Lobomycosis in Bottlenose Dolphins (Tursiops truncatus) from the Indian River Lagoon, Florida: Estimation of Prevalence, Temporal Trends, and Spatial Distribution

Abstract

Lobomycosis (lacaziosis) is a chronic fungal disease of the skin that affects only dolphins and humans. Previous studies have shown a high prevalence of lobomycosis in bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon, Florida (IRL). We studied the occurrence and distribution of lobomycosis in the IRL using photo-identification survey data collected between 1996 and 2006. Our objectives were to (1) determine the sensitivity and specificity of photo-identification for diagnosis of lobomycosis in free-ranging dolphins; (2) determine the spatial distribution of lobomycosis in the IRL; and (3) assess temporal patterns of occurrence. Photographs from 704 distinctly marked dolphins were reviewed for skin lesions compatible with lobomycosis. The presumptive diagnosis was validated by comparing the results of photographic analysis with physical examination and histologic examination of lesion biopsies in 102 dolphins captured and released during a health assessment and 3 stranded dolphins. Twelve of 16 confirmed cases were identified previously by photography, a sensitivity of 75%. Among 89 dolphins without disease, all 89 were considered negative, a specificity of 100%. The prevalence of lobomycosis estimated from photographic data was 6.8% (48/704). Spatial distribution was determined by dividing the IRL into six segments based on hydrodynamics and geographic features. The prevalence ranged from <1% in the Mosquito Lagoon to 16.9% in the south Indian River. The incidence of the disease did not increase during the study period, indicating that the disease is endemic, rather than emerging. In summary, photo-identification is a useful tool to monitor the course of individual and population health for this enigmatic disease.

Lobomycosis in Offshore Bottlenose Dolphins (Tursiops truncatus), North Carolina

“…The animal had a large region of raised epidermal gray to white nodules over the entire dorsal surface cranial to the dorsal fi n. These lesions are consistent with those seen in the other bottlenose dolphins in this report and lesions seen on bottlenose dolphins from the Indian and Banana rivers in Florida (10). The location of this sighting suggests that this dolphin is of the offshore ecotype (11,12).…”

“…The Indian River Lagoon dolphin population has been assessed for temporal and spatial prevalence of lobomycosis (10). A prevalence of 6.8% was observed in that population from 1996 through 2006, and most cases were observed in the southern portion of this elongate body of water (10).…”

Lacaziosis in Bottlenose Dolphins (Tursiops truncatus) in the Indian River Lagoon, Florida, USA

“…1) compared with 30% of the animals in the southern portion exhibiting the disease. Based on photographic analysis, another study estimated disease prevalence at 6.8% throughout the lagoon and 4.9% in our study area, the northern part of the IRL (Murdoch et al, 2008). Based on histologic examination, our study documented lacaziosis prevalence to be nearly twice the photographic estimate for the northern portion of the lagoon (3/33 or 9%).…”

Cutaneous Lesions in Cetaceans: An Indicator of Ecosystem Status?

“…The yeast-like, dimorphic fungus, Lacazia loboi (formerly known as Laboa loboi) causes invasive cutaneous lesions in dolphins and humans [58], known as lobomycosis, lacaziosis or keloidal blastomycosis [41,59,62]. The first case of keloidal blastomycosis was described in 1931 in a human patient from the Amazon valley [63].…”

“…On cellular level, the disease presents with superficial granulomatous dermatitis, associated with macrophages and multinucleated giant cells containing a variety of round yeast cells [61]. More cases of this disease affecting cetaceans have been added to the list and recently some authors suggested that the incidence of lobomycosis might represent opportunistic infections in immuno-compromised hosts [62,65]. The bio-accumulation of environmental contaminants in the affected dolphins was thought to possibly contribute to susceptibility to this disease [62].…”