Spirochetosis, Chicken Tick Paralysis, Fowl Spirochetosis, Fowl Tick Fever, Fowl Tick Paralysis, Chicken Tick Fever
Avian intestinal spirochetosis (AIS) is an enteric disease of birds caused by colonization of spirochetal bacteria of the genus Brachyspira
in the bird'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 historically in flocks of laying hens and broiler breeders. 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.
- 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.
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.