Trichina spiralis

Trichinella spiralis is a nematode parasite, occurring in rats, pigs, bears and humans, and is responsible for the disease trichinosis. It is sometimes referred to as the "pork worm" due to it being typically encountered in undercooked pork products.

Life Cycle

The life cycle of Trichinella spiralis can be broken down into several stages. Adult worms inhabit the small intestine of a definitive host. Each adult female produces batches of live larvae, which migrate into the striated muscles, where they encyst. The encysted larvae can remain viable for several years. When meat containing the encysted larvae is ingested by another host, the larvae are released from the cysts in the stomach and mature into adults in the intestine.

Morphology

Trichinella spiralis is a small nematode parasite, which can be up to 1.5mm long. It has a long, slender body with a blunt anterior end and a pointed posterior end. The body is covered with a cuticle, which is thickened at both ends. The mouth is located at the anterior end and is surrounded by three lips.

Pathogenesis and Clinical Features

Infection with Trichinella spiralis can lead to trichinosis. The severity of the disease depends on the number of encysted larvae ingested. Symptoms can include nausea, diarrhea, vomiting, fatigue, fever, and abdominal discomfort. Later on, patients may experience headaches, fevers, chills, cough, eye swelling, aching joints and muscle pains, itchy skin, diarrhea, or constipation.

Diagnosis and Treatment

Diagnosis of Trichinella spiralis infection can be confirmed by serological tests or muscle biopsy. The most effective treatment is with antihelminthic drugs such as mebendazole or albendazole. In severe cases, corticosteroids may be used to control the inflammatory response.

Prevention

Prevention of Trichinella spiralis infection is primarily achieved by properly cooking pork products. Freezing pork at -15°C for 3 weeks will also kill most larvae.

See Also

• Nematode
• Trichinosis
• Parasitology