Experimental microcyst sarcocystis infection in lambs: pathology

Area of Science:

• Veterinary Parasitology
• Ovine Pathology
• Infectious Diseases

Background:

• Sarcocystis species are important protozoan parasites affecting livestock.
• Understanding the pathogenesis of Sarcocystis infection in young sheep is crucial for animal health and productivity.

Purpose of the Study:

• To investigate the clinical, clinicopathological, and pathological changes in lambs experimentally infected with Sarcocystis sarcocysts.
• To characterize the tissue distribution and developmental stages of Sarcocystis in experimentally infected lambs.

Main Methods:

• Six coccidia-free lambs were inoculated with Sarcocystis sporocysts from ovine heart.
• Lambs were monitored for clinical signs and blood parameters.
• Necropsy and histopathological examinations were performed at multiple time points post-inoculation (14, 25, 33, 42, 60, 81 days).

Main Results:

• Clinical signs included transient fever and anorexia (25-33 days post-inoculation) and mild anemia (peak at 32 days).
• Meronts were observed in endothelial cells, predominantly in kidney glomeruli.
• Developing sarcocysts appeared by 42 days, becoming common in striated muscle and brain by 60-81 days.
• Histopathology revealed myositis and non-suppurative encephalitis/encephalomyelitis.
• Sarcocyst distribution varied, with high prevalence in myocardium and specific limb muscles, and low prevalence in the masseter.

Conclusions:

• Experimental Sarcocystis infection in lambs causes significant clinical and pathological alterations, including neurological and muscular lesions.
• The study provides a detailed timeline of Sarcocystis development and associated pathology in a susceptible ovine host.
• Findings underscore the importance of Sarcocystis as a pathogen in sheep, impacting muscle and nervous tissues.