Natural Leishmania (Viannia) spp. infections in phlebotomine sand flies (Diptera: Psychodidae) from the Brazilian Amazon region reveal new putative transmission cycles of American cutaneous leishmaniasis

In Amazonian Brazil the etiological agents of American cutaneous leishmaniasis (ACL) belong to at least seven Leishmania species but little is known about the putative phlebotomine sand fly vectors in different biomes. In 2002–2003 a survey of the phlebotomine fauna was undertaken in the “Floresta Nacional do Tapajós”, Belterra municipality, in the lower Amazon region, western Pará State, Brazil, where we recently confirmed the presence of a putative hybrid parasite, L. (V.) guyanensis × L. (V.) shawi shawi. Sand flies were collected from Centers for Disease Control (CDC) light traps, Shannon traps and by aspiration on tree bases. Females were dissected and attempts to isolate any flagellate infections were made by inoculating homogenized midguts into Difco B⁴⁵ medium. Isolates were characterized by monoclonal antibodies and isoenzyme electrophoresis. A total of 9,704 sand flies, belonging to 68 species or subspecies, were collected. Infections were found in the following sand flies: L. (V.) naiffi with Psychodopygus hirsutus hirsutus (1) and Ps. davisi (2); and L. (V.) shawi shawi with Nyssomyia whitmani (3) and Lutzomyia gomezi (1). These results provide strong evidence of new putative transmission cycles for L. (V.) naiffi and L. (V.) s. shawi.

Phenotypic characterization of Leishmania spp. causing cutaneous leishmaniasis in the lower Amazon region, western Pará state, Brazil, reveals a putative hybrid parasite, Leishmania (Viannia) guyanensis × Leishmania (Viannia) shawi shawi

We phenotypically characterized 43 leishmanial parasites from cutaneous leishmaniasis by isoenzyme electrophoresis and the indirect immunofluorescence antibody test (23 McAbs). Identifications revealed 11 (25.6%) strains of Leishmania (V.) braziliensis, 4 (9.3%) of L. (V.) shawi shawi, 7 (16.3%) of L. (V.) shawi santarensis, 6 (13.9%) of L. (V.) guyanensis and L. (V.) lainsoni, 2 (4.7%) of L. (L.) amazonensis, and 7 (16.3%) of a putative hybrid parasite, L. (V.) guyanensis/L. (V.) shawi shawi. McAbs detected three different serodemes of L. (V.) braziliensis: I-7, II-1, and III-3 strains. Among the strains of L. (V.) shawi we identified two populations: one (7 strains) expressing the B19 epitope that was previously considered to be species-specific for L. (V.) guyanensis. We have given this population sub-specific rank, naming it L. (V.) s. santarensis. The other one (4 strains) did not express the B19 epitope like the L. (V.) shawi reference strain, which we now designate as L. (V.) s. shawi. For the first time in the eastern Brazilian Amazon we register a putative hybrid parasite (7 strains), L. (V.) guyanensis/L. (V.) s. shawi, characterized by a new 6PGDH three-band profile at the level of L. (V.) guyanensis. Its PGM profile, however, was very similar to that of L. (V.) s. shawi. These results suggest that the lower Amazon region – western Pará state, Brazil, represents a biome where L. (V.) guyanensis and L. (V.) s. shawi exchange genetic information.

Canine visceral leishmaniasis due to Leishmania (L.) infantum chagasi in Amazonian Brazil: comparison of the parasite density from the skin, lymph node and visceral tissues between symptomatic and asymptomatic, seropositive dogs

Canine visceral leishmaniasis (CVL) is recognizable by characteristic signs of disease and is highly lethal. The infection, however, may be quite inapparent in some seropositive dogs, and this has raised the polemic question as to whether or not such animals can be a source of infection for Lutzomyia longipalpis, the vector of American visceral leishmaniasis (AVL). In this study we have examined 51 dogs with acute CVL from an AVL area in Pará State, northern Brazil, and compared the parasite density, amastigotes of Leishmania (L.) infantum chagasi, in the skin, lymph node and viscera of symptomatic with that of nine asymptomatic but seropositive dogs (IFAT-IgG). Post-mortem biopsy fragments of these tissues were processed by immunohistochemistry, using a polyclonal antibody against Leishmania sp. The X² and Mann Whitney tests were used to evaluate the means of infected macrophage density (p < 0.05). There was no difference (p > 0.05) in the skin (10.7/mm² x 15.5/mm²) and lymph node (6.3/mm² x 8.3/mm²), between asymptomatic and symptomatic dogs, respectively. It was higher (p < 0.05), however, in the viscera of symptomatic (5.3/mm²) than it was in asymptomatic (1.4/mm²) dogs. These results strongly suggest that asymptomatic or symptomatic L. (L.) i. chagasi-infected dogs can serve as a source of infection, principally considering the highest (p < 0.05) parasite density from skin (10.7/mm² x 15.5/mm²), the place where the vetor L. longipalpis takes its blood meal, compared with those from lymph node (6.3/mm² x 8.3/mm²) and viscera (1.4/mm²x 5.3/mm²).

