Acute and chronic histopathologic changes in wild typeTLR-2-/-, TLR-4-/-, TLR-6-/-, TLR-9-/-, CD14-/-, and MyD-88-/- mice experimentally infected with Plasmodium chabaudi

Malaria is caused by protozoan parasites of the genus Plasmodium, which is transmitted by Anopheline mosquitoes. Experimental murine models using rodent malaria are useful for studying pathologic aspects of severe malaria. We evaluated histopathologic lesions of TLR-2-/-, TLR-4-/-, TLR-6-/-, TLR-9-/-, CD14-/- and MyD88-/- mice experimentally infected with Plasmodium chabaudi. Frequencies and severity of microscopic lesions in the spleen and liver at one and four weeks post infection (wpi) were determined. At one wpi, adherence of macrophages to the endothelial surface was the most evident change, whereas at four wpi there was marked accumulation of cytoplasmic pigment in macrophages in the liver and spleen. Lesions were not markedly influenced by the absence of TLRs, MyD88 or CD14. Our findings suggest that acute and chronic phases of murine infection with P. chabaudi are characterized by distinct lesions. In addition, TLRs and MyD88 are not essential to promote these lesions during P. chabaudi infection.(AU)

Acute and chronic histopathologic changes in wild type or TLR-2-/-, TLR-4-/-, TLR-6-/-, TLR-9-/-, CD14-/-, and MyD-88-/- mice experimentally infected with Plasmodium chabaudi

Malaria is caused by protozoan parasites of the genus Plasmodium, which is transmitted by Anopheline mosquitoes. Experimental murine models using rodent malaria are useful for studying pathologic aspects of severe malaria. We evaluated histopathologic lesions of TLR-2-/-, TLR-4-/-, TLR-6-/-, TLR-9-/-, CD14-/-, and MyD-88-/- mice experimentally infected with Plasmodium chabaudi. Frequencies and severity of microscopic lesions in the spleen and liver at one and four weeks post infection (wpi) were determined. At one wpi, adherence of macrophages to the endothelial surface was the most evident change, whereas at four wpi there was marked accumulation of cytoplasmic pigment in macrophages in the liver and spleen. Lesions were not markedly influenced by the absence of TLRs, MyD88 or CD14. Our findings suggest that acute and chronic phases of murine infection with P. chabaudi are characterized by distinct lesions. In addition, TLRs and MyD88 are not essential to promote these lesions during P. chabaudi infection.

Preliminary Entomological and Parasitological Studies in Humboldt, Aripuanã, Mato Grosso State, Brazil.

ABSTRACT The preliminary results are given of studies on the sandfly fauna (Diptera: Psychodidae) in forest surrounding the Humboldt Research Centre, Municipio of Aripuanã, Mato Grosso State, Brazil. A total of 712 sandflies were obtained, including 26 different species: of these, 387 were caught off human bait; 317 from tree-trunks; 4 in a malaise-trap; 3 in rodent baited oil traps; and 1 in a light-trap. Man-biting species were absent or very rare during studies in the dry season (August and September, 1974), but relatively abundant at the end of the rainy season (June, 1975): this suggests a seasonal transmission of leishmaniasis. The species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) was a major man-biter, this species is an important vector of cutaneous leishmaniasis in North Pará, Brazil, and could be responsible for transmission in Aripuanã. Among a total of 349 female sandflies dissected, promastigote flagellates were found in 2 Lutzomyia yuilli; epimastigote flagellates in 1 L. yuilli; a microsporidian in Psychodopygus (1) complexus; a gregarine, probably Monocystis chagasi, in P. davisi; and a nematode larva in P. complexus. Inoculation of the promastigote flagellates into the skin of hamsters failed to give Leishmania infections: possibly they were developmental stages of some other parasite. Two research workers of Project RADAM acquired cutaneous leishmaniasis in the Humboldt area; and 6 cases of malaria were diagnosed, 3 due to P. falciparum and 3 to P. vivax. Transmission of malaria was shown to be taking place in the camp site itself. Finally, man-biting "black-flies" (Diptera: Simuliidae) were found to be a serious problem, necessitating constant use of insect repellent.

