The different species of
Spironucleus can be found in a variety of animal hosts, including fish, birds, and mice. One parasite in fish was previously known as
Spironucleus barkhanus, but was then redescribed as
Spironucleus salmonicida. This new classification was given to this organism so that
Spironucleus salmonicida could be discernible from the fish commensals
Spironucleus barkhanus as they were morphologically identical, but genetically different
. Spironucleus vortens species is often found in freshwater angelfish, where it affects the gastrointestinal tract and may cause head and lateral line erosion. Pathogenesis of
Spironucleus can be promoted by stressful environmental conditions, including poor water quality, malnutrition, overcrowding, and fluctuating temperatures. These pathogens can be found in wild fish, as well as farmed fish. However, farmed fish are more susceptible to the
Spironucleus pathogen due to the poor conditions that sometimes accompany aquaculture. A species found in birds is
Spironucleus columbae. A study in the Handbook of Avian Medicine states that this species of
Spironucleus causes hexamitiasis in pigeons. Young pigeons can become infected with
Spironucleus columbae by consuming droppings, food, or water that contain the protozoan. The colonization and division of this species in the intestinal tract can cause small ulcerative lesions and other accompanying physical digestive illnesses. Some accompanying illnesses due to the lesions may include vomiting, dehydration, diarrhoea, and weight loss. These symptoms may also be worsened by bacterial infections within the lesions. In serious conditions,
Spironucleus columbae may ultimately cause death. A species found in mice is
Spironucleus muris. It can be found in normal adult mice, where it would not cause severe symptoms. This species is more pathogenic in young, stressed, or immunocompromised mice. In addition to mice,
Spironucleus muris can also cause digestive illnesses to rats and hamsters as well. One illness that this species can cause on mice, rats, and hamsters includes the inflammation of the small bowel. Greaves (2012) states that this species can be seen in crypts and intervillous spaces of the gut and lists "blunting of intestinal villi, epithelial degeneration and mucin depletion, reactive epithelial hyperplasia, edema, and leukocyte infiltration" as associated symptoms. Additionally, Whary et al. (2015) lists some physical symptoms of an infected mouse include poor hair coat, sluggish behaviour, and weight loss. Like other
Spironucleus species, transmission occurs through the faecal or oral route to infect the intestinal tract and potentially cause lethal illnesses. == Genetics ==