Water is a vehicle for disseminating human and veterinary toxoplasmosis due to oocyst contamination. Several
outbreaks of toxoplasmosis throughout the world have been related to contaminated drinking water. We have developed
a method for the detection of Toxoplasma gondii
oocysts in water and we propose a strategy for the detection of
multiple waterborne parasites, including Cryptosporidium
spp. and Giardia. Water samples were filtered to recover
oocysts and, after the detection of Cryptosporidium
oocysts and Giardia
cysts by immunofluorescence,
as recommended by French norm procedure NF T 90-455, the samples were purified on a sucrose density gradient.
Detection of Toxoplasma
was based on PCR amplification and mouse inoculation to determine the presence and
infectivity of recovered oocysts. After experimental seeding assays, we determined that the PCR assay was more
sensitive than the bioassay. This strategy was then applied to 482 environmental water samples collected since 2001.
We detected Toxoplasma
DNA in 37 environmental samples (7.7%), including public drinking water; however, none
of them were positive by bioassay. This strategy efficiently detects Toxoplasma
oocysts in water and may be suitable
as a public health sentinel method. Alternative methods can be used in conjunction with this one to determine the
infectivity of parasites that were detected by molecular methods.