Title
Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations
Author(s)
Van Bressem, M. F.;Minton, G.;Sutaria, D.;Kelkar, N.;Peter, C.;Zulkarnaen, M.;Mansur, R. M.;Porter, L.;Vargas, L. H. R.;Rajamani, L.
Published
2014
Publisher
Diseases of Aquatic Organisms
Published Version DOI
https://doi.org/10.3354/dao02689
Abstract
The presence of cutaneous nodules is reported in vulnerable populations of Irra waddy dolphins Orcaella brevirostris from Malaysia (Kuching, Bintulu-Similajau, KinabatanganSegama and Penang Island), India (Chilika Lagoon) and Bangladesh (Sundarbans). Approximately 5700 images taken for photo-identification studies in 2004 to 2013 were examined for skin disorders. Nodules were detected in 6 populations. They appeared as circumscribed elevations of the skin and varied in size from 2 to > 30 mm, were sparse or numerous and occurred on all visible body areas. In 8 photo-identified (PI) dolphins from India and Malaysia, the lesions remained stable (N = 2) or progressed (N = 6) over months but did not regress. The 2 most severely affected individuals were seen in Kuching and the Chilika Lagoon. Their fate is unknown. Cutaneous nodules were sampled in a female that died in a gillnet in Kuching in 2012. Histologically, the lesions consisted of thick collagen bundles covered by a moderately hyperplasic epithelium and were diagnosed as fibropapillomas. Whether the nodules observed in the other O. brevirostris were also fibropapillomas remains to be investigated. Disease prevalence ranged from 2.2% (N = 46; Bintulu- Similajau) to 13.9% (N = 72; Chilika) in 4 populations from Malaysia and India. It was not significantly different in 3 study areas in eastern Malaysia. In Chilika, prevalence was significantly higher (p = 0.00078) in 2009 to 2011 (13.9%) than in 2004 to 2006 (2.8%) in 72 PI dolphins. The emergence of a novel disease in vulnerable O. brevirostris populations is of concern.
Keywords
Irrawaddy dolphin;Orcaella brevirostris;Malaysia;India;Bangladesh;Epidemiology;Fibropapillomas;Skin disease;Cutaneous nodules;Conservation;bottle-nosed dolphins;porpoises neophocaena-phocaenoides;lobomycosis-like disease;tursiops-truncatus;orcaella-brevirostris;phocoena-phocoena;southern brazil;small cetaceans;skin-disease;sperm;whale

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