Infection of white rat peritoneal macrophages with Toxoplasma gondii, (Coccidia: Sarcocystidae) after Trypanosoma lewisi (Kinetoplastida: Trypanosomatidae) infection.

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.

An in vivo model to study the anti-malaric capacity of plant extracts.

An in vivo model to study the antimalaric effect of plant extracts is described. White mice (25-30 g body weight) are treated subcutaneously with 0.6 ml of the diluted extract starting seven days before P. berghei infection; treatment continues until death or for 30 days. Simultaneously 0.2 ml of the extract are applied per os starting three days before infection. In a test of the model, treated and non-treated animals differed in body weight, survival time, haematocrite, parasitemia development, and spleen or liver weight of recent dead or killed mice.

[Eimeria species (Eucoccidida: Eimeriidae) found in the cotton rat Sigmodon hispidus in Costa Rica]. / Especies de Eimeria (Eucoccidida: Eimeriidae) en la rata de milpa Sigmodon hispidus de Costa Rica.

Cotton rats (Sigmodon hispidus) were collected from Ojo de Agua, Alajuela (N = 74) and Cañas, Guanacaste (N = 29). Feces had 31 E. sigmodontis, nine E. tuskegeensis, eight E. roperi, three E. webbae and two Eimeria sp. This is the first report of these coccidian parasites for Costa Rica.

Increasing of Toxoplasma gondii (Coccidia, Sarcocystidae) infections by Trypanosoma lewisi (Kinetoplastida, Trypanosomatidae) in white rats.

To demonstrate that T. lewisi infection increases T. gondii multiplication in white rats, groups of five Wistar or Sprague Dawley rats were inoculated with 10(6) T. lewisi trypomastigotes and four or seven days later infected with Toxoplasma tachyzoites. Host survival time was monitored, and the presence of T. gondii was confirmed in all dead rats by studying peritoneal exudate smears and lung tissue sections stained with haematoxylin-eosin. The presence of Toxoplasma cysts or antibodies was checked in the brain of surviving rats. The increase is observed four days after trypanosome inoculation and is dependent on rat strain, but not on inoculum size or rat age. Humoral and cellular factors may have a role in the increase as has been reported for other experimental infections with African trypanosomes and T. cruzi.

Toxoplasma gondii (Eucoccidia: Sarcoystidae) dissemination pattern in rats after oral infection with oocysts of an avirulent strain.

Differences in Toxoplasma gondii dissemination in white rats (Sprague Dowley) and mice (Wistar) after oral oocyst inoculation are described. Groups of five animals (both hosts) were infected per os with oocysts of the TCR-2 avirulent strain and the dissemination pattern was compared in brain tissue or by serology. Early dissemination was similar in both species. One hr after infection the parasite was present in blood and peritoneal exudate as well as in heart, lung, liver, spleen, lymph nodes and brain. However, after five days there were important differences between both hosts and after 30 days, the parasite was detected only in rat heart and brain, while in mice it persisted in fluids and all organs.

[A simple method for determining the presence of Toxoplasma gondii (Eucoccidia: Sarcocystidae) in meat]. / Método sencillo para determinar la presencia de Toxoplasma gondii (Eucoccidia: Sarcocystidae) en carne.

Presence of T. gondii in meat from several sources was determined by traditional methods and by a new simplified method in which animals are fed meat directly without any previous treatment with artificial gastric fluid. Tissues are ground and the animals ingest them naturally. Determination of Toxoplasma in lungs or brain (as well as by specific antibody test), showed no statistically significant differences between both methods.

[Susceptibility of Sigmodon hispidus (Rodentia: Cricetidae) to Toxoplasma gondii (Eucoccidia: Sarcocystidae)]. / Susceptibilidad de la rata Sigmodon hispidus (Rodentia: Cricetidae) al Toxoplasma gondii (Eucoccidia: Sarcocystidae).

Sigmodon hispidus, a cotton rat, was inoculated with tachyzoites or oocysts of Costa Rican strains of Toxoplasma gondii to demonstrate the resistance to this parasite, as compared with mice, hamster and white rat infection. Susceptibility to tachyzoite inoculation was higher in this animal than in white rats but lower than in the other animals. Independent to the Toxoplasma strain studied, oocyst infection was less lethal for S. hispidus when compared with mice and hamsters; the results were similar to those observed for white rats. There is a probable participation of this wild animal in the natural Toxoplasma life cycle.

Age influence in the natural resistance of white rat and mice to the protozoan Toxoplasma gondii.

Groups of 1, 5, 10, 15 and 30 day old rats (Sprague Dawley) and Wistar mice were infected per os with different inocula of Toxoplasma gondii oocysts from an avirulent strain. Infection pattern was followed by determination of survival time, tissue lesions, parasite presence and serology. Although all the animals survived the total experimental period (30 day), there were important differences between both rodents regarding to Toxoplasma natural resistance. Brain cysts, as well as tachyzoites in other organs were regularly present in mice but not in rats. On the other hand, most of the organs from mice presented characteristic T. gondii lesions, while in rats a normal tissues were observed, with the exception of an acute reaction found in the brain of a 15d old animal.

