Assessment of Toxoplasma gondii levels in zebra mussel (Dreissena polymorpha) by real-time PCR: an organotropism study

Abstract

Water quality is a public health concern that calls for relevant biomonitoring programs. Molecular tools such as polymerase chain reaction (PCR) are progressively becoming more sensitive and more specific than conventional techniques to detect pathogens in environmental samples such as water and organisms. The zebra mussel (Dreissena polymorpha) has already been demonstrated to accumulate and concentrate various human waterborne pathogens. In this study, first, a spiking experiment to evaluate detection levels of Toxoplasma gondii DNA in zebra mussel organs using real-time PCR was conducted. Overall, lower DNA levels in the hemolymph, digestive gland, and remaining tissues (gonad and foot) were detected compared to mantle, muscle, and gills. Second, an in vivo experiment with 1000 T. gondii oocysts per mussel and per day for 21 consecutive days, followed by 14 days of depuration time in protozoa-free water was performed. T. gondii DNA was detected in all organs, but greatest concentrations were observed in hemolymph and mantle tissues compared to the others organs at the end of the depuration period. These results suggest that (i) the zebra mussel is a potential new tool for measuring T. gondii concentrations and (ii) real-time PCR is a suitable method for pathogen detection in complex matrices such as tissues.

Zebra mussel as a new tool to show evidence of freshwater contamination by waterborneToxoplasma gondii

“…This detection level seems low, but compared to laboratory studies, it corresponds to the level found during the first 2 weeks of a 21‐day in vivo exposure to 1000 oocysts per mussel and per day (Palos Ladeiro et al . ). The sensitivity of the PCR method may have been affected by PCR inhibitors because shellfish homogenates are often laden with soil, sediment, organic matter, as well as chemical and biological pollutants (Castro‐Hermida et al .…”

Mussel as a Tool to Define Continental Watershed Quality

“…This study also shows that mussels accumulate protozoan proportionally to water contamination. Moreover, T. gondii was still present in the mussel tissues for up to 14 days postinoculation, reflecting the integrative character of D. polymorpha [27]. A field study was also carried out in order to test protozoa detection under environmental conditions.…”

Toxoplasmosis in Nigeria: the story so far (1950-2016): a review

“…The reasons for the scanty application of molecular technique include lack of funds, poor electricity supply for specimen preservation and lack/ shortage of trained personnel. The use of this approach cannot be overemphasised giving the advantages it has over other diagnostic techniques (Ajmal et al 2013, Wang et al 2014, Palos Ladeiro et al 2015, Shapiro et al 2015.…”