Special Veterinary Pathology

SETARIASIS

Definition

• Filariad worms of the genus Setaria are commonly found in the peritoneal cavity of most domestic animals

Aetiology

• Setaria digitata a parasite of the peritoneal cavity of cattle causes cerebrospinal nematodiasis

Pathogenesis

• Usually neither the adults nor the circulating microfilariae cause serious disease
• The parasites are found in the pleural cavity or eye
• It is a parasite of the peritoneal cavity of cattle causes cerebrospinal nematodiasis when it invades into the central nervous system of other animal species such as sheep, goat and horses and cause paralysis and blindness

Clinical signs

• Incordination, weakness and paralysis
• In sheep and goats this is known as lumbar paralysis and in horses ‘ kumri’( weakness of loin). The disease is prevalent in India
• In young horses and mules of one to two years of age, animals move with difficulty and on motion sway (wobble) from side to side.
• They may fall frequently and show difficulty in rising which might be due to trauma of spinal cord at the cervical region

Gross and microscopic Lesions

• Lesions are found in the brain and spinal cord and the severity depends on the number of parasites present
• Narrow tortuous tracks of haemorrhages and softening may be found denoting the path taken by the parasite
• Immature worms wander randomly throughout the brain leaving necrotic paths
• Bilateral symmetrical areas of malacia
• Gitter cells and infiltration of eosinophils and neutrophils surround the tracts

Diagnosis

• Careful microscopic examination of the central nervous system tissue and cerebrospinal fluid is necessary to see the larvae