Pathogenesis (development of disease)
Worms of the genus Echinococcus must undergo host switching. In this process, larvae develop in intermediate hosts (rodents, sheep, etc)/missing hosts. In the final hosts (carnivores, especially canines), the sexually mature worms parasitize.Alveolar echinococcosis (AE):In 99% of all cases, the liver is the primary target organ, where the six-hooked larva (oncosphere) undergoes metamorphosis to become a metacestode.Humans are a false host.
Echinococcus multilocularis (fox tapeworm)
Eggs of Echinococcus multilocularis are ingested orally by the intermediate host (rodents)/missing host. These usually infect the liver. Infiltrative growth occurs there, and the liver becomes infiltrated with parasitic epithelium. The final host becomes infected by eating infected rodents.
Infections of humans with Echinococcus multilocularis result in the clinical picture of alveolar echinococcosis (AE).
Echinococcus granulosus (dog tapeworm)
Eggs of Echinococcus granulosus are ingested by the intermediate host (ruminants, pigs)/missing host, and the larvae that form enter the bloodstream, primarily the liver, but also the lungs, and very rarely other organs. There, a hydatid (cyst) forms, which is encased in a connective tissue capsule. This connective tissue capsule is formed by the host. The larvae hatch in the intestine of the final host/missing host. Via the bloodstream they reach the liver, but also other organs such as lungs, brain, bones or spleen (= “metastatic infestation”).
Infections of humans with Echinococcus granulosus lead to the clinical picture of cystic echinococcosis (CE).
Etiology (causes) of alveolar echinococcosis (AE)
Behavioral causes
- Direct contact with infected animals (fur).
- Smear infection
- Work with contaminated soil
- Infection through contaminated water and contaminated food is questionable
Etiology (causes) of cystic echinococcosis (CE)
Behavioral causes
- Direct contact with infected animals (fur).
- Smear infection
- Work with contaminated soil
- Consumption of contaminated food (eg, wild berries).
