Background: Ara ararauna is widely distributed in South America and frequently affected by anthropogenic activities and environmental pressures such as illegal bird trafficking, and habitat loss. Also some endoparasites can threaten their health, and cause their death, or prevent the reintroduction of the animal to its natural environment. The objective of the present work was to report the occurrence of parasitism by Syngamus trachea in an Ara ararauna.Case: An adult, 900-gram female Ara ararauna from a project for the rehabilitation of the Brazilian fauna was kept in a collective nursery together with 12 specimens of the same species. Their diet was composed of typical fruits of the region, which were offered twice a day, and water ad libitum. The macaws had no previous history of anthelmintic treatment. The specimen evaluated presented progressive weight loss, constant sneezing, and reduced appetite for seven days. During physical examination the animal presented apathy, lethargy, spiked feathers, body condition score of 1/4, frequent sneezing, and inspiratory dyspnea. After this examination, the bird died, and the necropsy was performed. The postmortem findings were pale periocular, oral, and cloacal mucosae, cachexia, and presence of parasites of round shape, reddish color, with length of approximately 0.5 cm, in the proximal portion of the trachea. Another parasite with the same characteristics, but smaller in size, showing Y shape was found in the body. The trachea also showed colorless mucus and petechial hemorrhages in the proximal and middle portions of the mucosa. These parasites were subjected to morphological analysis in the Laboratory of Microscopy of the University Center of Triângulo and were identified as Syngamus trachea.Discussion: The diagnosis was based on morphological analysis of the parasite. This parasite can be transmitted through infected worms, which are paratenic hosts of S. trachea. Chickens may also be parasitized by S. trachea; consequently, they may have contributed to the dispersion of eggs of S. trachea in the environment, since they had free access to the entire rural property. There is a positive correlation between parasitism by S. trachea and body condition loss in other bird species that may be connected to the lowering of its feed conversion and food consumption. The mechanical irritation caused by parasites in the tracheal lumen was probably the cause of the clinical manifestations involving the respiratory tract, which were characterized by dyspnea and sneezing. Moreover, petechial hemorrhages, increased mucus production within the trachea, and paleness of the visible mucosa are alterations probably caused by traumatic action and the hematophagous habit of the nematode in the trachea of the bird. Climatic and soil conditions can favor the maintenance of S. trachea eggs and larvae and the permanence of the verminosis in the environment. Therefore, a strict sanitary control of the animals in conservation projects is necessary, with a routine of coproparasitological examinations. Although the actual epidemiological status of endoparasites in free-living Ara ararauna is unknown, deworming protocols for birds intended for release in natural environments are different from those used in specimens under observation. Birds that will return to free life receive antiparasites only in cases of clinical symptomatology associated with positive tests of verminoses to maintain the natural resistance of the birds to the parasites found in their natural environment. The results of this report, showing the occurrence of infection of Ara ararauna by Syngamus trachea denotes the importance of periodic coproparasitological exams.
