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Other Names: Weak Chicks

Paratyphoid (PT) is an important bacterial disease of chickens worldwide. It is one of several types of diseases caused by infection with Salmonella species. Chicks from hatcheries are most at risk.

When chicks hatch, their digestive tracts are virtually sterile. If raised by a mother hen, a chick obtains the beneficial microflora by consuming some of its mother's fecal material. In artificial incubation and brooding, chicks do not have this option. Therefore, baby chicks hatched in hatcheries are highly susceptible to different infections, and why all of the salmonella outbreaks that have occurred in humans in the United States have been linked back to chicks from hatcheries.

How Paratyphoid is Diagnosed

Paratyphoid is diagnosed in chickens through the identification of the presence of the Salmonella bacteria associated with disease. Simply detecting the presence of Salmonella here is not a diagnosis of paratyphoid. The two most common tests performed for your veterinarian to obtain a diagnosis are:
  • Bacterial culture: Using a swab, your veterinarian will obtain material from the suspected site, either internally (from a dead bird during a necropsy), or from the chicken's cloaca, throat, droppings or surgery site. Once collected, the swab is sent off to a diagnostic lab where it is cultured (i.e. grown) and bacteria identified. A follow up antibiotic sensitivity test is also useful in order for your veterinarian to determine which antibiotic will be most effective against the organism.
  • Antigen Detection Test: A simple test which detects the presence of protein on the surface of the bacteria. The sample can be obtained during a necropsy on a dead chicken or from a live bird.

Clinical Signs

Loss of appetite
Increased thirst
Huddling near neat source
Pasty butt
Swollen eye(s)
Droopy wings
Constant chirping noises
Head down with eyes closed
Reduced egg production
Swollen joints


  • History
  • Clinical signs
  • Laboratory tests
  • Necropsy


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
AntibioticsAmpicillin, trimethoprim-sulfamethoxazole, or chloramphenicol



  • Don't purchase chicks from hatcheries.
  • Avoid allowing chicks to drink from surface water instead of waterers
  • Minimize contact with wild birds or wild bird droppings
  • Control rodents
  • Give probiotics to young chicks.

Scientific References

Good Overviews

Age Range

1 to 2 week old chicks are most susceptible

Risk Factors

  • Chicks from hatcheries
  • Poor sanitation
  • Chilled brooder
  • Contamination of environment with wild bird or rodent feces
  • Overheating