Which McMaster egg counting technique is the most reliable?

Abstract

This study focuses on the comparison of three selected modifications of the McMaster counting technique, namely the McMaster method modified by Wetzel (W) and Zajíček (Z), as well as the concentration McMaster technique according to Roepstorff and Nansen (R&N). These modifications differ in the weights of faeces examined (W, 2 g/Z, 1 g/R&N, 4 g), flotation solutions (W, NaCl/Z, MgSO(4) + Na(2)S(2)O(3)/R&N, NaCl + glucose), centrifugation (W, none/Z, 2,000 RPM for 2 min and 2,000 RPM for 1 min/R&N, 1,200 RPM for 5 min), number of McMaster chambers investigated (W, 3/Z, 2/R&N, 2), and multiplication factors used (W, 67/Z, 33/R&N, 20). To investigate the sensitivity and reliability of these methods, nematode eggs (Teladorsagia circumcincta) were used. Parasite elements are distributed through negative binomial distribution in naturally infected host faeces, and the number of parasite elements in a given amount of faeces sample is unknown to man. Therefore, we decided to prepare the exact number of eggs which were added to the parasite negative faeces; the faecal sample was then investigated. From this perspective, this is the first time a comparison of the McMaster methods has been so accurately investigated. This approach allows us to evaluate the real sensitivity and reliability of the tested method. As the findings of this study indicate, the highest sensitivity and reliability were obtained using the Roepstorff and Nansen modification. This McMaster modification is able to detect 20 eggs per sample (in 70% of samples). Concentrations of 200 and 500 eggs can be found in almost 100% of samples. Moreover, this method is simple, cheap and fast. For these reasons, we can recommend this method for routine veterinary practice.

Gastrointestinal parasites of cats in Denmark assessed by necropsy and concentration McMaster technique

“…Although the c-McMaster is considered reliable and practical (Vadlejch et al, 2011), there are some limitations of coprological examination in general. The currently observed low diagnostic sensitivity of the c-McMaster for taeniid eggs implies that taeniid infections could be substantially underestimated (Bružinskaitė et al, 2009;Magi et al, 2009).…”

Haemonchus Contortus and Ovine Host: A Retrospective Review.

“…The McMaster method, which developed at the McMaster laboratory of the University of Sydney, is the most world-wide utilized FEC technique in veterinary and medical parasitology, and is supported by the World Association for the Advancement of Veterinary Parasitology for assessing the anthelmintic drug efficacy in ruminants [84], as well as for the anthelmintic resistance detection [82]. This method has improved diagnostic parasitology, both animal [85; 86; 87; 88; 89] [94], however the method reported by Roepstorff and Nansen proved to be the more sensitive and reliabile technique (Table 2). Packed cell volume:-The packed cell volume (hematocrit) is the ratio of the red blood cell volume (A) to the total blood volume (B) (Fig.10).…”

The contribution of simple random sampling to observed variations in faecal egg counts

“…Although this is the basic description of the technique, there are many minor variations undertaken in different laboratories. Some of these variations are described in Pereckiene et al (2008) and Vadlejch et al (2011). Counting parasite eggs in a McMaster chamber is analogous to that of counting yeast cells in a haemocytometer as described by Gosset in that eggs in a faecal suspension will be randomly distributed in the same way that yeast cells are randomly distributed in a fluid suspension.…”