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

Van Bressem, Marie-Francoise and Minton, Gianna and Sutaria, Dipani and Kelkar, Nachiket and Peter, Cindy and Mohammad, Zulkarnaen and Rubaiyat, M. Mansur and Porter, Lindsay and Rodriguez Vargas, Luz H. 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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Official URL: doi: 10.3354/dao02689

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 Type: Article
Uncontrolled Keywords: UNIMAS, Universiti Malaysia Sarawak, university, universiti, Borneo, Malaysia, Sarawak, kuching, samarahan, IPTA, education, research, Universiti Malaysia Sarawak, 2014, Irrawaddy dolphin, Orcaella brevirostris, India, Bangladesh, Epidemiology,Fibropapillomas, Skin disease,Cutaneous nodules, Conservation
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QL Zoology
Divisions: Academic Faculties, Institutes and Centres > Institute of Biodiversity and Environmental Conservation
Faculties, Institutes, Centres > Institute of Biodiversity and Environmental Conservation
Depositing User: Karen Kornalius
Date Deposited: 17 Mar 2015 08:11
Last Modified: 19 Mar 2015 02:47
URI: http://ir.unimas.my/id/eprint/6589

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