The specific diagnosis of gastrointestinal nematode infections in livestock: Larval culture technique, its limitations and alternative DNA-based approaches

Finishing lambs on a chicory-plantain mixture or a temperate grassbased pasture: live weight gain and gastrointestinal parasitism

“…It is also possible that some L1 or L2 did not survive the period trapped inside the feces. Uncertainties are also associated with the composition of feces and the moisture and temperature of the culture process, among other issues (Roeber and Khan, 2014), since ideal conditions vary for different species of nematodes. Conversely, Jørgensen et al (1998) proposed that part of the hatching ability and survival of infective larvae depends on immune host factors that operate directly on the eggs before they are expelled, though this hypothesis should be further studied.…”

“…Conversely, Jørgensen et al (1998) proposed that part of the hatching ability and survival of infective larvae depends on immune host factors that operate directly on the eggs before they are expelled, though this hypothesis should be further studied. Roeber and Khan (2014) suggested that the results of larvae culture are useful to evaluate the species present rather than to quantify them. Several conditions can affect the process of obtaining L3 from feces culture, e.g., naturally low fecundity that results in low numbers of eggs, low fertility or hatchability, low viability of intermediate larval stages and adverse conditions in the culture technique.…”

“…Nematodirus L3 were not in the culture, because the larvae develop to L3 inside the egg and hatch after being ingested by the host. For a more detailed review on the limitations of larval culture techniques, the reader is referred to Roeber and Khan (2014).…”

A real-time PCR approach to identify anthelmintic-resistant nematodes in sheep farms

“…Even though the differentiation of some trichostrongylid parasite species/genera is possible based on their egg morphology, this is not true for a wide range of strongylid genera including Haemonchus, Teladorsagia, and Trichostrongylus. For many decades, the technique of larval culture has been the only method to obtain species-or genus-specific results (Roeber and Kahn 2014). Larval culture involves incubating fecal samples containing eggs of strongylid nematodes to allow L1s to hatch and develop through to infective larvae (L3s).…”

“…PCR efficiency was high with Haemonchus genus (close to 100%) but lower with the two other genera (Teladorsagia and Trichostrongylus), 85% and 80%, respectively. Although useful in reducing time for setup and costs for PCR testing, multiplexing multiple assays in a single reaction volume are still difficult to design effectively especially when PCR efficiencies are different (Roeber and Kahn 2014). In this study, one separate single PCR reaction was used per strongylid genus to analyze mixed populations of L3s obtained after larval cultures because PCR efficiencies were different.…”