Plasmodium carmelinoi n. sp. (Haemosporida: Plasmodiidae) of the lizard Ameiva ameiva (Squamata: Teiidae) in Amazonian Brazil

Plasmodium carmelinoi n. sp. is described in the teiid lizard Ameiva ameiva from north Brazil. Following entry of the merozoites into the erythrocyte, the young, uninucleated trophozoites are at first tear-shaped and already possess a large vacuole: with growth, they may assume an irregular shape, but eventually become spherical or broadly ovoid. The vacuole reduces the cytoplasm of the parasite to a narrow peripheral band in which nuclear division produces a schizont with 8-12 nuclei. At first the dark, brownish-black pigment granules are restricted to this rim of cytoplasm but latterly become conspicuously concentrated within the vacuole. The mature schizonts are spherical to ovoid and predominantly polar in their position in the erythrocyte. They average 5.4 x 4,9 microm (4.4 x 4.4 - 6.6 x 5,9 microm), shape index 1.1, n = 50: 8-12 merozoites are produced and measure approximately 2.0 x 1,0 microm. Mature gametocytes are also polar in position, and spherical to subspherical. The macrogametocytes measure 5.7 x 5,2 microm (4.4 x 4.0- 5.9 x 5,1 microm), shape index 1.1, n = 50 and, following staining by Giemsa's method, possess a compact, pink-staining nucleus and a clear blue, faintly stained cytoplasm. Microgametocytes are slightly larger, 6.0 x 5,0 microm (5.2 x 4.4 - 6.2 x 5,2 microm), shape index 1.2, n = 45. They stain an over-all pink colour due to the dispersed nuclear chromatin. The vacuoles in both the macro- and microgametocytes are considerably smaller than those of the schizonts and of ovoid or spindle shape: they contain most of the pigment granules. The sex ratio, as seen in an inicial intense infection, was 1 male to 2.2 females. Prevalence of infection was low (5%) but, due to the very low parasitaemia which may result in a failure to detect parasites, it is probably higher than this.

Immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis in American cutaneous leishmaniasis

The immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis were reviewed in the light of more recent features found in the clinical and immunopathological spectrum of American cutaneous leishmaniasis. It was shown a dichotomy in the interaction between these Leishmania species and human T-cell immune response; while L. (V.) braziliensis shows a clear tendency to lead infection from the localized cutaneous leishmaniasis (LCL), a moderate T-cell hypersensitivity form at the centre of the spectrum, toward to the mucocutaneous leishmaniasis (MCL) at the T-cell hypersensitivity pole and with a prominent Th1-type immune response, L. (L.) amazonensis shows an opposite tendency, leading infection to the anergic diffuse cutaneous leishmaniasis (ADCL) at the T-cell hyposensitivity pole and with a marked Th2-type immune response. Between the central LCL and the two polar MCL and ADCL, the infection can present an intermediary form known as borderline disseminated cutaneous leishmaniasis, characterized by an incomplete inhibition of T-cell hypersensitivity but with a evident supremacy of Th1 over Th2 immune response (Th1 > or = Th2). These are probably the main immunopathogenic competences of L. (V.) braziliensis and L. (L.) amazonensis regarding the immune response dichotomy that modulates human infection outcome by these Leishmania parasites.

A cross-sectional study on the clinical and immunological spectrum of human Leishmania (L.) infantum chagasi infection in the Brazilian Amazon region

The objectives of this study were to identify individuals with symptomatic and/or asymptomatic infection due to Leishmania (L.) infantum chagasi; to study the two types of infection, both clinically and immunologically, and to determine the prevalence rate of infection at the beginning of the study. This was a cross-sectional study with a cohort of 946 individuals, of both genders, from the age of 1 year, living in the municipality of Barcarena, PA, Brazil, an area endemic for American visceral leishmaniasis (AVL). The leishmanin skin test (LST) and the indirect fluorescent test (IFAT), were used for the diagnosis of infection. One hundred and twenty cases of infection were diagnosed, with a prevalence rate of 12.6%; eight cases showed high seroreactivity (1280-10240, IgG) in IFAT and no LST reaction; four of these cases were typical AVL and four had subclinical oligosymptomatic infection. Using two immunological methods with a clinical examination of the infected individuals enabled the identification of five clinical-immunological profiles which may promote a better understanding of the interaction between L. (L.) i. chagasi and the human immune response: asymptomatic infection (AI) 73.4%; subclinical resistant infection (SRI) 15%; subclinical oligosymptomatic infection (SOI) 3%; symptomatic infection (AVL) 3% and indeterminate initial infection (III) 5%.

