Outbreak of Cryptosporidiosis in Galway


An extensive cryptosporisiosis outbreak has been identified in the HSE Western area with 125 laboratory-confirmed cases reported in March (up to 29/3/2007) compared with a March 2006 total of just 6 cases. A small number of human isolates have tested positive for Cryptosporidium hominis. Staff in public health, environmental health and clinical microbiology are undertaking an investigation in conjunction with colleagues in the relevant local authorities to determine the cause of the outbreak.
Although prior to 19th March, there had been little firm evidence to link the human illness with water, Galway City and County Council put in place an extensive, precautionary boil water notice on Thursday 15th March 2007 on the advice of HSE West. This notice affected about 90,000 people.
On 19th March 2007, test results from the suspected water supplies demonstrated significantly elevated levels of cryptosporidium oocysts in two of the water supplies. Preliminary typing results indicate the presence of both C. hominis and C. parvum in the water supply. Neither of the two supplies is treated by filtration. As a result, the boil water notice has been extended. The Environmental Protection Agency has requested an action plan (short, medium and long term) from the local authorities and this is expected soon.

It is quite possible that the area could have hosted international guests (particularly from the UK and other European countries, US and Canada) in the weeks prior to St Patrick’s Day. In order to identify visitors to Ireland who may have been exposed to contaminated water, an alert is being circulated through Enter-net (international surveillance network for gastrointestinal infections) and the EU’s Early Warning and Alert System (EWRS).

Further updates are available at www.galwaycity.ie. Information on cryptosporidiosis is available at www.hpsc.ie/hpsc/A-Z/Gastroenteric/Cryptosporidiosis/.