Submitted to: Veterinary Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/19/1995
Publication Date: N/A
Citation: Interpretive Summary: Infection by the protozoan parasite Toxoplasma gondii is widely prevalent in livestock and humans. It causes mental retardation and loss of vision in children and abortion in livestock. Cats are the main reservoirs of infection because they are the only hosts that excrete the environmentally resistant T gondii stage (oocyst) in feces. Infected cats rarely have clinical signs. Scientists at the Beltsville Agricultural Research Center and the Armed Forces Institute of Pathology report pathological changes in kittens congenitally infected with T. gondii. The lesions described will help in diagnosis of toxoplasmosis in neonatally infected cats.
Technical Abstract: Five pregnant queens were inoculated orally with Toxoplasma gondii tissue cysts. Twenty-two live and 3 dead kittens were born 16 to 31 days after inoculation. Four kittens were eaten by queens and thus, were not available for histologic examination. Twenty-one kittens that died or were euthanized on day 2 (2 kittens), 4 (1 kitten), 5 (5 kittens), 6 (5 kittens), 7 (1 kitten), 8 (4 kittens), 16 (2 kittens), and day 29 (1 kitten) after birth were studied histologically. Toxoplasma gondii was detected by bioassay and was seen in histologic sections of tissues from all 21 kittens. The histologic lesions associated with neonatal toxoplasmosis were widely disseminated infiltrates of macrophages and neutrophils often accompanied by necrosis; lymphocytes and plasma cells were occasionally present. The most consistent lesions were proliferative interstitial pneumonia (21/21); necrotizing hepatitis (20/21); myocarditis (21/21); skeletal myositis (21/21); glossal myositis (19/19); nonsuppurative encephalitis affecting the cerebrum (18/18), brain stem (15/15) and spinal cord (9/9); uveitis (19/19); necrotizing adrenal adenitis (18/18); and interstitial nephritis (16/21). Placental lesions (2/2) consisted of grossly visible areas of necrosis and mineralization.