New species of Eimeria and Isospora (Protozoa: Eimeriidae) in Geochelone spp. (Chelonia: Testudinidae) from Amazonian Brazil

Tetrasporocystic, dizoic oocysts of reptiles have been separated by some authors into the genera Eimeria, Choleoeimeria and Acroeimeria (Protozoa: Eimeriidae), based on the site and mode of development of their endogenous stages. The majority of Eimeria species have been, and still are, however, described on oocyst morphology alone. Four different oocysts with this basic morphology were encountered in the faeces of Brazilian tortoises, Geochelone carbonaria Spix, 1824 and are assigned to the genus Eimeria, with the view that they can readily be transferred to the genus Choleoeimeria or Acroeimeria if this is indicated by a future examination of their endogenous development. A morphological comparison distinguishes the oocysts from those of Eimeria spp., previously described in chelonids of the family Testudinidae, and the names E. amazonensis, E. carbonaria, E. carajasensis and E. wellcomei n. spp. are proposed. Coccidial infection appears to be common in G. carbonaria, with three of seven animals examined passing oocysts. Oocysts of Isospora rodriguesae n. sp. (Protozoa: Eimeriidae) are described in the faeces of Geochelone denticulata Linnaeus, 1766. They are morphologically very different from those of Isospora testudae, Davronov, 1985 in Testudo horsfieldi. Eimeria motelo Hůrková et al., 2000, previously described in Geochelone denticulata from Peru, is here recorded in the some chelonid from Amazonian Brazil.

A longitudinal study on the transmission dynamics of human Leishmania (Leishmania) infantum chagasi infection in Amazonian Brazil, with special reference to its prevalence and incidence

This was a longitudinal study carried out during a period over 2 years with a cohort of 946 individuals of both sexes, aged 1 year and older, from an endemic area of American visceral leishmaniasis (AVL) in Pará State, Brazil. The object was to analyze the transmission dynamics of human Leishmania (Leishmania) infantum chagasi infection based principally on the prevalence and incidence. For diagnosis of the infection, the indirect fluorescent antibody test (IFAT) and leishmanin skin test (LST) were performed with amastigote and promastigote antigens of the parasite, respectively. The prevalence by LST (11.2%) was higher (p < 0.0001) than that (3.4%) by IFAT, and the combined prevalence by both tests was 12.6%. The incidences by LST were also higher (p < 0.05) than those by IFAT at 6 (4.7% x 0.6%), 12 (4.7% x 2.7%), and 24 months (2.9% x 0.3%). Moreover, there were no differences (p > 0.05) between the combined incidences by both tests on the same point surveys, 5.2%, 6.3%, and 3.6%. During the study, 12 infected persons showed high IFAT IgG titers with no LST reactions: five children and two adults developed AVL (2,560-10,120), and two children and three adults developed subclinical oligosymptomatic infection (1280-2560). The combined tests diagnosed a total of 231 cases of infection leading to an accumulated prevalence of 24.4%.

Theileria electrophorin.sp., a parasite of the electric eel Electrophorus electricus (Osteichthyes: Cypriniformes: Gymnotidae) from Amazonian Brazil

The name Theileria electrophori n.sp. is proposed for a small parasite described in the erythrocytes of the electric eel, Electrophorus electricus, from Amazonian Brazil. Division of the organism in the erythrocyte produces only four bacilliform daughter cells which become scattered in the host cell, without a cruciform or rosette-shaped disposition. Exoerythrocytic meronts producing a large number of merozoites were encountered in Giemsa-stained impression smears of the internal organs, principally in the liver, and are presumably the source of the intraerythrocytic forms of the parasite. This developmental pattern is characteristic of piroplasms within the family Theileriidae, where the author considers the parasite of E. electricus to most appropriately belong. It effectively distinguishes the organism from the dactylosomatid parasites Babesiosoma Jakowska and Nigrelli, 1956 and Dactylosoma Labbé, 1894 also found in fishes. This appears to be the second report of Theileria Bettencourt, Franca and Borges, 1907 in a fish.

Lutzomyia (Nyssomyia) whitmani s.l . (Antunes & Coutinho, 1939)(Diptera: Psychodidae: Phlebotominae): geographical distribution and the epidemiology of American cutaneous leishmaniasis in Brazil Mini-review

The aim of the present study, in view of the widespread geographical distribution of Lutzomyia (Nyssomyia) whitmani s.l. in Brazil, in close association with the regions of transmission of Leishmania (Viannia) braziliensis and L. (V.) shawi, is to investigate the distribution of this sand fly species and American cutaneous leishmaniasis (ACL) in relationship to vegetation and landscape ecology throughout Brazil. Thematic maps were elaborated by the MapInfo programme, giving information on the spatial distribution of L. whitmani s.l., in accordance with types of vegetation and foci of ACL. With regards to the known areas of transmission of ACL in Brazil, it is notable that L. (N.) whitmani s.l. occurs in most of them, where it has been implicated as a possible vector of L. (V.) braziliensis. The presence of L. whitmani s.l. has been registered in 26 states, the one exception being Santa Catarina; in some states such as Roraima, Acre, Tocantins, and Mato Grosso do Sul this sand fly species has been recorded in a large number of municipalities. L. whitmani s.l. has been found in association with a variety of vegetation types, including the Amazonian forest, savanna ("campos cerrados"), and northeastern savanna ("caatingas nordestinas" or "savana estépica").

