context: On 25 June 2008 the local Health Protection Unit was informed by Anglian Water of an exceedence in the level of Cryptosporidium oocysts found in water supplied from the Pitsford Reservoir in Northamptonshire, United Kingdom, during 19 to 24 June 2008 [25]. The reservoir supplied a population of more than 250,000 in the Northampton area. A notice advising people in the affected areas to boil all drinking water was issued on 25 June 2008 and public health messages were circulated to local health services and to the general public via the media. Those members of the public who were concerned about health risks associated with the incident were asked to ring NHS Direct for clinical advice [26]. The HPA wrote to local GPs and hospitals asking them to monitor potential patients for signs and symptoms of Cryptosporidium infection and to submit faecal specimens to the local hospital diagnostic laboratory if patients presented with diarrhoea. Samples from 34 patients where Cryptosporidium infection was identified were sent to the UK Cryptosporidium reference unit for typing. On 30 June 2008, the Cryptosporidium oocysts found in the reservoir water were confirmed as being of the rabbit genotype Cryptosporidium cuniculus [27]. Subsequently, a dead rabbit was found in a treated water tank at the water treatment works. The genotype of Cryptosporidium oocysts in the rabbits large bowel was indistinguishable from that of the oocysts found in the water [27]. After remediation of the water supply and distribution, the boil water notice was lifted on 4 July and the following day the first case of cryptosporidiosis linked to the incident was identified by the reference laboratory (this case was infected with C. cuniculus). During the course of the outbreak (24 June- 18 July 2008, the dates of symptom onset in the first and last case, respectively), 23 cases of cryptosporidiosis were confirmed as being infected with C. cuniculus; one of the 23 was a secondary case. NHS Direct call proportions for gastrointestinal syndromes (diarrhoea and vomiting) for the East Midlands region in England, where Northampton is situated, were examined during the outbreak (24 June- 18 July 2008) and compared with those for England and Wales. 
  
answers: {'answer_start': [16], 'text': ['the local Health Protection Unit was informed by Anglian Water of an exceedence in the level of Cryptosporidium oocysts found in water']}