Water-borne diseases related to recreational water

This section presents statistics on three potentially water-borne diseases in Aotearoa New Zealand: campylobacteriosis, giardiasis and cryptosporidiosis. 

These gastrointestinal diseases cause symptoms like diarrhoea and vomiting. Contaminated recreational water is one way that people may contract these diseases. Other ways include contact with drinking water, farm animals, sick animals, faecal matter, other symptomatic people, and eating contaminated food [1].

Background information

Campylobacteriosis, giardiasis, and cryptosporidiosis are gastrointestinal diseases caused by Campylobacter bacteria, Giardia parasite, and Cryptosporidium parasite infection, respectively. These diseases may be transmitted through contact with the faeces of infected animals and humans, either through ingesting contaminated food or water or by contact with infected beings.

Poultry was once considered the primary source of campylobacteriosis in New Zealand, with poultry-associated strains of Campylobacter more likely to be found in urban than rural areas (Mullner et al, 2010). However, food-related interventions led to more than a 50% decrease in cases in 2008 (Sears et al, 2011; ESR, 2017). Other transmission routes such as untreated drinking water or contaminated recreational water bodies are relatively minor sources of campylobacteriosis (Gilpin et al, 2013). However, as food-borne campylobacteriosis cases decrease, these transmission vectors may become more prominent over time.

Waterborne disease notification rates related to contact with recreational water

In 2019, there were 146 notifications of campylobacteriosis, 120 notifications of giardiasis, and 39 notifications of cryptosporidiosis that reported contact with recreational water during the incubation period. 

However, risk factor information was not collected for a substantial proportion of notifications, so these numbers may be an underestimate. Risk factor information was only collected for 33% of campylobacteriosis notifications, 45% of giardiasis notifications, and 46% of cryptosporidiosis notifications. 

In 2015–19, the following District Health Boards (DHBs) had higher rates of campylobacteriosis, giardiasis and/or cryptosporidiosis where contact with recreational water was listed as a risk factor:
- West Coast DHB
- Tairāwhiti DHB
- Lakes DHB

However, low completion rates for risk factor information in many DHBs suggest the rates presented in the 'Notifications of potentially waterborne disease with recreational water as a risk factor' Surveillance report are likely to be underestimates (Figure 3a-c).

 Figure 3a: Risk factor completion rate for campylobacteriosis notifications, by DHB, 2015–19

 Figure 3b: Risk factor completion rate for cryptosporidiosis notifications, by DHB, 2015–19

 Figure 3c: Risk factor completion rate for giardiasis notifications, by DHB, 2015–19

Source: [6]

References

1. Duncan, G. 2014. Determining the health benefits of poultry industry compliance measures: the case of campylobacteriosis regulation in New Zealand. New Zealand Medical Journal 127(1391): 22–37.
2. ESR. 2020. Notifiable diseases EpiSurv data extraction. Porirua: Institute of Environmental Science and Research Limited. (personal communication with ESR Senior Analysts)
3. New Zealand Food Safety. 2019. Annual report concerning Foodborne Disease in New Zealand 2018. Ministry for Primary Industries
4. ESR. 2015. Notifiable and Other Diseases in New Zealand: Annual Report 2014. Porirua: The Institute of Environmental Science and Research. Available online: https://surv.esr.cri.nz/surveillance/annual_surveillance.php
5. ESR. 2017. Notifiable Diseases in New Zealand: Annual Report 2016. Porirua: Institute of Environmental Science and Research. https://surv.esr.cri.nz/PDF_surveillance/AnnualRpt/AnnualSurv/2016/2016AnnualNDReportFinal.pdf (Accessed 2019)
6. ESR. 2021. Notifiable diseases EpiSurv data extraction. Porirua: Institute of Environmental Science and Research Limited

7. Gilpin B, Walshe G, On S, Smith D, et al. 2013. Application of molecular epidemiology to understanding campylobacteriosis in the Canterbury region of New Zealand. Epidemiol Inf 141(6): 1253–66.

8. Mullner P, Shadbolt T, Collins-Emerson JM, Midwinter AC, et al. (2010). Molecular and spatial epidemiology of human campylobacteriosis: source association and geneotype-related risk factors. Epidemiol Infect 138:1372-1383.