[Experimental cutaneous leishmaniasis. III. Histopathological aspects of the developmental behavior of the cutaneous lesion induced in Cebus apella (Primates: Cebidae) by Leishmania (Viannia) lainsoni, L. (V.) braziliensis and L. (Leishmania) amazonensis]

We have studied the histopathological aspects related to the evolution of cutaneous lesions experimentally produced in the monkey Cebus apella (Primates: Cebidae) by Leishmania (V.) lainsoni, L. (V.) braziliensis and L. (L.) amazonensis. Microscopical examination of a series of biopsies obtained from these animals showed the kinetics of the cutaneous lesions regarding three species of Leishmania inoculated, as follows: 1) an initial non-specific chronic inflammatory infiltrate; 2) macrophagic nodules; 3) necrosis of parasitized phagocytic cells; 4) epitheliode granuloma; 5) absorption of the necrotic area (sometimes forming "foreign-body granuloma"); 6) a non-specific residual inflammatory infiltration; and 7) cicatrization. These pathological processes are, of course, responsible for both development and resolution of the leishmaniotic lesion. We also discuss some immunopathological mechanisms probably related with the sequential events, and that could be also responsible for the different clinical aspects found in man.

Production of a specific monoclonal antibody for the identification of Leishmania (Leishmania) venezuelensis

We describe a monoclonal antibody (Mab), V1, specific for Leishmania (Leishmania) venezuelensis. Previous Mabs and DNA probes were not specific for this parasite, and so it was not directly possible to distinguish L. (L.) venezuelensis from other Leishmania species. Immunofluorescent staining using Mabs may be performed on very few parasites, whereas other methods of identification usually require far greater numbers of organisms. L. (L.) venezuelensis frequently dies on subculture. Mab V1 can be used to identify this parasite by indirect immunofluorescence and radioimmunoassay.

Coccidia of Brazilian mammals: Eimeria corticulata n. sp. (Apicomplexa: Eimeriidae) from the anteater Tamandua tetradactyla (Xenarthra: Myrmecophagidae) and Eimeria zygodontomyis n. sp. from the cane mouse Zygodontomys lasiurus (Rodentia: Cricetidae)

Feces from a specimen of Tamandua tetradactyla (Linn.) from Portel, Pará State, north Brazil, contained two different coccidial oocysts; one identified as Eimeria tamanduae Lainson 1968, and the other as a new species, described here as Eimeria corticulata n. sp. Oocysts of E. corticulata are ellipsoidal, 37.4 x 30.4 (31.2-43.7 x 23.7-35.0) microns, shape index (length/width) 1.2 (1.0-1.5). Oocyst wall 2.5-3.7 microns thick and composed of two layers; an outer thick, brown-yellow one with radial striations, and a thin inner smooth one: no visible micropyle. Oocyst residuum a large globule of about 10.7 x 10.3 microns, usually accompanied by a number of smaller attached globules. Sporocysts ellipsoidal, 21.0 x 11.0 (20.0-22.5 x 10.0-12.5) microns, with a conspicuous Stieda body; shape index 1.9 (1.6-2.2). Sporocyst residuum a small number of scattered granules: sporozoites 18.7 x 5.0 microns, with a large posterior refractile body. Eimeria zygodontomyis n. sp. is described in feces from Zygodontomys lasiurus (Lund) from the Serra dos Carajás, Pará. Oocysts ellipsoidal to cylindrical, 16.5 x 12.0 (13.7-18.7 x 11.2-12.3) microns, shape index 1.4 (1.2-1.5). Wall colorless, smooth, single-layered and about 0.6 micron thick: no micropyle. No oocyst residuum, but a polar granule of about 1.8 x 1.0 microns is sometimes present. Sporocysts ellipsoidal, 8.4 x 5.5 (7.5-8.7 x 5.0-6.2) microns, shape index 1.5 (1.4-1.7), with a thin colorless wall and a delicate Stieda body. Sporozoites enclose a compact residuum of about 2.5 x 3.7 microns.

