P. Penin

Protective effect of Trypanosoma rangeli against infections with a highly virulent strain of Trypanosoma cruzi

Summary We investigated the protective effect of Trypanosoma rangeli against infection with Trypanosoma cruzi in animal models of various ages and with different doses of inoculum. The age of the mice and the dose of parasites determined the course of the infection. When T. cruzi was inoculated into mice after challenge with T. rangeli, parasitaemia was more controlled, mortality decreased and histopathology showed lower inflammatory infiltration and pseudocysts. This study proposes a new murine model of the protective effect of recombinant proteins of T. rangeli for possible application in the vaccines field.

Relationships between histopathological findings and phylogenetic divergence in Trypanosoma cruzi

Problems have been raised by natural genetic diversity of Trypanosoma cruzi, the causal agent of Chagas’ disease, and other protozoa in terms of both basic and applied science. T. cruzi manifests a great diversity of medical and biological properties which could be the origin of clinical variability in the disease. We propose possible correlations between genetic distances, or phylogenetic divergence, and histopathological data. To ascertain this aspect, 15 cloned stocks pertaining to three major clones or genotypes (19, 20 and 39) were compared. Sets of 24 mice infected with each stock were studied for histopathological lesions. Brain, heart, lung, liver, spleen, urinary bladder, bone marrow, colon, kidney and skeletal muscle were extracted from each mouse. Qualitative and quantitative differences showed at histopathological examination. An important encephalic softening was found in brains of most mice infected by genotype 20, corresponding to areas of inflammation and liquified necrosis. Other inflammatory tissue lesions in the histological sections of the three genotypes were similar. Skeletal muscle tropism was higher than cardiac tropism in all the studied genotypes. All three genotypes shared parasite presence in skeletal muscle. Differences related to cardiac tropism were important: in genotype 19, 50% of studied stocks presented pseudocysts; 20% in genotype 20 and 83% in genotype 39. Parasite presence in other tissues was scanty: in brain only in genotype 20 and in spleen and liver only in genotype 39. We found important histopathogenicity differences among the three studied genotypes, but they do not support the hypothesis of zymodeme pathogenic specificity due to the great diversity among stocks within each genotype.

The prevalence of enteropathy due to Strongyloidiasis in Puerto Maldonado (Peruvian Amazon)

Human strongyloidiasis is an important health problem in the southeast region of Peruvian Amazon, due to its prevalence and long term morbidity. An epidemiological study was conducted in the Peruvian Amazon area of Puerto Maldonado to determine the prevalence of strongyloidiasis in the population. Stool samples were collected from 1,133 patients at the outpatient department of our clinic. Strongyloidiasis affected 221 examined patients (20%). Prevalence was highest in males, mostly in children and elderly men. People living in urban and marginal urban areas, those coming from outside the region, and Andean people, showed the highest prevalences. Pre-school children were more likely to be parasitized than older children. The most common symptoms were diarrhea (55%), abdominal pain (32%) and cough (53%). One in 7 (13%) affected patients presented with moderate or severe symptoms, including life-threatening complications. Other intestinal parasites were found frequently in patients diagnosed with strongyloidiasis. Improved human waste disposal services are considered to be the main requirement to reduce the high prevalence of this disease.

Biological comparison between three clones of Trypanosoma cruzi and the strain of origin (Bolivia) with reference to clonal evolution studies

After isolating three clones of Trypanosoma cruzi (Bolivia), we first characterized them according to parasitaemia, pleomorphism and virulence, and then histopathologically. The studys interest lies on the hypothesis that clonal evolution of T. cruzi has a major impact on biologically relevant properties of this parasite. Data obtained from the studies of parasitaemia, pleomorphism and virulence showed no differences between the groups studied. As a final point, the histopathological study shows us a muscular tissue tropism both in clones and in their mother strain (Bolivia). In this paper, we conclude that Bolivia strain and clones isolated from it, pertaining to the same major clone share similar biological properties.

