"The presence of two resistent forms of protozoons, the oocysts from the Cryptosporidium genus and cysts of the Giardia genus, is one of the greatest public health problems in water supply, because these parasites can easily survive our water treatment systems", Jos Antonio Castro Hermida, a scientist at the Galician Institute for Food Quality in the Xunta de Galicia (regional government), tells SINC.
A team led by this researcher took 232 water samples in 55 Galician towns, and confirmed the presence of these infectious life forms in waste water treatment plants, drinking water treatment plants, and recreational areas.
The results of the study, which has been published in the journal Water Research, reveal that Cryptosporidium and Giardia are widely distributed in the environment, and also highlight the ineffectiveness of the treatments used to reduce and deactivate these parasites.
Giardia cysts appeared in 96% of the waste water samples discharged from treatment plants, at levels of up to 6,000 per litre, while 64% of samples contained Cryptosporidium oocysts. These figures were 36.5% and 32.7%, respectively, in the case of drinking water treatment plants, and around 60% in recreational areas, for both protozoons.
It was also found that treatment plants located along the coastal belt discharge their effluent directly into the sea, while those located in inland areas get rid of their water straight into rivers. "This represents a significant risk to human and animal health", warns Castro Hermida.
Cryptosporidiosis and giardiosis are parasitic illnesses that cause a syndrome of poor nutrient absorption and diarrhoea in mammals and birds. This causes high morbidity and mortality rates in domestic ruminants during their first month of life, leading to significant economic losses for livestock farms. In humans, the prevalence of these two illnesses is heightened among
FECYT - Spanish Foundation for Science and Technology