A novel detection method for Alaria alata mesocercariae in meat

Abstract

Distomum musculorum suis (DMS), the mesocercarial stage of the trematode Alaria alata, can cause severe damages within their hosts, and since several reports about cases of human larval alariosis have been published, it became apparent that infected game animals and in particular wild boars are a potential source of infection for both humans and animals. A final statement concerning the health risks for consumers could not be given due to the lack of information about both the prevalence of DMS and the suitability of Trichinella inspection methods to detect this parasite in wild boar meat. Our studies concentrate on (1) the verification of suitability of the official digestion methods for Trichinella spp. for DMS detection in wild boars, (2) development, optimization, and validation of methods, and (3) the distribution of the parasites within their paratenic hosts. A total of 868 individual samples/digests from 48 wild boars were analyzed by the reference method for Trichinella detection in meat samples according to regulation (EC) No. 2075/2005. In addition to the official protocol, a method modification with Pankreatin(c) and bile acid was applied for analysis of adipose tissue samples (n = 89). On the basis of our results, a new detection method based on a larvae migration technique was developed and used for detection of DMS in 574 single samples. Furthermore, the distribution patterns of DMS in wild boars in a total of 1377 single sample migrations/digestions from 35 positive animals were analyzed by application of all three methods. The official digestion method for Trichinella spp. in wild boars meat is inapplicable for the detection of A. alata mesocercariae as it shows shortcomings in both digestion and sampling. A direct comparison between the newly developed A. alata mesocercariae migration technique and the official digestion method for Trichinella spp. based on 574 single samples from 18 animals clearly shows that the sensitivity to detect A. alata developmental stages in tissues of wild boars of the new method is nearly 60% higher compared with the magnetic stirrer method for pooled sample digestion as laid down in regulation (EC) No. 2075/2005. Among other advantages, this method offers a simple, highly applicable, fast, and cost effective way to detect DMS in wild boars which is already applicable in routine veterinary inspection.