Histomoniasis is a parasitic disease caused by the protozoan Histomonas meleagridis, primarily affecting turkeys and chickens. The disease is commonly known as “blackhead disease” due to the characteristic cyanosis of the head in some affected birds.
SYMPTOMS
CAUSES
PREVENTION
TREATMENT
Symptoms
- Turkeys (Most Susceptible):
- High mortality (up to 100%)
- Sulfur-yellow diarrhea
- Drowsiness and drooping wings
- Darkened head
- Reduced appetite
- Death within 7-14 days
- Chickens:
- Lower mortality (10-20%)
- Milder symptoms
- Can be asymptomatic carriers
- Reduced egg production
- Less severe diarrhea
- Note: Waterfowl are generally resistant to the disease.
Causes and transmission
- Primary Cause:
- Histomonas meleagridis protozoan
- Transmission Routes:
- Through earthworm ingestion
- Cecal worm eggs (Heterakis gallinarum)
- Direct bird-to-bird contact
- Contaminated soil and equipment
- Mechanical vectors
Prevention strategies
- Management:
- Separate turkeys from chickens
- Regular deworming programs
- Clean and dry litter
- Proper drainage
- Free-Range rotation
- Biosecurity measures
- Environmental Control:
- Eliminate earthworms access
- Control soil moisture
- Regular cleaning
- Proper disposal of dead birds
Treatment options
- Current Situation:
- No approved treatments in many countries
- Prevention is critical
- Supportive Care:
- Electrolyte supplementation
- Isolation of affected birds
- Stress reduction
- Clean environment
Conclusion: Due to regulatory restrictions on antihistomonal drugs in many countries, prevention is the primary control strategy.
