SWIMMERS are unwittingly exposing themselves to a deadly parasite when they use our waterways, new research has found.
There are now concerns that cryptosporidium is "widespread in the aquatic environment".
Dr Frances Lucy, an ecologist and lecturer at the Department of Environmental Science at IT Sligo, has warned that anyone who feels ill following watersports on our lakes and rivers should contact a doctor.
Concerns were raised after tests were carried out at Lough Gill, Co Sligo, and from the River Liffey, Dublin, as part of a joint research project being undertaken by IT Sligo and UCD. Dr Lucy's warning relates to the dangers for people who accidentally swallow water while swimming or taking part in watersports.
Cryptosporidium is especially dangerous for anyone whose immune system is suppressed -- with AIDS patients, the elderly and babies regarded as particularly vulnerable.
Symptoms, which include diarrhoea, abdominal cramping, weight loss and dehydration, can last for two weeks.
The study, which is being funded by the Environmental Protection Agency, hopes to establish why there is a spring peak in the number of human cryptosporidiosis cases in Ireland.
Cryptosporidium was identified as a serious public health risk following a severe outbreak in Galway in 2007, when hundreds of people were affected and a boil water notice was in operation for six months. Tests found most people were infected with a cryptosporidium strain found in human waste.
The current research project on Lough Gill and the Liffey will not be completed until next year but the findings so far are "worrying". The tests were analysed at IT Sligo, UCD and at the Johns Hopkins University in Baltimore in the US. Cryptosporidium was found "in almost every sample".
While Lough Gill is the main source of drinking water for Sligo city and parts of Leitrim, Dr Lucy stressed that the water treatment system used by Sligo County Council is state of the art, and said there was no risk to public health from drinking the water once it is treated.
With the final report due to be published in the middle of 2012, Dr Lucy revealed the preliminary findings suggest contamination in both locations is due to both animal and human waste.
She pointed out that slurry was found to be contaminated and that the slurry spreading season in Ireland continues until mid-October.
Based on her previous research, Dr Lucy believes that had the samples been taken on any lake or river, the result could have been the same.
"I believe it is widespread in the aquatic environment. If we had picked any lake in the northwest we would have found cryptosporidium," she said.
Given many people living in the west of Ireland use local group water schemes which are supplied by lakes, Dr Lucy said adequate water filtration systems were vital.