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Biomedical subjects

R Lainson

Publications and source records attributed to R Lainson.

At least 19 recordsLinked to original sources
PubMed1994

Naturally acquired infections with Leishmania enriettii Muniz and Medina 1948 in guinea-pigs from São Paulo, Brazil.

Two domestic guinea-pigs (Cavia porcellus), bought in Pinheros, São Paulo State, Brazil, were taken by their owners to a farm in the rural district of Capão Bonito, close to the Atlantic Forest, São Paulo, where they both developed tumour-like and ulcerating lesions on the ears. The causative agent was identified as Leishmania (L.) enriettii, based on biological characters and isoenzyme profiles. Sources of the parasite in wild mammals, and the possible sandfly vector species are discussed.

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PubMed1994

Epidemiology of canine leishmaniasis: a comparative serological study of dogs and foxes in Amazon Brazil.

The paper describes a longitudinal field study of canine leishmaniasis in sympatric domestic dog and crab-eating fox (Cerdocyon thous) populations. Dogs were studied in house-to-house surveys, and foxes were studied by live-trapping and radio-telemetry. Because serological tests (IFAT in this case) for leishmaniasis are often of uncertain sensitivity and specificity, we draw conclusions comparatively. Both cross-sectional (age-prevalence) and longitudinal analyses indicate that incidence in dogs was highest in the dry season. Seasonal changes in the age-prevalence relationship for dogs suggest that serological conversion and recovery rates decline with prior exposure to infection, where 'recovery' may be due to loss of a positive antibody titre or death from leishmaniasis. The mean incidence in dogs was higher in the rural than in the urban population and higher in hunting dogs than pet dogs. Cross-sectional and longitudinal analyses of fox serological data suggest that foxes remain positive for longer than dogs on average, either because detectable antibody is more persistent or because they experience a lower mortality rate due to leishmaniasis.

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PubMed1991

Cutaneous leishmaniasis of man due to Leishmania (Viannia) shawi Lainson, de Souza, Póvoa, Ishikawa & Silveira, in Pará State, Brazil.

Leishmania (Viannia) shawi Lainson, Braga, de Souza, Póvoa, Ishikawa & Silveira, 1989, was originally recorded from monkeys (Cebus apella and Chiropotes satanas), sloths (Choloepus didactylus and Bradypus tridactylus) and coatis (Nasua nasua) and the sandfly, Lutzomyia whitmani. With a panel of Leishmania specific monoclonal antibodies, it was found that 30.5% of the Leishmania strains from patients, who had contracted cutaneous leishmaniasis in Pará State, were similar, but not identical to L. (V.) guyanensis. The enzyme profiles of 18 of these strains were determined, and it was found that 12 isolates belonged to the same zymodeme as the type strain of L. (V.) shawi. The other 6 belonged to a second L. (V.) shawi zymodeme that only differed from the other by having a slightly faster PEP band. These results are the first records of infections of L. (V.) shawi in man and suggest that this parasite is probably common in areas of Pará State to the south of the Amazon River.

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PubMed1991

Monoclonal antibodies that react with Leishmania (Viannia) naiffi.

Monoclonal antibodies were raised against Leishmania (Viannia) naiffi, which recently has been characterized as a new species. BALB/c mice were immunized with membrane-enriched fractions of a mixture of L. (V.) naiffi isolates. Subsequent fusion of immunized splenocytes with NS-1 myeloma cells resulted in the production of 5 Mabs (N1-N5). Screening by ELISA and indirect immunofluorescence against an extensive cross-panel of Leishmania strains revealed that N3 was species-specific and could thus be used to identify L. (V.) naiffi. N2 and N5 reacted only with strains of L. (V.) naiffi and Leishmania (Viannia) braziliensis, and therefore could be used in conjunction with N3 to identify L. (V.) braziliensis parasites. These species-specific Mabs will therefore be useful additions to the panel of antibodies already available for the identification of Leishmania species. N1 and N4 were found to recognize a small, glycosylated molecule present on all L. (V.) naiffi and L. (V.) braziliensis isolates that is related to the GIPL family of membrane glycophospholipids previously described for Leishmania (Leishmania) major.

