Postmortem findings in a finless porpoise (Neophocaena phocaenoides) calf stranded in Hong Kong

Eighteen-Year Study of South Australian Dolphins Shows Variation in Lung Nematodes by Season, Year, Age Class, and Location

“…These results are in contrast to studies of the harbor porpoise in which the number of lung nematodes did not differ between young and old animals (Balbuena et al, 1994). Other studies have shown that young odontocetes are infected with lung nematodes (Woodward et al, 1969;Balbuena et al, 1994;Parsons et al, 1999;Parsons and Jefferson, 2000;Kuramochi et al, 2000;Bossart et al, 2003;Kuwamura et al, 2007;Stockin et al, 2009), raising the question of how the parasites are transmitted. Three possibilities have been suggested: 1) via the placenta, 2) via the milk, and 3) via an intermediate host as a prey species.…”

“…Mazzariol et al (2007) found that pneumonia was frequently encountered in the 13 odontocete carcasses they investigated and that lung nematodes were associated with many of these. An association between lung nematodes and bacterial and viral infections in marine mammals was reported by Parsons et al (1999), Siebert et al (2001), and Stroud and Rolfe (1979). Thus, it is possible that many of the South Australian dolphins died from a secondary infection, not from the direct effect of the parasites.…”

“…Other studies showed that lung nematode infections were not the direct cause of death in dolphins (Baker, 1992;Mazzariol et al, 2007). Parsons and Jefferson (2000) found that about 30% of the finless porpoise (Neophocoena phocaenoides) they studied in Hong Kong had moderate to heavy infections and, in some of these, the cause of death was attributed to parasite load. However, these authors did not study bacteriology in all animals they necropsied.…”

“…Lesions caused by lung nematodes have been described in the common bottlenose dolphin (Tursiops truncatus), short-beaked common dolphin (Delphinus delphis), and striped dolphin (Stenella coeruleoalba) from the Mediterranean Sea (Raga et al, 1987). Many pathologic changes, including fatalities, are caused by lung nematode infections (Gibson et al, 1998;Parsons and Jefferson, 2000).…”

“…Studies have been conducted in Europe, the USA, Japan, and Hong Kong (Measures, 2001) but these locations are likely to be areas of high observer effort rather than true hot spots of nematode infection in marine mammals. Most studies have concentrated on the taxonomy of the nematodes (Baylis and Daubney, 1925;Johnston and Mawson, 1941;Arnold and Gaskin, 1975;Raga et al, 1987;Balbuena et al, 1994;Gibson et al, 1998;Lehnert et al, 2005) or the pathology of host species (Testi and Pilleri, 1969;Woodard et al, 1969;Dailey and Stroud, 1978;Viale, 1981;Tsocheva et al, 1992;Parsons et al, 1999;Siebert et al, 2001;Bossart et al, 2003;Kuwamura et al, 2007). Of the cetaceans, the harbor porpoise (Phocoena phocoena) has been particularly well studied, with studies in the Baltic Sea finding a relationship between water pollution and lung nematode infections (Siebert et al, 2001).…”