Parasites in water

This article published in Communicable Diseases Intelligence Volume 22, No 9, 3 September 1998 contains information on outbreaks of cryptosporidiosis that have been linked to swimming pools.

Page last updated: 15 September 1998

A print friendly PDF version is available from this Communicable Diseases Intelligence issue's table of contents.

In February this year, CDI reported on outbreaks of cryptosporidiosis in the Australian Capital Territory and New South Wales associated with swimming pools.1 Outbreaks of cryptosporidiosis also occurred in Queensland and Victoria. An outbreak of cryptosporidiosis associated with a swimming pool in the Hutt Valley, New Zealand, in the first quarter of 1998 has also been reported.2 Closure of the pools for cleaning and the implementation of other control measures, such as discouraging people with diarrhoea from using swimming pools, brought the outbreaks under control.

In July, and again in August, both Cryptosporidium parvum and Giardia lamblia were detected in the Sydney water supply. Although no increase in the number of cases of diarrhoeal illness was found, Sydney residents were advised, as a precautionary measure, to boil their water before drinking. Investigations have been undertaken to detect the cause of the problem and measures to clear the organisms from the water supply have been implemented.

These separate incidents involving protozoal contamination of water have highlighted a number of complex issues relating to the microbiological testing of water and the effectiveness of water-treatment methods for removing organisms which are resistant to chlorination. Over the next month, two separate meetings and a conference will be held to examine these issues in the Australian context.


The New South Wales health authorities are convening a meeting of invited experts on 4 September 1998 to review the implications of parasites in Sydney water in light of present knowledge about these organisms and their control. The meeting will consider the development of a consensus position on the place of routine testing of water supplies and the management of contamination incidents.

On 6 October 1998, the Victorian health authorities are holding a meeting of invited participants and experts to develop a consensus strategy on central issues.


The first Australian Conference on Cryptosporidium in Water will be held on 5 October 1998 in Melbourne. Further information is presented below.


1. Anonymous. Cryptosporidiosis outbreak. Commun Dis Intell 1998;22:22.

2. Baker M, Russell N, Roseveare C, O'Hallahan J, Palmer S and Bichan A. Outbreak of cryptosporidiosis linked to Hutt Valley swimming pool. The New Zealand Health Report 1998;5:41-45.

This article was published in Communicable Diseases Intelligence Volume 22, No 9, 3 September 1998.

Communicable Diseases Intelligence subscriptions

Sign-up to email updates: Subscribe Now

This issue - Vol 22, No 9, 3 September 1998