The contamination of drinking water with human waste is the primary cause of Galway's cryptosporidium crisis, according to the latest laboratory results.
Tests on 123 samples from people who fell ill during the outbreak show they were infected with a cryptosporidium strain normally found in human waste.
Just 25 samples were identified as having been caused by cryptosporidium from animal waste.
The exact cause of the contamination in Lough Corrib, which is the source of the city's water supply, has yet to be identified, but the human waste source had previously been played down by officials.
Possible sources include a number of facilities pumping almost untreated sewage into the lake. The possibility of septic tank sewage been swept into the lake via rivers has also been investigated.
Details of the tests emerged as the city prepares to host a major national conference today and tomorrow on water quality.
Organised by the Environmental Protection Agency, it was booked months before the water crisis emerged in Galway.
The latest figures show 236 cases of cryptosporidium were confirmed in the Galway area since the beginning of the year. However, there has been a tailing-off of cases in the regionto three a week, which is a normal "background" number of cases expected for an area of its size.
However, the drinking water ban, in place since March, is unlikely to be lifted until the end of next month. The HSE has indicated to Galway City and Galway County Council that it would only lift the notice when problems at the Terryland water treatment works are addressed.
© 2007 The Irish Times