scholarly journals Prevalence and Intensity of Cardicola spp. Infection in Ranched Southern Bluefin Tuna and a Comparison of Diagnostic Methods

Pathogens ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1248
Author(s):  
Cecilia Power ◽  
Shannon Evenden ◽  
Kirsten Rough ◽  
Claire Webber ◽  
Maree Widdicombe ◽  
...  
Keyword(s):  
Best Practice ◽  
Quantitative Polymerase Chain Reaction ◽  
Parasite Load ◽  
Bluefin Tuna ◽  
Diagnostic Methods ◽  
Health Concern ◽  
Infection Prevalence ◽  
Adult Fluke ◽  
Blood Fluke ◽  
Southern Bluefin Tuna

The parasitic blood flukes Cardicola forsteri and C. orientalis are an ongoing health concern for Southern Bluefin Tuna Thunnus maccoyii (SBT) ranched in Australia. In this study we compared the effect of treatment, company, and ranching year on blood fluke infections in ranched SBT. SBT were sampled during the 2018 and 2019 ranching seasons from praziquantel (PZQ) treated pontoons and untreated pontoons managed by two companies. Severity of infection was diagnosed by several criteria including adult fluke counts from hearts, egg counts from gill filaments and the use of specific quantitative polymerase chain reaction (qPCR) for detection of C. forsteri and C. orientalis ITS-2 DNA in SBT hearts and gills. PZQ treatment remains highly effective against C. forsteri infection. Prevalence and intensity of Cardicola spp. infection was lower in 2019 than 2018 for Company A in treated pontoons at week 12 and week 17 of ranching, and lower for Company A than Company B in untreated pontoons at month 5 of ranching. Results indicate re-infection may be less likely in the environment near Company A pontoons, and consistent years of treatment may have lowered the parasite load in the environment. qPCR demonstrated higher sensitivity when comparing diagnostic methods for C. forsteri in heart, and higher specificity when comparing diagnostic methods for Cardicola spp. in gills. Continuing to monitor blood fluke infections in ranched SBT can help to detect changes in drug efficacy over time and help industry to develop a best practice for treatment.

scholarly journals Correlation of Humoral Immune Response in Southern Bluefin Tuna, T. maccoyii, with Infection Stage of the Blood Fluke, Cardicola forsteri

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e45742 ◽  
Author(s):  
Nicole T. Kirchhoff ◽  
Melanie J. Leef ◽  
Victoria Valdenegro ◽  
Craig J. Hayward ◽  
Barbara F. Nowak
Keyword(s):  
Immune Response ◽  
Humoral Immune Response ◽  
Bluefin Tuna ◽  
Blood Fluke ◽  
Humoral Immune ◽  
Southern Bluefin Tuna ◽  
Infection Stage

Serological evidence of an antibody response in farmed southern bluefin tuna naturally infected with the blood fluke Cardicola forsteri

2008 ◽  
Vol 25 (1-2) ◽  
pp. 66-75 ◽  
Author(s):  
Hamish M. Aiken ◽  
Craig J. Hayward ◽  
Philip Crosbie ◽  
Marianne Watts ◽  
Barbara F. Nowak
Keyword(s):  
Antibody Response ◽  
Bluefin Tuna ◽  
Serological Evidence ◽  
Blood Fluke ◽  
Southern Bluefin Tuna

Simulating blood fluke, Cardicola forsteri, infection in farmed southern bluefin tuna, Thunnus maccoyii, using stochastic models

Aquaculture ◽  
2009 ◽  
Vol 293 (3-4) ◽  
pp. 204-210 ◽  
Author(s):  
Hamish Aiken ◽  
Craig Hayward ◽  
Angus Cameron ◽  
Barbara Nowak
Keyword(s):  
Stochastic Models ◽  
Bluefin Tuna ◽  
Blood Fluke ◽  
Southern Bluefin Tuna

scholarly journals Comparison of the egg recovery rates and limit of detection for soil-transmitted helminths using the Kato-Katz thick smear, faecal flotation and quantitative real-time PCR in human stool

