The aim of the study was to determine the presence of Trypanosoma spp in Rattus spp from food markets and pig farms in Lima, Peru, to identify the species of Trypanosoma spp by morphological and biometric characterization, and to correlate the presence of the parasite with the variables sex, age (juvenile and adult), origin and species. The study was conducted in eight food markets of six districts (n = 62 rats) and three pig farms (n = 99) from three districts of Lima. Blood samples were collected and analysed using the thin blood smear technique and stained with «Hemacolor» to determine the presence of the parasite. The identification of the Trypanosome species was based on international keys based on the morphological and biometric characteristics of the trypomastigotes present in blood smears stained with Giemsa. T. lewisi was the only species found in a frequency of 22.5 and 21.2% in rats from the food markets and pig farms, respectively. The frequency of T. lewisi in R. norvegicus and R. rattus was 10.2 and 26.7%, in male and female rats was 21.1 and 22.0%, and in adults and juveniles was 17.0 and 26.5%, respectively. There was no significant association with the variables of origin, sex, and age. R. rattus showed a significant risk factor (OR: 3.77) against R. norvegicus for the presentation of T. lewisi

El objetivo del estudio fue determinar la presencia de Trypanosoma spp en Rattus spp de mercados de abasto y granjas porcinas en Lima, Perú, identificar las especies de Trypanosoma spp mediante caracterización morfológica y biométrica, y correlacionar la presencia del parásito con las variables sexo, edad (juvenil y adulto), procedencia y especie. El estudio se desarrolló en ocho mercados de abasto de seis distritos (n=62 ratas) y en tres granjas porcinas (n=99) de tres distritos de Lima. Se colectaron muestras de sangre y se analizaron mediante la técnica de frotis sanguíneo delgado coloreado con la tinción rápida «Hemacolor» para determinar la presencia del parásito. La identificación de las especies de tripanosomas se hizo con claves internacionales con base a las características morfológicas y biométricas de los tripomastigotes presentes en frotis sanguíneos coloreados con Giemsa. Se identificó la presencia de T. lewisi en 22.5 y 21.2% de ratas en los mercados de abasto y granjas porcinas, respectivamente. Se halló una frecuencia de T. lewisi en R. norvegicus y R. rattus de 10.2 y 26.7%, en ratas machos y hembras de 21.1 y 22.0%, y en adultas y juveniles de 17.0 y 26.5%, respectivamente. No se evidenció asociación significativa con las variables procedencia, sexo y edad. R. rattus mostró un factor de riesgo significativo (OR: 3.77) frente a Rattus norvegicus para la presentación de T. lewisi.

La prevalencia de infecciones por Toxoplasma gondii en el ser humano es de 5-90% según la zona geográfica; en Costa Rica por ejemplo, la seroprevalencia es de un 58%, por lo que es importante comprender algunos procesos inmunológicos, propios en estas afectaciones parasitarias. Con el objeto de determinar si el Trypanosoma musculi ejerce procesos de inmunosupresión sobre Toxoplasma gondii se realizó un experimento en el que se inocularon ratones Swiss con T. musculi cuatro, cinco, seis y siete días previos a la infección con T. gondii, ocurriendo la inmunosupresión cuando la inoculación con T. musculi fue hecha cuatro días antes. Además, la cantidad de tripomastigotos inoculados no influyó en el proceso. Se probaron tres cepas de T. gondii aisladas de las heces de un gato casero (TFC), de un Leopardus pardalis (TLP), de un Leopardus wiedii y de la carne de un Bos taurus (TBT). La cepa TLP resultó ser muy patógena, matando a los animales en un tiempo corto, independientemente de la inoculación con T. musculi; para las otras cepas se mantuvo el patrón de inmunosupresión en los ratones. Se reporta entonces un modelo experimental de inmunosupresión, aspecto muy en boga en este momento, por su relación con enfermedades que inducen esta condición en el ser humano, especialmente a enfermedades como el cáncer y el SIDA. Este modelo es más fácil de aplicar experimentalmente que el correspondiente con T. lewisi previamente descrito, el cual usa ratas blancas de más difícil manejo que los ratones usados en este estudio.

