Page 120 - AIDSBK23C

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leishmaniasis in peripheral blood may be useful and may also help to determine relapse
following treatment.[514] Histologically, the amastigotes appear as round to oval 2 to 5 micron
basophilic structures in the cytoplasm of macrophages with H&E stain. The organisms are
positive with Giemsa stain. In some cases, the organisms can appear extracellularly in
connective tissues or in vascular lumens. The macrophages may demonstrate organisms with a
“double dot” appearance due to staining of both amastigote nucleus and kinetoplast with
hematoxylin-eosin and Giemsa stains. Accompanying inflammation is typically minimal. By
electron microscopy, the amastigotes are characterized by the presence within a cell membrane
of a kinetoplast, large vacuole, microtubules, flagellar root, and eccentric nucleus with clumped
chromatin.[515]
The mononuclear phagocyte system, including liver, spleen, lymph nodes, and bone
marrow, are most often involved, but the gastrointestinal tract and respiratory tract may also be
affected in immunocompromised hosts, and unusual sites of involvement such as the heart, skin,
and adrenal may occur, particularly when the CD4 count is less than 50/µL. In the small bowel,
biopsies will demonstrate mucosal infiltration by macrophages that lead to shortening and
widening of villi. Liver biopsies will reveal the amastigotes in Kupffer cells, macrophages, or
vessels accompanied by a portal chronic inflammatory cell infiltrate. Bone marrow biopsies
show organisms within macrophages or in vessels. Skin biopsies show the amastigotes in dermal
macrophages, connective tissue, or vessels.[516]
Leishmaniasis in persons with HIV infection in endemic areas outside of Southern
Europe, including cases caused by L tropica and L braziliensis, is likely more prevalent. Up to
30% of patients with visceral leishmaniasis in some parts of Ethiopia may also be HIV-infected.
India and Brazil also have experienced increasing prevalence of leishmaniasis with HIV.[517]
Visceral leishmaniasis in Brazil, with infection by L chagasi, occurs at a rate 10 to 100
times greater in HIV-infected persons. The most common findings include splenomegaly,
weight loss, cough, fever, asthenia, and diarrhea. The viral load was usually >50,000 copies/mL.
Most patients recovered with therapy.[518]

BRUCELLOSIS.-- Contact with animals or animal products such as unpasteurized milk
may transmit Brucella organisms, which are small non-motile coccobacillary gram negative
bacteria. Brucella mainly infects tissues of the mononuclear phagocyte system. Most infected
persons are seropositive but asymptomatic. Symptomatic disease may become more aggressive
in immunocompromised persons. Bone marrow involvement can lead to cytopenias, mainly
anemia and leukopenia. Persons with HIV infection in endemic areas for brucellosis are more
likely to be seropositive. Though they are no more likely to be anemic than HIV positive
persons seronegative for brucellosis, they are more likely to have leukopenia.[519] The
serologic evidence for Brucella infection along with HIV is more likely to occur in endemic
areas for brucellosis, but symptomatic infection (0.1%) is still infrequent.[520]

CHAGAS' DISEASE.-- In endemic locations for Chagas disease, caused by the
protozoan parasite Trypanosoma cruzi spread via the reduviid bug. Patients with AIDS may also
be at risk for infection with T cruzi or reactivation of remote T cruzi infections. Such infections
associated with AIDS are marked in most cases by a severe diffuse or multifocal
meningoencephalitis that often presents with clinical features resembling an intracranial
neoplasm. The diagnosis can be confirmed by lumbar puncture or intracranial biopsy.
Microscopic examination shows multifocal, extensive, hemorrhagic necrotic encephalitis, with