2021 ◽  
Vol 15 (5) ◽  
pp. e0009395
Author(s):  
Patsy A. Zendejas-Heredia ◽  
Vito Colella ◽  
Sze Fui Hii ◽  
Rebecca J. Traub
Keyword(s):  
Diagnostic Performance ◽  
Large Scale ◽  
Limit Of Detection ◽  
Quantitative Polymerase Chain Reaction ◽  
Diagnostic Methods ◽  
Infection Prevalence ◽  
Recovery Rates ◽  
Necator Americanus ◽  
Control Programs ◽  
Thick Smear

Background Monitoring the success of soil-transmitted helminth (STH) control programs relies on accurate diagnosis and quantitative assessment of infection prevalence and intensity. As preventative chemotherapeutic program coverage for STH expands, the necessity of gaining insights into the relative or comparative sensitivities, in terms of limits of detection (LOD) and egg-recovery-rates (ERR) for microscopy and quantitative polymerase chain reaction qPCR-based diagnostic techniques becomes imperative to inform suitability for their intended use for large scale STH monitoring and treatment efficacy studies. Methodology/Principal findings The diagnostic performance in terms of ERR and LOD of the Kato-Katz (KK) thick smear technique, sodium nitrate (NaNO3) faecal floatation (FF) and qPCR for the accurate detection and enumeration of STH eggs were calculated and expressed in eggs per gram (EPG), by experimentally seeding parasite-free human faeces with Ascaris spp., Trichuris spp. and Necator americanus eggs representing low, medium and high intensity infections. The efficiency of NaNO3 flotation was also calculated over a range of specific gravities (SpGr) for the optimum recovery of STH eggs. FF of SpGr 1.30 recovered 62.7%, 11% and 8.7% more Trichuris spp., Necator americanus and Ascaris spp. eggs respectively, than the recommended SpGr of 1.20. All diagnostic methods demonstrated strong direct correlation to the intensity of seeded EPG. KK and FF (SpGr 1.30) resulted in significant lower ERRs compared to qPCR (p <0.05). qPCR demonstrated significantly (p <0.05) greater sensitivity with an ability to detect as little as 5 EPG for all three STH, compared to 50 EPG by KK and FF (SpGr 1.30). Conclusions/Significance This study compares the diagnostic parameters in terms of LOD and ERRs of STHs for the KK, FF and qPCR. These results indicate that the diagnostic performance of qPCR assays should be considered by control programs in the phase that aims to seek confirmation of transmission break and cessation of preventive chemotherapy in low-transmission settings, in line with the control targets of the WHO neglected tropical diseases 2030 Roadmap.

scholarly journals Changes in the Splenic Melanomacrophage Centre Surface Area in Southern Bluefin Tuna (Thunnus maccoyii) Are Associated with Blood Fluke Infections

Pathogens ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 79
Author(s):  
Barbara F. Nowak ◽  
Mai Dang ◽  
Claire Webber ◽  
Lukas Neumann ◽  
Andrew Bridle ◽  
...  
Keyword(s):  
Surface Area ◽  
Bluefin Tuna ◽  
Its2 Rdna ◽  
Farmed Fish ◽  
Blood Fluke ◽  
Blood Flukes ◽  
Copy Numbers ◽  
Southern Bluefin Tuna ◽  
Gill Filaments ◽  
Pre Treatment

Melanomacrophage centres (MMCs) are aggregates of macrophages accumulating various pigments. They have been proposed as an indicator of fish immune response. Blood flukes are common parasites in farmed fish. Two cohorts of wild Southern Bluefin Tuna (Thunnus maccoyi) were examined at transfer, before treatment against blood flukes (pre-treatment) and at harvest. MMCs were assessed in histological sections using image analysis, while Cardicola forsteri and Cardicola orientalis infection severity was determined using qPCR, count of adult flukes in heart flushes and count of eggs in gill filaments. Fish from both cohorts showed the same pattern in the changes in the surface area of MMCs. The surface area of splenic MMCs increased over the ranching duration and was positively correlated to the PCR determined copy numbers of Cardicola forsteri ITS2 rDNA in the gills of those fish. However, the infection with blood fluke was more variable, both between cohorts and individuals within the same cohort. Eggs of blood fluke were detected in renal MMCs using histology. Cardicola forsteri had a higher prevalence than Cardicola orientalis. This study contributes to our understanding of blood fluke infections in Southern Bluefin Tuna and their interactions with MMCs.

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