- Many rabbits are asymptomatic carriers of the microsporidian, E. cuniculi.
- Encephalitozoon may be spread through contact with rabbit urine.
- The immunocompromised are at risk for encephalitozoonosis.
- Clinical disease in humans varies.
- Avoid contact with the urine of infected or health rabbits, and always utilized good sanitation practices.
The physical and psychological benefits of pet ownership have been well established (4), however close contact with pets is not without risks including the potential for transmission of zoonotic disease. There are no serious zoonotic diseases that can be spread from rabbits to healthy humans (11), but rabbits can carry a number of potential pathogens including Encephalitozoon cuniculi (Fig 1).
Encephalitozoon cuniculi is an obligatory intracellular microsporidian parasite that can infect a wide range of mammals, including humans (5,13). The primary host for this primitive fungus is the rabbit. Infections in rabbits are typically subclinical (5.9).
Transmission of E. cuniculi is urine-oral in rabbits (9,13). Humans are exposed to spores through contact with rabbit urine. Spores are excreted in the urine, feces, or sputum and are very resistant in the environment. Exposure to rabbit secretions as well as ingestion of contaminated food or water are possible sources of human infection (3,13). Another route of infection, although less frequent, is inhalation of spores (13).
Who is at risk?
Little is known about the prevalence or importance of infection with Encephalitozoon spp. in immunocompetent individuals (6,7,13). Serological studies suggest that human exposure to microsporidia may be common but without clinical significance (15).
Although E. cuniculi is a rare cause of infection in human patients, microsporidiosis is considered an emerging, opportunistic infection in AIDS patients and other immunocompromised individuals (9,13), such as organ transplant recipients, young children, the elderly. Complications due to E. cuniculi infection have been reported in severely immunocompromised patients (2,3,8,10). Contact lens wearers are also at increased risk of clinical disease (2).
Disease in humans
Clinical symptoms in humans include fever, headache, nausea, vomiting, diarrhea, breathlessness and other respiratory signs, as well as weakness (13). Clinical reports of E. cuniculi infection have described a wide range of organ involvement, including peritonitis, hepatitis, granulomatous liver necrosis, renal failure, pneumonia, sinusitis, rhinitis, myalgia, otitis media, keratoconjunctivitis, cerebral and disseminated microsporidiosis, and seizure disorder (2,3,6,10,16).
Prevention and control
Avoid contact with the urine of infected or healthy rabbits, and always practice good sanitation when handling animals (12).
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- Kicia M, Wesolowska M, Kopacz Z, et al. Disseminated infection of Encephalitozoon cuniculi associated with osteolysis of hip periprosthetic tissue. Clin Infect Dis. 2018;67(8):1228-1234. doi: 10.1093/cid/ciy256. PMID: 29659738.
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