THE TIME TAKEN to identify the
diarrhoea-causing microorganism Cryptosporidium
in water samples has been reduced from 15 hours to three, and the new
technique enables the most harmful species to be identified so that sources
of contamination can be more readily identified.
The technology is based on the detection of
the Cryptosporidium species
usually found in human faeces using fluorescent probes that target specific
sequences of nucleic acid. Existing immuno-chromatographic
and immuno-fluorescence-based assays do not
provide species or genotype-specific information and polymerase chain
reaction techniques involve expensive equipment and reagents.
“The probes can distinguish C. parvum
and C. hominis
which are responsible for most of the outbreaks that are harmful to
humans,” says Anitha Alagappan,
test developer and a PhD candidate at Australia’s Environmental
biotechnology Cooperative Research Centre.
“Species data is important to understand
the risk of infection to exposed people. There are many different species
of Cryptosporidium, some of which
are infectious to humans and some which aren’t. Many current testing
methods only detect the presence or absence of Cryptosporidium, but not the species of concern.”
The new rapid screening tool uses
fluorescent in situ hybridisation
technology. The reliability of the new technology was tested against one of
the standard methods applied in the water industry in collaboration with
the Cryptosporidium Reference
Laboratory in the UK.
A strong correlation (0.994) between the two methods confirmed that the species
identification method was as reliable as currently-used methods.
“The test has been validated now and could
be used by water utilities worldwide as it fits into current testing
methods quite easily,” says Belinda Ferrari team leader from the University of New South Wales.
The diarrhoeal illness, cryptosporidiosis,
can be life threatening in immuno-compromised
people and currently there is no effective treatment. Public swimming pools
and drinking water have been sources of the disease in the UK and the US.