Trichinella spiralis
From IDWiki
Background
- Also known as the pork worm, not to be confused with pork tapeworm (Taenia solium)
Life Cycle
- Can complete its life cycle in a human, pig, boar, bear, walrus, fox, and other animals
- Life cycle involves ingestion of meat with cysts, which develop into adult worms, which release eggs, which invade through gut mucosa and migrate to muscle, where it becomes a muscle cyst
Epidemiology
- Acquired in humans by ingestion of undercooked meat
- Present in carnivores and omnivores worldwide
- Commercial pork is the most common source of infection in humans, but can also be acquired from a number or wild game meats
Clinical Manifestations
- Spectrum of illness from asymptomatic (most common) to fulminant infection
- Incubation period less than 1 month
- After ingestion of contaminated meat:
- Within first week, may experience abdominal discomfort, nausea, vomiting, and diarrhea
- After another 2 to 8 weeks, may have fever, myalgia, periorbital edema, urticarial rash, conjunctival hemorrhage, and subungual hemorrhage, related to migration of larvae into tissues
- In severe disease, after 1 to 2 months, can develop myocarditis, neurological symptoms, and pneumonitis
- Can cause an eosinophilic myositis
- Often has eosinophilia during migratory phase (70%)
- Larvae are viable in tissues to years, with calcification usually occurring between 6 and 24 months
Diagnosis
- Usually made clinically based on exposure history, eosinophilia, and symptoms
- Serology exists, and can be used as paired acute and convalescent titres
- Positive after 2 to 3 weeks, and can stay positive for years
- Cross-reacts with other nematodes (and sometimes with other helminths)
Management
- Treated by albendazole or mebendazole