The immunosuppression caused by species of the gender Trypanosoma has been widely documented. The influence over experimental infections with Toxoplasma gondii is evident when using Trypanosoma lewisi, a natural parasite of white rats. We decided to test the effect of Trypanosoma musculi from mice, an organism with very similar biological characteristics to T. lewisi, to see if this trypanosomatid could induce a similar effect. Four groups of Swiss mice were inoculated with T. musculi previously to infection with T. gondii, and we determined the survival of the animals, as well as the number of cysts developed in the brain of survivors. We isolated and tested different strains of T. gondii from different sources. In a first experiment, the animals were previously inoculated with T. musculi at different times prior to the infection with Toxoplasma; this allowed us to determine that the immunosuppression process resulted more evident when T. musculi inoculation was made four days before. In a second experiment, we used different inoculi dose and found that it did not influenced the process. Furthermore, the results were negative when evaluating if the amount of the inoculated trypomastigote influenced the process. In order to demonstrate if there were differences in the immnosuppressive effect, related to Toxoplasma strains, groups of mice were inoculated with brain cysts of TFC, TLP, TLW and TBT strains. Excluding the TLP strain, that resulted to be very pathogenic regardless the previous inoculation with T. lewisi, the other strains kept the same pattern of immunosuppression in mice, whose survival time was shorter as the presence of cysts in the brain was higher. These observations were in agreement with an experi- mental immunosuppression model, associated with immunosuppressive diseases, specially cancer and AIDS.

El efecto inmunosupresor de la infección de T. lewisi sobre la multiplicación de T. gondii fue comparado en macrófagos peritoneales (MP) y alveolares (MA) de rata. El número de parásitos (taquizoitos) intracelulares (TI) fue contado por microscopía de luz. Los macrófagos alveolares y peritoneales (MP) de animales con 4 días de infección con T. lewisi muestran un aumento significativo en la multiplicación de T. gondii. A diferencia de los MP (que muestran un aumento en la multiplicación de T. gondii al cuarto día de infección con T. lewisi disminuyendo hacia el séptimo día), los MA mantienen un aumento en la multiplicación del parásito desde el cuarto, aumentando hacia el séptimo día de infección. Esta diferencia se puede deber a la ruta de infección utilizada para los experimentos que afectan directamente los MP donde se observa un efecto mayor y más temprano en comparación con los MA aislados de los pulmones, compartimiento afectado cuando la infección se vuelve sistémica entre el cuarto y sexto día de infección. La inmunidad contra T. gondii es similar entre ambas células fagocíticas, pero el tiempo de infección y el compartimiento donde se encuentren las células hace la diferencia en el tiempo de respuesta contra un parásito dado, en nuestro caso T. gondii. No hubo evidencia de que los sobrenadantes de cultivos de macrófagos provenientes de ratas infectadas ni el lisado de tripanosomas indujeran el efecto inmunosupresor.

The immunosuppressant effect of T. lewisi (Kinetoplastidae) infection on the multiplication of Toxoplasma gondii (Sarcocystidae) on alveolar and peritoneal macrophages of the white rat. The immunosuppressant effect of T. lewisi infection on the multiplication of T. gondii was compared in peritoneal (MP) and alveolar macrophages (MA) of white rat. Two animal groups were infected with T. lewisi and sacrificed after four days and seven days post infection. A group without infection was maintained as a control. The number of intracellular parasites (tachyzoites) (IT) was counted by light microscopy, calculating the rate infection rate per 100 total cells (TC) and per infected cells (IC) for each group of phagocyte cells. The relation quotient IT, TC or IC multiplied percent, provided a statistical ratio (RE) of the relative number of parasites in both cellular types for each time interval. MA as well as MP obtained after 4 days showed a significant increase in the multiplication of T. gondii with respect to the control. Unlike the MP (which had an increase in the multiplication of T. gondii the fourth day of infection with T. lewisi diminishing towards the seventh day), the MA had an increase in the multiplication of the parasite from the fourth to the seventh day. This difference can be related to the route of infection used for the experiments, that affect the MP directly with a greater effect in comparison with the MA of the lungs. Lung compartment will be affected later, when the infection becomes systemic between the fourth and sixth day of infection. The immunity against T. gondii is similar between both phagocytes, but the time of infection and the compartment where the cells are located, makes the difference in the response time against T. gondii. Supernatants from macrophage cultures or T. lewisi by rat did not induced any immunosuppression. Rev. Biol. Trop. 57 (1-2): 13-22. Epub 2009 June 30.