Observations on Eimeria species of Dasyprocta leporina (Linnaeus, 1758)(Rodentia: Dasyproctidae) from the state of Pará, North Brazil

Redescriptions are given of the mature oocysts of Eimeria aguti Carini 1935, E. cotiae Carini, 1935 and E. paraensis Carini, 1935, in the faeces of five specimens of the rodent Dasyprocta leporina (Rodentia: Dasyproctidae) from the state of Pará, North Brazil. New information is provided on the sporulation time of these parasites and the prepatent period in experimentally infected D. leporina. Some endogenous stages of E. cotiae are described in the epithelial cells of the ileum, and the absence of any oocysts in the gall-bladder contents of the infected animals indicates that the intestine is also the site of development of E. aguti and E. paraensis. Difficulties in separating E. cotiae and E. paraensis on morphology of the oocysts are discussed. The oocysts of both parasites share many structural features and have a wide size range. It is concluded that although it is at present best to maintain these names, the possibility exists that they were separately given to oocysts of smaller dimensions (E. cotiae) and larger dimensions (E. paraensis) of a single parasite. Location of an endogenous site of development for E. paraensis that is distinctly separate from that of E. cotiae might establish more definitely the separate specific status of the two parasites.

Eimeria lepidosirenis n.sp. (Apicomplexa:Eimeriidae) of the South American lungfish Lepidosiren paradoxa (Osteichthyes:Dipnoi) from Amazonian Brazil

The mature oocysts of Eimeria lepidosirenis n.sp. are described in faeces removed from the lower region of the intestine of a single specimen of the South American lungfish Lepidosiren paradoxa, from Belém, state of Pará, Amazonian Brazil. Oocysts with endogenous sporulation: spherical to slightly subspherical, 30.8 x 30.3 microm (28.1 x 25.9 -33.3 x 31.8), shape-index (ratio length/width) 1.0, n = 25. Oocyst wall a very thin, single layer approximately 0.74 microm thick, smooth, colourless, with no micropyle and rapidly breaking down to release the sporocysts. Oocyst residuum a bulky ovoid to spherical mass of approximately 20.0 x 15 microm, composed of fine granules and larger globules and enclosed by a very fine membrane: no polar bodies seen. Sporocysts 15.5 x 9.0 microm (14.5 x 8.0 16.0 x 9.0), shape index 1.7 (1.6-1.8), n = 30, ovoid, with one extremity rather pointed and with a very delicate Stieda body but no sub-Stieda body: sporocyst wall a single extremely thin layer with no valves. Sporocyst residuum a spherical to ovoid mass of approximately 5.0 x 4.0 microm, composed of fine granules and small globules and enclosed by a very fine membrane. Sporozoites strongly recurved at their ends and apparently with only a single refractile body. Site of development in the host uncertain: no evidence of endogenous stages was found in fresh scrapings and stained smears of the intestinal epithelium.

Parasites of the squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Amazonian Brasil, with particular reference to Eimeria damnosa n. sp. (Apicompiexa: Eimeriidae)

A description is given of the mature oocysts and endogenous stages of Eimeria damnosa n. sp. from the small intestine of the red squirrel, Sciurus spadiceus, from the State of Acre, north Brazil. Ten of 12 animals examined were infected. Oocysts ovoid to ellipsoidal, occasionally cylindrical but not with parallel sides, 30.2 x 20.0 microm (18.0 x 15.0-40.2 x 30.0), shape-index (ratio length/width) 1.5 (1.3-1.8), n = 40. Oocyst wall smooth, colourless, with no micropyle, apparently of a single layer measuring approximately 1.0-1.5 microm thick. No oocyst residuum, but approximately 50 % of the oocysts with a single spherical, ovoid or dumbbell-shaped polar body. Sporocysts pear-shaped, 15.0 x 8.0 microm (11.0 x 6.0-16.0 x 8.0), shape index 1.9 (1.8-2.0), n = 33. Stieda body, if it merits this name, appears only as a slight thickening of the sporocyst wall at the more pointed extremity. Endogenous stages intracytoplasmic in the epithelial cells of the duodenum and throughout the ileum, above the host cell nucleus. Sporulation frequently completed in the lumen of the intestine, but most oocysts mature outside the host at some time within 24 hours. Massive infections may result in extensive desquamation of the gut epithelium, and sometimes in the death of the animal. In addition to this coccidian, one squirrel showed abundant trophozoites of a Giardia sp., in the ileum. The liver of two others contained developing and mature meronts, producing large numbers of slender merozoites, and other cyst-like bodies containing a small number of large zoites (sporozoites?). No parasites were detected in the blood of any of the squirrels that could be associated with this unidentified protozoan. Histological sections of the ileum of one squirrel revealed a globidium-like parasite in the lamina propria: it contained a very large number of slender, curved zoites. Three animals were with a sheathed microfilaria in the peripheral blood and liver smears. Finally, a Trypanosoma cruzi-like trypanosome was isolated from the blood of one squirrel and a T. lewisi-like trypanosome from two others.

