Echinococcosis
Background
- 2 most important forms are cystic and alveolar caused by E. granulosus and E. multilocularis
- Humans are accidental immediate hosts by ingesting parasitic eggs from contaminated food, soil, water, or direct contact with definitive hosts
- Usual intermediate hosts-sheep, goat, swine, cattle, rodents and camel
- Definitive hosts-dogs, cats, fox, and wolves
- Ingested eggs then hatch, penetrate intestinal mucosa, and spread hematogenously to final destination to form cysts
Clinical Features
- Asymptomatic for many years
- Abdominal cysts- pain, distension, nausea and vomiting
- Alveolar abscess-chest pain, shortness of breath, chronic cough
- Musculoskeletal pain, blindness, headache, and stroke like symptoms if involving muscles, bones, eyes or brain
Differential Diagnosis
- Cysticercosis (brain)
Hepatic abscess
- Pyogenic abscess
- Aerobic: Escherichia coli, Klebsiella, Pseudomonas
- Anaerobic: Enterococcus, bacteroides, anaerobic streptococci
- Echinococcosis
- Amebiasis
- Benign cysts/malignancy
- Tuberculosis
- Mycosis
Workup
- Abdominal Ultrasound (most widely used)
- CT
- MRI
- ELISA-sensitivity inversely related to antigen sequestration in cysts
- Percutaneous aspiration
Management
- Tissue stage/hydatid disease: albendazole 400 mg BID x 28 days, repeat as needed every 2 weeks x 3 cycles
- Surgical removal
- Do not aspirate cysts (risk of seeding disease or anaphylactoid reaction from spillage of hydatid sand which contains antigenic proteins)
- PAIR (Percutaneous aspiration, injection, reaspiration)
- Inject with 95% ethanol or hypertonic saline, leave in for 15 minutes, then reaspirate
Disposition
- Home if no complications
See Also
Sources
- McManus DP, Zhang W, Li J, Bartley PB. Echinococcosis. Lancet. 2003 Oct 18;362(9392):1295-304.
- Moro P, Schantz P. Echinoccococis: A Review. International Journal of Infectious Disease. (2009) 13, 125-133.
- WHO factsheet Echinococccosis updated March 2014 http://www.who.int/mediacentre/factsheets/fs377/en/