Detection of Spirocerca lupi and an unknown Trichinella-like nematode in raccoon (Procyon lotor).

The raccoon Procyon lotor (Carnivora: Procyonidae) is an invasive species of growing importance for the introduction of alien pathogens or as additional hosts for autochthonous pathogens in Europe, including zoonotic parasites. As the population is steadily increasing and outcompeting the red fox (Vulpes vulpes) in Germany, the consumption of raccoon meat raises concerns about pathogens they may transmit. Therefore the presence of Trichinella larvae was here investigated in muscle samples (n = 904) of raccoons from northern Germany. No Trichinella larvae were found, thus confirming the general low occurrence of this parasite in Germany. However, Spirocerca lupi (n = 12) and an unidentified Trichinella-like nematode (n = 1) were accidently detected in the examined samples. The first is not a zoonotic parasite but has a high veterinary relevance as it can cause severe diseases in dogs. It is the first documented autochthonous infection of this nematode in Germany. The larvae of an unidentified Trichinella-like nematode were found in high abundance in all examined muscles of one raccoon, though they could not be identified to species level. Histological investigation revealed intramuscular cystic structures. This is the largest study investigating muscular parasites of raccoons in Europe so far, which suggests that this invasive animal species is infected by S. lupi and by a yet unknown Trichinella -like parasite.

Reprint of: Survival of Trichinella spiralis in cured meat products.

Processing of meat is one possible approach to control meat-borne parasites. Processing methods such as freezing, cooking and irradiation are recommended for the control of Trichinella in pork, horse or game meat if specific technical conditions are fulfilled. Curing is a widely used preservation process influencing product characteristics such as shelf life, food safety, and taste. As curing methods are characterized by high parameter variability and predictions about inactivation of parasitic stages in raw meat products are difficult, curing and smoking are not recommended for Trichinella control. The objective of this study was to investigate the survival of T. spiralis in cured raw sausages taking into account water activity (aw-value), pH value, temperature, and time. For this purpose, four different types of sausage (Knackwurst, vacuum packed Knackwurst, short ripened salami, long ripened salami) were produced using T. spiralis infested batter. After production, the sausages were stored at product specific conditions for up to 35 days. During storage, pH value and aw-value of the sausages were monitored over time. Further, sausages of each type were digested using the magnetic stirrer method and the viability of the isolated larvae was assessed using a previously published larval motility test as a proxy for viability and infectivity of Trichinella larvae. In this context, we also introduce a three-level rated infectivity score (RIS) with a clear categorization scheme allowing the assessment of the infectivity of larvae. Based on the RIS, larvae isolated from the salamis were regarded as potentially infective until day 2 (short ripened salami) or day 3 (long ripened salami) post ripening, whereas in Knackwurst, potentially infective larvae were still found by day 8 post ripening. In contrast potentially infective larvae were detected in vacuum-packed Knackwurst until day 24 post ripening. Finally, using the RIS approach, data from previously published studies were collected and subjected to a correlation analysis to identify matrix factors linked to short Trichinella inactivation times.

Survival of Trichinella spiralis in cured meat products.

Processing of meat is one possible approach to control meat-borne parasites. Processing methods such as freezing, cooking and irradiation are recommended for the control of Trichinella in pork, horse or game meat if specific technical conditions are fulfilled. Curing is a widely used preservation process influencing product characteristics such as shelf life, food safety, and taste. As curing methods are characterized by high parameter variability and predictions about inactivation of parasitic stages in raw meat products are difficult, curing and smoking are not recommended for Trichinella control. The objective of this study was to investigate the survival of T. spiralis in cured raw sausages taking into account water activity (aw-value), pH value, temperature, and time. For this purpose, four different types of sausage (Knackwurst, vacuum packed Knackwurst, short ripened salami, long ripened salami) were produced using T. spiralis infested batter. After production, the sausages were stored at product specific conditions for up to 35 days. During storage, pH value and aw-value of the sausages were monitored over time. Further, sausages of each type were digested using the magnetic stirrer method and the viability of the isolated larvae was assessed using a previously published larval motility test as a proxy for viability and infectivity of Trichinella larvae. In this context, we also introduce a three-level rated infectivity score (RIS) with a clear categorization scheme allowing the assessment of the infectivity of larvae. Based on the RIS, larvae isolated from the salamis were regarded as potentially infective until day 2 (short ripened salami) or day 3 (long ripened salami) post ripening, whereas in Knackwurst, potentially infective larvae were still found by day 8 post ripening. In contrast potentially infective larvae were detected in vacuum-packed Knackwurst until day 24 post ripening. Finally, using the RIS approach, data from previously published studies were collected and subjected to a correlation analysis to identify matrix factors linked to short Trichinella inactivation times.

Performance of three molecular methods for detection of Toxoplasma gondii in pork.

Comparison of epidemiological data on the occurrence of Toxoplasma (T.) gondii tissue cysts in meat is hampered by the lack of standardization and a great variety of methods for molecular detection. Therefore, this study aimed to compare and validate three different polymerase chain reaction (PCR) methods for detection of T. gondii DNA in pork. Analytical performance characteristics of two real time PCRs (qPCRs; Tg-qPCR1, Tg-qPCR2) and one conventional endpoint PCR (cPCR), all targeting the 529 repeated element, were assessed using genomic DNA of three clonal T. gondii types prevailing in Europe and North America. qPCR efficiencies for all three clonal types ranged between 93.8 and 94.4% (Tg-qPCR1) and 94.3-95.6% (Tg-qPCR2). Tg-qPCR1 and Tg-qPCR2 showed an overall PCR performance score of 85% and displayed a similar 95% detection limit of 1.067 and 1.561 genome equivalents per PCR reaction (GE/PCR), respectively. However, T. gondii DNA could be detected at concentrations as low as 0.1 GE/PCR. Reliable quantification is possible over 4 log ranges from 105 to 100 GE/PCR with mean repeatability relative standard deviations of ≤11% and reproducibility relative standard deviations of ≤12.7%. Presumably, both qPCRs are similarly suitable for sensitive and specific detection of T. gondii DNA in pork. In contrast, the cPCR using primer pair TOX5/Tox-8 proved to be highly sensitive with a detection limit of 1.41 GE/PCR, but not suitable for detection of T. gondii DNA in pork as unspecific amplification of porcine DNA was observed resulting in bands with similar size to the desired T. gondii-specific PCR product.