Parasites of Interest

At Invetus we are exposed to a wide range of parasites and associated diseases, and from time to time will report those of interest. 

 

Ostertagia lyrata

Young Angus cattle sourced in the Armidale district (NSW) with a naturally acquired gastrointestinal nematode infection were used as a test model in a recent Total Worm Count (TWC) efficacy study conducted by Invetus. Following sacrifice, TWCs revealed 2 species of Ostertagia (ostertagi and lyrata). Ostertagia ostertagi (Figure 1) is accountable for approx. 90% of Ostertagia infections and predominately found in cattle but can also infect sheep and goats.

 

Ostertagia lyrata however, is a morph species and not commonly seen. This species infects mainly cattle. The spicules of the male adult worm have distinct morphological features to ostertagi being stout and branching into 3 lobes posteriorly (Figure 2). Ostertagia infections are considered a major pathogen of cattle.

   Figure 1:    Ostertagia ostertagi adult male spicules (400x magnification)

Figure 1: Ostertagia ostertagi adult male spicules (400x magnification)

   Figure 2:    Ostertagia lyrata adult male spicules (400x magnification)

Figure 2: Ostertagia lyrata adult male spicules (400x magnification)

The lyrata species of worm is found worldwide, but with low prevalence. It is a morphed species of ostertgaia and although different in morphology there is ongoing work to prove a genetic variant. As far we know, it has the same pathogenicity as ostertagia ostertagi and prevalence is defined by chance.