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Emerging myxosporean parasites of Australian frogs take a ride with fresh fruit transport.

Hartigan A, Peacock L, Rosenwax A, Phalen DN, Slapeta J - Parasit Vectors (2012)

Bottom Line: We present a possible mechanism for the emergence of Cystodiscus parasites and a non-invasive screening method to be used as a diagnostic test.In the future, vigilance and communication between wildlife managers/researchers and veterinarians will provide valuable information about these parasites, their host range and true distribution.This will aid risk management assessments for threatened populations within the range of Cystodiscus parasites and ultimately enhance conservation efforts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia. ashlie.hartigan@paru.cas.cz

ABSTRACT

Background: The spread of wildlife pathogens into new geographical ranges or populations is a conservation concern for endangered species. Cystodiscus australis and Cystodiscus axonis are two species of myxosporean parasites infecting Australian frogs and tadpoles that have been recently recognised as important disease agents impacting amphibian conservation. Yet despite their importance to wildlife health, the mechanism of emergence for these parasites is unknown. We hypothesise that these parasites are capable of being accidentally translocated with their amphibian hosts in fresh produce (agricultural, horticultural and industrial) shipments into naïve environments and host populations.

Methods: We surveyed 33 Australian "Banana box" frogs from Sydney fruit markets during 2011 using faecal smears and multiplex species specific PCR on DNA isolated from frog faeces or using histopathology to demonstrate the presence of both C. australis and C. axonis.

Results: One of the "Banana box" frogs, the Dainty green tree frog (Litoria gracilenta) was positive for C. australis and C. axonis in its faeces and continuously shed the parasites for eight months.

Conclusions: We present a possible mechanism for the emergence of Cystodiscus parasites and a non-invasive screening method to be used as a diagnostic test. In the future, vigilance and communication between wildlife managers/researchers and veterinarians will provide valuable information about these parasites, their host range and true distribution. This will aid risk management assessments for threatened populations within the range of Cystodiscus parasites and ultimately enhance conservation efforts.

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A Litoria gracilenta , the Dainty tree frog infected with Cystodiscus axonis and C. australis . B Cystodiscus myxospore in faecal smear preparation, scale 10 μm. C Multiplex species specific PCR result, 1- Positive control showing C. axonis (upper 597 bp band) and C. australis (lower 498 bp band), 2- faecal sample from L. gracilenta (positive for both C. axonis and C. australis) and 3- negative (water) control. Samples (5 μl) were run on 2% agarose gel, stained with Gel Red (Biotium, Australia) with Hyperladder II (Bioline, Australia) DNA ladder.
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Figure 1: A Litoria gracilenta , the Dainty tree frog infected with Cystodiscus axonis and C. australis . B Cystodiscus myxospore in faecal smear preparation, scale 10 μm. C Multiplex species specific PCR result, 1- Positive control showing C. axonis (upper 597 bp band) and C. australis (lower 498 bp band), 2- faecal sample from L. gracilenta (positive for both C. axonis and C. australis) and 3- negative (water) control. Samples (5 μl) were run on 2% agarose gel, stained with Gel Red (Biotium, Australia) with Hyperladder II (Bioline, Australia) DNA ladder.

Mentions: Faeces from 31 frogs were examined, a single Dainty GREEN tree frog (L. gracilenta) adult was found to be shedding Cystodiscus spores in its faeces (1/31, 3.23%) (Figure 1A). The individual appeared in good health throughout the study (September 2011 to April 2012), with an average faecal sample weight of 10-40 mg. All two-weekly parasitological examinations were positive for Cystodiscus spores (Figure 1B). Quantitative analysis of the faecal samples revealed an average of 416 myxospores per sample (average 30 mg) (range = 147–777, mean =417, st. dev = 139, CI 95% = 352- 481). Myxospores measured 14.8 (14–16) × 8.2 (7–9) μm (n = 30), had 5–10 transverse ridges on each valve, and the presence of caudal filaments was not clearly determined. The myxospore morphology overlapped those of C. australis, 16.0 (15–18) × 8.7 (8–10) μm with 5–11 transverse ridges, and C. axonis, 14.1 (13–15.5) × 8.5 (8–10.5) μm with 5–12 transverse ridges and caudal filaments.


Emerging myxosporean parasites of Australian frogs take a ride with fresh fruit transport.