[Experimental skin leishmaniasis: II--course of the infection in the Cebus apella primate (Cebidae) caused by Leishmania (V.) braziliensis and L. (L.) amazonensis]

As a means of assessing the usefulness of the monkey Cebus apella as an experimental model for the study of cutaneous leishmaniasis, 5 of these animals were inoculated intradermally at 8 sites along the tail with 3 X 10(6) promastigotes of L. (V.) braziliensis, while a further 5 monkeys received similar inoculations with 3 X 10(6) promastigotes of L. (L.) amazonensis. Following the inoculations, weekly examinations and monthly biopsies showed evolution of resulting skin lesions to be as follows: a) L. (V.) braziliensis: lesions were first visible 15-20 days post-inoculation (p.i), and at 30 days they were clearly of an erythematous-papular nature, which assumed a nodular form at 60 days; after 3 months a spontaneous ulceration of these lesions was noted and, at 4 months, the initiation of healing. In one animal total healing was apparent 5 months p.i; in two others at 6 months, in another monkey after 7 months, and in the last animal at 10 months p.i. Amastigotes were demonstrated in smears from the lesions of all monkeys up to 90 days p.i; up to 120 days in two animals, and at 180 days p.i. in the monkey which showed resolution of the lesions after 10 months. b) L. (L.) amazonensis lesions were first apparent after 20 days p.i; at 30 days they were of an erythematous-papular nature, developing into nodules at 60 days. From the third month of infection onwards, however, the lesions diminished rapidly and, at 90 days p.i. amastigotes were no longer detectable in the skin.(ABSTRACT TRUNCATED AT 250 WORDS)

[Sensitivity of the culture of circulating leukocytes in the detection of Leishmania in the peripheral blood of patients with tegumentary leishmaniasis]

The possible presence of Leishmania in the peripheral blood of 60 patients with American cutaneous leishmaniasis was investigated by the culture of circulating leucocytes. Patients were selected with a variety of clinical forms of the disease and in different evolutionary stages of infection. Biopsies of skin and/or mucosal lesions were made in order to isolate the parasites, which were identified using monoclonal antibodies. 40 isolations were obtained, including 5 of Leishmania (Viannia) braziliensis, 3 L. (V.) guyanesis, 1 L. (V.) lainsoni, 13 L. (Leishmania) amazonensis and 18 which could only be identified as parasites of the braziliensis complex. Cultures of circulanting leucocytes were consistently negative, and the authors conclude that this method is of little use in diagnosis of cutaneous or mucocutaneous leishmaniasis.

[Experimental cutaneous leishmaniasis: I--on the susceptibility of the primate Cebus apella (Cebidae) to the infection caused by Leishmania (Viannia) lainsoni Silveira, Shaw and Ishikawa, 1987]

The susceptibility of the monkey Cebus apella (Cebidae) to experimental infection by Leishmania (Viannia) lainsoni has been investigated. For this purpose, five young monkeys, 2 males and 3 females, were intradermally, inoculated, in eight different places along the dorsal surface of the tail with 3 x 10(6) promastigotes of the parasite (MHOM/BR/81/M6426, Benevides, Pará), from stationary phase culture in Difco B45 medium. After inoculations, infection in the monkeys was indicated by the presence of amastigotes in the skin lesions produced in these animals at the points of inoculation, confirming the susceptibility of the monkey Cebus apella to experimental infection by Leishmania lainsoni, with an infection period of four months. This represents a suitable period for testing antileishmanial drugs or studying the pathogenesis of the disease caused by this parasite.

Leishmania (Viannia) naiffi sp. n., a parasite of the armadillo, Dasypus novemcinctus (L.) in Amazonian Brazil

A new leishmanial parasite, Leishmania (Viannia) naiffi sp. n., is described from the nine-banded armadillo, Dasypus novemcinctus (Edentata: Dasypodidae), from Para State, north Brazil. The parasite grows luxuriantly in Diffco blood-agar medium (B47), but poorly in the skin of intradermally inoculated hamsters. A comparison of isoenzyme profiles by starch gel electrophoresis separates the parasite from L. (V) braziliensis and L. (V.) guyanensis by the enzymes ASAT, ALAT, PGM, GPI, G6PD, PEP, MPI and GD, and from Leishmania (Leishmania) chagasi, L. (L.) amazonensis and L. (L.) deanei by ASAT, ALAT, PGM, GPI, MPI, G6PD, MDH, PEP and ACON. Finally, L. (V.) naiffi is serologically differentiated from L. (V.) braziliensis, L. (V.) guyanensis and L. (V.) panamensis on monoclonal antibodies specific for these parasites.