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PubMed1990

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.

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PubMed1990

Cutaneous leishmaniasis of man due to Leishmania (Viannia) naiffi Lainson and Shaw, 1989.

Until recently mammalian hosts of Leishmania (Viannia) naiffi Lainson & Shaw, 1989 have been limited to armadillos, Dasypus novemcinctus, in Amazonian Brazil. Past evidence for human cutaneous leishmaniasis due to this parasite is reviewed, and a recent infection in man reported, with identification of the parasite by isoenzyme profiles and a specific monoclonal antibody. The role of some phlebotomine sandfly species as vectors is discussed.

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PubMed1989

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.

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PubMed1989

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.

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PubMed1988

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.

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PubMed1988

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.

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PubMed1987

Leishmaniasis in Brazil. XXIV. Natural flagellate infections of sandflies (Diptera: Psychodidae) in Pará State, with particular reference to the rôle of Psychodopygus wellcomei as the vector of Leishmania braziliensis braziliensis in the Serra dos Carajás.

Between July 1983 and December 1984 natural flagellate infections were found in 114 (1%) of 11,586 female phlebotomine sandflies (Diptera: Psychodidae) of 21 species. A further 1084 females of 17 other species were not infected. Identification of the organisms on a number of occasions confirms the exclusive parasite/vector relationship of Leishmania mexicana amazonensis/Lutzomyia flaviscutellata and Le. braziliensis braziliensis/Psychodopygus "wellcomei". Undescribed or unidentified Leishmania spp. were isolated from Lu. shawi, Lu. ubiquitalis, Lu. whitmani, Ps. hirsutus, Ps. paraensis Ps. "wellcomei", and trypanosomes from Lu. nordestina and Lu. trinidadensis. Flagellate infections were recorded in 8 of 21 species examined for the first time, and some were isolated directly from insects into cultures. Le. b. braziliensis was transmitted to a hamster by the bite of a wild-caught, naturally infected Ps. "wellcomei". 7 of the 35 infected Ps. "wellcomei" were allowed to oviposit and the eggs were reared to adults. Four produced Ps. wellcomei males only, confirming the rôle of this species as the major vector of Le. b. braziliensis.

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PubMed1987

Leishmaniasis in Brazil: XXIII. The identification of Leishmania braziliensis braziliensis in wild-caught neotropical sandflies using monoclonal antibodies.

Using the indirect immunofluorescence test natural flagellate infections of wild-caught sandflies, from the Serra dos Carajás region of Pará State, Brazil, were identified by sequentially staining smears made from the infected flies with monoclonal antibodies. With normal methods of isolation 30% of the infections were identifiable, but when monoclonal antibodies specific to Leishmania braziliensis braziliensis were used a further 26% were identified. The staining of organisms in smears of natural infections was different from that seen with culture forms and with forms from experimentally infected wild flies. A monoclonal antibody previously thought to be specific for Leishmania did not react with culture forms of Endotrypanum, but did react with those of monoxenous insect parasites.

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PubMed1987

Leishmaniasis in Brazil. XXV. Sandfly vectors of Leishmania in Pará State, Brazil.

Leishmania of the braziliensis complex were isolated from various members of the squamiventris series sandflies, including Psychodopygus chagasi (Costa Lima), P.s.maripaensis (Ready et al.), P.s.squamiventris (Lutz & Neiva), and also P.ayrozai (Barreto & Coutinho) and Lutzomyia umbratilis Ward & Fraiha. Three different serodemes of Le.b.guyanensis Floch were isolated from Lu.anduzei Rozeboom, Lu.umbratilis and Lu.whitmani Antunes & Coutinho, simultaneously captured in the same area. Unidentified Leishmania were isolated from P.claustrei Abonnenc et al., and trypanosomes from Lu.pinottii Damasceno & Arouck and an unidentified species of Lutzomyia. A naturally infected female P.s.maripaensis transmitted a braziliensis complex Leishmania, by bite, to a hamster.

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