Fascioliasis

Pathogen and epidemiology

The disease is caused by the helminth Fasciola hepatica, also known in Russian-language literature as the liver fluke. The geographical distribution of this parasitosis is uneven: it is a common pathology in regions such as France and Cuba, whereas only extremely rare, isolated cases of infection are registered in the Russian Federation.

Life cycle of the parasite

The development of the liver fluke is a complex process involving alternating hosts and environments.

Two groups of hosts are distinguished in the life cycle:

• Definitive hosts: humans, as well as various species of farm animals (cattle, small ruminants, pigs, horses). It is in their bodies that the parasite reaches sexual maturity.
• Intermediate host: the freshwater snail — Galba truncatula (dwarf pond snail).

Stages of development:

1. The eggs of the parasite are released into the environment and must reach a freshwater body.
2. In the water, motile larvae emerge from the eggs, find a specific intermediate host — the dwarf pond snail — and penetrate it.
3. Having completed the developmental cycle in the snail's body, the new larval forms leave it, return to the water, and encyst, transitioning into the infectious stage for the definitive host.

Routes of transmission and pathogenesis

Humans and animals are infected via the alimentary route. Infection occurs when drinking raw water from open water bodies containing encysted parasite larvae.

Upon entering the digestive tract, the parasite migrates and localizes predominantly in the bile ducts and gallbladder. Very rarely, the fluke can be found in other internal organs.

The main link in pathogenesis is associated with the mechanical and toxic effects of the helminth. Parasitization in the lumen of the bile ducts causes direct damage to their epithelial lining. These damaged areas of the mucous membrane serve as an ideal entry gate for secondary pyogenic microflora, triggering a cascade of severe inflammatory reactions.

Surgical complications and diagnostics

The introduction of pyogenic bacteria against the background of parasitic infestation leads to the development of serious surgical pathologies. The main complications of fascioliasis include:

• Purulent cholecystitis
• Cholangitis
• Liver abscesses
• Obstructive jaundice (due to duct obstruction)

Diagnostics of complicated forms is based on two approaches:

1. Clinical: fascioliasis is suspected if a patient with a previously confirmed diagnosis of this helminthiasis (and with other causes excluded) suddenly develops prominent signs of a purulent-inflammatory process in the gallbladder or ducts.
2. Intraoperative: definitive confirmation of the parasitic nature of the complication occurs right on the operating table. The surgeon visually detects adult flukes in the lumen of the bile ducts or inside the cavity of an opened liver abscess.

Principles of treatment

Treatment of complicated fascioliasis requires a combined approach:

• Surgical intervention: performed according to strict general rules of purulent surgery of the liver and biliary tract. The scope and tactics of the surgery depend entirely on the specific localization of the destructive process and the type of complication that has developed (e.g., abscess drainage or cholecystectomy).
• Drug therapy: to eradicate the causative agent itself (Fasciola hepatica), a specific antiparasitic drug is used — emetine.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanisms of liver abscess formation in helminthiases
• Differential diagnosis of obstructive jaundice of parasitic etiology
• Surgical tactics for destructive cholecystitis associated with infestation
• Pharmacological properties and mechanism of action of emetine

Other topics in the section "CHAPTER 15. PARASITIC SURGICAL DISEASES"

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