Alveolar hydatid disease
| Alveolar hydatid disease | |
| ICD-10 | B67.7 |
|---|---|
| ICD-9 | 122.7 |
| DiseasesDB | 4048 |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Alveolar hydatid disease, also known as Alveolar echinococcosis, Echinococcosis Alveolar and Echinococciasis multilocular is a disease that originates from the parasitic flatworm Echinococcus multilocularis. This disease is not to be confused with the similar Echinococcosis, which originates from the parasite Echinococcus granulosus
Geographic Specifications
Alveolar hydatid disease is found worldwide, mostly in northern latitudes. Cases have been reported in central Europe, Russia, China, Central Asia, Japan, and North America. In North America E. multilocularis is found primarily in the north central region from eastern Montana to central Ohio, as well as Alaska and Canada. Human cases have been reported in Alaska, the province of Manitoba, and Minnesota. Prevalence among wild foxes and coyotes is high, and may reach over 50% in some areas; however, even in these areas, transmission to humans has been low.
Pathophysiology
Infestations of Animals
Wild foxes, coyotes, and cats get infected when they eat Echinococcus multilocularis larvae in infected rodents, field mice, or voles. Cats are less susceptible than dogs, but because they catch and eat rodents often, may also become infected. Once the animal becomes infected, the tapeworm matures in its intestine, produces eggs, and the infected animal passes eggs in the stool. These tapeworm eggs, which are directly infectious to other animals, are too tiny to see, and will stick to anything with which they come in contact. Coyotes, foxes, dogs, and cats are not harmed by the tapeworm and do not have symptoms of AE.
Routine fecal examinations are not sufficient to diagnose E. multilocularis infection. Infection with the E. multilocularis tapeworm and other tapeworms may occur at the same time. Eggs of Taenia species tapeworms and Echinococcus tapeworms are similar in shape and size and are very difficult to tell apart.
Infestation of Human
By accidentally swallowing the eggs of the E. multilocularis tapeworm. Humans can be exposed to these eggs in two main ways, both of which involve "hand-to-mouth" transfer or contamination:
- By directly ingesting food items contaminated with stool from foxes or coyotes. This might include grass, herbs, greens, or berries gathered from fields.
- By petting or handling household cats and dogs infected with the E. multilocularis tapeworm. These pets may shed the tapeworm eggs in their stool, and their fur may be contaminated. Some dogs "scent roll" in foreign material (such as wild animal feces) and may become contaminated this way.
Associated conditions
- Cardiac and vascular conditions such as myocarditis or pericarditis
- Hypersensitivity type 1 reactions such as Anaphylaxis
- Neurologic conditions such as aseptic meningitis
- Infection and infective conditions such as a lung abscess and lung cavitation
Signs and symptoms
AE is caused by tumor-like or cyst-like tapeworm larvae growing in the body. AE usually involves the liver, but can spread to other organs of the body. Because the cysts are slow-growing, infection with AE may not produce any symptoms for many years. Pain or discomfort in the upper abdominal region, weakness, and weight loss may occur as a result of the growing cysts. Symptoms may mimic those of liver cancer and cirrhosis of the liver. As a summary:
Other Findings
Laboratory findings
Imaging findings
- Intracranial calcification
Treatment
Surgery is the most common form of treatment for AE, although removal of the entire parasite mass is not always possible. After surgery, medication may be necessary to keep the cyst from growing back.