Fasciola hepatica: migration of newly excysted juveniles in resistant rats
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Abstract:
Using transmission and scanning electron microscopy, the early migration of juvenile Fasciola hepatica was examined in naive and resistant rats. In naive rats, the migration of flukes to the peritoneal cavity was uneventful. In resistant rats, flukes were rapidly coated with antibody whilst still in the gut lumen and a proportion of the flukes were unable to penetrate the intestinal wall. Those that did penetrate were unharmed as they crossed the gut wall, but on entering the peritoneal cavity they were coated with antibody and host cells including eosinophils, neutrophils, macrophages, and mast cells. Eosinophils were seen degranulating onto the fluke surface, and this appeared to result in the erosion of the tegumental syncytium.
Insights
Resistant rats mount an early immune response against juvenile Fasciola hepatica flukes, coating them with antibodies and immune cells. This hinders fluke migration and damages their outer layer, impacting parasite survival.
Area of Science:
- Parasitology
- Immunology
- Veterinary Science
Background:
- Fasciola hepatica, a liver fluke, causes significant disease in livestock and humans.
- Understanding early fluke migration is crucial for developing effective control strategies.
Purpose of the Study:
- To investigate the early migration of juvenile Fasciola hepatica in naive versus resistant rat models.
- To elucidate the host immune response to fluke penetration and migration in resistant hosts.
Main Methods:
- Transmission and scanning electron microscopy were employed.
- Juvenile Fasciola hepatica migration was observed in both naive and resistant rat models.
Main Results:
- In resistant rats, flukes were coated with antibodies in the gut lumen, impeding intestinal penetration.
- Flukes entering the peritoneal cavity of resistant rats were opsonized by antibodies and attacked by eosinophils, neutrophils, macrophages, and mast cells.
- Eosinophil degranulation led to erosion of the fluke's tegumental syncytium.
Conclusions:
- Host resistance significantly impacts early Fasciola hepatica migration and survival.
- Immune cell infiltration and antibody coating are key mechanisms in rejecting fluke infections in resistant hosts.
- Damage to the fluke tegument by host immune cells may impair parasite establishment.