2017 – Bega (New South Wales) – Cryptosporidium

Drinking water repeatedly contaminated with pathogens in rural NSW towns

9 October 2017: http://www.abc.net.au/news/2017-09-06/drinking-water-contaminated-with-pathogens-in-nsw-towns/8875464

NSW Health documents obtained by the ABC reveal areas where deadly pathogens are regularly detected at dangerous levels in unfiltered drinking water pumped from rivers, lakes and dams.

The water safety reports, obtained after a lengthy freedom-of-information battle, also show more than 100,000 NSW residents were issued protective boil-water alerts in the last five years.

Grafton, Kempsey, Scone, Jindabyne and Bega are cited as the five worst-performing areas, with repeated “contamination incidents” triggering “potential health risks”.

Around Grafton, a population of 40,000 are at risk from cryptosporidium, a parasite that causes gastrointestinal illness.

Residents have faced 10 boil-water alerts since 2006, issued “in response to the inability of the water supply system to manage risks”.

The documents say faecal contamination from cattle, and even swimmers along the lower Clarence River catchment, is the parasite’s source.

Similar problems plague the Bemboka River catchment, near Bega, with four boil-water alerts issued by Bega Valley Council in 10 years.

Deadly bugs originate in “onsite sewerage system discharges”, “failures and presence of septic systems” and from dairy farms upstream.

The documents say “chlorine-resistant pathogens” — not killed by chemical treatments — are a threat to more than 40,000 people.

Around Kempsey, the risk identified is cyanobacteria — a toxic blue-green algae that can shut supply for 15,000 residents.

Grazing dairy cattle and raw sewage discharges near the Steuart McIntyre Dam trigger algae outbreaks here.

Alarmingly, the documents say “all pathogen groups” including e. coli are present in Kempsey water, and that a further “vulnerability assessment” should be undertaken.

In the Upper Hunter, more than 6,000 residents in Scone, Murrurundi and Aberdeen are rated at “very high risk” from dangerous pathogens flowing from an abattoir and septic tanks in the catchment.

The alpine towns of Jindabyne and Barry Way also face a “moderate risk from the presence of cryptosporidium” as well as toxic “blue-green algae” in their catchment.

Livestock faeces, and sewage, including from the Perisher ski resort are blamed.

The documents also identify other communities with one-off water concerns.

Last year boil-water alerts were issued in Dubbo, as well as villages including Toomelah, Gravesend, and Jubullum.

In the Upper Hunter, more than 6,000 residents in Scone, Murrurundi and Aberdeen are rated at “very high risk” from dangerous pathogens flowing from an abattoir and septic tanks in the catchment.

The alpine towns of Jindabyne and Barry Way also face a “moderate risk from the presence of cryptosporidium” as well as toxic “blue-green algae” in their catchment.

Livestock faeces, and sewage, including from the Perisher ski resort are blamed.

The documents also identify other communities with one-off water concerns.

Last year boil-water alerts were issued in Dubbo, as well as villages including Toomelah, Gravesend, and Jubullum.

“In recent years, Cryptosporidium has come to be regarded as one of the most important waterborne human pathogens in developed countries. Over 30 outbreaks associated with drinking water have beenreported in North America and Britain, with the largest infecting an estimated 403,000 people (Mackenzieet al. 1994). Recent research has led to improved methods for testing water for the presence of humaninfectious species, although such tests remain technically demanding and relatively expensive.

Cryptosporidium is an obligate parasite with a complex life cycle that involves intracellular development in the gut wall, with sexual and asexual reproduction. Thick-walled oocysts, shed in faeces are responsible for transmission. Concentrations of oocysts as high as 14,000 per litre in raw sewage and 5,800 per litre in surface water have been reported (Madore et al. 1987). Oocysts are robust and can survive for weeks to months in fresh water under cold conditions (King and Monis 2007).

There are a number of species of Cryptosporidium, with C. hominis and C. parvum identified as the main causes of disease (cryptosporidiosis) in humans. C. hominis appears to be confined to human hosts, while the C. parvum strains that infect humans also occur in cattle and sheep. C. parvum infection sare particularly common in young animals, and it has been reported that infected calves can excrete up to 10 billion oocysts in one day. Waterborne outbreaks of cryptosporidiosis have been attributed to inadequate or faulty treatment and contamination by human or livestock (particularly cattle) waste.

C. hominis and C. parvum can be distinguished from one another and from other Cryptosporidium species  by a number of genotyping methods. Infectivity tests using cell culture techniques have also been developed. Consumption of contaminated drinking water is only one of several mechanisms by which transmission (faecal-oral) can occur. Recreational waters, including swimming pools, are an important source of cryptosporidiosis and direct contact with a human carrier is also a common route of transmission.Transmission of Cryptosporidium can also occur by contact with infected farm animals, and occasionally through contaminated food.” ADWG 2011