Serological survey for antibodies to Encephalitozoon cuniculi in cats within the United States

Endoparasites of rabbits and hares

Nematode, cestode, protozoan, microsporidian, and pentastomid parasites affect domesticated and wild rabbits, hares, and jackrabbits of the genera Brachylagus, Lepus, Oryctolagus, Pentalagus, and Sylvilagus. Some endoparasite infections are of limited or no significance, whereas others have potentially profound consequences. Accurate identification of endoparasites of rabbits, hares, and jackrabbits is an important facet of the work of veterinary pathologists engaged in lagomorph pathology. Here I review endoparasites from the pathologist's perspective, focusing on pathogenesis, lesions, and implications of infection. Stomach nematodes Graphidium strigosum and Obeliscoides cuniculi are infrequently pathogenic but may cause gastritis and gastric mucosal thickening. Nematodes Passalurus ambiguus, Protostrongylus spp., Trichostrongylus spp., and Trichuris spp. are rarely associated with disease. Adult Capillaria hepatica (syn. Calodium hepaticum) nematodes and non-embryonated eggs cause granulomatous hepatitis in wild Oryctolagus cuniculus and Lepus europaeus, resulting in multifocal, off-white, hepatic lesions, which may be misdiagnosed as hepatic eimeriosis. When the rabbit is an intermediate host for carnivore cestodes, the space-occupying effects of Cysticercus pisiformis and Coenurus serialis may have pathologic consequences. Eimeria stiedai is a major cause of white-spotted liver in O. cuniculus, particularly in juveniles. Enteric coccidiosis is a noteworthy cause of unthriftiness in young animals, and frequently manifests as diarrhea with grossly appreciable multifocal off-white intestinal lesions. O. cuniculus is the natural host for the zoonotic microsporidian Encephalitozoon cuniculi. Infection may be acute and focused mainly on the kidneys, or it may follow a chronic disease course, frequently with neurologic lesions. A latent carrier status may also develop.

A multidisciplinary review about Encephalitozoon cuniculi in a One Health perspective

Encephalitozoon cuniculi is a microsporidian parasite mostly associated with its natural host, the rabbit (Oryctolagus cuniculus). However, other animals can be infected, like other mammals, birds, and even humans. Although it usually causes subclinical infection, it can also lead to encephalitozoonosis, a clinical disease characterized by neurological, ocular, and/or renal signs that can be even fatal, especially in immunocompromised individuals. Therefore, this multidisciplinary review contributes with updated information about the E. cuniculi, deepening in its molecular and genetic characterization, its mechanisms of infection and transmission, and its prevalence among different species and geographic locations, in a One Health perspective. Recent information about the diagnostic and therapeutic approach in the main host species and the prophylaxis and infection control measures currently suggested are also discussed.

Feline intralenticular Encephalitozoon cuniculi: three cases from California

Case series summary

Three domestic shorthair cats from California presented to veterinary ophthalmologists with immature cataracts. Other presenting clinical signs included corneal edema, anisocoria, anterior uveitis, elevated intraocular pressure, blepharospasm and/or lethargy. All patients were immunocompromised due to concurrent diseases and/or immunomodulatory drugs. Diagnostics included serial comprehensive ophthalmic examinations with tonometry, ocular ultrasound, electroretinogram and testing for other causes of feline uveitis. Testing for Encephalitozoon cuniculi included serology, histopathology and/or PCR of aqueous humor, lens material or paraffin-embedded whole eye. Treatments included antiparasitic medication, anti-inflammatory medication and supportive care in all three cases. Surgical treatment included enucleation (one case), bilateral phacoemulsification and unilateral intraocular lens placement (one case) and bilateral phacoemulsification with bilateral endolaser ciliary body ablation and bilateral intraocular lens implantation (one case). Both cats for which serologic testing for E cuniculi was performed were positive (1:64-1:4096). In all cats, diagnosis of intraocular E cuniculi was based on at least one of the following: lens histopathology or PCR of aqueous humor, lens material or paraffin-embedded ocular tissue. The clinical visual outcome was best in the patient undergoing phacoemulsification at the earliest stage of the cataract.

Relevance and novel information

Encephalitozoon cuniculi should be considered as a differential cause of cataracts and uveitis in cats in California, the rest of the USA and likely worldwide.

Zoonotic Risk of Encephalitozoon cuniculi in Animal-Assisted Interventions: Laboratory Strategies for the Diagnosis of Infections in Humans and Animals

The involvement of animals for therapeutic purposes has very ancient roots. To date, it is clear that animal-assisted interventions (AAIs), in addition to ensuring the replacement of missing or deficient affects, improves psychophysiological parameters connected to human health. However, AAI could potentially present risks related to the transmission of infectious agents from animals to humans. Among these microorganisms, E. cuniculi is a microspore which induces pathological effects (fever, headache, nausea, vomiting, diarrhea, breathlessness, respiratory symptoms, and weakness) in both humans and animals. Consequently, an accurate and fast diagnosis of E. cuniculi infection, as well as the identification of new diagnostic approaches, is of fundamental importance. This literature review was carried out to provide an extensive and comprehensive analysis of the most recent diagnostic techniques to prevent and care for E. cuniculi-associated risks in the AAI field.