Microbiology
Tapeworms. E. canadensis, E. granulosus, E. multilocularis, E. vogeli. Echinococcus oligarthrus, Echinococcus shiquicus, Echinococcus equinus, Echinococcus ortleppi.
Epidemiologic Risks
Eating dog or other carnivore poop. Really. Dog poop carries the tapeworm and is on the food when you eat it. E. granulosis E. multilocularis: Sheep, goats, camels, and horses. Worldwide distribution, including Ontario Canada (PubMed).
E. canadensis is found in Alaska and N. Canada (PubMed); moose and elk the most important intermediate hosts; dogs and wolves the definitive hosts.
Historically has been present in N. America and may be under-recognized today (PubMed).
Syndromes
Hydatid cyst disease, with liver involvement > lung > greater than other organs.
Most problems are due to mass action of the cysts; sudden rupture can lead to death from anaphylaxis. A percutaneous sampling of a cyst is probably much safer than a spontaneous rupture during a rugby game.
As a systematic review put it "Lethal anaphylaxis occurred in 0.03% of PT procedures, corresponding to 0.04% of treated cysts, while reversible allergic reactions complicated 1.7% of PTs, corresponding to 1.8% of treated echinococcal cysts. Analysis of the literature shows that lethal anaphylaxis related to percutaneous treatment of CE is an extremely rare event and is observed no more frequently than drug-related anaphylactic side effects."
Treatment
Asymptomatic cysts should be observed. If symptomatic, removal by someone who knows what they are doing. Medical therapy (without drainage) includes albendazole (preferred) or mebendazole for prolonged periods; there are a variety of regimens. Probably not curative (about 50%).
Notes
Directions for removal of hydatid cysts, visualize the cyst, remove some fluid, and inject a cysticidal agent, hypertonic (30%) saline, iodophor, or 95% ethanol wait 30 minutes then remove all the fluid. This has been done under CT (preferred) as well as in the operating room.
It has been found in 8000-year-old human remains.
Last Update: 02/01/19.