Understanding temporal and spatial distribution of intestinal nematodes of horses using faecal egg counts and DNA metabarcoding.

The research article focuses on tracking the distribution over time and space of two types of intestinal nematodes in Thoroughbred horses across various climates in Australia. The findings will be instrumental in forming comprehensive management strategies for parasite control in horses on farms.

Methods of Study

• The study collected 2046 faecal samples from individual horses and analyzed them using the “modified McMaster technique” for faecal egg counts (FECs). This method involved counting the number of eggs per gram (EPG) of faeces to measure the concentration of parasites.
• The study used PCR-guided next-generation sequencing to identify the nematode species present in the samples. The genetic material under analysis was the second internal transcribed spacer (ITS-2) of ribosomal DNA.

Findings of Study

• The research showed that the prevalence and numbers of strongyle eggs was greatest in yearlings, followed by weanlings, foals, wet mares, and dry mares.
• For another genus of nematodes, Parascaris spp., the prevalence was highest in foals, then weanlings, then yearlings.
• The study found that of the horses that were adults at the time of sampling, 77% of mares were considered low strongyle egg-shedders, meaning they contained fewer than 250 EPG.
• The mean FEC counts were greatest in horses residing in the Mediterranean, followed by summer, winter, and non-seasonal rainfall zones.

Species of Nematodes Detected

• The study successfully detected twenty-six nematode species in the samples. The most frequently detected species were Cylicostephanus longibursatus, Cylicocyclus nassatus, and Coronocyclus coronatus.
• Their frequencies and relative abundance in the samples varied according to factors such as the age of the horse, the season, and the climate zone.
• The study also detected Strongylus equinus and Triodontophorus spp. (T. brevicauda and T. serratus).

Implications of Study

• The study provides useful insights about the prevalence and burdens of intestinal nematodes in Australian horses which can be useful for developing integrated management techniques to control horse parasites in farmed horses.
• The results illustrate that both season and climate impact the types and magnitudes of parasitic burdens in horses.
• Understanding the distribution of these parasites will help to inform treatment and prevention strategies, ensuring healthier environments for horses.