Queenstown cryptosporidiosis outbreak

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In September 2023, an outbreak of cryptosporidiosis, a parasitic illness, started in Queenstown, New Zealand. It was Queenstown's first gastroenteritis outbreak in 40 years. [1] [2] Queenstown issued a water boil notice on 18 September, which ended on 8 December. The most probable cause of the outbreak was human fecal matter. [3] During the outbreak, district mayor Glyn Lewers was concerned with how it would impact the town's reputation. [4] As of 24 September, most cases are between the ages of 15 and 39, but there has been a case under the age of 10. [5] As of 29 September 2023, three people had been hospitalised, all of whom had been discharged. [6]

Contents

Timeline

On 8 September 2023, after various social media posts about people getting sick, the Queenstown-Lakes District Council (QLDC) increased their levels of monitoring and testing, [7] including residual chlorine level checks, and tests for E. coli and other bugs. [7] After many of these tests, on 14 September, the council said that the water supply in Fernhill was not contaminated, [8] but they said that it cannot be ruled out. [1] On the afternoon of 18 September, the council issued a notice urging people in Queenstown to boil their water for at least a minute or use bottled water. At that point, eight cases were known and it was not yet known if the water supply was the culprit. [7] It was that day, cryptosporidiosis became the known cause of the sicknesses previously reported on social media. [9] Around 24 September, investigators further broadened their search for the source outside of the water supply. Heat maps of cases showed that they were mostly from the central business district. Flooding during the outbreak in the South Island caused temporary difficulty investigating the source. [5] On 29 September, temporary ultraviolet disinfecting equipment was ordered with an installation timeframe at Two Mile on 8 December. [10]

On 21 September, parasitologist Bruce Russell from the University of Otago said that the timing of the outbreak and seasonal changes may indicate that the outbreak could have been caused by animal waste contaminating the water supply. [2] That same day, the adult spa pool at Alpine Aqualand was closed as a precaution. Other pools around the area were kept open, and followed Recreation Aotearoa's pool protocol for crypto outbreaks, which included cancelling swimming lessons for children under the age of 8. [11] On 5 October the boil water notice for Kelvin Heights was lifted. [12]

On 5 October, the QLDC lifted the boil water notice for some Queenstown suburbs and Frankton after isolating the water supply from the Kelvin Heights treatment plant, which had already installed a barrier against cryptosporidiosis. [13] On 6 October, Te Whatu Ora said that the most likely source of the outbreak is human faecal matter contaminating the water supply from Lake Wakatipu. Possible contamination sources identified included dispersal from watercraft, swimmers, or wastewater overflows. Te Whatu Ora said that faecal matter from one person is enough to cause the outbreak. [12] [14]

The boil notice for Queenstown was lifted on 8 December 2023, after the district had met its compliance order of installing UV filters. [3]

Cases

Date (2023)Confirmed casesProbable casesUnder investigationReference
19 September15 [1]
21 September18 [2]
23 September29 [15]
24 September30 [5]
29 September48123 [16]
1 October56128 [9]
3 October601310 [17]
6 October621824 [12]
10 October651826 [18]
14 November72202 [19]

Responses

On 21 September, Taumata Arowai gave the Queenstown-Lakes District Council a compliance order to upgrade its water supply to ensure that it is safe. This was done although the water supply had not been found to be contaminated. It was reported that a membrane barrier that this would require would cost $30 million. [4] On 23 September the council sourced a UV water filter from Waimakariri District Council to place in a water treatment plant. [20]

On 5 October, Taumata Arowai published a list of 84 water suppliers did not have adequate UV filtering facilities to protect against protozoa organisms. This list affected over 310,000 people across a total of 27 councils, including 169,000 Christchurch residents. The Christchurch and Wainui water suppliers were identified as lacking a protozoa barrier. Other affected councils included the Queenstown-Lakes District Council, the Waimakariri District Council, the Grey District Council and Gore District Council. Taumata Arowai's head of regulatory Steve Taylor confirmed that the water regulator had written to all affected council, government and private suppliers, informing them that they had until 30 June 2024 to develop plans for installing protozoa barriers. [13] On 6 October, Taylor stated during an interview with Newstalk ZB broadcaster Mike Hosking that Taumata Arowai preferred to avoid prosecuting water suppliers and councils in order to ensure that money was invested in the infrastructure needed to keep water safe. [21]

