Eustrongylidosis

Eustrongylidosis is named after the causative agent Eustrongylides, and typically occurs in eutrophicated waters where concentrations of nutrients and minerals are high enough to provide ideal conditions for the parasite to thrive and persist.

Because eutrophication has become a common issue due to agricultural runoff and urban development, cases of eustrongylidosis are becoming prevalent and hard to control.

Eustrongylidosis can be diagnosed before or after death by observing behavior and clinical signs, and performing fecal flotations and necropsies.

Methods to control it include preventing eutrophication and providing hosts with uninfected food sources in aquaculture farms.

[1] These roundworms cause a high mortality rate in nesting egrets and other wading birds, including other coastal populations.

Therefore, the lifecycle is indirect because the parasite has to infect other species to reach its final host and become sexually mature and reproduce.

[3] The cycle repeats itself when the parasite becomes sexually mature and sheds eggs through the feces of the bird to the external environment.

have been found in a variety of wildlife species, including freshwater fishes,[5] such as perch (Perca fluviatilis), sheat fish (Silurus glanis), pike (Esox lucius), pikeperch (Sander lucioperca), and sun perch (Lepomis eupomotis gibbosus).

[4] These species are also found in nesting habitats of birds, including areas with a low tree understory.

Finally, their growth rates become suppressed, so they tend to die before the parasite becomes sexually mature and sheds eggs.

A common behavior in both young and old birds includes regurgitation of food, which leads to lack of appetite and eventually anorexia or emaciation.

In some cases, the parasite can inhabit the lung and cause respiratory problems that increase stress levels and severity of the disease.

As with birds, prominence of the keel could be a determinant in diagnosis, but natural history of the species needs to be understood to avoid potential misdiagnoses.

While palpation is practical and simple, errors can be made in nestlings' examinations because their ribs have the potential to present as lesions.

Encouraging responsible farming practices to reduce chemical run-off can help prevent this disease from occurring.

[9] Once an outbreak of eustrongylidosis has occurred, ecosystem managers can do little to stop the spread in oligochaetes, fish, and birds.