Ultrastructural study of the gametocytes and merogonic stages of Fallisia audaciosa (Haemosporina: Garniidae) that infect neutrophils of the lizard Plica umbra (Reptilia: Iguanidae)

Little is known regarding the ultrastructure of the genus Fallisia (Apicomplexa: Haemosporina: Garniidae). This report describes the fine structure of some developmental stages of Fallisia audaciosa that infect neutrophils in the peripheral blood of the Amazonian lizard Plica umbra (Reptilia: Iguanidae). The parasites lie within a parasitophorous vacuole and exhibit the basic structures of members of the Apicomplexa, such as the pellicle and the cytostome. Invaginations of the inner membrane complex were seen in the gametocytes and may be concerned with nutrition. The meronts were irregularly shaped before division, a feature unusual among members of the Apicomplexa. The unusual presence of a parasitic protozoan within neutrophils, in some way interfering with or modulating the microbicidal activity of such cells, is discussed.

Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review

An historical review is given of American visceral leishmaniasis (AVL), with particular reference to the eco-epidemiology of the disease in Brazil. Following the first records of AVL in this country, in 1934, the sandfly Lutzomyia longipalpis (Lutz and Neiva, 1912) was incriminated as the principal vector. It is now generally accepted, however, that there exist a number of cryptic species under the name of Lu. longipalpis s.l. and that variations in the quantity of the vasodilatory peptide maxadilan in the saliva of flies from different populations of Lu. longipalpis s.l., may account for the variable clinical manifestations of AVL seen in different geographic regions. Distribution of AVL has been shown to extend throughout most of South and Central America, with the domestic dog serving as the principal reservoir of infection for man. However, while one hypothesis suggests that the causative parasite is Leishmania infantum, imported from Europe with the Portuguese and Spanish colonists, the demonstration of a high rate of benign, inapparent infection in foxes in Amazonian Brazil raised an opposing suggestion that the parasite is indigenous to the Americas. Recent reports of similar infections in native marsupials, and possibly rodents, tend to support this view, particularly as Lu. longipalpis is primordially a silvatic sandfly. Although effective control measures in foci of the disease will diminish the number of canine and human infections, the presence of such an enzootic in a variety of native animals will render the total eradication of AVL unlikely.

The genus Cyclospora (Apicomplexa: Eimeriidae), with a description of Cyclospora schneideri n.sp. in the snake Anilius scytale scytale (Aniliidae) from Amazonian Brazil--a review

A review is made of the recorded species of the coccidian genus Cyclospora and major events leading up to the discovery of C. cayetanensis, which is responsible for serious outbreaks of diarrhoea in man and is one of the aetiological agents of "traveller's diarrhoea". Humans appear to be the specific hosts, with the entire life-cycle in the intestine: to date there is no convincing evidence that the disease is a zoonosis. A description is given of oocysts and endogenous stages of C. schneideri n.sp., in the snake Anilius scytale scytale. Sporulation is exogenous and completed after about one week at 24-26 degrees. Mature oocysts 19.8 x 16.6 (15.1 x 13.8-25.7 x 20.1), shape-index 1.2 (1.0-1.3): no oocyst residuum or polar bodies. Oocyst wall a single colourless, smooth layer with no micropyle: it is rapidly deformed or broken. Sporocysts 13.6 x 9.4 (11.3 x 8.3-15.1 x 9.9), shape-index 1.4 (1.2-1.5) with an inconspicuous Stieda body. Sporozoites 11-13 x 2.5-3. Endogenous stages are intracytoplasmic in the epithelial cells of the small intestine and with the characters of the Eimeriorina.