Hartigan A, Peacock L, Rosenwax A, Phalen DN, Slapeta J - Parasit Vectors (2012)

A Litoria gracilenta , the Dainty tree frog infected with Cystodiscus axonis and C. australis . B Cystodiscus myxospore in faecal smear preparation, scale 10 μm. C Multiplex species specific PCR result, 1- Positive control showing C. axonis (upper 597 bp band) and C. australis (lower 498 bp band), 2- faecal sample from L. gracilenta (positive for both C. axonis and C. australis) and 3- negative (water) control. Samples (5 μl) were run on 2% agarose gel, stained with Gel Red (Biotium, Australia) with Hyperladder II (Bioline, Australia) DNA ladder.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475081&req=5

Figure 1: A Litoria gracilenta , the Dainty tree frog infected with Cystodiscus axonis and C. australis . B Cystodiscus myxospore in faecal smear preparation, scale 10 μm. C Multiplex species specific PCR result, 1- Positive control showing C. axonis (upper 597 bp band) and C. australis (lower 498 bp band), 2- faecal sample from L. gracilenta (positive for both C. axonis and C. australis) and 3- negative (water) control. Samples (5 μl) were run on 2% agarose gel, stained with Gel Red (Biotium, Australia) with Hyperladder II (Bioline, Australia) DNA ladder.
Mentions: Faeces from 31 frogs were examined, a single Dainty GREEN tree frog (L. gracilenta) adult was found to be shedding Cystodiscus spores in its faeces (1/31, 3.23%) (Figure 1A). The individual appeared in good health throughout the study (September 2011 to April 2012), with an average faecal sample weight of 10-40 mg. All two-weekly parasitological examinations were positive for Cystodiscus spores (Figure 1B). Quantitative analysis of the faecal samples revealed an average of 416 myxospores per sample (average 30 mg) (range = 147–777, mean =417, st. dev = 139, CI 95% = 352- 481). Myxospores measured 14.8 (14–16) × 8.2 (7–9) μm (n = 30), had 5–10 transverse ridges on each valve, and the presence of caudal filaments was not clearly determined. The myxospore morphology overlapped those of C. australis, 16.0 (15–18) × 8.7 (8–10) μm with 5–11 transverse ridges, and C. axonis, 14.1 (13–15.5) × 8.5 (8–10.5) μm with 5–12 transverse ridges and caudal filaments.

Bottom Line: We present a possible mechanism for the emergence of Cystodiscus parasites and a non-invasive screening method to be used as a diagnostic test.In the future, vigilance and communication between wildlife managers/researchers and veterinarians will provide valuable information about these parasites, their host range and true distribution.This will aid risk management assessments for threatened populations within the range of Cystodiscus parasites and ultimately enhance conservation efforts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Veterinary Science, University of Sydney, Sydney, NSW 2006, Australia. ashlie.hartigan@paru.cas.cz

ABSTRACT

Background: The spread of wildlife pathogens into new geographical ranges or populations is a conservation concern for endangered species. Cystodiscus australis and Cystodiscus axonis are two species of myxosporean parasites infecting Australian frogs and tadpoles that have been recently recognised as important disease agents impacting amphibian conservation. Yet despite their importance to wildlife health, the mechanism of emergence for these parasites is unknown. We hypothesise that these parasites are capable of being accidentally translocated with their amphibian hosts in fresh produce (agricultural, horticultural and industrial) shipments into naïve environments and host populations.

Methods: We surveyed 33 Australian "Banana box" frogs from Sydney fruit markets during 2011 using faecal smears and multiplex species specific PCR on DNA isolated from frog faeces or using histopathology to demonstrate the presence of both C. australis and C. axonis.

Results: One of the "Banana box" frogs, the Dainty green tree frog (Litoria gracilenta) was positive for C. australis and C. axonis in its faeces and continuously shed the parasites for eight months.

Conclusions: We present a possible mechanism for the emergence of Cystodiscus parasites and a non-invasive screening method to be used as a diagnostic test. In the future, vigilance and communication between wildlife managers/researchers and veterinarians will provide valuable information about these parasites, their host range and true distribution. This will aid risk management assessments for threatened populations within the range of Cystodiscus parasites and ultimately enhance conservation efforts.

Show MeSH