Surveillance of Giardia and Cryptosporidium in sewage from an urban area in Brazil.

Cryptosporidium and Giardia are protozoan parasites that cause diarrhea in humans and animals. Molecular characterization of these pathogens in sewage may provide insight on their occurrence and prevalence in Brazil. This study aimed to investigate the presence of Giardia and Cryptosporidium in raw and treated sewage from Londrina, Paraná, Brazil. Samples were collected every two weeks during a year. Samples were concentrated, then DNA was extracted and subjected to a nested PCR targeting the Giardia 18S rRNA gene and the Cryptosporidium 18S rRNA gene. Species of Cryptosporidium were characterized by restriction fragment length polymorphism (RFLP). All raw sewage and 76% of the treated sewage were positive for Giardia; 84% of raw sewage samples and 8% of treated sewage were positive for Cryptosporidium. C. muris, C. hominis, C. baileyi, C. parvum and C. suis were detected in 100%, 19%, 9%, 9% and 4% of raw sewage, respectively. C. muris was the only species found in treated sewage. Multiple species of Cryptosporidium were present in 19.04% of the raw sewage. Treated sewage water can pose a threat to human health. The speciation of Cryptosporidium revealed the presence of non-common zoonotic species as C. suis and C. muris.