Determination of Toxoplasma gondii in several organs of cattle by carbon immunoassay (CIA) testing.

Samples of muscle, heart, liver and lung were tested for the presence of Toxoplasma gondii using mice as a biologic detector and the carbon immunoassay (CIA) for immunological diagnosis. In positive tissues the percentage of samples positive ranged from 10 to 50% which indicates the importance of cattle in the epidemiology of Toxoplasma in Costa Rica. We discuss these findings in relation to the transmission of the parasite in Costa Rica.

Cockroaches as transport hosts of the protozoan Toxoplasma gondii

Las cucarachas Eurycotis biolleyi y Blatella germanica ingieren heces de gato aún en presencia de azúcar, queso o masa de maíz. Además, los ooquistes de Toxoplasma pueden mantenerse viables externa e internamente en esos insectos hasta 19 días después de la exposición experimental. Se agregan así dos nuevos vectores mecánicos en la transmisión de T. gondii

Natural and induced blood dissemination of Toxoplasma gondii: experimental model in white mice and hamsters.

Blood inoculation in mice showed that Toxoplasma organisms circulate in blood after 1 h of oocyst infection. Parasites were detected up to 15 days later and then disappeared from the bloodstream concomitantly with cyst formation in the brain, probably due to antibody presence. Immunosuppression caused by cortisone acetate treatment induced Toxoplasma bloodstream invasion in chronically infected mice and hamsters, causing death in some. Natural dissemination is discussed in relation with congenital toxoplasmosis. Induced immunosuppressive effect is compared with that produced by natural diseases such as Hodgkin, lymphoma, AIDS and others.

Natural and induced blood dissemination of Toxoplasma gondii: experimental model in white mice and hamsters

Blood inoculation in mice showed that Toxoplasma organisms circulate in blood after 1 h of oocyst infection. Parasites were detected up to 15 days later and then disappeared from the bloodstream concomitantly with cyst formation in the brain, probably due to antibody presence. Immunosuppression caused by cortisone acetate treatment induced Toxoplasma bloodstream invasion in chronically infected mice and hamsters, causing death in some. Natural dissemination is discussed in relation with congenital toxoplasmosis. Induced immunosuppressive effect is compared with that produced by natural diseases such as Hodgkin, lymphoma, AIDS and others

[Effect of corticosteroids on the congenital transmission of experimental toxoplasmosis]. / Efecto de los corticosteroides en la trasmisión congénita de toxoplasmosis experimental.

Female white mice with chronic toxoplasmosis were treated with cortisone acetate (3mg for each 25 g of body weight) 12, 8, 4 and 0 days before mating. Cortisone induces congenital transmission of T. gondii.

Efecto de los corticosteroides en la trasmisión congénita de toxoplamosis experimental / Effect of corticosteroids in the congenital transmission of experimental toxoplasmosis

Female white mice with chronic toxoplamosis were treated with cortisone acetate (3mg for each 25 g of body weight) 12, 8, 4 and 0 days before mating. Cortisone induces congenital transmission of T. gondii

[The presence of cysts in Tritrichomonas muris]. / Presencia de quistes en Tritrichomonas muris.

Cysts of Tritrichomonas muris are reported. The morphology of this evolution stage is described under light and electron microscopy. The biologic and epidemiologic importance of this finding is discussed.

Presencia de quistes en Tritrichomonas muris / The presence of cysts in Tritrichomonas muris

Se describen formas quísticas de Tritrichomonas muris tal y como se observan a fresco, teñidas con hematoxilina y en preparaciones estudiadas al microscopio electrónico. Se comenta la importancia del hallazgo desde los puntos vista biológico y epidemiológico

Rat macrophage activity against Toxoplasma gondii studied by electron microscopy.

An electron microscope model was used to study the effect of rat peritoneal macrophages on Toxoplasma gondii. 10(7) tachyzoites were injected i.p. in 30 days-old rats. After 1, 2, 4, 8 and 24 h peritoneal exudate was withdrawn and infected phagocytic cells were prepared for electronic microscope studies. Toxoplasma organisms inside of rat macrophages showed remarkable lesions such as vacuolization and organisms were totally lysed inside of macrophages of more than 8 h infection rats. The results confirm at molecular level, the importance of rat macrophages in the natural adaptation of this rodent to T. gondii.

[Natural adaptation of the white rat to Toxoplasma gondii]. / Adaptación natural de rata blanca a Toxoplasma gondii.

White rats were found to be resistant to 3 x 10(7) Toxoplasma gondii organisms (RH strain) inoculated either sc or ip. That resistance was age-dependent since survival time of 1- or 5-day-old rats inoculated with 10(4) or 10(6) tachyzoites was lower as compared with those 10 or 15 days old. Organisms kept in contact with a lysate of white rat complete peritoneal exudate showed reduced capacity to infect mice. Peritoneal exudate of 5-day-old rats showed a stronger effect than that of 1, 2, 3, or 4 day-infected animals. After 10 days the anti-toxoplasma effect diminished and it almost disappeared after 15 days of infection. Apparently age and macrophage activity are very important factors in the natural adaptability of the white rat to Toxoplasma gondii.