Protozoa are among the most important pathogens that can
cause infections in immunocompromised hosts. These microorganisms particularly
infect individuals with impaired cellular immunity, such as those with hematological
neoplasias, renal or heart transplant patients, patients using high doses
of corticosteroids, and patients with acquired immunodeficiency syndrome.
The protozoa that most frequently cause disease in immunocompromised patients
; the first two species cause severe acute meningoencephalitis and acute
sp. causes mucocutaneous or visceral disease, and
can lead to chronic diarrhea with hepatobiliary involvement. Various serological,
parasitological, histological and molecular methods for the diagnosis of
these infections are currently available and early institution of specific
therapy for each of these organisms is a basic measure to reduce the morbidity
and mortality associated with these infections.