Introducción. La enfermedad de Chagas y la leishmaniasis son patologías de gran importancia en salud pública debido a su alta frecuencia y amplia distribución en América Latina. El estudio de los animales reservorios es vital para una comprensión global de estas enfermedades. Objetivo. En el presente trabajo nos propusimos identificar parásitos de la familia Trypanosomatidae en animales silvestres con la finalidad de establecer posibles relaciones debidas a la coinfección. Materiales y métodos. En El Carrizal, un área rural del estado Mérida, Venezuela, entre julio de 1998 y febrero de 2000 se realizaron capturas sistemáticas de animales silvestres con la finalidad de poner en evidencia la presencia de parásitos pertenecientes a la familia Trypanosomatidae. Las capturas fueron realizadas con trampas caseras tipo Tomahawk, colocadas 15 noches por mes durante el periodo del estudio. A los animales capturados se les practicó punción cardiaca bajo anestesia para extracción de sangre con la cual se realizaron los siguientes estudios: examen en fresco, extendido para coloración con Giemsa y cultivo en agar-sangre. Se realizaron algunos xenodiagnósticos. Los aislamientos obtenidos por medio de cultivo se identificaron por medio de análisis de restricción e hibridación con sondas específicas. Resultados. Se capturaron y estudiaron 215 animales pertenecientes a tres especies: Rattus spp. (135), Sigmodon hispidus (73) y Didelphis marsupialis (7). Igualmente, se identificaron tres especies de Trypanosomatidae: Leishmania ( V) guyanensis, Trypanosoma cruzi y Trypanosoma lewisi. Mientras T. cruzi fue identificado en D. marsupialis (4/7), S. hispidus (1/73) y Rattus spp. (1/135), L.( V) guyanensis y T. lewisi sólo se identificaron en Rattus spp. (1/135 y 12/135, respectivamente). Conclusión. El estudio de la coexistencia de estas diferentes especies de flagelados genéticamente relacionados nos parece de importancia por las interacciones inmunológicas que se pueden establecer en los animales reservorios y las posibles implicaciones que esto puede tener en el huésped susceptible. Finalmente, las identificaciones de L.( V) guyanensis y T. cruzi en Rattus spp. y S. hispidus, respectivamente, son las primeras reportadas en Venezuela.

Introduction. Chagas disease and leishmaniasis are important public health problems due to their high frequency and broad distribution in Latin America. Understanding of the roles of reservoir animals is crucial for a global assessment of the epidemiology of these diseases. Objective. To identify parasites classed as Trypanosomatidae as they occurred in sylvatic animals, and to establish rates of coinfection. Materials and methods. Sylvatic animals were systematically captured in the rural area of El Carrizal, Merida State, Venezuela, betweenJuly, 1998 and February, 2000. The captures were made in Tomahawk type homemade traps, placed 15 nights per month throughout the study period. Blood was extracted from each captured and anesthetized animal by means of cardiac puncture. The search for trypanosomatids was undertaken by fresh blood examination, Giemsa stained blood smears and by means of blood-agar culture. Occasional xenodiagnoses were made to check diagnostic accuracy. The isolates obtained in culture media were identified by restriction fragment analysis and hybridization with specific probes. Results. Three species of sylvatic animals (n=215) were captured: Rattus spp. (135), Sigmodon hispidus (73) and Didelphis marsupialis (7). From them, three species of Trypanosomatidae were identified: Leishmania (Viannia) guyanensis, Trypanosoma cruzi and Trypanosoma lewisi. Trypanosoma. cruzi was identified in D. marsupialis (4/7), S. hispidus (1/73) and Rattus spp. (1/ 135), whereas L.(V.) guyanensis and T. lewisi were identified only in Rattus spp., 1/135 and 12/ 135, respectively. Conclusions. The coexistence of these genetically related hemoflagellates in sylvatic hosts was important for understanding the immunological interactions that may be established in reservoir animals, and the possible implications that this may have for the susceptible host. Finally, the identification of L.(V.) guyanensis in Rattus spp and T. cruzi in S. hispidus constituted the first reports of this relationship in Venezuela.

