Toxoplasmagondiioocysts,Giardiacysts andCryptosporidiumoocysts in outdoor swimming pools in Brazil

The accidental ingestion of treated recreational water is an important transmission route of waterborne protozoa worldwide. The present study aimed to provide the first evaluation of swimming pools in Brazil, analysing the presence of pathogenic protozoa (Toxoplasma gondii,Cryptosporidiumspp. andGiardiaspp.) by parasitological and molecular methods. A total of 57 samples were collected from 21 public swimming pools, either directly from the pool or filter backwash water and concentrated using the membrane filtration technique.Giardiacysts andCryptosporidiumoocysts were visualized by direct immunofluorescence assay after purification by immunomagnetic separation.Toxoplasma gondiioocysts were detected by autofluorescence visualization using the supernatant discarded during the purification step as a sample. Positive samples were submitted to molecular analysis. The molecular markers were used:SSU-rRNA,tpi,gdhandbg, forGiardiaDNA amplification, and18S rRNAgene fragment amplification was used for theCryptosporidiumoocysts. The 529-bp repeat element (REP529) fragment and the 35-fold repetitive B1 gene were employed as a target forT. gondii. Amplified products were submitted to sequencing and phylogenetic analysis.Giardiacysts were detected in 19.0% andCryptosporidiumoocysts in 9.5% of swimming pools. In one swimming pool (4.7%), both protozoa were detected on at least one occasion. Structures similar toT. gondiioocysts were detected in 33.3% of the samples, ranging from one to 23 per slide.Giardiawas confirmed by DNA amplification in three swimming pools;Giardia duodenalisAssemblage A was identified by the phylogenetic positioning of the beta-giardin gene.Toxoplasma gondiiDNA was detected in 14.2% of swimming pools. The present study represents the first report of the occurrence ofT. gondiioocysts in swimming pools. Recreational activity in swimming pools contaminated by chlorine-resistant protozoa can represent a high risk of infection for bathers and swimmers.