Further observations on clinical, histopathological, and immunological features of borderline disseminated cutaneous leishmaniasis caused by Leishmania (Leishmania) amazonensis

Leishmania (Leishmania) amazonensis has for some time been considered as the causative agent of two distinct forms of American cutaneous leishmaniasis (ACL): localized cutaneous leishmaniasis (LCL), and anergic diffuse cutaneous leishmaniasis (ADCL). Recently, a new intermediate form of disease, borderline disseminated cutaneous leishmaniasis (BDCL), was introduced into the clinical spectrum of ACL caused by this parasite, and in this paper we record the clinical, histopathological, and immunological features of eight more BDCL patients from Brazilian Amazonia, who acquired the disease in the Pará state, North Brazil. Seven of them had infections of one to two years' evolution and presented with primary skin lesions and the occurrence of metastases at periods varying from six to 12 months following appearance of the first lesion. Primary skin lesions ranged from 1-3 in number, and all had the aspect of an erythematous, infiltrated plaque, variously located on the head, arms or legs. There was lymphatic dissemination of infection, with lymph node enlargement in seven of the cases, and the delayed hypersensitivity skin-test (DTH) was negative in all eight patients prior to their treatment. After that, there was a conversion of DTH to positive in five cases re-examined. The major histopathological feature was a dermal mononuclear infiltration, with a predominance of heavily parasitized and vacuolated macrophages, together with lymphocytes and plasma cells. In one case, with similar histopathology, the patient had acquired his infection seven years previously and he presented with the largest number of disseminated cutaneous lesions. BDCL shows clinical and histopathological features which are different from those of both LCL and ADCL, and there is a good prognosis of cure which is generally not so in the case of frank ADCL.

Ultrastructural aspects of Fallisia effusa (Haemosporina: Garniidae) in thrombocytes of the lizard Neusticurus bicarinatus (Reptilia: Teiidae)

The fine structure of the different stages of the Fallisia effusa (Haemosporina: Garniidae), infecting the thrombocytes of the semi-aquatic Amazonian lizard Neusticurus bicarinatus (Reptilia: Teiidae) is described. Gametocytes, meronts, and merozoites of Fallisia effusa were found within a parasitophorous vacuole (PV). Multiple infections of micro- and macrogametocytes were observed. A circumferential coil of microtubules was seen in the cytoplasm of the infected host cell and this microtubule array was pronounced in cells harboring gametocytes. A deep invagination of the inner membrane complex of gametocytes may be involved in nutrition. The non-pigmented parasites underwent both merogony and gametogony in thrombocytes of the peripheral blood. No infection of the erythrocytes was observed. These observations confirm that Fallisia effusa displays characteristic features distinguishing it from other members of the Haemosporidian families, and that it has the ability to modulate microtubule assembly.

Hepatozoon cf. terzii (Sambon & Seligman, 1907) infection in the snake boa constrictor constrictor from north Brazil: transmission to the mosquito Culex quinquefasciatus and the lizard Tropidurus torquatus

Specimens of Hepatozoon-infected Boa constrictor constrictor were obtained from localities in Pará State, north Brazil. Gametocytes in erythrocytes of the peripheral blood measured 10 x 2.5-16.2 x 3.7 microns. They were similar to those described as Haemogregarina terzii by Sambon & Seligmann (1907) in B. c. constrictor, in that they did not distort the infected erythrocyte, and their dimensions approximated those given by Carini (1947). Lungs and liver of infected snakes contained actively dividing meronts of a single type, and cysts containing two to six cystozoites were also present in the liver. Our initial feeding of Culex quinquefasciatus on infected snakes consistently resulted in a heavy death-rate of the engorged mosquitoes, with only a few surviving till the 9th day post feeding. These contained numerous oocysts which were undivided or in early stages of division. A fifth and final experiment, however, provided a few mosquitoes surviving up to 21 days post infection (dpi), and these contained fully sporulated oocysts measuring 190-200 microns in diameter and containing over 60 sporocysts of 19-30 microns in diameter. The number of sporozoites in each sporocyst was estimated as approximately 50. The nature of the parasite's sporogonic cycle in the mosquito thus justifies inclusion of this haemogregarine in the genus Hepatozoon. Two wild-caught specimens of the lizard Tropidurus torquatus were fed with mosquitoes containing fully developed oocysts (21 dpi). When sacrificed, three months later, large numbers of dizoic, tetrazoic and hexazoic cysts were demonstrated in their livers. Cystozoites released from these cysts were shown to possess a conspicuous refractile body.

Blood and intestinal parasites of squirrels (Rodentia: Sciuridae) in Amazonian Brazil

We report the result of an examination for blood and intestinal protozoa in 12 specimens of the red squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Birroque, municipality of Placido de Castro, state of Acre, Brazil. No parasites were detected in thin, Giemsa-stained blood films of the animals, but culture of the blood of three in Difco B45 medium blood-agar slants gave rise to isolates of epimastigotes. Inoculation of one isolate into laboratory mice resulted in the appearance of Trypanosoma cruzi-like trypomastigotes in their peripheral blood, and the other two isolates gave rise to transient infections with a T. lewisi-like parasite in inoculated mice and hamsters. The failure of the latter parasite to develop in the triatomine bug Rhodnius robustus suggests that it is probably not T. rangeli. This appears to be the first record of a T. lewisi-like trypanosome in neotropical squirrels. Oocysts of an Eimeria sp., were detected in the faeces of 10 animals (83.3%). The parasite develops in the epithelial cells of the intestine, where it may cause severe damage and sometimes results in death of the animal. No oocysts were detected in bile.

