Introduction Cryptosporidium is an important protozoan cause of waterborne disease worldwide of concern to public health authorities. To prevent outbreaks of cryptosporidiosis, the monitoring of this parasite in drinking water is necessary. In the present work, the polymerase chain reaction (PCR) and nested-PCR techniques were used to detect Cryptosporidium in raw water from catchment points of four water treatment plants (WTP) in Curitiba, Paraná, Brazil. Methods First, DNA extraction techniques were tested in samples containing decreasing amount of oocysts in reagent water, and PCR and nested-PCR with specific primers for 18SSU rDNA of Cryptosporidium were conducted to determine their sensitivity. In reagent water, a commercial extraction kit provided the best analytical sensitivity, and PCR and nested-PCR allowed the detection of five and two oocysts, respectively, with the primers XIAOR/XIAOF and XIAO1F/XIAO2R. Results In the spiking experiments, only the PCR with the primers AWA995F/AWA1206R was successful at detecting concentrations of 0.1 oocysts/mL. Two catchments samples of raw water and/or water sludge from four WTPs were contaminated with Cryptosporidium. Conclusions The application of the techniques to monitor Cryptosporidium in water and detect contamination in water catchments of WTPs in Curitiba are discussed in the present work.

INTRODUÇÃO: A produção de anticorpos policlonais anti-Cryptosporidium e sua utilização na imunofluorescência para determinar a presença de Cryptosporidium em água são descritas no presente trabalho. MÉTODOS: Dois coelhos foram imunizados com antígeno solúvel e particulado provenientes de oocistos purificados de Cryptosporidium. O soro produzido foi preparado para a extração de imunoglobulinas G, que foram purificadas e conjugadas com isotiocianato de fluoresceína (FITC). Lâminas contendo quantidades conhecidas de oocistos foram preparadas para determinar a sensibilidade da técnica. Para testar a especificidade foram preparadas lâminas contendo cistos de Giardia duodenalis. RESULTADOS: O conjugado foi usado com sucesso em amostras de água contaminadas experimentalmente com oocistos de Cryptosporidium, sendo capaz de detectar até cinco oocistos/spots que corresponde a uma contaminação de 250 oocistos/mL. CONCLUSÕES: As três imunizações realizadas nos coelhos foram suficientes para produção de anticorpos contra Cryptosporidium; a reação de imunofluorescência direta padronizada permitiu a detecção de cinco oocistos em 20% das amostras; não houve reação cruzada com cistos de Giardia duodenalis.

INTRODUCTION: The production of anti-Cryptosporidium polyclonal antibodies and its use in direct immunofluorescence assays to determine the presence of Cryptosporidium in water are described in the present work. METHODS: Two rabbits were immunized with soluble and particulate antigens from purified Cryptosporidium oocysts. The sera produced were prepared for immunoglobulin G extraction, which were then purified and conjugated with fluorescein isothiocyanate (FITC). Slides containing known amounts of oocysts were prepared to determine the sensitivity of the technique. To test the specificity, slides containing Giardia duodenalis cysts were prepared. RESULTS: The conjugate was successfully used in water samples experimentally contaminated with Cryptosporidium oocysts, and it was possible to detect up to five oocysts/spot, corresponding to contamination of 250 oocysts/mL. CONCLUSIONS: The three immunizations performed in the rabbits were enough to produce antibodies against Cryptosporidium, the standard direct immunofluorescence assay permitted the detection of five oocysts in 20% of the samples, and no cross-reaction with Giardia duodenalis cysts occurred.