Disseminated Toxoplasmosis in a Mediterranean Pregnant Risso's Dolphin (Grampus griseus) with Transplacental Fetal Infection

Abstract

Fatal disseminated toxoplasmosis was diagnosed in a Risso's dolphin (Grampus griseus) dam and its fetus on the basis of pathologic findings, immunohistochemistry, and structure of the parasite. The dolphin was stranded alive on the Spanish Mediterranean coast and died a few hours later. At necropsy the dam was in good condition. From the standpoint of pathology, however, it had generalized lymphadenomegaly and splenomegaly, enlargement of and multifocal hemorrhage in the adrenal glands, diffuse mucosal hemorrhage of the glandular and pyloric stomach, ulcerative glossitis and stomatitis, focal erosions and reddening of the laryngeal appendix, and severe paraotic sinusitis with intralesional nematodes Crassicauda grampicola. The dolphin was pregnant, most probably in the first gestational trimester. The most prominent microscopic lesions were multifocal granulomatous encephalomyelitis, diffuse subacute interstitial pneumonia, mild multifocal necrotizing hepatitis and nonsuppurative cholangiohepatitis, gastritis and adrenalitis, mild lymphoid depletion, medullary sinus and follicular histyocitosis, and systemic hemosiderosis. The fetus had foci of coagulative and lytic necrosis in the kidneys, the lung, and the heart. Most lesions were associated with tachyzoites and tissue cysts of Toxoplasma gondii. The diagnosis was confirmed immunohistochemically. This is the first report on toxoplasmosis in a Risso's dolphin (G. griseus) and on transplacental transmission to an early-stage fetus in any cetaceans.

Risso's dolphin Grampus griseus in the Mediterranean Sea

“…Among the other parasites documented in Mediterranean Risso's dolphins are Crassicauda grampicola and Pennella sp. (found in or on a few animals dead-and live-stranded in Spain and Italy; Cornaglia et al, 2000;Domingo et al, 2000;Resendes et al, 2002;Zucca et al, 2004Zucca et al, , 2005Marcer et al, 2008). Also, Fernández et al (2003) reported 5 species of gastrointestinal helminths found in 17 Risso's dolphins stranded in the western Mediterranean.…”

“…For example, a Risso's dolphin and its fetus stranded alive on the Spanish Mediterranean coast with what was diagnosed as a fatal toxoplasmosis infection (Resendes et al, 2002). Infections with the protozoan agent Toxoplasma gondii are common in the western Mediterranean and especially prevalent in coastal areas, but only animals with compromised immune systems are at risk of becoming seriously ill (Domingo et al, 2000;Resendes et al, 2002;Cabezon et al, 2004). Among the other parasites documented in Mediterranean Risso's dolphins are Crassicauda grampicola and Pennella sp.…”

Qualitative risk assessment of impact of Toxoplasma gondii on health of beluga whales, Delphinapterus leucas from the Eastern Beaufort Sea, Northwest Territories

“…Transplacental transmission of T. gondii has been linked to abortion, still birth, neonatal death, or congenital cerebral malformations in marine mammals such as sea otters, dolphins, and Hawaiian monk seals (Jardine and Dubey 2002;Resendes et al 2002;Miller et al 2008b;Shapiro et al 2016). Such reproductive failure suggests that toxoplasmosis can be a risk to wildlife populations, especially those under pressure from other sources of mortality and reproductive stressors (Barbieri et al 2016;Shapiro et al 2016).…”

“…Transplacental transmission of T. gondii has been described in Risso's dolphin, Grampus griseus (Resendes et al 2002), Indo-Pacific bottlenose dolphin, Tursiops aduncus (Jardine and Dubey 2002), southern sea otter (Miller et al 2008b), Hawaiian monk seal (Barbieri et al 2016), and California sea lion (Zalophus californianus; Carlson-Bremer et al 2015). Transmammary transmission has only been documented in domestic and laboratory animals (Tenter et al 2000).…”

“…Toxoplasma gondii can be associated with reproductive loss and mortalities, as well as population reduction in free-ranging animals (Jardine and Dubey 2002;Resendes et al 2002;Kreuder et al 2003;Roe et al 2013;Herder et al 2015;Carlson-Bremer et al 2015;Barbieri et al 2016). Cats and wild felids shed oocysts of Toxoplasma in feces, and contaminate the environment, food, and water.…”