Serological diagnosis of fasciolosis (Fasciola hepatica) in humans, cattle, and sheep: a meta-analysis

The eukaryotic expression of SAP-2 shows higher sensitivity than the prokaryotic expressed SAP-2 protein in the detection of antibodies against bovine fasciolosis

Bovine fasciolosis, caused by Fasciola gigantica and Fasciola hepatica, represents a major economic burden to the livestock industry. Developing a reliable diagnostic antigen is crucial for advancing diagnostic kits for bovine fasciolosis, which could effectively mitigate these economic losses. FgSAP-2 has demonstrated​​​ considerable potential as a diagnostic antigen when expressed in prokaryotic systems. Computational analyses suggest that FgSAP-2 undergoes glycosylation, promoting the investigation of whether eukaryotic expression systems--capable of performing post-translational modifications--might enhance its antigenic properties and improve its suitability for diagnostic kit development. To explore this possibility, FgSAP-2 was expressed in Pichia pastoris (reFgSAP-2), purified and used to establish an indirect ELISA. The sensitivity, specificity, and stability of the ELISA were subsequently evaluated. Field serum samples from Guangxi were tested using the reFgSAP-2-based ELISA and compared to results from ELISAs employing prokaryotically expressed FgSAP-2 (rpFgSAP-2) and Excretory-Secretory Products (FgESP). The reFgSAP-2 ELISA exhibited positive detection at a serum dilution of 1:1600, with a coefficient of variation (CV) below 10 % in both intra-batch and inter-batch repeatability tests. Furthermore, no cross-reactivity was observed with sera positive for Schistosoma japonicum and Toxoplasma gondii. The positive detection rates of the reFgSAP-2-ELISA were comparable to those of the FgESP-ELISA, both surpassing the detection performance of the rpFgSAP-2-ELISA. CONCLUSION: An indirect ELISA detection method based on eukaryotically expressed FgSAP-2 was successfully developed, demonstrating high sensitivity, specificity, and repeatability. This approach shows promise for further development in the preparation of diagnostic kits.

The herd-level prevalence of Fasciola hepatica infection in the goat population of Poland

Introduction

Fasciola hepatica, also known as the common liver fluke, is a globally distributed trematode parasite responsible for high economic losses in ruminants. Infection with F. hepatica occurs in Polish cattle and sheep; however, very little is known about its occurrence in goats. Therefore, a serological and coproscopic survey was carried out in Polish goats to determine the herd-level prevalence of F. hepatica infection in the goat population of Poland.

Material and Methods

Between 2014 and 2022, 33 randomly selected goat herds were serologically screened in the regions of Poland for which risk of F. hepatica infection was estimated as increased based on the spatial distribution model developed within the frame of the GLOWORM project. Virtually all adult goats (>1 year-old) were tested using a commercial MM3-SERO ELISA. Risk factors for seropositive herd status were analysed in contingency tables. Also, faecal samples from 214 goat herds monitored for gastrointestinal nematode infections and anthelmintic resistance were examined using a sedimentation method.

Results

At least one seropositive goat was detected in 11 of 33 herds, indicating herd-level seroprevalence of 33.3% (95% confidence interval (CI 95%): 19.7%-50.4%). At the animal level, only 17 of 1,464 tested goats were seropositive (1.2%, CI 95%: 0.7%-1.9%). The within-herd seroprevalence ranged from 0.8% to 11.1%. The serological status of the herd was not significantly associated with the characteristics of the herd or the extent of contact with sheep. In one herd, located in central Poland, a single positive faecal sample was found indicating a herd-level prevalence of F. hepatica infection of 0.5% (CI 95%: 0.1%-2.6%). The animal's post-mortem examination revealed liver lesions typical of chronic fasciolosis.

Conclusion

F. hepatica infection occurs sporadically in Polish goat population and its prevalence is much lower than in cattle or sheep. Therefore, treatment or prevention of fasciolosis should only be considered if it has been reliably confirmed by an accurate diagnostic test. This applies also to goats inhabiting geographical areas where F. hepatica infection appears to be widespread in cattle and sheep, very likely due to the fact that goats avoid wet areas.

