Water-borne diseases related to recreational water

This section presents statistics on three potentially water-borne diseases in 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, or other symptomatic people; and eating contaminated food [1].

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Over 9500 cases of campylobacteriosis, giardiasis and cryptosporidiosis were notified in 2016
In 2016, 212 notifications of potentially water-borne diseases reported contact with recreational water 

Over 9500 cases of campylobacteriosis, giardiasis and cryptosporidiosis were notified in 2016

In 2016, there were 7173 notifications of campylobacteriosis, 1379 notifications of giardiasis, and 962 notifications of cryptosporidiosis (Figure 1). Campylobacteriosis cases have accounted for the majority of notified water-borne disease notifications since 2001.

These cases could have been contracted through a number of ways, not just through contact with recreational water. The major drop in campylobacteriosis cases in 2007-08 is likely due to interventions to reduce contamination of poultry around this time [2].

Figure 1

In 2016, 212 notifications of potentially water-borne diseases reported contact with recreational water 

In 2016, there were 104 notifications of campylobacteriosis, 78 notifications of giardiasis, and 30 notifications of cryptosporidiosis that reported contact with recreational water (river, lake or sea) during the incubation period. 

However, risk factor information was only collected for a proportion of notifications, so these numbers may be an underestimate. In particular, risk factor information was only collected for 30% of campylobacteriosis notifications, 47% of giardiasis notifications, and 69% of cryptosporidiosis notifications. 

In 2012-16, the following District Health Boards (DHBs) had higher rates of campylobacteriosis, giardiasis and/or cryptosporidiosis with a risk factor of contact with recreational water:
- West Coast DHB
- Tairawhiti DHB
- Lakes DHB
- Hawke's Bay DHB.

See the factsheets for more information (available from the downloads box).

Information about the data

Notifications of campylobacteriosis, cryptosporidiosis and giardiasis 

Source: Institute of Environmental Science and Research (ESR)

This section presents the number of notifications of campylobacteriosis, giardiasis and cryptosporidiosis.

  • Notifications of diseases may underestimate the true number of cases of diseases, as not everyone will go to a doctor when sick.
  • Cases that had been overseas during the incubation period were excluded as they were unlikely to be infected in New Zealand. 
  • Not every case reported a ‘risk factor’ (such as untreated drinking water and recreational water contact). The reported number of water-borne disease cases by risk factor is smaller than the actual number.

References

 1. ESR. 2015. Notifiable and Other Diseases in New Zealand: Annual Report 2014. Porirua, New Zealand. Available online: https://surv.esr.cri.nz/surveillance/annual_surveillance.php

2. Sears A, Baker MG, Wilson N, Marshall J, Muellner P, Campbell DM, et al. 2011. Marked campylobacteriosis decline after interventions aimed at poultry, New Zealand. Emerging Infectious Diseases 17(6).