Mycoplasma and Chronic Respiratory Disease in Poultry
Mycoplasma drains poultry farms quietly. There is rarely heavy mortality, but you find birds rattling, breathing through open beaks, low production and houses that never fully recover. The two key species are Mycoplasma gallisepticum, which causes chronic respiratory disease, and Mycoplasma synoviae, linked to sinusitis. In Egypt infection usually arrives through eggs and hatcheries, then flares up with poor ventilation and dust.
MG and MS: infection through the egg
Mycoplasma passes vertically from infected hens into the chick through the egg, which is the most dangerous route because it places infection inside the flock from day one. It also spreads horizontally in droplets and nasal or eye secretions, and on equipment and hands. Multi-age farms make continuous transmission between houses easy.
What turns latent infection into visible disease is stress: high summer heat, elevated ammonia, dust, harsh vaccination and poor airflow. This is why signs often appear after a heat wave or a litter change. Carrier birds may show nothing while shedding the organism and infecting others.
Chronic respiratory disease: the classic signs
Signs include rattling audible when you approach the birds, frequent sneezing, nasal discharge and eye inflammation with foam or tears. Advanced cases show swelling of the infraorbital sinus and a puffy face, and birds shake their heads as if trying to clear the throat. They eat less and look thin.
In layers there is a drop in egg numbers and hatchability, with small or misshapen eggs. The bigger problem is that Mycoplasma opens the door to E. coli, turning the case into a combined respiratory infection with noticeable mortality. This interaction is why farms lose far more than the mild signs suggested. The risk climbs in houses that combine high humidity, weak airflow and heavy stocking.
Diagnosis and treatment
Diagnosis starts with signs and farm history, then confirmation by serology such as slide agglutination or ELISA, or by PCR on swabs. Laboratory testing is important to rule out Newcastle disease and infectious bronchitis, which look similar. New flocks should be tested before entry.
Treatment does not eliminate the organism; it reduces signs and losses. The veterinarian may use tylosin, tiamulin or doxycycline depending on the case, age and withdrawal period. Random use produces resistant strains and makes the next treatment harder. Vaccination with killed or live Mycoplasma vaccines, according to the programme, helps reduce losses.
- Test new flocks before entry and request a Mycoplasma-free certificate.
- Apply all-in, all-out and never mix different ages in one house.
- Improve ventilation to cut ammonia and dust before reaching for drugs.
- Use antibiotics at the full dose and set duration only.
- Record any production drop or early respiratory sign for the veterinarian.
Prevention in Egyptian houses
The best prevention is buying chicks from Mycoplasma-free breeder flocks, which lowers the risk from the start. Then comes house management: sensible density, ventilation that keeps ammonia low, dry litter and dust control during distribution. Summer heat stress should be avoided with well-planned fans and foggers.
Daily temperature and humidity checks reveal a deteriorating environment before signs appear, and a digital thermometer makes this practical. Immune support with vitamins and minerals through poultry vitamins is used under veterinary supervision, and house equipment is in our poultry supplies.
Conclusion
Mycoplasma is controlled by prevention, not repeated treatment. Chicks from clean breeders, good ventilation, dry litter and responsible antibiotic use under veterinary supervision stop a mild cold from becoming a lost season.
This article is general guidance and is not a substitute for examining your animal by a licensed veterinarian. In emergencies, contact your vet immediately.