Fasciola hepatica: Updates on egg morphology, host range, and distribution

During a survey for helminths in reindeer (Rangifer tarandus) across the Palearctic region, eggs were found in zoo reindeer feces. These were identified as eggs of Fasciola hepatica based on their morphology, morphometrics, location, and analysis of their partial sequence of ITS rDNA region. Some of the eggs had an appendage, previously unreported. Additionally, adults of F. hepatica were studied. Eggs derived from their uteri were also appendaged. Diagnostic morphological traits of F. hepatica eggs (abopercular appendage, knob, egg shell thickening, and egg shape) are discussed in this article. Three dimensional models of F. hepatica eggs were created to demonstrate the eggs features as best as possible. Since fecal examination remains gold standard in diagnosing fasciolosis in humans and animals worldwide, our findings may contribute to improved diagnostics. This research has also shown that reindeer can be a final host for F. hepatica. We also discuss whether the Novaya Zemlya archipelago might be the northernmost site of fasciolosis.

Diagnosis of fasciolosis antibodies in Brazilian cattle through ELISA employing both native and recombinant antigens

Bovine fasciolosis is a parasitic disease with a global reach. Coprological based on egg detection in fecal samples and liver inspection to evaluate the presence of the parasite is currently the gold standard for diagnosing chronic fasciolosis in cattle. However, these techniques are labor-intensive and ineffective during the acute phase of the disease. Serodiagnosis using native and recombinant antigens has become an interesting alternative in efforts to identify cattle fasciolosis. We evaluated cattle from abattoir (n = 139) and farms (n = 500) through liver inspection and coprological examination, respectively. Our laboratory team optimized and validated enzyme-linked immunosorbent assay tests based on somatic antigen, excretory/secretory proteins, and the recombinant antigen cathepsin L-1 to detect serum antibodies against fasciolosis in cattle. For animals from abattoir, 10 were positive for fasciolosis according to liver inspection. Both FhES and FhrCL-1 presented an area under the receiver operating characteristic (AUROC) curve of 0.80, with a sensitivity of 0.80 (95% CI: 0.46-0.95) and 0.70 (95% CI: 0.38-0.90) and specificity of 0.81 (95% CI: 0.73-0.87) and 0.87 (95% CI: 0.80-0.92), respectively. For those cattle from farms, 28 were positive only for fasciolosis according to coprological examination. In this scenario, FhES gave the best performance, with an AUROC of 0.84, sensitivity of 0.79 (95% CI: 0.60-0.90), and specificity of 0.86 (95% CI: 0.82-0.89). In conclusion, our study highlights the potential of serodiagnosis for accurately screening cattle fasciolosis. The promising sensitivity and specificity values of FhES when compared to liver inspection or coprological examination enhance its importance for cattle fasciolosis diagnosis.

IMPORTANCE

The aim of this article was to identify antibodies against fasciolosis in cattle in Brazil. The methodology was reproduced in our laboratory and applied for the first time to the Brazilian cattle herd. The antigens tested can be used as a screening test and thus speed up the diagnosis of bovine fascioliasis.

Comparative evaluation of real-time PCR and ELISA for the detection of human fascioliasis

Fascioliasis is a zoonotic parasitic infection caused by Fasciola species in humans and animals. Despite significant advances in vaccination and new therapeutic agents, little attention has been paid to validating methods for the diagnosis of fascioliasis in humans. Serological techniques are convenient assays that significantly improves the diagnosis of Fasciola infection. However, a more sensitive method is required. The aim of this study was to compare the Real-Time PCR technique with the indirect-ELISA for the detection of Fasciola hepatica in human. Using a panel of sera from patients infected with Fasciola hepatica (n = 51), other parasitic infections (n = 7), and uninfected controls (n = 12), we optimized an ELISA which employs an excretory-secretory antigens from F. hepatica for the detection of human fascioliasis. After DNA extraction from the samples, molecular analysis was done using Real-Time PCR technique based on the Fasciola ribosomal ITS1 sequence. Of 70 patient serum samples, 44 (62.86%) samples were identified as positive F. hepatica infection using ELISA and Real-Time PCR assays. There was no cross-reaction with other parasitic diseases such as toxoplasmosis, leishmaniasis, taeniasis, hydatidosis, trichinosis, toxocariasis, and strongyloidiasis. The significant difference between the agreement and similarity of the results of patients with indirect ELISA and Real-Time PCR was 94.4% and 99.2%, respectively (Cohen's kappa ≥ 0.7; P = 0.02). Based on the Kappa agreement findings, the significant agreement between the results of ELISA and Real-Time PCR indicates the accuracy and reliability of these tests in the diagnosis of F. hepatica in humans.