It’s time for a new approach to internal parasites

Using species-specific qualitative analysis for a more holistic approach to internal parasite control.

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Submitted by Elanco Animal Health

For a long time, the cattle industry has thought about internal parasite control as a “solution in a syringe.” The last new molecule for internal parasite control was introduced into the marketplace nearly 15 years ago, which means we must help elongate the effectiveness of currently available molecules to combat resistance. It is time to think of managing parasites of economic concern to a level we can live with economically and our cattle can live with physiologically.

Parasite management and mitigation is a big-picture approach to internal parasites that includes pasture management, stocking density, seasonal grazing patterns, refugia and targeted and timely treatment(s).

Several tools exist to evaluate parasites, the species present and effectiveness of a given treatment. These include:

  • Fecal egg counts (FEC).

  • Coproculture: hatching parasite eggs in the lab to identify the species in a given sample.

  • Fecal egg count reduction test (FECRT): the difference in egg counts before and after treatment.

  • Nemabiome sequencing: a PCR panel that describes the parasite species present in a sample.

  • PCRs to detect genes that code for resistance to one or more anthelmintics.

While each has a place in a parasite management strategy, each also has strengths and weaknesses. For example, FEC gives results as eggs per gram (EPG) of feces. On the surface it seems to represent the parasite load of a given host, but as a standalone number EPG can be an inaccurate indication of severity of parasite load due to time of year, age of host and species of parasite present. All of which influence the number and interpretation of the test.

This is why it’s important to understand what species of internal parasites are present. There are around 15 species of parasitic worms affecting cattle but four or five are responsible for most of the economic losses. These top five can have regional differences in both importance and severity of infection. The females of each species also have different reproductive capacities.

For example, thread-necked intestinal worms lay 50-100 eggs a day while a barber’s pole worm can lay 10,000 or more. One of the most significant and costly parasites, brown stomach worms, will lay only 100-200 eggs a day. While it may seem obvious to use FEC, when one species is laying 100 times more eggs than another species, results can be misleading. Additionally, four of the most common and economically important worms have eggs that are not distinguishable from each other under the microscope. By performing FEC alone without coproculture, we can only conclude the animal has parasites as represented by some number of eggs seen from the test results with no idea of species, economic significance or how to treat.

Species-Specific Quantitative Analysis (SSQA) is a holistic and innovative approach to parasite management that uses a combination of the tools above to evaluate the need for treatment and potential treatment options including:

  • The estimated relative parasite load using FEC.

  • Parasite species present, which is evaluated by coproculture and/or nemabiome sequencing.

  • Pathologic potential of the species represented.

  • Estimated percent of the population represented by each species within a given herd or production unit.

  • Evaluation of efficacy of previous or current treatment using FECRT.

As with many things in life, making informed decisions helps us move forward. By using SSQA to evaluate the parasites present, producers and their veterinarians can make more informed choices in their parasite treatment protocols, which will help reduce the risk of developing resistance and help to ensure the longevity of the currently available molecules for internal parasite control.

Learn more implementing SSQA protocols onto your operation by talking with your Elanco representative today.

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