On the basis of previous studies on Trypanosoma lewisi immunosuppression model groups of 5 Wistar rats were infected with. T. gondii and T. lewisi according to the following protocol. One group was inoculated i.p. with 10(6) T. lewisi tripanomastigotes and 4 days later with 10(7) T. gondii tachyzoites. The second and third groups were infected only with T. lewisi or T. gondii respectively. The fourth group was not infected and served as control. Rats were bled before the infection and then every day for seven days. Serum samples were collected and the levels of IFN-g, IL-2 and TNF-a were measured. The results indicates that the level of IFN-g is very high 24 hour after infection in rats inoculated with T. gondii only, while in those animals infected with both parasites (first group), IFN-g was not detected 24 hours after infections with T. gondii. These data give evidence that a reduction of IFN-g levels is one of the reasons for the immunosuppressive effect induced by T. lewisi, increasing T. gondii multiplication in an animal as the rat, which is remarkable resistant to this parasite

De acuerdo con estudios anteriores, en donde se ha demostrado el efecto de inmunosupresión producido por Trypanosoma lewisi sobre infecciones con Toxoplasma gondii, grupos de 5 ratas Wistar fueron inoculadas según el siguiente protocolo. Un grupo fue inoculado i.p. con 10(6) tripomastigotos de T. lewisi y 4 días después con 10(7) taquizoitos de T. gondii. El segundo y el tercer grupo fueron inoculados sólo con T. gondii o con T. lewisi respectivamente. Un cuarto grupo no fue infectado y sirvió como control. Las ratas fueron sangradas antes de la infección y luego cada día durante 7 días. Los sueron fueron colectados para determinar la presencia de IFN-g, IL-2 y TNF-a .El nivel de IFN-g fue muy alto después de 24 h de infección en las ratas inoculadas únicamente con T. gondii, mientras que en los animales infectados con ambos parásitos (el primer grupo) el IFN-g no fue detectado en el mismo período de infección con T. gondii; IL-2 y TNF-a no fueron detectados. Estos datos son una evidencia preliminar de que en este proceso de inmuno-supresión, existe una reducción en los niveles deIFN-g, inducida por T. lewisi, lo cual es probablemente una de las razones por las que la rata se ve disminuida en su resistencia natural al T. gondii

Peritoneal macrophages (PM) from normal Wistar rats were treated in vitro with peritoneal supernatant or sera, obtained from rats infected with 10(6) Trypanosoma lewisi trypomastigotes before the infection with Toxoplasma gondii tachyzoites. In this experimental model, Toxoplasma multiplication in PM was increased, as compared to macrophages treated with supernatant or sera from control rats not infected with T. lewisi. This effect was observed only if the active supernatant or sera came from rats infected with the T. lewisi 3 to 6 d before Toxoplasma inoculation. Furthermore, immunosuppressive activity was only detectable after at least 24 h incubation with the supernatant or sera. These results are in accordance with our in vivo previous studies which demonstrated a clear immunosuppressive effect of T. lewisi during T.gondii infection of the remarkably resistant Wistar rats

From April 1984 to March 1985, a Trypanosoma lewisi prevalence of 21.7% was found in 429 Rattus norvegicus trapped in Belo Horizonte, State of Minas Gerais, Brazil. The infection rates were higher in male and young rats and could be attributed to ecological and behavioral factors. T. lewisi was observed in rats measuring between 60 and 250 mm. Data about monthly T. lewisi infections throughout the year are presented for the first time in Brazil, with the highest prevalences observed in the warm-rainy season (October to March).

