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Biological controls in mixed trichostrongyle infections
Parasitology
|June 1, 1976
Summary
Natural Haemonchus contortus cayugensis infections in lambs offered protection against parasite superinfections. However, this protection was limited by environmental factors and host susceptibility, suggesting a form of premunition.
Area of Science:
- Veterinary Parasitology
- Animal Immunology
- Sheep Health
Background:
- Parasitic gastroenteritis is a significant threat to sheep health and productivity.
- Understanding host-parasite interactions is crucial for developing effective control strategies.
Purpose of the Study:
- To investigate the protective effects of natural trichostrongyle infections, particularly Haemonchus contortus cayugensis, against superinfections in lambs.
- To explore the influence of environmental factors and host diathesis on parasite burden.
Main Methods:
- Determined parasite reaction phenotype in 80 lambs with natural infections.
- Assigned lambs to outcome and treatment groups.
- Employed novel analytical techniques to assess protection against varying levels of infective larvae.
Main Results:
- Mixed natural trichostrongyle infections protected against high-dose (35,000 larvae) superinfections.
- Protection against low-dose (1,000 larvae/day) superinfections was constrained by the barn ecosystem.
- More susceptible (diathetic) sheep exhibited lower parasite biomass, irrespective of infection dose.
Conclusions:
- Natural infections can confer resistance to superinfections, but this is modulated by environmental and host factors.
- The study provides evidence for premunition rather than anaphylactoid 'self-cure' in this experimental setup.
- Host-parasite-environment interactions significantly influence parasite biomass in sheep.