[Strongyloides westeri Ihle, 1917 (Nematoda: Strongyloididae. II. Parasitological and haematological features of experimental infection (author’s transl)].

The research conducted experimental infections using a Strongyloides westeri parasite, observing their impact on Shetland ponies. The outcomes varied based on the ponies’ age groups and previous exposure to the parasite.

Experimental Setup

• In this study, the studied subjects were seven Shetland ponies, divided into two groups based on their age – four foals (young ponies) and three yearlings (one-year-old ponies). Each of the ponies was worm-free before the experiment.
• The experimental plan included infecting these ponies with 600,000 infective larvae of Strongyloides westeri – a type of parasitic roundworm found in horses.

Findings in Foals

• Among the foals, the incubation period of the parasite (prepatent period) ranged between ten to fourteen days, with the patent period (the time during which the parasite is mature and starts producing eggs) spanned from forty-three to eighty-three days.
• The study recorded a decrease in the haemoglobin concentration and increase in the beta-globulin fraction in their blood around two months after infection.
• These changes practically coincided with the maximum S. westeri faecal egg counts.

Findings in Yearlings

• The prepatent period among the yearlings varied from sixteen to eighteen days, while the patent period ranged from fifty-five to seventy-three days.
• Interestingly, in a yearling which had previously had S. westeri infection as a foal, the infection did not become patent when infected again at the yearling stage with an identical parasite dose.
• Unlike the foals, the yearlings didn’t show any changes in the haematological parameters following the experimental infection.

Implications

• This research provides insights into the behavior of the S. westeri parasite in ponies of different ages. The findings are important in understanding the life cycle and impact of the parasites in the host, which would be useful in diagnosing and treating such infections in horses.
• The anomalies spotted in the re-infected yearling offer a ground for future study to understand the natural immunity development against this parasite.