Clinical and immunopathological spectrum of American cutaneous leishmaniasis with special reference to the disease in Amazonian Brazil: a review

The wide variety of Leishmania species responsible for human American cutaneous leishmaniasis combined with the immune mechanisms of the host results in a large spectrum of clinical, histopathological, and immunopathological manifestations. At the middle of this spectrum are the most frequent cases of localized cutaneous leishmaniasis (LCL) caused by members of the subgenera Leishmania and Viannia, which respond well to conventional therapy. The two pathogenicity extremes of the spectrum generally recognized are represented at the hypersensitivity pole by mucocutaneous leishmaniasis (MCL) and at the hyposensitivity pole by anergic diffuse cutaneous leishmaniasis (ADCL). Following the present study on the clinical, histopathological and immunopathological features of cutaneous leishmaniasis in Amazonian Brazil, we propose the use of the term "borderline disseminated cutaneous leishmaniasis" for the disseminated form of the disease, due to parasites of the subgenera Leishmania and Viannia, which might be regarded as intermediate between LCL and the extreme pathogenicity poles MCL and ADCL.

Blood monocyte alteration caused by a hematozoan infection in the lizard Ameiva ameiva (Reptilia: Teiidae)

Although hematozoa have been described from many different host species, little is known about the infection and its relationship to the physiology of the host. We studied a hematozoan, regarded as a species of Lainsonia Landau, 1973 (Lankestereliidae), which infects the monocytes of the lizard Ameiva ameiva. The infected animals show a huge monocytosis and morphological changes in the monocytes. Ultrastructurally, the parasite has an apical complex, dense bodies, electron lucent structures, plasma membrane projections and folding which may be involved with nutrition. The parasite occupies a parasitophorous vacuole (PV) exhibiting high electron density at its membrane. Mitochondria and the Golgi complex of the monocytes were concentrated around the PV, and the cytoplasm was totally occupied by a vimentin type of intermediate filament radiating from (or to) the cytosolic surface of the PV. Vimentin was identified by diameter measurement, immunofluorescence and immunoelectron microscopy. These observations indicate that this infection alters the physiological state of the host and suggest that this parasite has the ability to modify monocyte vimentin assembly.

Haematozoan parasites of the lizard Ameiva ameiva (Teiidae) from Amazonian Brazil: a preliminary note

Three different haematozoan parasites are described in the blood of the teiid lizard Ameiva ameiva Linn. from North Brazil: one in the monocytes and the other two in erythrocytes. The leucocytic parasite is probably a species of Lainsonia Landau, 1973 (Lankesterellidae) as suggested by the presence of sporogonic stages in the internal organs, morphology of the blood forms (sporozoites), and their survival and accumulation in macrophages of the liver. One of the erythrocytic parasites produces encapsulated, stain-resistant forms in the peripheral blood, very similar to gametocytes of Hemolivia Petit et al., 1990. The other is morphologically very different and characteristically adheres to the host-cell nucleus. None of the parasites underwent development in the mosquitoes Culex quinquefasciatus and Aedes aegypti and their behaviour in other haematophagous hosts is under investigation. Mixed infections of the parasites commonly occur and this often creates difficulties in relating the tissue stages in the internal organs to the forms seen in the blood. Concomitant infections with a Plasmodium tropiduri-like malaria parasite were seen and were sometimes extremely heavy.

Some coccidial parasites of the lizard Amphisbaena alba (Reptilia: Amphisbaenia: Amphisbaenidae)

Five parasites are described in the lizard Amphisbaena alba (Amphisbaenidae) from the state of Par , North Brazil. Mature oocysts of Choleoeimeria amphisbaenae n. sp., are passed already mature in the faeces. They are ellipsoidal-cylindrical, average 33.7 x 22.8 m and are devoid of micropyle, oocyst residuum or polar body. The colourless wall is smooth and of 2 layers. The 4 dizoic sporocysts have no Stieda body and average 13 x 9.3 m. Endogenous stages develop in the epithelial cells of the gall-bladder in the manner described for the genus and may cause extensive tissue damage. Sporulation of Isospora capanemaensis n. sp., is completed 3 days after the oocysts are voided in the faeces. They average 14.8 x 14.5 m and have no micropyle, oocyst residuum or polar body. The 2 tetrazoic sporocysts are pear-shaped, average 8.6 x 6.6 and have an inconspicuous Stieda body. Endogenous development is in the epithelial cells of the ileum, and heavy infections cause considerable tissue destruction. Multisporocystic oocysts passed in the faeces of one A. alba possibly originated from an invertebrate host ingested by the lizard. A globidium-like cyst in the digestive tract of A. alba measured 105 x 85 m and contained many hundreds of merozoites. A stained kidney smear of the same lizard revealed the presence of an unidentified parasite producing multinucleate cyst-like stages.

