Concentrations of pathogens and indicators in animal feces in the Sydney watershed

Cox, P., Griffith , M., Angles, M., Deere, D. and Ferguson , C. (2005) Applied and Environmental Microbiology, 71 (10); 5929-34.

A study was conducted to provide a cross-sectional estimate of the intensity of shedding of pathogenic and indicator microorganisms in animal faeces in the drinking water watersheds of Sydney , Australia . Estimating the pathogen source loads is an important step in the modelling of pathogen origin, fate and transport in watersheds. Pathogens from animal faeces may enter waterways through direct deposition or by overland runoff containing faecal material.

Four watersheds within the Sydney Catchment Authority were studied. These watersheds have mixed land use with significant agricultural activities mixed with urban and rural residential areas. The main agricultural land uses are sheep and cattle grazing. Samples of animal faeces were collected from each watershed during April and May 2002. Samples collected came from a range of domestic animals including: cattle, calves, sheep, pigs, dogs, horses, poultry and cats. Native and feral animal faecal samples were also collected in May and June 2002. Faecal samples were analysed for pathogenic protozoa ( Cryptosporidium and Giardia ), enteric viruses (adenovirus, enterovirus and reovirus), and indicator organisms (faecal coliforms and C lostridium perfringens spores).

The concentrations of C. perfringens spores, Cryptosporidium and Giardia and enteric viruses were all higher in the faeces of domestic animals than in the faeces of wildlife animals. C. perfringens was isolated mostly from domestic animal faeces and was rarely found in wildlife faeces. C. perfringens may be a useful indicator of faecal inputs from agricultural and urban development in watersheds. Faecal coliforms were isolated from the majority of the faecal samples from domestic and wildlife animals and mostly in high concentrations. The levels of faecal coliforms found were substantially higher than the pathogen levels found. Using faecal coliforms as surrogates for pathogen loads could therefore lead to an overestimation of the risk. Reoviruses were the most often isolated viruses. These viruses are ubiquitous and infect and range of vertebrates.

Future studies are required in this watershed to investigate the seasonal and other temporal effects on pathogen input loads especially from domestic animals. Even though potential human pathogens were isolated in this study area, there have been no outbreaks of waterborne disease in the population that is served by this watershed.