In contrast, the prevalence is low in modern rodent facilities. The primary significance of E. cuniculi in laboratory rodents is as a contaminant of transplantable tumors. In addition to infected tumors, transmission is via exposure to infectious urine. Following ingestion, sporoplasm from infectious spores gains entrance to host intestinal epithelium, where multiplication occurs. Continued multiplication results in eventual host cell rupture, with dissemination to other organs, including the brain, kidneys, liver, and lungs.
Infection is usually asymptomatic in immunocompetent rodents.
Lesions are most commonly found in the kidneys and brain. In the kidneys, lesions consist of intracellular parasites in the renal tubular epithelium and inflammatory changes, with eventual focal destruction of tubules and replacement by fibrous connective tissue, resulting in pitting of the renal surface. In the brain, lesions consist of meningoencephalitis. In rats, but not in mice, there is also multifocal granulomatous inflammation. Macrophage microbicidal activity may involve nitrite NO2.