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Avian Intestinal Spirochetosis

Avian Spirochetosis, Avian Borroliosis, Spirochetosis, Chicken Tick Paralysis, Fowl Spirochetosis, Fowl Tick Fever, Fowl Tick Paralysis, Chicken Tick Fever

Avian intestinal spirochetosis (AIS) is an enteric disease that affects all bird species, pigs, and humans. AIS is a potentially zoonotic disease that is caused by infection with spirochetal bacteria of the genus Brachyspira. The bacteria colonize in the chicken's intestines (specifically the cecum and rectum). There are seven types of Brachyspira that infect birds, however the four main pathogenic (disease-causing) species in chickens include B. intermedia, B. pilosicoli, B. alvinipulli and B. hyodysenteriae. AIS is known to cause mild to moderate, subacute to chronic disease in chickens. The severity of the infection depends on the particular strain of Brachyspira, extent of colonization, the chicken's age and overall health and immune status.

Cases of AIS have been documented in poultry worldwide, with incidents reported in North America, Europe and Australia. In the United Kingdom, infection with Brachyspira in commercial laying flocks was reported to cause an estimated annual cost of circa 18 million pounds to the commercial laying industry in 2014.

Clinical signs
  • Delayed onset of egg production in pullets.
  • Reduced egg production in egg laying hens.
  • Smaller and lighter eggs (decreased egg weight) often with reduced egg shell quality.
  • Frequent changes in fecal consistency.
  • Eggshells are frequently stained with feces.
  • Increased fecal output and amount of water present in feces.
  • Yellowish-brown, mucoid and/or foamy diarrhea with increased lipid content.
Transmission
Brachyspira can be initially introduced into chicken flocks through wild birds, rodents, insects (such as flies), domestic and feral dogs or cats, other livestock (pigs or horses), other poultry species (ducks, geese, turkeys, pheasants, etc.), and even humans. Ducks in particular, are known to be subclinical carriers of Brachyspira spp., meaning that they are often easily infected but never develop clinical signs of disease, however they will shed the bacteria in their feces. Brachyspira are most commonly spread between flock members through environmental contamination with feces from infected birds. When chickens are exposed to the same environments as infected hosts, they are at risk of becoming infected.

Clinical Signs

Delayed onset of lay
Reduced egg production
Chickens never laying eggs
Reduced egg weight
Wet feces
Yellowish-brown diarrhea
Mucoid and/or foamy diarrhea
Fecal staining of eggshells

Diagnosis

  • History
  • Clinical signs
  • Fecal exam
  • PCR assay
  • Bacterial culture
  • Necropsy

Treatment

NameSummary
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.
TiamulinAdministered in drinking water according to manufacturer recommendations. Has been found to be effective at reducing severity of clinical signs related to colonization by certain species of Brachyspira in egg laying hensMJ Woodward et al., 2015
Antimicrobials
Probiotics
Vaccination

Prevention

  • Practice good sanitation
  • Clean and disinfect waterers daily, as certain strains of Brachyspira can survive for extended periods of time in water, particuarly at colder temperatures.
  • Do not house chickens and ducks together.
  • Provide chickens with water sources that are inaccessible by ducks, to minimize contamination and spread through water.

Scientific References

Risk Factors

  • Poor sanitary practices
  • Free range chicken flocks
  • Keeping ducks and chickens housed together
  • Letting chickens drink from swimming pools used by ducks.

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