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Blood (Intracellular) and Other Tissue Protozoa 83

of both. A microscopic examination for evidence of the LEISHMANIA MEXICANA
oval amastigote forms in tissue macrophages are direct COMPLEX (NEW WORLD
evidence of infection. For the various species of Leishma-
nia, isoenzyme studies and molecular diagnostic proce- CUTANEOUS LEISHMANIASIS)
dures may be utilized. A skin test called the Montenegro
New World leishmaniasis is found from southern Texas
(Leishmania) skin test is used to screen large numbers
through Mexico and Central and South America and
of individuals in endemic areas and is a delayed hyper-
is disseminated by a number of animal vectors. The
sensitivity test similar to that of the PPD for tuberculosis.
species diagnosed in these regions are: Leishmania
The Centers for Disease Control and Prevention also has
Mexicana, Leishmania pifanoi, Leishmania pifanoi,
a noncommercial serologic test not in general use that in-
Leishmania amazonensis, Leishmania venezuelensis,
cludes an indirect fluorescent antibody assay.
and Leishmania garnhami. The treatment and pre-
vention of these strains are similar to the organisms re-
Treatment and Prevention sponsible for Old World leishmaniasis. Morphological
forms are similar for both Old World and New World
Antimonial medications are often effective by intramus-
leishmaniasis as well as the transmission, pathogenesis,
cular injections for 10 days. Resistant infections may
and identification of the two types with a few notable
require repeated treatments. Amphotericin B and an
exceptions. The following tables list the basic data for
antifungal preparation called ketoconazole may provide
differentiation of each species of the various types of
effective treatment if patients suffer from prolonged
Leishmania (see Tables 4-2, 4-3, 4-4).
infections.
Prevention is accomplished through controlling
sand fly populations by destroying the vectors and by MALARIA
controlling rodents in endemic areas where the sand flies
may also find hosts. In addition, individuals infected with Malaria is one of the most common infectious diseases
Leishmania organisms should be quickly treated to pre- in the world, and its history extends into ancient history,
vent further transmission to other humans from insects no doubt impacting the migration of humans about the
that bite the victim and then transmit the organisms to world. The disease in humans is caused by four spe-
others, leading to a significant and rapid increase in the cies of the genus Plasmodium: P. falciparum, P. vivax,
number of cases of the disease. P. ovale, and P. malariae. Ring-form trophozoites in

TABLE 4-2 Mexican Leishmaniasis Complex—New World

GEOGRAPHICAL
ORGANISM FORM OF DISEASE VECTOR REGION RESERVOIR HOSTS
L. mexicana Diffuse cutaneous form Lutzomyia Belize, Guatemala, Opossums, forest rodents,
sand fly Yucatán Peninsula domestic dogs and cats
L. pifanoi Diffuse cutaneous form Lutzomyia Amazon River basin, Opossums, forest rodents,
sand fly isolated parts—Brazil, domestic dogs and cats
Venezuela
L. amazonensis Both cutaneous and Lutzomyia Amazon basin of Brazil Opossums, forest rodents,
diffuse cutaneous forms sand fly domestic dogs and cats
L. venezuelensis Cutaneous form Lutzomyia Remote forested Opossums, forest rodents,
sand fly regions—Venezuela domestic dogs and cats
L. garnhami Cutaneous form Lutzomyia Venezuelan Andean Opossums, forest rodents,
sand fly region domestic dogs and cats