Eustrongylidosis is a parasitic disease that mainly affects wading birds worldwide; however, the parasite’s complex, indirect life cycle involves other species such as aquatic worms and fish. Moreover, this disease is zoonotic which means the parasite can transmit disease from animals to humans. 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, clinical signs and performing fecal flotations and necropsies. Methods to control Eustrongylidosis include preventing eutrophication and providing hosts with uninfected food sources in aquaculture farms. Parasites are known to be indicators of environmental health and stability and should therefore be studied further to better understand the parasite’s life cycle and how it affects predator-prey interactions and improve conservation efforts.

Diagnosis in a live specimen is possible in the field by palpating the abdomen. 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. However, the best form of diagnosis still remains as necropsy. During the necropsy, the best diagnosis can be determined by the adult nematodes by scanning them with electron microscopy. Different species of Eustrongylidosis nematodes can be differentiated by specific gender characteristics, i.e. “Male specimens of E. ignotus have a caudal sucker that lacks cuticular cleft, while a cuticular cleft is present in the caudal sucker of male specimens of E. excisus”. “Eustrongylidosis can often be misdiagnosed as starvation in nestling because they are often emaciated at the time of death”.

Before necropsy takes place, diagnosis by palpitation can be used to find tubular lesions. Those tubular lesions are firm, firmly attached to organs, and are felt in the subcutaneous tissue. While palpitation is practical and simple, errors can be made in nestlings’ examinations because their ribs have the potential to present as lesions. Diagnosis is also attainable by examining fecal samples, but has the high potential of false negatives. That possibility is increased in fledging feces “where severe disease may precede appearance of eggs in the feces”.