Peritoneal macrophages from Wistar rats, inoculated and non-inoculated with 10(6) T. lewisi trypomastigotes, were cultured and infected with 10(6) T. gondii tachyzoites. Multiplication rates of this parasite were studied after 1, 24 and 48 h of infection but there were not significant differences between the number of parasites found inside of macrophages coming, either from T. lewisi infected or non infected rats. On the other hand, in vivo studies of Toxoplasma multiplication inside peritoneal macrophages, showed that there is an increase of parasite number in cells from T. lewisi infected rats, as compared with those macrophages from non infected rats. This effect was statistically significant and was more evident after four days of infection. Therefore, it has been demonstrated that in vivo, but not in vitro T. lewisi infections, causes an important decrease of the natural resistance to T. gondii of the white rats, which is manifested by the major invasion and multiplication of the parasite inside of peritoneal macrophages.

White rats were inoculated with 10(6) trypomastigotes of Trypanosoma lewisi, simultaneously or two days before and after inoculation with 10(5) oocysts of T. gondii. A greater number of cysts was found in the brain of the animals having concomitant inoculations, as compared with rats inoculated with either one of the two parasites. An apparent immunosuppressive effect is likely. Since both organisms can be found in rat, it is possible that infections with T. lewisi, could make this rodent another intermediate host for Toxoplasma infections.

Exame direto de sangue e xenodiagnóstico de 47 roedores sinantrópicos (Rattus rattus, R. norvegicus, Mus musculus) capturados no Vale de Caracas, Venezuela, revelaram infecção por tripanosoma em 12 R. rattus, 10 com T. lewisi e 2 com T. cruzi. Dos últimos o curso de parasitemia, o pleomorfismo dos tripomastigotas na corrente sanguínea, tropismo tissular em ratos e camundongos natural e experimentalmente infectados, mortalidade dos hospedeiros, morfologia dos parasitas fecais em Rhodnius prolixus usados para xenodiagnóstico e infectividade das fezes do "barbeiro" para camundongos NMRI, foram todos característicos de Trypanosoma (Schizotrypanum) cruzi. Um rato com parasitemia patente, tinha numerosos ninhos de amastigotas no músculo cardíaco e parasitismo moderado do músculo liso do duodeno e do músculo esquelético. Camundongos inoculados com flagelados fecais de "barbeiros" tinham tropismo tissular moderado nos mesmos órgãos e também no cólon e pâncreas. O possível papel do R. rattus no estabelecimento de focos de doença de Chagas em Caracas é discutido

Direct blood examination and xenodiagnosis of 47 synanthropic rodents (Rattus rattus, R. norvegicus, Mus musculus) captured in the valley of Caracas, Venezuela, revealed trypanosomal infections in 12 R. rattus, 10 with T. lewisi and 2 with T. cruzi. Of the latter the course of parasitemia, the pleomorphism of the bloodstream trypomastigotes, tissue tropism in naturally and experimentally infected rats and mice, host mortality, morphology of fecal parasites in Rhodnius prolixus used for xenodiagnosis, and infectivity of the bug feces for NMRI mice, were all characteristic of Trypanosoma (Schizotrypanum) cruzi. One rat, with a patent parasitemia, had numerous nests of amastigotes in cardiac muscle and moderate parasitism of the smooth muscle of the duodenum and of skeletal muscle. Mice inoculated with fecal flagellates from the bugs had moderate tissue tropism in the same organs and also in the colon and pancreas. The possible role of R. rattus in the establishment of foci of Chagas’ disease in Caracas is discussed

The authors report the finding of trypanosoma cruzi - like and lewisi in rodents trapped in the Araripe region of the State of Pernambuco, Brazil.