Ultrastructural studies on the sporogony of Hepatozoon spp. in Culex quinquefasciatus say, 1823 fed on infected Caiman crocodilus and Boa constrictor from northern Brazil

Laboratory reared Culex quinquefasciatus Say, 1823 originating from the vicinity of Belem, in northern Brazil, were allowed to engorge on caimans (Caiman c. crocodilus) infected with Hepatozoon caimani (Carini, 1909) and boas (Boa constrictor) infected with H. cf. terzii (Sambon and Seligmann, 1907) both from Para State. Engorged mosquitoes killed on successive days post-feeding (p.f.) were studied by transmission electron microscopy. Images of oocysts from 13 days p.f., caiman-fed mosquitoes were also examined by scanning electron microscopy. The Hepatozoon spp. from the respective hosts differed in their ability to develop in C. quinquefasciatus. Most female mosquitoes fed on caimans, became fully engorged, and survived beyond 22 days p.f., whereas those engorged on boa became debilitated and did not survive beyond 9 days p.f. In boa-fed mosquitoes oocysts were found on the 6th day p.f. The few mosquitoes surviving to the 9th day p.f. contained either undivided oocysts or those that had already commenced sporogenic division. By 8-10 days p.f. caiman-fed mosquitoes contained uninucleate oocysts. Sporogonic divisions were observed from day 12 p.f. onwards. Although sporogenic development conformed in general with the previously reported accounts, the study allowed a more detailed examination of the plasmalemmal endocytotic system, and the consolidation of the crystalline body in specialized 'factories' of cystalline material. Sporozoite differentiation occasionally started on the 18th day p.f., but otherwise was observed only on day 22 p.f.

Leishmania (Viannia) utingensis n. sp., a parasite from the sandfly Lutzomyia (Viannamyia) tuberculata in Amazonian Brazil

A leishmanial parasite isolated in 1977 from a specimen of the sandfly Lutzomyia tuberculata from Pará State, Amazonian Brazil, has been characterized following its comparison with other species of Leishmania from the same region, using isoenzyme profiles, monoclonal antibodies and characterization of the miniexon gene repeat, using the polymerase chain reaction technique (PCR). It is described here under the name of Leishmania (Viannia) utingensis n. sp.

Development of Hepatozoon caimani (Carini, 1909) Pess a, De Biasi & De Souza, 1972 in the Caiman Caiman c. crocodilus, the frog Rana catesbeiana and the mosquito Culex fatigans

The sporogony of Hepatozoon caimani has been studied, by light microscopy, in the mosquito Culex fatigans fed on specimens of the caiman Caiman c. crocodilus showing gametocytes in their peripheral blood. Sporonts iniciate development in the space between the epithelium of the insect gut and the elastic membrane covering the haemocoele surface of the stomach. Sporulating oocysts are clustered on the gut, still invested by the gut surface membrane. Fully mature oocysts were first seen 21 days after the blood-meal. No sporogonic stages were found in some unidentified leeches fed on an infected caiman, up to 30 days following the blood-meal. When mosquitoes containing mature oocysts were fed to frogs (Leptodactylus fuscus and Rana catesbeiana), cysts containing cystozoites developed in the internal organs, principally the liver. Feeding these frogs to farm-bred caimans resulted in the appearance of gametocytes in their peripheral blood at some time between 59 and 79 days later, and the development of tissue cysts in the liver, spleen, lungs and kidneys. Transmission of the parasite was also obtained by feeding young caimans with infected mosquitoes and it is suggested that both methods occur in nature. The finding of similar cysts containing cystozoites in the semi-aquatic lizard Neusticurus bicarinatus, experimentally fed with infected C. fatigans, suggests that other secondary hosts may be involved.

Fine structure of erythrocytic stages of a Plasmodium tropiduri-like malaria parasite found in the lizard Kentropyx calcarata (Teiidae) from north Brazil

The fine structure is described of the merogonic stages and gametocytes of a Plasmodium tropiduri Aragão et Neiva, 1909-like parasite infecting the teiid lizard Kentropyx calcarata Spix from North Brazil. The trophozoites are bordered by two membranes, and with growth a pellicle is formed by the addition of an inner, thick double layer and fragmented membrane. The same type of inner membrane occurs in the pellicle of the merozoites differentiating from the meronts. Merozoites contained a large electron-dense body, sometimes seen to be embraced by a tubular mitochondrion with a dense matrix. Micro- and macrogametocytes are bounded by a double membrane, closely apposed by the detached wall of the parasitophorous vacuole. Both contain osmiophilic bodies. The microgametocyte contains an electron-dense aggregate, and the macrogametocyte has a large mitochondrion and a complex of tubuli and cisternae. These features are compared with those described in other malarial parasites.