Comparative Innate and Adaptive Immune Responses in Atlantic Bottlenose Dolphins (Tursiops truncatus) With Viral, Bacterial, and Fungal Infections.

Free-ranging Atlantic bottlenose dolphins (n = 360) from two southeastern U.S. estuarine sites were given comprehensive health examinations between 2003 and 2015 as part of a multi-disciplinary research project focused on individual and population health. The study sites (and sample sizes) included the Indian River Lagoon (IRL), Florida, USA (n = 246) and Charleston harbor and associated rivers (CHS), South Carolina, USA (n = 114). Results of a suite of clinicoimmunopathologic tests revealed that both populations have a high prevalence of infectious and neoplastic disease and a variety of abnormalities of their innate and adaptive immune systems. Subclinical infections with cetacean morbillivirus and Chlamydiaceae were detected serologically. Clinical evidence of orogenital papillomatosis was supported by the detection of a new strain of dolphin papillomavirus and herpesvirus by molecular pathology. Dolphins with cutaneous lobomycosis/lacaziasis were subsequently shown to be infected with a novel, uncultivated strain of Paracoccidioides brasiliensis, now established as the etiologic agent of this enigmatic disease in dolphins. In this review, innate and adaptive immunologic responses are compared between healthy dolphins and those with clinical and/or immunopathologic evidence of infection with these specific viral, bacterial, and fungal pathogens. A wide range of immunologic host responses was associated with each pathogen, reflecting the dynamic and complex interplay between the innate, humoral, and cell-mediated immune systems in the dolphin. Collectively, these studies document the comparative innate and adaptive immune responses to various types of infectious diseases in free-ranging Atlantic bottlenose dolphins. Evaluation of the type, pattern, and degree of immunologic response to these pathogens provides novel insight on disease immunopathogenesis in this species and as a comparative model. Importantly, the data suggest that in some cases infection may be associated with subclinical immunopathologic perturbations that could impact overall individual and population health.

Toward the identification, characterization and experimental culture of Lacazia loboi from Atlantic bottlenose dolphin (Tursiops truncatus).

Lobomycosis (lacaziosis) is a chronic, granulomatous, fungal infection of the skin and subcutaneous tissues of humans and dolphins. To date, the causative agent, the yeast-like organism Lacazia loboi, has not been grown in the laboratory, and there have been no recent reports describing attempts to culture the organism. As a result, studies on the efficacy of therapeutics and potential environmental reservoirs have not been conducted. Therefore, the objective of the current study was to utilize both classical and novel microbiological methods in order to stimulate growth of Lacazia cells collected from dolphin lesions. This included the experimental inoculation of novel media, cell culture, and the use of artificial skin matrices. Although unsuccessful, the methods and results of this study provide important insight into new approaches that could be utilized in future investigations of this elusive organism.

Lobomycosis: risk of zoonotic transmission from dolphins to humans.

Lobomycosis, a fungal disease of the skin and subcutaneous tissues caused by Lacazia loboi, is sometimes referred to as a zoonotic disease because it affects only specific delphinidae and humans; however, the evidence that it can be transferred directly to humans from dolphins is weak. Dolphins have also been postulated to be responsible for an apparent geographic expansion of the disease in humans. Morphological and molecular differences between the human and dolphin organisms, differences in geographic distribution of the diseases between dolphins and humans, the existence of only a single documented case of presumed zoonotic transmission, and anecdotal evidence of lack of transmission to humans following accidental inoculation of tissue from infected dolphins do not support the hypothesis that dolphins infected with L. loboi represent a zoonotic hazard for humans. In addition, the lack of human cases in communities adjacent to coastal estuaries with a high prevalence of lobomycosis in dolphins, such as the Indian River Lagoon in Florida (IRL), suggests that direct or indirect transmission of L. loboi from dolphins to humans occurs rarely, if at all. Nonetheless, attention to personal hygiene and general principals of infection control are always appropriate when handling tissues from an animal with a presumptive diagnosis of a mycotic or fungal disease.