Background
Microbiology
- Echinococcus granulosus sensu stricto (G1 to G3), the major cause of cystic echinococcosis
- Echinococcus equinus (G4)
- Echinococcus ortleppi (G5)
- Echinococcus canadensis (G6 to G10)
- Echinococcus multilocularis, the major cause of alveolar echinococcosis
- Echinococcus vogeli, causes polycystic echinococcosis
- Echinococcus oligarthrus, extremely rare cause of human echinococcosis
- Echinococcus felidis
- Echinococcus shiquicus
Epidemiology
| Species | Intermediate Hosts | Definitive Hosts | Distribution | Risk Factors |
|---|---|---|---|---|
| Echinococcus granulosus | sheep, cattle, pigs, camels, and goats | dogs and other canids | worldwide, with highest prevalence in Mediterranean, Russia, China, central Asia, north and east Africa, Australia, and South America | shepherds, exposure to feral dogs, slaughterhouse, unsanitary living conditions |
| Echinococcus multilocularis | rodents, domestic pigs, wild boars, dogs, monkeys | foxes, dogs, cars | mostly described in Europe and Asia, rare in North America | |
| Echinococcus vogeli | rodents | bush dogs | Central and South America | |
| Echinococcus oligarthus | Central and South America |
Clinical Manifestations
- Any many present asymptomatically
- Rarely present with anaphylaxis from cyst rupture
Cystic Echinococcus
- Liver is the most common site (60%), followed by lung (20-30%)
- Can infect other sites including brain (10%)
- Can cause anaphylaxis when ruptures
- Can cause cholangitis
Alveolar Echinococcus
- Presents as liver cancer or metastases of unknown primary
- Liver involvement is present in 95% of cases
Diagnosis
- Generally made with ultrasound, possibly with MRI
- Serology can be helpful, but not necessarily that sensitive or specific
- Aspiration may be considered, but there is a risk of allergic reaction and a risk of secondary recurrence from leakages of hydatid fluid or protoscolices
