Trichinosis

Trichinosis (also know as Trichinellosis) is caused by the ingestion of encysted larvae of Trichinella spp. within undercooked meat. Larvae are released, mature and mate in the small intestine to produce more larvae which migrate and encyst, most commonly in striated muscle.

Initial symptoms are predominantly abdominal including nausea and vomiting, abdominal discomfort, diarrhoea and can include fever and fatigue. As the larvae encyst, they can result in further fevers, facial swelling, muscle pains, pruritus and diarrhoea/constipation.

Diagnosis of Trichinosis by microscopy

• Sample type: muscle biopsy.

Crush/digested preparations of muscle biopsy specimens may reveal larvae.

Biopsies should also be fixed and sent for histology.

Diagnosis of Trichinosis by serology

• Sample type: A minimum of 0.5ml of serum is required.

Serology is the mainstay for diagnosing this condition.

Except in the rare event of an outbreak in the UK, serology is usually requested for symptoms suggestive of the stage of muscle encystment: myalgia, eosinophilia, and, in the early stages, fever. The IFAT (screening titre 1/32) has proved reliable and specific with positive titres of about 1/128.