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References

  1. 1 2 3 "Cases rise to 15 in first gastro outbreak in Queenstown for 40 years". NZ Herald. 21 September 2023. Archived from the original on 20 September 2023. Retrieved 21 September 2023.
  2. 1 2 3 "Animal waste 'most likely' source of Queenstown gastro outbreak – expert". 1 News. Archived from the original on 3 October 2023. Retrieved 21 September 2023.
  3. 1 2 "Queenstown boil water notice lifted after more than two months". 1 News. Retrieved 8 December 2023.
  4. 1 2 Radcliffe, Debbie Jamieson and Kiah (21 September 2023). "Queenstown council faces $30m water upgrade as restaurants face months of imported tank water". Stuff. Archived from the original on 24 September 2023. Retrieved 24 September 2023.
  5. 1 2 3 "Investigation into Queenstown's cryptosporidium outbreak intensifies, will leave 'no stone unturned'". Stuff. 23 September 2023. Archived from the original on 24 September 2023. Retrieved 24 September 2023.
  6. ↑ Littlewood, Matthew (29 September 2023). "Three hospitalised since crypto outbreak began". Otago Daily Times Online News. Archived from the original on 2 October 2023. Retrieved 1 October 2023.
  7. 1 2 3 Jack, Amberleigh (18 September 2023). "Queenstown and Frankton residents warned to boil water after eight people confirmed sick". Stuff. Archived from the original on 18 September 2023. Retrieved 21 September 2023.
  8. ↑ "QLDC clears water supply as Fernhill gets slammed by gastro bug". Crux. Archived from the original on 3 October 2023. Retrieved 21 September 2023.
  9. 1 2 "More than 50 cases of cryptosporidium as Queenstown outbreak grows". RNZ. 1 October 2023. Archived from the original on 3 October 2023. Retrieved 1 October 2023.
  10. ↑ "Queenstown gets equipment to help fight cryptosporidium outbreak, now at 48 cases". RNZ. 29 September 2023. Archived from the original on 30 September 2023. Retrieved 1 October 2023.
  11. ↑ Interactive (https://www.nvinteractive.com), N. V. (21 September 2023). "Update from QLDC regarding cryptosporidium outbreak in Queenstown". www.qldc.govt.nz. Archived from the original on 25 September 2023. Retrieved 25 September 2023.
  12. 1 2 3 Reporter, Regional (6 October 2023). "Human faeces likely cause of Queenstown cryptosporidium outbreak". Stuff. Archived from the original on 6 October 2023. Retrieved 7 October 2023.
  13. 1 2 "84 water suppliers do not have sufficient UV filtering facilities, Taumata Arowai says". Radio New Zealand . 5 October 2023. Archived from the original on 5 October 2023. Retrieved 6 October 2023.
  14. ↑ "One swimmer could have caused Queenstown cryptosporidiosis outbreak". Radio New Zealand . 7 October 2023. Archived from the original on 14 October 2023. Retrieved 14 October 2023.
  15. ↑ "29 confirmed cases of cryptosporidium in Queenstown". Archived from the original on 3 October 2023. Retrieved 23 September 2023.
  16. ↑ "Queenstown gets equipment to help fight cryptosporidium outbreak, now at 48 cases". Radio New Zealand . 29 September 2023. Archived from the original on 30 September 2023. Retrieved 1 October 2023.
  17. ↑ "Cryptosporidium: 60 confirmed cases in Queenstown outbreak". Radio New Zealand . 2 October 2023. Archived from the original on 2 October 2023. Retrieved 2 October 2023.
  18. ↑ "Crypto cases still rising in Queenstown". Otago Daily Times Online News. 10 October 2023. Retrieved 14 October 2023.
  19. ↑ "Queenstown cryptosporidium outbreak: Four more weeks of boiling water". RNZ. 14 November 2023. Retrieved 15 November 2023.
  20. ↑ "Queenstown cryptosporidium outbreak: Special filter sourced for Two Mile water supply". Archived from the original on 22 September 2023. Retrieved 23 September 2023.
  21. ↑ ""Prosecution has a cost": Regulators prefer to invest in water safety". Newstalk ZB . 6 October 2023. Archived from the original on 6 October 2023. Retrieved 6 October 2023.
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