Infectious diseases are considered biologic threats in different dolphin populations.1,2 Among them, Toxoplasma gondii, papillomavirus and poxvirus are well documented worldwide.2 This abstract describes the presence of these diseases in Brazil. Toxoplasma gondii was seen in a Guiana dolphin (Sotalia guianensis) from the Brazilian Southwest. Tissue cysts and groups of tachyzoites were observed in lung, liver, kidney, adrenal gland, eye, and intestinal samples, mostly surrounded by mononuclear cells and necrosis. Immunohistochemistry was performed using a polyclonal antibody to T. gondii. All tissues were positive to this protozoan agent. By ultrastructural assessment, tachyzoites were observed being engulfed by Kupffer cells and within glomerular tufts in the liver and kidney samples, respectively.
Papillomas were observed in the oral mucosa and surrounded the genital slit of a rough-toothed dolphin (Steno bredanensis) from the Brazilian Southeast. Histologically, these masses were composed of epithelial hyperplasia, elongation of the dermal papillae, koilocytosis, some bizarre mitoses in the basal epithelium and mild dermatitis. Inclusion bodies were not observed. Ultrastructurally, round to hexagonal intra-nuclear viral particles approximately 40 nm in diameter, compatible with papillomavirus, were observed in the epithelial cells.
Poxvirus-like lesions (“tattoo lesions”) were diagnosed in a Guiana dolphin from the Brazilian Northeast. Grossly, it was observed as an irregular, dark skin lesion near the dorsal fin. Histologically, acidophilic cytoplasmic inclusion bodies were observed within epithelial cells.
These findings show that Brazilian dolphins are exposed to infectious agents that cause morbidity and mortality. Furthermore, the presence of these infectious diseases may represent an important tool to assess the marine environmental conditions along the Brazilian coast as related to incidence of infectious disease.
1. Di Guardo, G., S. Mazzariol and A. Fernández. 2011. Biologically threatened dolphins and whales. Environmental Microbiology 13: 2833–2834.
2. Van Bressem, M. F., J. A. Raga, G. Di Guardo, et al. 2009. Diseases of Aquatic Organisms. 83: 143–157.