Abstract
Fascioliasis is a neglected trematode infection caused by Fasciola gigantica and Fasciola hepatica. Routine diagnosis of fascioliasis relies on macroscopic identification of adult worms in liver tissue of slaughtered animals, and microscopic detection of eggs in fecal samples of animals and humans. However, the diagnostic accuracy of morphological techniques and stool microscopy is low. Molecular diagnostics (e.g., polymerase chain reaction (PCR)) are more reliable, but these techniques are not routinely available in clinical microbiology laboratories. Matrix-assisted laser/desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) is a widely-used technique for identification of bacteria and fungi; yet, standardized protocols and databases for parasite detection need to be developed. The purpose of this study was to develop and validate an in-house database for Fasciola species-specific identification. To achieve this goal, the posterior parts of seven adult F. gigantica and one adult F. hepatica were processed and subjected to MALDI-TOF MS to create main spectra profiles (MSPs). Repeatability and reproducibility tests were performed to develop the database. A principal component analysis revealed significant differences between the spectra of F. gigantica and F. hepatica. Subsequently, 78 Fasciola samples were analyzed by MALDI-TOF MS using the previously developed database, out of which 98.7% (n = 74) and 100% (n = 3) were correctly identified as F. gigantica and F. hepatica, respectively. Log score values ranged between 1.73 and 2.23, thus indicating a reliable identification. We conclude that MALDI-TOF MS can provide species-specific identification of medically relevant liver flukes.
Highlights
For the creation of main spectra profiles (MSPs) to be included in the in-house database, we included seven randomly selected adult flukes obtained from cattle in Nigeria, which had previously been identified as F. gigantica based on morphological characteristics, and one adult F. hepatica provided from Switzerland
There was some heterogeneity with regard to the spectra within the F. gigantica cluster, which was further substantiated by a principal component analysis and discriminant analysis (Figure 3)
Our results show that MSPs created from repetitive measurements of eight adult Fasciola specimens, utilized as part of a helminth-specific in-house database, allowed for an unambiguous identification of 78 additional Fasciola samples
Summary
Fascioliasis is a food-borne parasitic disease in animals and humans, caused by the digenetic trematodes Fasciola gigantica and Fasciola hepatica [1]. F. gigantica is restricted to areas of Asia and Africa [2,3], F. hepatica is widely distributed throughout Africa, Asia, Europe, Oceania and the Americas [4,5,6,7]. Fascioliasis and other food-borne trematode infections are classified as neglected tropical diseases. 2.4–17 million people are infected with Fasciola spp. These numbers may be considerable underestimations of the true number of infections, and the global
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