. All C. parvum specimens belonged to subtype family IIc. Analysis of risk factors did not show associations with specific Cryptosporidium spp. genotypes or subtypes. These findings strongly suggest that Cryptosporidium spp. and subtypes are linked to different clinical manifestations in children.

Human infection by leptospires has highly variable clinical manifestations, ranging from subclinical infection to fulminant disease. We conducted a population-based, cross-sectional seroepidemiologic study in Peru to determine potential relationships of environmental context to human exposure to Leptospira and disease associated with seroconversion. Three areas were studied: a flooded, urban slum in the Peruvian Amazon city of Iquitos; rural, peri-Iquitos villages; and a desert shantytown near Lima. Seroprevalence in Belen was 28% (182/650); in rural areas, 17% (52/316); and in a desert shantytown, 0.7% (1/150). Leptospira-infected peridomestic rats were found in all locales. In Belen, 20 (12.4%) of 161 patients seroconverted between dry and wet seasons (an incidence rate of 288/1,000); seroconversion was associated with history of febrile illness; severe leptospirosis was not seen. Human exposure to Leptospira in the Iquitos region is high, likely related both to the ubiquity of leptospires in the environment and human behavior conducive to transmission from infected zoonotic sources.

We compared the epidemiologic characteristics of cyclosporiasis and cryptosporidiosis in data from a cohort study of diarrhea in a periurban community near Lima, Peru. Children had an average of 0.20 episodes of cyclosporiasis/year and 0.22 episodes of cryptosporidiosis/year of follow-up. The incidence of cryptosporidiosis peaked at 0.42 for 1-year-old children and declined to 0.06 episodes/child-year for 5- to 9-year-old children. In contrast, the incidence of cyclosporiasis was fairly constant among 1- to 9-year-old children (0.21 to 0.28 episodes/child-year). Likelihood of diarrhea decreased significantly with each episode of cyclosporiasis; for cryptosporidiosis, this trend was not statistically significant. Both infections were more frequent during the warm season (December to May) than the cooler season (June to November). Cryptosporidiosis was more frequent in children from houses without a latrine or toilet. Cyclosporiasis was associated with ownership of domestic animals, especially birds, guinea pigs, and rabbits.

In 50 healthy Peruvian shantytown residents, zinc cream applied to tuberculosis skin-test sitescaused a 32% increase in induration compared with placebo cream. Persons with lower plasma zinc had smaller skin-test reactions and greater augmentation with zinc cream. Zinc deficiency caused false-negative skin-test results, and topical zinc supplementation augmented antimycobacterial immune responses enough to improve diagnosis.