Toxoplasma gondii transplacental infection is described in man,
sheep, goat, and pigs, and occurs when the dam acquires infection for first time during
pregnancy.1 Transplacental infection can cause early embryonic death and
reabsorption, fetal death and mummification, abortion, stillbirth and neonatal death, depending
on the stage of pregnancy at which the infection takes place.1 In humans, babies
become more severely affected when the mother is infected in early pregnancy.1 On the
other hand, when it occurs in a later stage generally results in a neonatal subclinical
infection.1 Toxoplasmosis has been previously reported in a wide variety of captive
and wild marine mammals.4,7 Moreover, transplacental transmission was most probably
the origin of T.gondii infection in some species of marine mammals: California sea lion
(Zalophus californianus), Harbour seal (Phoca vitulina), bottlenose dolphin
(Tursiops truncatus) and beluga whale (Delphinapterus leucas).5,8
Recently a stillborn Indo-pacific bottlenose dolphin (Tursiops aduncus) was diagnosed
with congenital toxoplasmosis.6
This study confirms transplacental T. gondii transmission in a
Risso's dolphin (Grampus griseus), where a disseminated toxoplasmosis was diagnosed in
the dam and her fetus. The diagnosis was based on pathologic findings, immunohistochemistry, and
the structure of the parasite. At necropsy the dam had a good body condition, generalized
lymphadenomegaly and splenomegaly, enlargement and multifocal hemorrhage in the adrenal glands,
diffuse mucosal hemorrhage of the glandular and pyloric stomach, ulcerative glossitis and
stomatitis. The dolphin was pregnant, most probably in the first gestational trimester (fetus
12.5 cm long). The most prominent microscopic lesions in the dam 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 histiocytosis. The fetus had foci of coagulative and
lytic necrosis in the kidney, lung, and heart. Most lesions were associated with tachyzoites and
tissue cysts of T. gondii, that stained positively with an anti-toxoplasma
In contrast with other species no gross placental lesions were observed. The
fetus lesions were severe and similar in nature to others transplacental-infections
reports.2,3,6 This is the first report of toxoplasmosis in a Risso's dolphin
(Grampus griseus) and of transplacental transmission to an early stage fetus in any
cetaceans. These findings indicate that toxoplasmosis should be included in the differential
diagnosis of reproductive failure in cetaceans.
1. Dubey JP, CP Beattie. 1988. Toxoplasmosis of animals and
man. CRC Press, Boca Raton, Florida, 220 pp.
2. Dubey JP, DH Schlafer, JF Urban Jr., DS Lindsay. 1990. Lesions
in fetal pigs with transplacentally-induced toxoplasmosis. Veterinary Pathology 27:
3. Dubey JP, Mattix ME, TP Lipscomb. 1996. Lesions of neonatally
induced toxoplasmosis in cats. Veterinary Pathology. 33: 290-295.
4. Holshuh HJ, AE Sherrod, CR Taylor, BF Andrews, EB Howard, 1985.
Toxoplasmosis in a feral northern fur seal. Journal of the American Veterinary Medical
Association 187: 1229-1230.
5. Inskeep II.W, CH Gardiner, RK Harris, JP Dubey, RT Goldston,
1990.Toxoplasmosis in Atlantic bottle-nosed dolphin (Tursiops truncatus). Journal of
Wildlife Diseases 377-382.
6. Jardine JE, JP Dubey, 2002. Congenital toxoplasmosis in a
Indo-Pacific Bottle-Nose dolphin (Tursiops aduncus). Journal of Parasitology (in
7. Lindsay DS, NJ Thomas, AC Rosypal, JP Dubey. 2001. Dual
Sarcocystis neurona and Toxoplasma gondii infection in a Northern sea otter from
Washington state, USA. Veterinary Parasitology 97: 319-327.
8. Mikaelian I, J Boisclair, JP Dubey, S Kennedy, D Martineau,
2000. Toxoplasmosis in Beluga Whales (Delphinapterus leucas) from the St Lawrence
Estuary: Two case reports and a serological survey. Journal of Comparative Pathology 122: