Fatal Disseminated Toxoplasmosis in a Spinner Dolphin (Stenella longirostris)

Abstract

Toxoplasmosis is a common, mainly asymptomatic infection in warm-blooded mammals and bird^.^.^ The infection appears to be more common in some animal species than in others, and there are relatively few reports involving marine mammals. Among marine mammals, toxoplasmosis has been reported in several pinnipeds2 and a manatee' but not in cetaceans. A recent infection involving a female Atlantic bottle-nosed dolphin (Tursiops truncatus) and her calf found beached in Florida is on file at the Armed Forces Institute of Pathology.6We report toxoplasmosis in a wild, free-living male spinner dolphin (Stenella longirostris). The animal was 199 cm long and was found beached on Chun's Reef, Haleiwa, Oahu, Hawaii. The carcass was thin, dehydrated, and had very little ingesta in the stomach, and the intestine was empty. Numerous ulcers were noted on the gums, tongue, and oral mucosa. Unidentified tapeworm cysts were found in the skeletal muscle. Consolidation was present in the anterior portion of the left lung, and numerous small nodules were scattered throughout the liver.Although not all of the organs were available for histologic examination, the adrenal glands were severely affected, with numerous large, discrete areas of coagulative necrosis in the cortex (Fig.1). Fewer lesions were in the medulla. Mononuclear leukocytic aggregates composed of lymphocytes and macrophages were found at the periphery of the necrotic areas. In the parenchymal cells were numerous organisms of Toxoplasma gondii, including both tachyzoites (Fig. 2) and tissue cysts. The bradyzoites in tissue cysts stained positively with the periodic acid-Schiff technique (Fig. 3). A diffuse encephalitis was present with numerous small foci of gliosis associated with tissue cysts. The liver had many small, randomly distributed, necrotic foci containing mononuclear leukocytic infiltrates, and T. gondii organisms were found occasionally in hepatocytes. The testes had several small necrotic foci, but no T. gondii was seen. A severe subacute to chronic

Cerebral Toxoplasmosis in Striped Dolphins (Stenella coeruleoalba) Stranded Along the Ligurian Sea Coast of Italy

“…9,27 The epidemiology of T gondii infection of offshore species such as Risso's dolphins (Grampus griseus) and striped dolphins is more difficult to explain but has been speculatively linked to the release of ship ballast waters contaminated by onboard rodents, cats, or contaminated soil. 32 Although T gondii is commonly regarded as an opportunistic pathogen in aquatic mammals, 24,26 as clearly documented in striped dolphins during the 1990-1992 Mediterranean Sea DMV epidemic, 7,21 the present findings suggest that T gondii had a primary etiologic role in the meningoencephalitis seen in the seropositive animals under study. A similar role has been suggested for captive and feral pinniped and cetacean species.…”

“…11 Although the potential of this protozoan to affect cetacean populations has not been thoroughly investigated thus far, a number of reports clearly suggest that T gondii infection is of potential concern to cetacean health and conservation. 9,11,32 T gondii is commonly believed to be an opportunistic pathogen for aquatic mammals, 24,26 as was the case in striped dolphins (Stenella coeruleoalba) during the dolphin morbillivirus (DMV) epidemic in the Mediterranean Sea from 1990 to 1992. 7,21 Between late 2006 and early 2007 another morbillivirus epidemic was reported in pilot whales (Globicephala melas) in the Mediterranean Sea near Gibraltar 12 and, in the following months, in pilot whales and striped dolphins along the Spanish coast.…”

ASSESSEMENT OF SERUM AMYLOID A LEVELS IN THE REHABILITATION SETTING IN THE FLORIDA MANATEE (TRICHECHUS MANATUS LATIROSTRIS)

“…Northern sea otters in Alaska rarely test positive (FWS unpublished data). Source of infection not clearly defined but hypothesized to be associated with freshwater inputs to the ocean in California (Miller et al 2002;Dailey 2001;Migaki 1990). …”

Evidence of Feline Immunodeficiency Virus, Feline Leukemia Virus, and Toxoplasma gondii in Feral Cats on Mauna Kea, Hawaii

“…Toxoplasmosis has caused mortality of native Hawaiian birds such as captive Nē nē (Nesochen sandvicensis), wild Red-footed Booby (Sula sula) (Work et al, 2002), and critically endangered Alalā (Corvus hawaiiensis) (Work et al, 2000). Moreover, T. gondii oocysts may enter marine environments in municipal sewage or storm water runoff, sporulate in seawater (Lindsay et al, 2003) and thereby infect a variety of marine mammals, including dolphins (Migaki et al, 1990) and seals (Holshuh et al, 1985).…”