Sources of human microsporidial infection remain speculative, but possible
animal reservoirs are emerging. Of the common human microsporidial infectio
ns, Enterocytozoon bieneusi has now been identified in non-human primates,
pigs, dogs and a cat; Encephalitozoon intestinalis in dogs, pigs, cows, goa
ts and donkeys and Encephalitozoon hellem in budgerigars and parrots. Evide
nce of species heterogeneity is also emerging suggesting that some animal i
solates mal, be distinctive. Further molecular epidemiological studies need
to be undertaken to clarify which animal genotypes can also infect humans.
Some of the less common microsporidial infections found in humans, such as
those involving Pleistophora-like species, may be the result of infrequent
accidental exposure (for example, inadequately cooked infected fish muscle
) and establishment, particularly if the individual is severely immunocompr
omised. Curr Opin Infect Dis 12:473-480. (C) 1999 Lippincott Williams & Wil
kins.