Leishmania (Viannia) shawi sp. n., a parasite of monkeys, sloths and procyonids in Amazonian Brazil

Leishmania (Viannia) shawi sp. n., is described from the monkeys Cebus apella and Chiropotes satanus, the sloths Choloepus didactylus and Bradypus tridactylus, the procyonid Nasua nasua, and the phlebotomine sandfly Lutzomyia whitmani, all from primary forest in the State of Pará, north Brazil. L. (V.) shawi is variably distinguished from all other known species within the subgenus Viannia by a combination of biological, biochemical and serological characters, as revealed by studies on morphology, isoenzyme profiles, kDNA buoyant densities and monoclonal antibodies.

Ecological interactions in the transmission of the leishmaniases

Epidemiological studies on the leishmaniases are disclosing a multiplicity of Leishmania species infecting a wide range of wild mammalian hosts, from marsupials to monkeys. In the primitive, silvatic habitat these parasites are transmitted by an equally wide variety of phlebotomine sandfly species (Diptera: Psychodidae: Phlebotominae). Transmission is not haphazard, however, and available evidence points to the existence of environmental barriers that normally limit the different Leishmania species to specific sandfly vectors, transmitting to certain mammalian species, within distinct ecotopes. In this situation, humans may become infected by a variety of leishmanial parasites when intruding into the different enzootics, if the sandfly vectors are anthropophilic. Many are not, however, and their parasites rarely, if ever, make contact with the human host. Natural or man-made ecological changes may result in modification of the epidemiological pattern of leishmaniasis, leading to either a reduction or an increase in the human disease.

Observations on the development of Leishmania (L.) chagasi Cunha and Chagas in the midgut of the sandfly vector Lutzomyia longipalpis (Lutz and Neiva)

Previous observations have shown that forms of Leishmania, infective to hamsters, are present in the midgut of experimentally infected sandflies from 15-221 hours after the infective bloodmeal. In a continuation of these studies, stained smears of the midgut contents of Lutzomyia longipalpis infected with Leishmania (L.) chagasi, made at intervals between 15-120 hours, revealed two lines of parasite development. One of these is the direct transformation of small, non-dividing amastigotes into very small promastigotes, which are considered to represent the "infective" or "metacyclic" flagellates involved in subsequent transmission of the parasite. The other stems from enlarged, highly vacuolated amastigotes which undergo at least two divisions before giving rise to large, elongate and non-dividing promastigotes. These are thought to represent the non-infective forms of the parasite seen in in vitro cultures, and their function remains speculative.

Infective stages of Leishmania in the sandfly vector and some observations on the mechanism of transmission

Infective stages of Leishmania (Leishmania) amazonensis, capable of producing amastigote infections in hamster skin, were shown to be present in the experimentally infected sandfly vector Lutzomyia flaviscutellata 15, 25, 40, 49, 70, 96 and 120 hours after the flies had received their infective blood-meal. Similarly, infective stages of Leishmania (L.) chagasi were demonstrated in the experimentally infected vector Lu. longipalpis examined 38, 50, 63, 87, 110, 135, 171 and 221 hours following the infective blood-meal, by the intraperitoneal inoculation of the flagellates into hamsters. The question of whether or not transmission by the bite of the sandfly is dependent on the presence of "metacyclic" promastigotes in the mouthparts of the vector is discussed.

The transmission of suprapylarian leishmania by the bite of experimentally infected sand flies (Diptera: Psychodidae)

Lutzomyia furcata transmitted Leishmania chagasi to a hamster 10 days after being experimentally fed on an infected spleen. An individual female Psychodopygus carrerai carrerai that had fed on a hamster lesion caused by Leishmania mexicana amazonensis transmitted this parasite 6 days later to another hamster. Transmission electron microscopy of this fly's head revealed a small number of degenerate promastigotes in the foregut, but only a few were attached.