Skin lesions on common bottlenose dolphins (Tursiops truncatus) from three sites in the Northwest Atlantic, USA.

Skin disease occurs frequently in many cetacean species across the globe; methods to categorize lesions have relied on photo-identification (photo-id), stranding, and by-catch data. The current study used photo-id data from four sampling months during 2009 to estimate skin lesion prevalence and type occurring on bottlenose dolphins (Tursiops truncatus) from three sites along the southeast United States coast [Sarasota Bay, FL (SSB); near Brunswick and Sapelo Island, GA (BSG); and near Charleston, SC (CHS)]. The prevalence of lesions was highest among BSG dolphins (P = 0.587) and lowest in SSB (P = 0.380), and the overall prevalence was significantly different among all sites (p<0.0167). Logistic regression modeling revealed a significant reduction in the odds of lesion occurrence for increasing water temperatures (OR = 0.92; 95%CI:0.906-0.938) and a significantly increased odds of lesion occurrence for BSG dolphins (OR = 1.39; 95%CI:1.203-1.614). Approximately one-third of the lesioned dolphins from each site presented with multiple types, and population differences in lesion type occurrence were observed (p<0.05). Lesions on stranded dolphins were sampled to determine the etiology of different lesion types, which included three visually distinct samples positive for herpesvirus. Although generally considered non-fatal, skin disease may be indicative of animal health or exposure to anthropogenic or environmental threats, and photo-id data provide an efficient and cost-effective approach to document the occurrence of skin lesions in free-ranging populations.

Modeling lacaziosis lesion progression in common bottlenose dolphins Tursiops truncatus using long-term photographic records.

Lacaziosis (lobomycosis) is a skin disease caused by Lacazia loboi, occurring naturally only in humans and dolphins. Attempts to culture the pathogen in vitro have been unsuccessful, and inoculation studies of lacaziosis development in mice have provided only limited, short-term data on the progression and propagation of L. loboi. The present study used photographic data from long-term photo-identification and health assessment projects to model and quantify the progression of lacaziosis lesions in 3 common bottlenose dolphins Tursiops truncatus from Sarasota Bay, Florida, USA. Dorsal fin images throughout each animal's sighting history were examined for lesion growth, and the proportion of lesion coverage in each photograph was estimated using image analysis tools in Adobe Photoshop. The progression of lacaziosis lesions and lesion growth rates were modeled using a non-linear monomolecular growth model. As data on lacaziosis development and advancement are limited in humans and laboratory animals, dolphins with a long-term case history of the disease may serve as a good animal model to better understand lacaziosis progression. Furthermore, this study demonstrates the utility of long-term population monitoring data for tracking the progression of a poorly understood disease that is relevant to both dolphin and human health.