Presence of Giardia cysts and Cryptosporidium oocysts in drinking water supplies in northern Spain

Abstract

Aims: To evaluate the prevalence of Cryptosporidium and Giardia in surface water supplies from the province of Álava, northern Spain, and to investigate possible associations among the presence of these pathogenic protozoa with microbiological, physicochemical and atmospheric parameters. Methods and results: A total of 284 samples of drinking and recreational water supplies were analysed. Cryptosporidium oocysts were found in 63·5% of river samples, 33·3% of reservoirs samples, 15·4% and 22·6% of raw water samples from conventional and small water treatment facilities (respectively), 30·8% of treated water from small treatment facilities, and 26·8% of tap water from municipalities with chlorination treatment only. Giardia cysts were found in 92·3% of river samples, 55·5% of reservoirs samples, 26·9% and 45·2% of raw water samples from conventional and small water treatment facilities (respectively), 19·2% of treated water from small treatment facilities, and 26·8% of tap water from municipalities with chlorination treatment only. The presence of Cryptosporidium and Giardia had significant Pearson's correlation coefficients (P < 0·01) with the turbidity levels of the samples, and a number of significant associations were also found with the count levels for total coliforms and Escherichia coli. The samples were positive for Cryptosporidium significantly (P < 0·05) more frequently during the autumn season than during the spring and winter seasons. No significant differences were found in the seasonal pattern of Giardia. A moderate association (r = 0·52) was found between rainfall and the presence of Cryptosporidium oocysts. Conclusions: Cryptosporidium and Giardia are consistently found at elevated concentrations in surface waters for human consumption from the province of Álava, northern Spain. Significance and Impact of the Study: Water treatments based on rapid filtration process and/or chlorination only are often unsatisfactory to provide safe drinking water, a situation that represents an important public health problem for the affected population because of the risk of waterborne outbreaks.

Cryptosporidium spp. and Giardia spp. in surface water supply of Campinas, Southeast Brazil

“…Table 2 (Table 2), might have been due to the influence of the turbidity in the filtration process, with the obstruction of the membranes pores by the increased sediment. Consequently, The highest densities of protozoa were found in sample 2 ( Comparative studies about the risk of waterborne epidemic outbreaks of cryptosporidiosis suggest that actions such as awareness about the source of contamination and changes in treatment must be taken when numbers of $3 to 30 oocysts or cysts/100 litres of treated water are found, for that already indicates risk of an epidemic outbreak (Carmena et al 2007). …”

Climate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

“…For example, in the United States extreme precipitation events precede on the order of 68% of waterborne disease outbreaks 6 . Heavy precipitation has been implicated in cryptosporidiosis in Milwaukee, USA 53 , New Zealand 54 and Spain 55 , as well as in emergency visits for diarrhea in the springtime in New York 56 . Recreational waters and harvesting of shellfish are often closed following extreme precipitation events due to the high probability of contamination 6 .…”

Zebra mussel as a new tool to show evidence of freshwater contamination by waterborneToxoplasma gondii

“…; Fayer ; Carmena et al . ). To define a precise seasonal pattern and the ecodynamics of protozoa, particularly T. gondii , an active approach applied over a large geographical (spatial) scale and at different seasons appears to be a particularly cogent strategy.…”

“…The odds of detecting T. gondii are more than 12 times higher in California mussels sampled during the wet season as compared to the dry season (Shapiro et al 2014). The application of cattle manure on land and heavy rainfalls during wet weather spells could explain this trend, as they could facilitate transport of cat faeces into ponds and rivers (Atherholt et al 1998;Curriero et al 2001;Fayer 2004;Carmena et al 2007). To define a precise seasonal pattern and the ecodynamics of protozoa, particularly T. gondii, an active approach applied over a large geographical (spatial) scale and at different seasons appears to be a particularly cogent strategy.…”