Characterization of a Trypanosoma rangeli strain of colombian origin

A Colombian strain of Trypanosoma rangeli was characterized by analyzing its behaviour in different axenic and cellular culture, its infection rate and the histopathological lesions produced in experimental animals. Although slight inflammatory infiltrations were shown in different histopathological sections, no pseudocysts could be observed. Graces insect medium is better than liver infusion tryptose or artificial triatomine urine supplemented with proline when studying T. rangeli metacyclogenesis, with a peak of 32% trypomastigotes. High infection rates were found in VERO and J774 cells. Because of its 100% infectivity rates and adequacy of parasitemia levels, C23 strain is a suitable model of T. rangeli biology study.

Trypanosoma rangeli : increase in virulence with inocula of different origins in the experimental infection in mice

Abstract We compared two murine models of Trypanosoma rangeli infection. The same inoculum dose and age-matched hosts were used in both cases. One group was infected with trypomastigotes obtained from passages in mice and the other, with trypomastigotes obtained from cell culture after a passage in mice. We observed that trypomastigotes obtained from the in vitro cellular infection showed increased virulence in␣experimental animals, with a 70% rate of death being noted in experimental mice instead of the lack of mortality seen when in vivo-derived parasites were used. The greatest levels of parasitemia and tissual lesions in the presence of the parasite also occurred when in vitro-derived parasites were used.

An epidemiological study of malaria in Bioko and Annobón islands (Equatorial Guinea).

A seroparasitological study of malaria was carried out in two of the more important islands of Equatorial Guinea, Bioko (ex Fernando Poo) and Annobón. The study involved a randomly-chosen population of children aged from two to nine years. In Bioko 1130 children were chosen from 29 of the 51 villages on the island; in Annobón 185 children were chosen from the capital town, where all the population lived. Indirect immunofluorescence tests (IFAT) showed a prevalence of malaria infection of 29.8% in Bioko and 55.7% in Annobón. The parasitic prevalence (malaria index) was 26.6% and 55.1% respectively, and the splenic index was 57.0% and 54.6% respectively. The results indicate that this is an area of stable hyperendemic malaria, which may benefit from an antimalarial programme.

Is the malaria diagnosis expensive

Malaria remains the most important of the tropical diseases, widespread throughout the tropics, but also occurring in many temperate regions. The disease causes a heavy toll of illness and death, especially among children in endemic areas. It also poses a risk to business travellers, tourists and inmigrants and imported cases of malaria are increasingly seen in non-endemic areas. We discuss here how microscopical diagnosis is essential for identifyingPlasmodium species responsible of the infection and discarding possible mixed infections. Thus, a correct treatment can be administered in 30 min, avoiding secondary stays and saving important amounts of money. Problems of drug resistance have to be distinguished from those arising due to erroneous diagnosis.

A clinical-parasitological monotherapy cure in the treatment of experimental infection by a highly virulent strain of Toxoplasma gondii

Toxoplasmic encephalitis in patients with the acquired immunodeficiency syndrome (AIDS) is treated classically with pyrimethamine plus sulfadiazine. Unfortunately, up to 40% of these patients are unable to complete, the course of therapy because of adverse reactions to sulfonamides. This study considers the possible usefulness of monotherapies in the treatment of acute toxoplasmosis, producing parasitological cures 2–3 months after the date of infection. With this therapy, the main adverse effects are suppressed. Groups of mice infected with the RH strain ofToxoplasma gondii were treated with pyrimethamine alone, sulfadiazine alone, and pyrimethamine plus sulfadiazine for 7 d. Treatment with pyrimethamine plus sulfadiazine produced clinical cures in 100% of the infected mice 1 month after infection. Treatment with pyrimethamine gave a 60% survival rate (clinical cure), at 1 month postinfection. Finally, treatment with sulfadiazine produced a 60% survival rate at 1 month postinfection. Although the antitoxoplasmic regimen with pyrimethamine plus sulfadiazine has proven to be effective in intensive treatment of toxoplasmic encephalitis, relapses occur in more than 80% of cases after cessation of antitoxoplasmic therapy, making secondary prophylaxis mandatory. In this study the efficacy of treatment was also evaluated in terms of parasitological cure. None of the three therapies showed parasitological cure after 1 month of treatment. When the intervals were extended to a 3-month observation, monotherapy with pyrimethamine and sulfadiazine alone produced a parasitological cure.