title: Cutaneous nodules in Irrawaddy dolphins: an emerging disease in vulnerable populations.
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.
authors.affiliation: Cetacean Conservation Medicine Group (CMED), Centro Peruano de Estudios Cetológicos (CEPEC), Lima 20, Peru.
authors.forename: Marie-Francoise
authors.initials: MF
authors.lastname: Van Bressem
authors.forename: Gianna
authors.initials: G
authors.lastname: Minton
authors.forename: Dipani
authors.initials: D
authors.lastname: Sutaria
authors.forename: Nachiket
authors.initials: N
authors.lastname: Kelkar
authors.forename: Cindy
authors.initials: C
authors.lastname: Peter
authors.forename: Mohammad
authors.initials: M
authors.lastname: Zulkarnaen
authors.forename: Rubaiyat M
authors.initials: RM
authors.lastname: Mansur
authors.forename: Lindsay
authors.initials: L
authors.lastname: Porter
authors.forename: Luz H
authors.initials: LH
authors.lastname: Vargas
authors.forename: Leela
authors.initials: L
authors.lastname: Rajamani
mesh_terms: D000818:Animals; D001459:Bangladesh / Q000453:epidemiology; D004289:Dolphins; D005260:Female; D007194:India / Q000453:epidemiology; D008296:Malaysia / Q000453:epidemiology; D012871:Skin Diseases / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*