What is it?
E.cuniculi is a tiny single celled organism called a protozoon, which has to live inside a host cell to survive (an obligate intracellular parasite). It belongs to the phylum Microspora. These are spore-forming parasites with a wide host distribution. Recent research has indicated that they may be more closely related to fungi than to protozoa (Wasson and Peper, 2000), which means that novel antifungal drugs may be of use in treating this disease. Microsporidia contain a unique internal structure called the polar filament, which plays an important role in infection of the host cell.
E.cuniculi primarily infects rabbits and is a significant cause of disease. It is also important to rabbit owners since it is potentially zoonotic (can spread to humans) and has been associated with infections in immunocompromised people. Infection has been diagnosed in rabbits in Europe, Africa, America and Australia. In the United Kingdom this parasite is frequently encountered in laboratory rabbits (Gannon, 1980), but is thought to be rare in the wild rabbit population (Cox and Ross, 1980). It has been diagnosed in pet rabbits (Harcourt-Brown and Holloway, 2003) and a recent study has shown a 52% incidence of exposure in normal healthy domestic rabbits (Keeble and Shaw, in press).
Background
The first mammalian infections were described in rabbits in the 1920's (Wright and Craighead, 1922) and the infection was recognised in humans in the 1950's, with increasing reports during the 1980's related to the AIDS pandemic. Microsporidia are now also thought to be a cause of diarrhoea in children and travellers (Hollister and others, 1991). E.cuniculi may also be found in other mammal species, including rodents, guinea pigs, foxes, monkeys, cats, dogs, sheep, goats, pigs, llamas and snakes (Shadduck and others, 1979, Pang and Shadduck, 1985, Illanes and others, 1993, Lobo and others, 2003).
Three strains of E.cuniculi have been identified (Didier and others, 1995). Strain I is found in rabbits ('rabbit strain') and has been isolated from humans in Switzerland (Deplazes and others, 1996). Strain II is found in rodents ('rodent strain') and has so far not been seen in people. Strain III occurs in dogs ('dog strain') and has been seen in immunocompromised humans in the Unites States (Didier and others, 2000) and one case in the United Kingdom (Hollister and others, 1996). In the human infections in Switzerland there was no history of recent contact with rabbits. E.cuniculi strains from humans can infect rabbits (Mathis and others, 1997) and have been shown to be the same as those found in rabbits. It is likely that E. cuniculi infections in rabbits pose a zoonotic risk to immunocompromised humans. Close contact between owners and susceptible pet species could lead to an increase in human exposure to the parasite. Infection in humans is thought to be from the environment following contamination with spores from other infected humans or animals.
Lifecycle and Transmission
Once a rabbit has the disease it passes infectious spores in its urine. Transmission to another rabbit occurs by eating these spores in urine contaminated food and water. The unborn kits may also be infected across the placenta during pregnancy. Inhalation of spores has been shown to cause infection, although these last two routes are thought to occur less frequently (Cox and others, 1979). Once the parasite has entered the rabbit's body it is carried in the blood circulation to target organs such as the liver, kidney and central nervous system (brain and spinal cord). It then infects the cells of these organs by ejecting the polar filament, which injects the spore into the cell. Once inside the host cell the parasite multiples causing the cell to enlarge and eventually rupture, which releases spores. These in turn infect nearby cells and pass into the blood to other organs. The life cycle lasts three to five weeks. Rupture of the host cell causes inflammation, primarily in the liver, kidney, brain and spinal cord and results in clinical signs in the rabbit.
Taken from the BRC website
Was looking to see if the E.c parasite could a guinea pig