Veterinary Parasitology 194 (2013) 106–109 Contents lists available at SciVerse ScienceDirect Veterinary Parasitology jou rn al h om epa ge: www.elsevier.com/locate/vetpar Trichinella detection: Identification and statistical evaluation of sources of error in the magnetic stirrer method for pooled sample digestion Katharina Riehn a,* , Dirk Hasenclever b , David Petroff c , Karsten Nöckler d , Anne Mayer-Scholl d , Gregor Makrutzki a , Ernst Lücker a a Institute of Food Hygiene, Faculty of Veterinary Medicine, University of Leipzig, Germany b Institute for Medical Informatics, Statistics and Epidemiology, Medical Faculty, University of Leipzig, Germany c Coordination Centre for Clinical Trials, Medical Faculty, University of Leipzig, Germany d Federal Institute for Risk Assessment, Berlin, Germany a r t i c l e i n f o Keywords: Trichinella Detection Magnetic stirrer Standardized protocols a b s t r a c t Proficiency testing (PT) is the use of inter-laboratory comparisons to determine the per- formance of individual laboratories for specific tests or measurements, and to monitor a laboratory’s performance. Participation in proficiency testing provides laboratories with an objective means of assessing and demonstrating the reliability of the data they are producing. To ensure the reliability of Trichinella detection and meat hygiene within the European Union and afford optimal protection to the consumer, PT is conducted under the direction of the European National Reference Laboratories for Trichinella. Evaluation of data from the national PT showed that lab-internal shortcomings are frequent. These shortcomings are specifically related to: (1) improper sample collection and prepara- tion; (2) incorrect transposition and application of the protocol as laid down in Annex I, Chapter I, Nr. 3 (a–g) of the Commission Regulation (EC) No. 2075/2005; (3) insuf- ficient sedimentation times; and (4) improper equipment.(e.g. Prost and Nowakowski, 1990; Rossi and Pozio, 2008; Forbes and Gajadhar, 1999; Rossi and Pozio, 2008). To test the hypothesis that both method based errors as well as internal lab errors can influence the accuracy and precision of the magnetic stirrer method for pooled sam- ple digestion (MSM), we initiated a study to evaluate the analytical uncertainty of the MSM. Results presented here are based on: (i) data from PT in Germany (2008, 2009, and 2010); (ii) within-lab performance conducting high volumes of MSM; (iii) larval recovery experiments; and (iv) statistical evaluation of data resulting from these procedures. Quan- titative data from the PT show that on average only 60% of Trichinella larvae were detected. Even laboratories that showed relatively good performance (>80% larva recovery, no false negative or false positive results), frequently reported samples with an unexpectedly low larval count (loss of >2 larvae). In our own laboratory, high numbers of repeated analyses of standards and re-analyses of residual fluids indicated that these outliers could be described by a binomial distribution based on a laboratory-specific Trichinella-detection probability. Results of recovery experiments indicate that only a part of the total larval losses can be attributed to lab-internal shortcomings inasmuch as a significant number of L1 could be isolated from the residual and washing fluids. © 2013 Elsevier B.V. All rights reserved. * Corresponding author. E-mail address: riehn@vetmed.uni-leipzig.de (K. Riehn). 1. Introduction In order to monitor and efficiently control trichinel- losis in humans and animals, the European Union (EU) 0304-4017/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.vetpar.2013.01.031