Ascaris suum

Ascaris suum is a parasitic nematode (roundworm) that primarily infects pigs, but can also infect humans, causing a condition known as ascariasis. It is closely related to Ascaris lumbricoides, the roundworm that infects humans. A. suum is of significant veterinary importance due to its impact on swine health and production.

Morphology

Ascaris suum is a large nematode, with adult females measuring up to 40 cm in length and males being slightly smaller. The worms are cylindrical, with a tapered anterior end and a blunt posterior end. They have a simple digestive system with a mouth, pharynx, intestine, and anus. The body is covered by a tough cuticle that protects them from the host's digestive enzymes.

Life Cycle

The life cycle of Ascaris suum is direct, involving a single host. Eggs are passed in the feces of infected pigs and develop in the environment. Under optimal conditions, the eggs become infective within 2-4 weeks. Pigs ingest the infective eggs, which hatch in the intestine. The larvae penetrate the intestinal wall and migrate to the liver, then to the lungs via the bloodstream. After migrating up the trachea, they are swallowed and mature into adults in the small intestine.

Pathogenesis

In pigs, Ascaris suum can cause respiratory symptoms due to larval migration through the lungs, known as "thumps," and liver damage, known as "milk spots." Heavy infections can lead to intestinal obstruction, poor growth, and reduced feed efficiency. In humans, infection is usually asymptomatic but can cause similar symptoms to those seen in pigs.

Diagnosis

Diagnosis of Ascaris suum infection is typically made by identifying eggs in fecal samples using microscopic examination. In pigs, necropsy can reveal adult worms in the intestines and characteristic lesions in the liver and lungs.

Control and Treatment

Control of Ascaris suum involves good sanitation practices to reduce environmental contamination with eggs, regular deworming of pigs, and proper management of pig housing. Anthelmintics such as ivermectin and fenbendazole are effective treatments.

Also see

• Ascariasis
• Ascaris lumbricoides
• Nematode
• Parasitic diseases