Value of present diagnostic methods for gastrointestinal nematode infections in ruminants

Abstract

In this paper the different options for the diagnosis of gastrointestinal nematode infections are discussed. Diagnostic tests have a role in confirming the clinical diagnosis of parasitic gastroenteritis, but are more important for herd health monitoring of nematode infections, in particular for cattle. Therefore, emphasis is placed on discussing the available diagnostic parameters on their usefulness for that purpose. For clinical diagnosis the clinical signs, combined with the history of the animals is usually sufficient and a laboratory confirmation is not required. Faecal egg counts are, with two exceptions, not suitable for confirmation of the clinical diagnosis, because correlation between faecal egg counts and infection levels is usually low. These exceptions are the diagnosis of haemonchosis in small ruminants and the detection of anthelmintic resistance. This also limits the value of DNA-based tests of faecal material; even quantitative tests of nematode species specific DNA will have little value for diagnosis and monitoring. Pasture larval counts and worm counts are useful parameters for basic epidemiological studies on nematode infections. However, they are too laborious to be used for either routine diagnosis or monitoring. Blood parameters, such as gastrin and pepsinogen and serology are valuable tools for diagnosis. Pepsinogen and ELISAs based on recombinant proteins show most promise as parameters for herd health monitoring. However, extensive epidemiological studies are still needed before these parameters can be implemented in routine herd health monitoring schemes for parasitic gastroenteritis.

Control of gastrointestinal parasitism with nematodes in dairy goats by treating the host category at risk

“…Identification of animals based on coproscopical examination is probably easier to apply in horses or cattle than in small ruminants because of the number of samples required and the related cost. As underlined by Eysker and Ploeger [21], the cost of a diagnostic test should be low enough for farmers and veterinarians to accept it as a tool. In contrast, the FAMACHA  method is of low cost even for large flocks.…”

Managing helminths of ruminants in organic farming

“…The treatments may be applied selectively to the most susceptible group of hosts as proposed in dairy-goats [29] or to the individually most susceptible hosts in conditions where they can readily be identified [61]. Most of the indicators for gastrointestinal parasites are efficient for groups (faecal egg counts, plasma pepsinogen, or antibody response: [22]) but they remain poor on an individual basis. Indirect evaluation based on bodyweight and body condition score has not yet been proven useful for managing the control of parasites on an individual scale.…”

Predicting the effect of anthelmintic treatment on milk production of dairy cattle in Canada using an Ostertagia ostertagi ELISA from individual milk samples

“…Diagnostic techniques to identify and/or quantify intestinal parasites have improved over the years. Fecal egg counts have traditionally been utilized to identify and quantify infections, however, this test is plagued with false negatives, high variability between consecutive tests (low repeatability), and overall underestimation of the level of infection (Gross et al, 1999;Agneessens et al, 2000;Borgsteede et al, 2000;Eysker and Ploeger, 2000). Serum pepsinogen tests have had some success with quantifying levels of parasitism in first-season grazers, but were less reliable when used to quantify infections in adult cattle (Gross et al, 1999;Agneessens et al, 2000;Borgsteede et al, 2000).…”

“…The first enzyme-linked immunosorbent assay (ELISA) test to quantify nematode infections in cattle was developed in 1981 (Keus et al), and since then, many in-house ELISAs have been developed for studies to quantify the infections and their related production losses (Kloosterman et al, 1984;Canals and Gasbarre, 1990;Dohoo et al, 1997;Eysker and Ploeger, 2000;Sanchez et al, 2001;Sithole et al, 2005b). More recently, Svanova (Svanova Veterinary Diagnostics, Uppsala, Sweden) developed a commercial ELISA (Svanovir ® ) available in Europe (Charlier et al, 2005a;Guiot et al, 2007;Forbes et al, 2008;Almería et al, 2009).…”