New Zealand Journal of Marine and Freshwater Research abstracts
Distinguishing human from animal faecal contamination in water: a review
L. W. SINTON
R. K. FINLAY
Christchurch Science Centre
Institute of Environmental Science
& Research Ltd
P. O. Box 29 181
Christchurch, New Zealand
D. J. HANNAH
Environmental Risk Management Authority
P. O. Box 10 840
Wellington, New Zealand
Abstract Management of faecal contamination of water would be
improved if sources could be accurately identified through water analysis.
Human faeces are generally perceived as constituting a greater human health
risk than animal faeces, but reliable epidemiological evidence is lacking.
United States waterborne disease data suggest that human-specific enteric
viruses account for over half the documented outbreaks. However, in New
Zealand, where there is a high grazing animal:human ratio (increasing the
relative importance of water-transmissible zoonoses), it seems prudent to
assume that human and animal faecal pollution both constitute a risk to human
health. Irrespective of the relative risks, the ability to identify sources
would assist in overall management of microbial water quality. Faecal
streptococci do not appear to provide reliable faecal source identification.
Human and animal sources, respectively, may be distinguishable by two tests on
Bifidobacterium spp.--growth at 45deg.C in trypticase phytone yeast
broth and sorbitol fermentation. Different species of
Bacteroides tend to be present in humans and animals, but poor
survival in water is a problem. Phages of the
Bacteroides
fragilis strain HSP40 appear to be human specific, but low counts in
effluent in some countries, including New Zealand, may limit their usefulness.
Different F-RNA phage subgroups appear to be associated with human and animal
faecal sources. The actinomycete
Rhodococcus coprophilus has
potential as a grazing animal indicator but it is persistent, and existing
culturing techniques are time consuming. The development of DNA-based
techniques, such as polymerase chain reaction (PCR), may assist in the assay of
some microbial faecal source indicators. Various faecal sterol isomers offer
the possibility of distinguishing between human and animal sources, and even
between different animals. Washing powder constituents such as fluorescent
whitening agents, sodium tripolyphosphate and linear alkyl benzenes, offer
useful human source identifiers. It is unlikely that any single determinand
will be useful in all situations, but statistical analysis of appropriate
"baskets" of microbial and chemical determinands offers the possibility of
identifying and apportioning human and animal faecal inputs to natural
waters.
Keywords faecal source identifiers; faecal streptococci;
bifidobacteria; Bacteroides fragilis; bacteriophages; Rhodococcus
coprophilus; faecal sterols; fluorescent whitening agents; sodium
tripolyphosphate; linear alkyl benzenes
M97014
Received 3 April 1997; accepted 24 November 1997
PDF file of entire paper: medium quality (2498K); (scanned from paper original: notes about this process)
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