Sumário São apresentados os resultados preliminares do estudo da fauna flebotomínea (Diptera, Psychodidae, Phlebotominae) da floresta que circunda o Centro de Pesquisa de Humboldt, Aripuanã, Estado de Mato Grosso, Brasil. Foi obtido um total de 712 flebotomíneos, incluindo 26 espécies diferentes, 387 dos quais capturados com isca humana, 317 em troncos de árvores, 4 em armadilha tipo "malaise", 3 com isca-roedor, e 1 com armadilha luminosa. Espécies antropófilas foram muito raras durante os estudos na época seca (agosto e setembro), mas relativamente abundantes durante as investigações no fim da época chuvosa (junho), sugerindo a ocorrência de uma transmissão sazonal de leishmaniose cutânea na área. Lutzomyia anduzei seg. Floch & Abonnenc (1942), foi uma das espécies antropófilas mais comumente encontradas, e, sendo um dos vetores mais importantes da leishmaniose cutânea no Norte do Pará, Brasil, é possível que seja também responsável pela transmissão na área do Aripuanã. 349 fêmeas de flebotomíneos foram dissecadas, tendo sido encontrados: flagelados do tipo promastigoto em 2 Lutzomyia yuilli, e do tipo epimastigoto em um exemplar da mesma espécie; um microsporídio, em 1 Psychodopygus complexus; uma gregarina, provavelmente Monocystis chagasi, em 1 P. davisi; e uma larva de nematódeo, em 1 P. complexus. A inoculação dos flagelados promastigotos na pele de hamster não produziu infecção leishmaniótica, possivelmente por se tratar de estágio de desenvolvimento de qualquer outro parasita, como Endotrypanum, por exemplo. Dois casos de leishmaniose cutânea foram registrados em pesquisadores do Projeto RADAM trabalhando na área de Humboldt, assim como 6 casos de malária, determinados por P. falciparum (3) e P. vivax (3). Finalmente, a grande densidade de piuns (Diptera: Simuliidae) antropófilos, constitui um sério problema na área, obrigando ao uso constante de repelentes.

Preliminary Entomological and Parasitological Studies in Humboldt, Aripuanã, Mato Grosso State, Brazil

ABSTRACT The preliminary results are given of studies on the sandfly fauna (Diptera: Psychodidae) in forest surrounding the Humboldt Research Centre, Municipio of Aripuanã, Mato Grosso State, Brazil. A total of 712 sandflies were obtained, including 26 different species: of these, 387 were caught off human bait; 317 from tree-trunks; 4 in a malaise-trap; 3 in rodent baited oil traps; and 1 in a light-trap. Man-biting species were absent or very rare during studies in the dry season (August and September, 1974), but relatively abundant at the end of the rainy season (June, 1975): this suggests a seasonal transmission of leishmaniasis. The species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) was a major man-biter, this species is an important vector of cutaneous leishmaniasis in North Pará, Brazil, and could be responsible for transmission in Aripuanã. Among a total of 349 female sandflies dissected, promastigote flagellates were found in 2 Lutzomyia yuilli; epimastigote flagellates in 1 L. yuilli; a microsporidian in Psychodopygus (1) complexus; a gregarine, probably Monocystis chagasi, in P. davisi; and a nematode larva in P. complexus. Inoculation of the promastigote flagellates into the skin of hamsters failed to give Leishmania infections: possibly they were developmental stages of some other parasite. Two research workers of Project RADAM acquired cutaneous leishmaniasis in the Humboldt area; and 6 cases of malaria were diagnosed, 3 due to P. falciparum and 3 to P. vivax. Transmission of malaria was shown to be taking place in the camp site itself. Finally, man-biting "black-flies" (Diptera: Simuliidae) were found to be a serious problem, necessitating constant use of insect repellent.

Sumário São apresentados os resultados preliminares do estudo da fauna flebotomínea (Diptera, Psychodidae, Phlebotominae) da floresta que circunda o Centro de Pesquisa de Humboldt, Aripuanã, Estado de Mato Grosso, Brasil. Foi obtido um total de 712 flebotomíneos, incluindo 26 espécies diferentes, 387 dos quais capturados com isca humana, 317 em troncos de árvores, 4 em armadilha tipo "malaise", 3 com isca-roedor, e 1 com armadilha luminosa. Espécies antropófilas foram muito raras durante os estudos na época seca (agosto e setembro), mas relativamente abundantes durante as investigações no fim da época chuvosa (junho), sugerindo a ocorrência de uma transmissão sazonal de leishmaniose cutânea na área. Lutzomyia anduzei seg. Floch & Abonnenc (1942), foi uma das espécies antropófilas mais comumente encontradas, e, sendo um dos vetores mais importantes da leishmaniose cutânea no Norte do Pará, Brasil, é possível que seja também responsável pela transmissão na área do Aripuanã. 349 fêmeas de flebotomíneos foram dissecadas, tendo sido encontrados: flagelados do tipo promastigoto em 2 Lutzomyia yuilli, e do tipo epimastigoto em um exemplar da mesma espécie; um microsporídio, em 1 Psychodopygus complexus; uma gregarina, provavelmente Monocystis chagasi, em 1 P. davisi; e uma larva de nematódeo, em 1 P. complexus. A inoculação dos flagelados promastigotos na pele de hamster não produziu infecção leishmaniótica, possivelmente por se tratar de estágio de desenvolvimento de qualquer outro parasita, como Endotrypanum, por exemplo. Dois casos de leishmaniose cutânea foram registrados em pesquisadores do Projeto RADAM trabalhando na área de Humboldt, assim como 6 casos de malária, determinados por P. falciparum (3) e P. vivax (3). Finalmente, a grande densidade de piuns (Diptera: Simuliidae) antropófilos, constitui um sério problema na área, obrigando ao uso constante de repelentes.