Publikationsdatenbank

Alaria alata:
prevalence study in Brandenburg and development of protein- and molecular-based assays for identification of incidental parasite findings during official meat inspection (2022)

Art

Hochschulschrift

Autor

Kästner, Carolyn Marion (WE 8)

Quelle

Berlin: Mensch & Buch Verlag, 2022 — 88 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/35498

Kontakt

Institut für Lebensmittelsicherheit und -hygiene

Königsweg 69
14163 Berlin
+49 30 838 62551 / 52790
lebensmittelhygiene@vetmed.fu-berlin.de / fleischhygiene@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Wild boar meat infested with foodborne parasites such as the nematode species Trichinella can cause human disease through consumption of raw or insufficiently cooked meat or meat products. For this reason, the Implementing Regulation (EU) No. 2015/1375 makes official Trichinella inspection mandatory for wild boars and other susceptible species intended for human consumption. During these examinations, larval nematodes other than Trichinella spp. as well as mesocercariae of the trematode Alaria (A.) alata appeared as incidental findings in wild boar meat in the past few years in Germany and Europe. Amongst the broad spectrum of nematodes other than Trichinella spp. incidentally found during mandatory Trichinella testing, non-zoonotic and potentially zoonotic helminths can be identified. At the beginning of this thesis, a universal method for detection of a wide variety of larval nematodes different from the Trichinella genus was not available. Therefore, the first study of this thesis targeted the development of a standardized method based on both morphological examination and molecular analysis for a reliable identification of a multitude of larval nematodes found during official Trichinella inspection. The first step of this approach is based on either the microscopic examination by morphological criteria or the performance of an 18S PCR in order to classify the unknown nematodes towards a taxonomic group such as the families Ascaridae, Toxocaridae and Metastrongylida or the order Strongylida and Rhabditida. After this first classification, a specific PCR targeting genes such as ITS2, cox I or 28S needs to be performed in order to identify the species of the unknown nematodes. Also, it was found that the 18S PCR allows not only for the classification of unknown nematode larvae, but also for the identification of larval trematodes such as A. alata mesocercariae (AM), where the focus of this thesis lies on. As data on the prevalence of AM in wild boars from Germany are scarce, the second aim of this work was to conduct a prevalence study on AM in wild boars from the German federal state of Brandenburg to obtain long-term prevalence data and better evaluate temporal and spatial variations in this area over a longer period of time. In this survey, a total AM prevalence of 28.3% (100/354) was observed among all sampled wild boars. The AM prevalences in the examined counties ranged from 11.5% (3/26) to 64.1% (25/39). In one county, no AM (0/16) were found. Further, the parasite load ranged from zero to 908 AM per animal. In total, the mean parasite load was 9.60 AM per animal which varied widely between the AM positive counties from 0.23 AM per animal to 62.18 AM per animal. Further, a statistically significant correlation between prevalence and age group of the sampled wild boars was observed (p=0.001). Here, the AM prevalence increased with age. To date, AM found during official Trichinella inspection are initially identified by morphological examination using the stereomicroscope. This preliminary diagnosis is currently confirmed by the Alaria spp.-specific PCR which, however, is quite time-consuming, labor-intensive and expensive. Therefore, in the third study of this thesis, a standardized MALDI-TOF-based method for a rapid and reliable identification of AM in wild boar meat was developed. First, a MALDI-TOF protein extraction protocol based on the use of ten AM was designed. This protocol allowed for the generation of high-quality single spectra which were used for creation of main spectra profiles (MSPs). Finally, a total of 61 MSPs representing one host individual each were stored in a newly created AM-specific reference spectra database. Further, this newly established protein extraction protocol was optimized for the use of one single A. alata mesocercaria, which enables application in routine diagnostic laboratories.The next step will be to adapt this MALDI-TOF assay for identification of a broad spectrum of larval helminths found during mandatory Trichinella testing, which further will improve the data situation regarding the occurrence and diversity of parasites in wild boar meat in the long term. In conclusion, all three publications presented in this thesis contribute to improve the data situation concerning helminthic parasites incidentally found during official Trichinella examination.