Fowl Spirochetosis (Borrelia anserina): Argas Tick Vector Guide
Veterinary guide covering Borrelia anserina spirochetes, Argas persicus soft tick transmission, splenomegaly, and Penicillin therapy.
Scientific Overview
Fowl Spirochetosis is an acute, tick-borne septicemic disease of chickens, turkeys, and ducks caused by the spirochete bacterium Borrelia anserina. Transmitted primarily by the soft fowl tick Argas persicus, it causes high fever, severe anemia, greenish diarrhea, massive splenomegaly, and high flock mortality.
Etiology & Soft Tick Vector (Argas persicus)
Fowl Spirochetosis is defined as a blood-borne spirochetal septicemia caused by Borrelia anserina, a helical motile spirochete bacterium.
The primary vector is the soft fowl tick (Argas persicus). Ticks become infected while feeding on viremic birds and pass spirochetes transovarially to tick offspring, allowing environmental reservoirs to persist in coop crevices for years.
Clinical Symptoms & Pathognomonic Lesions
Clinical pathology presentation:
- High Fever & Anemia: Core temperature reaches 43°C (109°F), accompanied by pale comb/wattles and bright green diarrhea.
- Massive Splenomegaly: Spleen is enlarged 4 to 6 times normal size, displaying a mottled 'marmoreal' pattern of infarction.
- Dark Blood Microscopy: Dark-field microscopic examination of fresh blood smears reveals abundant undulating motile spirochetes.
Treatment & Acaricide Vector Control
Procaine Penicillin G or Oxytetracycline injections produce rapid clinical recovery if given early. Vector control requires spraying coops with synthetic pyrethroid acaricides to eliminate Argas persicus tick populations.
All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:
- Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
- Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
- Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
- Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.