Histopathological study of experimental and natural infections by Trypanosoma cruzi in Didelphis marsupialis

Didelphis marsupialis, the most important sylvatic reservoir of Trypanosoma cruzi, can also maintain in their anal scent glands the multiplicative forms only described in the intestinal tract of triatomine bugs. A study of 21 experimentally and 10 naturally infected opossums with T. cruzi was undertaken in order to establish the histopathological pattern under different conditions. Our results showed that the inflammation was predominantly lymphomacrophagic and more severe in the naturally infected animals but never as intense as those described in Chagas' disease or in other animal models. The parasitism in both groups was always mild with very scarce amastigote nests in the tissues. In the experimentally infected animals, the inflammation was directly related to the presence of amastigotes nests. Four 24 days-old animals, still in embryonic stage, showed multiple amastigotes nests and moderate inflammatory reactions, but even so they survived longer and presented less lesions than experimentally infected adult mice. Parasites were found in smooth, cardiac and/or predominantly striated muscles, as well as in nerve cells. Differing from the experimentally infected opossums parasitism in the naturally infected animals predominated in the heart, esophagus and stomach. Parasitism of the scent glands did not affect the histopathological pattern observed in extraglandular tissues.

The influence of sugars and amino acids on the blood-feeding behaviour, oviposition and longevity of laboratory colony of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae, Phlebotominae)

Schneider's Drosophila medium, a complex amino acid rich medium was tested alone and with seven different sugars for some aspects of the biology of Lutzomyia longipalpis. Statistically significant results were obtained when sucrose was used alone, indicating that among the sugars tested, this is still the most suitable and practical one for the maintenance of L. longipalpis colonies. However, the addition of Schneider's medium to a pool of different sugars, was suggested to be related with the acceptance of the first and second blood meals and to longevity, these being, obviously, quite relevant aspects when tansmission experiments are contemplated.

Trypanosoma cruzi infection in the opossum Didelphis marsupialis: absence of neonatal transmission and protection by maternal antibodies in experimental infections

The high rate of natural Trypanosoma cruzi infection found in opossums does not always correlate with appreciable densities of local triatomid populations. One alternative method which might bypass the invertebrate vector is direct transmission from mother to offspring. This possibility was investigated in five T. cruzi infected females and their litters (24 young). The influence of maternal antibodies transferred via lactation, on the course of experimental infection, was also examined. Our results show that neonatal transmission is probably not responsible for the high rate of natural T. cruzi infection among opossums. In addition antibodies of maternal origin confer a partial protection to the young. This was demonstrated by the finding of a double prepatency period and 4,5 fold lower levels of circulating parasites, in experimentally infected pouch young from infected as compared to control uninfected mothes. On the other hand, the duration of patent parasitemia was twice as long as that observed in the control group

Trypanosoma cruzi: course of infection in platelets-depleted mice

The effect of platelet depletion on the course of Trypanosoma cruzi infection in BALB/c mice was investigated. Thrombocytopenia was achieved by inoculation of rabbit anti-platelet IgG during the parasitemic phase of the infection. The number of parasites in the blood of anti-platelet IgG treated was significantly higher than that of non-treated control mice, during the phase of high parasitemia. Cumulative mortality of platelet-depleted mice was consistently but not significantly higher than that of control mice up to the 32nd day of infection; from the 33rd day on they were equivalent, no mortalities occurring from then on, until observations were discontinued on the 60th day. These results suggest that platelets participate of the mechanisms of parasites removal from the bloodstream, but do not have an effective role in the mechanisms of defence against T. cruzi, during the acute phase of infection.

Infection of a mammal by monogenetic insect trypanosomatids (Kinetoplastida, trypanosomatidae)

Tripanosomatídeos monogenéticos de insetos, dos gêneros Crithidia, Leptomonas e Herpetomonas foram inoculados no lumen das glândulas de cheiro do gambá ae aí se multiplicaram como em culturas axênicas durante muitos meses. No soro dos animais foram detectados anticorpos específicos mas näo houve evidência de invasäo dos tecidos pelos parasitas

From a mono to a digenetic life-cycle: how was the jump for flagellates of the family trypanosomatidae?

Foi verificado que tanto espécies digenéticas do gênero Trypanosoma como espécies de tripanosomatídeos monogenéticos de insetos, podem desenvolver-se no lúmen das glândulas de cheiro do gambá, reproduzindo o ciclo que fazem no tubo digestivo dos insetos que lhes servem de hospedeiros e/ou transmissores. Com base nesses achados especula-se sobre o ciclo incompletamente conhecido de muitos tripanosomas de mamíferos e sobre a evoluçäo da família Trypanosomatidae

Are asian monkeys the original mammalian hosts of Trypanosoma conorhini

Apresenta-se a hipótese de que os hospedeiros originais do Trypanosoma cororhini poderiam ser macacos asiáticos, porque a infecçäo natural destes tem sido achada, o vetor entre ratos é um Triatomíneo tropicopolita que pertence a um complexo de espécies asiáticas e os primatas têm-se mostrado mais suscetíveis ao parasito do que os ratos

Anothor Trypanosoma, distinct from T. cruzi, multiplies in the lumen of the anal glands the opossum Didelphis marsupialis

Um tripanosoma ainda näo identificado foi encontrado multiplicando-se como epimastigotas extracelulares na glândulas anais de um gambá. Trata-se possivelmente do T. (M.) freitasi. O achado demonstra que tal localizaçäo näo se restringe ao T. cruzi e sugere que os tripanosomatídeos devem ser buscados nesta e em outras situaçöes inortodoxas, no organismo dos hospedeiros vertebrados

Trypanosoma cruzi: strain selection by diferent schedules of mouse passage of an initially mixed infection.

De uma infeccao inicialmente dupla em camundongo, estabelecida por inoculo simultaneo e equivalente de formas sanguineas das cepas Y e F de Trypanosoma cruzi, duas linhagens foram originadas por subinoculacoes: uma (W) passada casa semana, a outra (M) cada mes. Por metodos biologicos e bioquimicos apenas a cepa Y foi identificada ao fim a 10a. e 16a. passagens da linhagem W e apenas a cepa F na 2a. e 4a.passagens de linhagem M. Os resultados demonstram a selecao de cepas atraves de manipulacao em laboratorio de populacoes inicialmente mistas de T. cruzi

Trypanosoma cruzi: vertebrate and invertebrate cycles in the same mammal host, the opossum Didelphis marsupialis.

No gamba (Didelphis marsupialis) foi observado um ciclo extracelular do Trypanosoma cruzi: o parasita crescia abundantemente no material de secrecao acumulado no lumen das glandulas anais de animais criados em cativeiro e infectados por via subcutanea com fezes de triatomineos