A comparison of detection methods of Alaria alata mesocercariae in wild boar (Sus scrofa) meat

Abstract

Distomum musculorum suis (DMS), the mesocercariae of Alaria alata , is typically found accidently during examination of wild boar meat for Trichinella spp. The aim of the study was to compare DMS detection methods. Briefly, 232 wild boar meat samples were tested by mesocercariae migration technique (AMT) as a reference method; of these, 104 were found to be positive. Selected positive samples were tested again with the three other methods: compressorium method (Compressor), digestion with magnetic stirrer (Digestion) and by modified digestion with Pancreatin® bile and pancreatic enzymes (D + P). The results were analyzed by logistic regression, the non-parametric Kruskal-Wallis test and the Mann-Whitney U test. Of the 43 samples found positive by the AMT, 20 were found positive by Digestion and 25 by D + P. The Compressor identified DMS in seven of the 19 tested samples. The Digestion and D + P methods gave similar intensities (P = 0.506), i.e. 1.4 and 1.3 DMS respectively, but the AMT detected seven times higher number of parasites. The probability of detection of DMS in the meat sample by the Digestion or by D + P was higher than 0.5 when at least seven (Digestion) or five (D + P) DMS were present in the sample (AMT). The Compressor was the least sensitive method: at least 14 DMS must be present in the meat sample for detection. AMT should be considered the most accurate method of DMS detection.

Investigation of the Food-Transmitted Parasites Trichinella spp. and Alaria spp. in Wild Boars in Greece by Classical and Molecular Methods and Development of a Novel Real-Time PCR for Alaria spp. Detection

“…In this context, it has been repeatedly shown that even though the parasite may be found by the compression method and by AD, the most effective is the AMT, probably because mesocercariae are sensitive to the AD procedure and many are destroyed [28,58]. In a recent comparative study, Strokowska et al [11] showed that of the 43 mesocercariae positive samples found by AMT, only 20 were positive by the magnetic stirrer AD method, and 25 by AD using Pancreatin ® bile and pancreatic enzymes, while the less sensitive method was compression. Even though AMT is the most effective method for mesocercariae detection, a combination of AD and AMT would reveal more Alaria positive meat samples than any one of these methods alone [58].…”

“…Humans become infected by eating raw or undercooked meat from infected second intermediate and paratenic hosts, such as wild boars [6]. The species Alaria americana is incriminated for most human cases, and it is present in the Americas where the species Alaria mustelae, Alaria intermedia, Alaria marcianae, Alaria arisaemoides, Alaria canis, and Alaria taxideae have also been identified [6,10,11]. Alaria alata is the species found in Europe, and it is closely related to the zoonotic A. americana, as it has a similar life cycle with various wild animals as paratenic hosts that harbor mesocercariae.…”

“…Furthermore, it has been shown that A. alata mesocercariae are infectious for primates (the Rhesus monkey Macaca mulatta) [12], and thus, it is most likely infectious for humans as well. As a possible cause of FBPD, A. alata is included in the list of zoonotic agents in some countries, e.g., Switzerland and Germany [6,11].…”

“…can be also detected by Alaria spp. migration technique (AMT) [11]. At the food inspection level and according to the EU legislation [21], examination for Trichinella is obligatory for all slaughtered pigs and wild boars, as well as for meat from other game animals, and it is performed by magnetic stirrer artificial digestion before releasing to the consumption.…”

Predicting the risk of Alaria alata infestation in wild boar on the basis of environmental factors

“…The prevalence of A. alata in wild boar in a given province was estimated based on data from this study and recent literature data ( Table 1 ). All sources employed similar methods of A. alata detection ( Strokowska et al, 2021b ), which allowed us to increase the number of samples in a given province and minimize bias due to low sample size. In total, the prevalence A. alata was determined based on three sources, with the final prevalence being calculated as a weighted mean of these sources, based on the number of studied samples.…”