Contribution of treated wastewater to the contamination of recreational river areas with Cryptosporidium spp. and Giardia duodenalis

• Published in: Water research (Oxford) Vol. 42; no. 13; pp. 3528 - 3538
• Main Authors: Castro-Hermida, José Antonio, García-Presedo, Ignacio, Almeida, André, González-Warleta, Marta, Correia Da Costa, José Manuel, Mezo, Mercedes
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-07-2008; Elsevier Science
• Subjects: Animals; Applied sciences; Cryptosporidium - genetics; Cryptosporidium - isolation & purification; Cryptosporidium andersoni; Cryptosporidium parvum; Cryptosporidium spp; DNA, Protozoan - genetics; Exact sciences and technology; Genotype; Giardia - genetics; Giardia - isolation & purification; Giardia duodenalis; Other industrial wastes. Sewage sludge; Pollution; Public health; Recreational river areas; Rivers - parasitology; Spain; Waste Disposal, Fluid - methods; Wastes; Wastewater; Water quality; Water treatment and pollution; Europe; Spain; Spain, Galicia; Cryptosporidium spp; Water quality; Recreational river areas; Giardia duodenalis; Wastewater; Public health; Spain; Protozoa; Cryptosporidium; Apicomplexa; Microbiology; Parasite; Sewage treatment plant; Waste water; Health and environment; Pathogenic; Surface water; Stream; Water pollution; Waste water purification; Biological contamination; Environmental protection
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2008.05.001

Samples of the influent and final effluent from 12 wastewater treatment plants from Galicia (NW, Spain) were analyzed for the presence of
Cryptosporidium spp. oocysts and
Giardia duodenalis cysts. All of the plants discharge effluent to a hydrographic basin in which there are numerous recreational areas and fluvial beaches. The samples (25–50
liters) were collected in spring, summer, autumn and winter of 2007. A total of 96 samples were analyzed using techniques included in the US Environmental Protection Agency Method 1623. To identify the genotypes present, the following genes were amplified and sequenced: 18S SSU rRNA (
Cryptosporidium spp.) and
β-giardina (
G. duodenalis). Both parasites were detected in influent and effluent samples from all treatment plants (100%) throughout the year, and
G. duodenalis always outnumbered
Cryptosporidium spp. The mean concentration of
G. duodenalis per liter of influent was significantly higher (
P<0.05) than the mean concentration of
Cryptosporidium spp. per liter of influent. The mean concentrations of parasites in influent samples ranged from 6 to 350
Cryptosporidium spp. oocysts per liter and from 89 to 8305
G. duodenalis cysts per liter. In final treated effluent, the mean concentration of parasites ranged from 2 to 390
Cryptosporidium spp. oocysts per liter and from 79 to 2469
G. duodenalis cysts per liter. The distribution of results per season revealed that in all plants, the highest number of (oo)cysts were detected in spring and summer.
Cryptosporidium parvum,
Cryptosporidium andersoni,
Cryptosporidium hominis and assemblages A-I, A-II, E of
G. duodenalis were detected. The risk of contamination of water courses by
Cryptosporidium spp. and
G. duodenalis is therefore considerable. It is important that wastewater treatment authorities reconsider the relevance of the levels of contamination by both parasites in wastewater, and develop adequate countermeasures.