Queenstown cryptosporidiosis outbreak explained

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. During the outbreak, district mayor Glyn Lewers was concerned with how it would impact the town's reputation.[3] 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.[4], three people had been hospitalised, all of whom had been discharged.[5]

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,[6] including residual chlorine level checks, and tests for E. coli and other bugs. After many of these tests, on 14 September, the council said that the water supply in Fernhill was not contaminated,[7] but they said that it cannot be ruled out. 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. It was that day, cryptosporidiosis became the known cause of the sicknesses previously reported on social media.[8] 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. On 29 September, temporary ultraviolet disinfecting equipment was ordered with an installation timeframe at Two Mile on 8 December.[9]

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. 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.[10] On 5 October the boil water notice for Kelvin Heights was lifted.

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.[11] 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] [13]

The boil notice for Queenstown was lifted on 8 December 2023, after the district had met its compliance order of installing UV filters.[14]

Cases

!Date (2023)!Confirmed cases!Probable cases!Under investigation!Reference
19 September15
21 September18
23 September29[15]
24 September30
29 September48123[16]
1 October56128
3 October601310[17]
6 October621824
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. 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. 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]

Notes and References

  1. Web site: 2023-09-21 . Cases rise to 15 in first gastro outbreak in Queenstown for 40 years . 2023-09-21 . NZ Herald . en-NZ . 20 September 2023 . https://web.archive.org/web/20230920164945/https://www.nzherald.co.nz/nz/queenstown-gastro-outbreak-cases-rise-to-15/GCDKGAHVX5HHZCNIM2MDSAANCU/ . live .
  2. Web site: Animal waste 'most likely' source of Queenstown gastro outbreak – expert . 2023-09-21 . 1 News . en . 3 October 2023 . https://web.archive.org/web/20231003073059/https://www.1news.co.nz/2023/09/21/animal-waste-most-likely-source-of-queenstown-gastro-outbreak-expert/ . live .
  3. Web site: Radcliffe . Debbie Jamieson and Kiah . 2023-09-21 . Queenstown council faces $30m water upgrade as restaurants face months of imported tank water . live . https://web.archive.org/web/20230924003559/https://www.stuff.co.nz/national/health/300974872/queenstown-council-faces-30m-water-upgrade-as-restaurants-face-months-of-imported-tank-water . 24 September 2023 . 2023-09-24 . Stuff . en.
  4. Web site: 2023-09-23 . Investigation into Queenstown's cryptosporidium outbreak intensifies, will leave 'no stone unturned' . 2023-09-24 . Stuff . en . 24 September 2023 . https://web.archive.org/web/20230924032012/https://www.stuff.co.nz/national/300976787/investigation-into-queenstowns-cryptosporidium-outbreak-intensifies-will-leave-no-stone-unturned . live .
  5. Web site: Littlewood . Matthew . 2023-09-29 . Three hospitalised since crypto outbreak began . 2023-10-01 . Otago Daily Times Online News . en . 2 October 2023 . https://web.archive.org/web/20231002005808/https://www.odt.co.nz/regions/queenstown/three-hospitalised-crypto-outbreak-began . live .
  6. Web site: Jack . Amberleigh . 2023-09-18 . Queenstown and Frankton residents warned to boil water after eight people confirmed sick . 2023-09-21 . Stuff . en . 18 September 2023 . https://web.archive.org/web/20230918221615/https://www.stuff.co.nz/national/300973195/queenstown-and-frankton-residents-warned-to-boil-water-after-eight-people-confirmed-sick . live .
  7. Web site: QLDC clears water supply as Fernhill gets slammed by gastro bug . 2023-09-21 . Crux . en-NZ . 3 October 2023 . https://web.archive.org/web/20231003071557/https://crux.org.nz/crux-news/qldc-clears-water-supply-as-fernhill-gets-slammed-by-gastro-bug/ . live .
