Abstract
ABSTRACT The protozoa Cryptosporidium spp. and Giardia spp. are etiological agents responsible for the transmission of gastroenteritis, mainly due to the consumption of contaminated water. Their (oo)cysts are resistant to adverse environmental conditions, as well as to most conventional water treatment processes. Thus, the objective of this work was to evaluate the occurrence of (oo)cysts of these protozoans in surface water collected for human consumption in the state of Goiás, Brazil. Fifteen samples of raw water were collected to assess the occurrence of (oo)cysts of the protozoa using the Membrane Filtration method, in addition to turbidity and pH analyses. Recovery rates in tests with ultrapure water reached the USEPA (2012) criteria for Giardia (78.1% ± 0%) and for Cryptosporidium (60.6% ± 32.6%); however, recovery in raw water was lower due to turbidity. All samples (n = 15) were positive for Cryptosporidium spp. oocysts, with a maximum concentration of 250 oocysts/L, demonstrating that these protozoa are disseminated in the aquatic environment of the state of Goiás and pose a risk to public health. Due to the use of water sources for public consumption, it is recommended that public authorities and sanitation companies act to preserve and maintain water courses, carry out periodic monitoring of treatment plants that supply the Cerrado, Santana and São Manoel streams and improve existing treatment technologies. The results did not allow to infer whether animal load and grazing area promote an increase in contamination of the lotic aquatic systems.
Highlights
Waterborne diseases are a relevant public health concern
Results regarding the performance of the Membrane Filtration (MF) method with samples contaminated with Giardia spp. cysts and Cryptosporidium spp. oocysts are provided in Table 3 for ultrapure water, and Table 4 for in natura raw water samples from the Santana stream
Coli higher than that established by the standard and low densities of cattle (1.88 per hectare). These results indicate that the characteristics of land occupation positively influenced the parasitological quality of raw water (DIAS et al, 2008), due to the smaller area of pasture that was reflected in a smaller number of cattle in the region, since studies in other countries reported that a bovine is capable of releasing 50 to 3.9 × 105cysts/g of feces (FARIZAWATI et al, 2005)
Summary
Waterborne diseases are a relevant public health concern. around 829,000 deaths from diarrhea worldwide each year (WHO, 2019) have been related to the use of water contaminated by microorganisms from untreated domestic sewage (CHENG et al, 2009) or surface runoff from livestock farms (IMRE et al, 2017).Among the protozoa transmitted by water, the genera Cryptosporidium (4.0–6.0 μm in diameter) and Giardia (8–18 μm in length by 5–15 μm in width), stand out as being widely distributed in developed and developing countries (COTRUVO et al, 2004).These protozoa have been responsible for numerous waterborne outbreaks worldwide (KARANIS; KOURENTI; SMITH, 2007), since the oral ingestion of at least 10 cysts or a single oocyst can cause infection in susceptible individuals (KARANIS, 2011).The outbreaks caused by these etiological agents are associated with severe diarrhea, and have been well documented (Table 1).The occurrence of these outbreaks can be attributed to the high resistance of these organisms to the environment (KARANIS, 2011) and their high infectivity (THOMPSON, 2004). Among the protozoa transmitted by water, the genera Cryptosporidium (4.0–6.0 μm in diameter) and Giardia (8–18 μm in length by 5–15 μm in width), stand out as being widely distributed in developed and developing countries (COTRUVO et al, 2004). These protozoa have been responsible for numerous waterborne outbreaks worldwide (KARANIS; KOURENTI; SMITH, 2007), since the oral ingestion of at least 10 cysts or a single oocyst can cause infection in susceptible individuals (KARANIS, 2011).
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