Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations

Van Bressem, Marie-Francoise, Minton, Gianna, Sutaria, Dipani, Kelkar, Nachiket, Peter, Cindy, Zulkarnaen, Mohammad, Mansur, Rubaiyat M., Porter, Lindsay, Vargas, Luz H. Rodriguez, and Rajamani, Leela (2014) Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations. Diseases of Aquatic Organisms, 107 (3). pp. 181-189.

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Abstract

The presence of cutaneous nodules is reported in vulnerable populations of Irrawaddy dolphins Orcaella brevirostris from Malaysia (Kuching, Bintulu-Similajau, Kinabatangan Segama 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.

Item ID: 31096
Item Type: Article (Research - C1)
ISSN: 1616-1580
Keywords: Irrawaddy dolphin, Orcaella brevirostris, Malaysia, India, Bangladesh, epidemiology, fibropapillomas, skin disease, cutaneous nodules, conservation
Funders: Sarawak Shell Berhad, Ocean Park Conservation Foundation, Malaysian Ministry of Science, Technology and Innovation, Rio Tinto, LEAP, Abraham Foundation, Woodstiger Fund, Universiti Sains Malayasia, James Cook University (JCU), Wildlife Conservation Society
Projects and Grants: Universiti Sains Malaysia Grant 304/PPANTAI/6311103
Date Deposited: 12 Feb 2014 00:07
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050211 Wildlife and Habitat Management @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 100%
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