Dermatite Clostridial e Surto de Bouba Aviária em Emas (Rhea americana) no Nordeste do Brasil

Abstract

Greater Rheas (Rhea americana) are Brazil’s largest birds. This species, though slightly exploited commercially in Brazil, is an important part of the ecosystem and suffer with deforestation of its biomes, illegal hunt, predation and trafficking of native species. They are currently classified as “Near Threatened” at the International Union for Conservation of Nature (IUCN) Red List of Endangered Species. Greater Rheas diseases are poorly documented in Brazil. This work aimed to do a literature review regarding the main infectious illnesses that affect the species and to report (i) a case of gangrenous dermatitis and cellulitis in an adult female Greater Rhea and (ii) an outbreak of Avian Pox in Greater Rheas in Northeastern Brazil. The infectious diseases which were found were divided into viral, bacterial, fungal and parasitic diseases. The non-infectious diseases were compiled into one section. Chapter one reports the first case of clostridial dermatitis caused by an association of Clostridium perfringens type A, C. chauvoei and C. septicum in an adult Rhea in Brazil and the clinical, histopathological and microbiological aspects of the infection. Clostridial dermatitis is frequently diagnosed in poultry and seldomly, if ever, in wild birds. In our report, the bird had shown apathy, inappetence and was found dead the following day after its arrival. Macroscopically, there was na extensive, blackened, apteric lesion on its dorsal pelvic region, in addition to the presence of gas in the subcutaneous tissue and inflammation. Microscopically, there was coagulative necrosis of the skin associated to an intense heterophilic infiltrate that reached its underlaying subcutaneous and muscular tissues. Fragments from tissue were collected and cultured for bacterial growth and molecular identification of pathogens. The bird died suddenly due to toxemia. The second chapter regards an outbreak of avian pox in juvenile rheas in Northeastern Brazil and its clinical and histopathological findings. Thirteen rheas developed crostous whiteish, rounded, multifocal to coalescent skin lesions and respiratory signs such as nasal discharge and shortness of breath. Nine of the rheas died shortly after presenting clinical signs. Necropsy was performed in on the cadavers and microscopical lesions included hyperkeratosis, acantholytic lesions and the presence of inclusion bodies known as Bollinger bodies in its keratinocytes’ cytoplasm. Macroscopic findings included severe atrophy of the heart and ventricular fat. After 30 days, another rhea died, and necropsy was also performed. This rhea did not recover from pox lesions as the others and a metallic object was found piercing through its ventricle. The last rhea’s lesions were more severe than the previous necropsied one, and inclusion bodies were also found in its keratinocytes. Both diseases, clostridial dermatitis and avian pox, were never reported in rheas in Brazil before. The investigation of the causa mortis of wild native birds is essential to the preservation of species. The necroscopic examination allows us to detect pathogens and take prophylactic measures to avoid decreasings numbers of wild populations.