Pullorum Disease in Chickens: Symptoms, NPIP Testing and Control

Salmonella Pullorum is a host-adapted pathogen specific to chickens and turkeys that has been nearly eliminated from US commercial flocks through the NPIP but persists in unmonitored backyard and heritage breed flocks.

• Transovarial (vertical) transmission: S. Pullorum uniquely infects the ovary and oviduct of carrier hens. The organism colonizes the developing egg yolk before shell formation. Infected chicks hatch already infected and begin dying within their first week. This is the primary source of new flock infections.
• Horizontal spread in the hatcher: Infected chicks hatch and shed massive numbers of bacteria in the hatcher environment. Uninfected hatchmates inhale or ingest contaminated dust and feces, spreading the infection to the entire hatch group.
• Environmental persistence: S. Pullorum survives in manure, dust, and on equipment for weeks to months. Contaminated hatchery equipment, brooders, and coops serve as ongoing sources without proper disinfection.
• Carrier adults: Recovered birds and adults from infected flocks are lifelong carriers. They show no signs but continuously shed the organism in feces and pass it transovarially. Purchasing birds at auctions or from unknown sources is the most common way Pullorum enters a clean flock.

Pullorum disease is diagnosed by the combination of clinical presentation and confirmatory testing. Reporting to state veterinary authorities is legally required in the US.

• Clinical diagnosis: White pasty diarrhea with high mortality in chicks 1-3 weeks old, especially in newly hatched flocks, is Pullorum until proven otherwise.
• Whole Blood Test (WBT) for adults: A rapid agglutination test performed on a drop of fresh blood. Positive birds show visible clumping within 1 minute. Used routinely for NPIP certification.
• Tube Agglutination Test (TAT): More sensitive than WBT. Used for confirmation and NPIP certification testing in most US states.
• Culture: Organ culture (liver, spleen, ovaries) from dead chicks or euthanized suspect birds on selective Salmonella media confirms S. Pullorum.
• Reporting: Contact your state veterinarian immediately upon suspicion or confirmation. Pullorum is listed under the NPIP as a reportable condition in all 50 states.

Treatment of Pullorum disease in chicks can reduce mortality but does not eliminate the carrier state. The regulatory approach is test-and-cull, not treatment.

NPIP test-and-cull protocol: All reactors identified by WBT or TAT are culled. Repeat testing of the flock at 21-30 day intervals until two consecutive negative tests are achieved. This is the only path to NPIP Pullorum-Typhoid Clean status.

Antibiotic supportive treatment for chicks: Tetracyclines (chlortetracycline), furazolidone (where legal), or sulfamethazine in water can reduce chick mortality during an active outbreak. Treatment suppresses clinical signs but does not clear the carrier state. Survivors become carriers.

Environmental decontamination: Complete depopulation followed by thorough disinfection with quaternary ammonium or phenolic disinfectants, then a minimum 3-4 week downtime before restocking with tested, clean birds.

• Purchase birds only from NPIP Pullorum-Typhoid Clean certified flocks. This certification requires regular testing and is the primary line of defense for clean flocks.
• Test your flock annually if you show birds, transport them across state lines, or sell hatching eggs. Most states require NPIP testing for these activities.
• Never purchase birds at auctions, swaps, or flea markets without confirmed NPIP status. This is the single most common way Pullorum is introduced into previously clean flocks.
• Quarantine all new birds 30 days before integration, even from certified flocks. Test during quarantine if there is any doubt about certification validity.
• Thoroughly disinfect incubators and hatchers between hatches. S. Pullorum spreads explosively in the hatcher environment from a single infected egg.