Water-borne diseases related to drinking-water

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

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

On this page:

Over 8600 cases of campylobacteriosis, cryptosporidiosis and giardiasis were notified in 2014
Untreated water was a risk factor for a number of cases

Over 8600 cases of campylobacteriosis, cryptosporidiosis and giardiasis were notified in 2014

In 2014, there were 6552 notifications of campylobacteriosis (142 per 100,000 population), 542 notifications of cryptosporidiosis (14 per 100,000 population) and 1541 notifications of giardiasis (37 per 100,000 population) (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 drinking-water. The major drop in campylobacteriosis case rates in 2007–08 is likely due to interventions to reduce contamination of poultry around this time [1].  

Figure 1

Untreated water was a risk factor for some cases

In 2014, there were 524 notifications of campylobacteriosis (12.4 per 100,000 population), 113 notifications of cryptosporidiosis (3.0 per 100,000 population) and 193 notifications of giardiasis (4.6 per 100,000 population) with untreated drinking-water as a risk factor in New Zealand.

Not all cases reported risk factors, so these numbers may be an underestimate. 

Figure 2

Information about the data

Notifications of campylobacteriosis, cryptosporidiosis and giardiasis 

Source: Institute of Environmental Science and Research (ESR)

This section presents the number of cases of campylobacteriosis, cryptosporidiosis and giardiasis notified in 2010.

  • It excludes people who had been overseas during the incubation period, as they were unlikely to be infected in New Zealand. 
  • 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. 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).
  2. 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