  8. Web site: 2023-10-01 . More than 50 cases of cryptosporidium as Queenstown outbreak grows . 2023-10-01 . RNZ . en-nz . 3 October 2023 . https://web.archive.org/web/20231003070054/https://www.rnz.co.nz/news/national/499153/more-than-50-cases-of-cryptosporidium-as-queenstown-outbreak-grows . live .
  9. Web site: 2023-09-29 . Queenstown gets equipment to help fight cryptosporidium outbreak, now at 48 cases . 2023-10-01 . RNZ . en-nz . 30 September 2023 . https://web.archive.org/web/20230930021247/https://www.rnz.co.nz/news/national/499054/queenstown-gets-equipment-to-help-fight-cryptosporidium-outbreak-now-at-48-cases . live .
  10. Web site: Interactive (https://www.nvinteractive.com) . N. V. . 21 September 2023 . Update from QLDC regarding cryptosporidium outbreak in Queenstown . 2023-09-25 . www.qldc.govt.nz . en-US . 25 September 2023 . https://web.archive.org/web/20230925170427/https://www.qldc.govt.nz/2023/september/23-09-21-update-from-qldc-regarding-cryptosporidium-outbreak-in-queenstown . live .
  11. News: 84 water suppliers do not have sufficient UV filtering facilities, Taumata Arowai says . 6 October 2023 . . 5 October 2023 . https://web.archive.org/web/20231005073111/https://www.rnz.co.nz/news/national/499475/84-water-suppliers-do-not-have-sufficient-uv-filtering-facilities-taumata-arowai-says . 5 October 2023.
  12. Web site: Reporter . Regional . 2023-10-06 . Human faeces likely cause of Queenstown cryptosporidium outbreak . 2023-10-07 . Stuff . en . 6 October 2023 . https://web.archive.org/web/20231006152648/https://www.stuff.co.nz/national/300984406/human-faeces-likely-cause-of-queenstown-cryptosporidium-outbreak . live .
  13. News: One swimmer could have caused Queenstown cryptosporidiosis outbreak . 14 October 2023 . . 7 October 2023 . https://web.archive.org/web/20231014033440/https://www.rnz.co.nz/news/national/499632/one-swimmer-could-have-caused-queenstown-cryptosporidium-outbreak . 14 October 2023. live.
  14. Web site: Queenstown boil water notice lifted after more than two months . 2023-12-08 . 1 News . en.
  15. Web site: 29 confirmed cases of cryptosporidium in Queenstown . 23 September 2023 . 3 October 2023 . https://web.archive.org/web/20231003070056/https://i.stuff.co.nz/southland-times/300976559/29-confirmed-cases-of-cryptosporidium-in-queenstown . live .
  16. Web site: 29 September 2023 . Queenstown gets equipment to help fight cryptosporidium outbreak, now at 48 cases . 1 October 2023 . . en-nz . https://web.archive.org/web/20230930021247/https://www.rnz.co.nz/news/national/499054/queenstown-gets-equipment-to-help-fight-cryptosporidium-outbreak-now-at-48-cases. 30 September 2023. live.
  17. News: Cryptosporidium: 60 confirmed cases in Queenstown outbreak . 2 October 2023 . . 2 October 2023 . https://web.archive.org/web/20231002133259/https://www.rnz.co.nz/news/national/499234/cryptosporidium-60-confirmed-cases-in-queenstown-outbreak . 2 October 2023. live.
  18. Web site: 2023-10-10 . Crypto cases still rising in Queenstown . 2023-10-14 . Otago Daily Times Online News . en.
  19. Web site: 2023-11-14 . Queenstown cryptosporidium outbreak: Four more weeks of boiling water . 2023-11-15 . RNZ . en-nz.
  20. Web site: Queenstown cryptosporidium outbreak: Special filter sourced for Two Mile water supply . 23 September 2023 . 22 September 2023 . https://web.archive.org/web/20230922210325/https://www.nzherald.co.nz/nz/queenstown-cryptosporidium-outbreak-special-filter-sourced-for-two-mile-water-supply/J4CR2VIJCFC6VIC3MNGPU4PNLE/ . live .
  21. News: "Prosecution has a cost": Regulators prefer to invest in water safety . 6 October 2023 . . 6 October 2023. https://web.archive.org/web/20231006012310/https://www.newstalkzb.co.nz/on-air/mike-hosking-breakfast/audio/steve-taylor-taumata-arowai-head-of-regulatory-on-the-council-warnings/. 6 October 2023. live.

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