Experimental Encephalitozoonosis in Neonatal Dogs

Abstract

Abstract. The in vivo infection of neonatal dogs by the microsporidian protozoan parasite, Encephalitozoon cuniculi, was studied. Microscopic examination of tissues from infected animals showed granulomatous nephritis, meningoencephalitis, hepatitis, and pneumonitis. A large component of the inflammatory infiltrate consisted of plasma cells and lymphocytes. In addition, hyperplasia of B-lymphocyte-dependent regions of lymph nodes and erythrophagocytosis were consistently seen in infected dogs. Infected dogs developed lymphocytosis, hypergammaglobulinemia, anti-encephalitozoon antibodies, and an antigen-specific blastogenic response to E. cuniculi spores. Lymphocyte blastogenic responses to the lectin phytohemagglutinin A (PHA) were depressed compared to controls. Dogs dying during the 2-month experimental trial were bacteremic. The findings of these experiments suggest that postnatal infection results in a demonstrable although seemingly ineffective immune and inflammatory response without detectable clinical disease.

Infectious Hepatopathies in Dogs and Cats

“…Typical organs of localized infection include the kidney, liver, lungs, and brain with resultant granulomatous inflammation. 99,100 Cats and older dogs are not commonly affected, and renal disease predominates in young dogs. Cytological examination of fluids (particularly urine) is important in making a diagnosis in animals with disseminated disease as other tests are commercially unavailable.…”

Mammalian Microsporidiosis

“…89 Clinical signs in pups and kits include reduced appetite and stunted growth, ataxia, tremors, posterior weakness, and blindness with progression to circling, aggressive behavior, and convulsions. 87,132 Gross lesions include pale radial streaks extending from the cortex to the renal pelvis on cross sections of kidney and edematous, distended meninges. Thickened, necrotic, and tortuous medium-size to small arteries (consistent with polyarteritis nodosa) are often observed at necropsy in cardiac, intestinal, and central nervous system tissues in blue foxes.…”

“…95 Histologic lesions in dogs and foxes include multifocal microgranulomatous hepatitis, interstitial lymphocytic-plasmacytic nephritis, interstitial pneumonia, and lymphocytic-plasmacytic meningoencephalitis with perivascular cuffing and occasional intracellular parasitic cysts containing gram-positive spores. 132 Surviving animals shed parasites in the urine. 87 Morbidity and mortality vary within a litter of pups or kits, and the parents typically remain unaffected.…”

Immunohistochemical identification of Encephalitozoon cuniculi in phacoclastic uveitis in four rabbits

“…dogs, cat, foxes, monkeys) and in immunocompromised human patients it is responsible for severe life‐threatening infections 2–4 . Conversely, in lagomorphs, encephalitozoonosis is an essentially asymptomatic, chronic disease 2,3 with a reported incidence of infection varying from 5 to 75% in laboratory rabbits 5 . Characteristic microscopic lesions associated with E. cuniculi infection in rabbits are mostly diagnosed at necropsy as small focal granulomatous lesions of brain and kidney 3,5,6 …”