Human trypanosome infection and the presence of intradomicile Rhodnius pallescens in the western border of the Panama Canal, Panama. (49/251)

An entomologic search was carried out to collect intradomicile triatomines in dwellings from rural communities in the western border of the Panama Canal, Panama. Sixty-nine triatomines were collected inside 20 houses of 67 houses investigated. Rhodnius pallescens was the only triatomine species found and included adults of both sexes and nymphs. A significantly high Trypanosoma cruzi (72.7%) and T. rangeli (40%) vector infection rate was detected. Blood meal analysis showed that 68% of R. pallescens had fed on humans. Human serologic analysis and hemoculture performed on inhabitants from triatomine-infested houses showed that 32.1% (18 of 56) of the samples were trypanosome infected. Thirteen samples (23.2%) had antibodies against T. cruzi. Six of these seropositive samples were from children less than 15 years old. Trypanosoma rangeli was isolated in five hemoculture samples, all from children less than 11 years old. The epidemiologic implications of these findings in terms of human infection are discussed.  (+info)

Phenotypic plasticity and geographic variation in thermal tolerance and water loss of the tsetse Glossina pallidipes (Diptera: Glossinidae): implications for distribution modelling. (50/251)

Using the tsetse, Glossina pallidipes, we show that physiologic plasticity (resulting from temperature acclimation) accounts for among-population variation in thermal tolerance and water loss rates. Critical thermal minimum (CT(Min)) was highly variable among populations, seasons, and acclimation treatments, and the full range of variation was 9.3 degrees C (maximum value = 3.1 x minimum). Water loss rate showed similar variation (max = 3.7 x min). In contrast, critical thermal maxima (CT(Max)) varied least among populations, seasons, and acclimation treatments, and the full range of variation was only approximately 1 degree C. Most of the variation among the four field populations could be accounted for by phenotypic plasticity, which in the case of CT(Min), develops within 5 days of temperature exposure and is lost rapidly on return to the original conditions. Limited variation in CT(Max) supports bioclimatic models that suggest tsetse are likely to show range contraction with warming from climate change.  (+info)

Molecular profiling improves diagnoses of rejection and infection in transplanted organs. (51/251)

The monitoring of transplanted hearts is currently based on histological evaluation of endomyocardial biopsies, a method that is fairly insensitive and that does not always accurately discriminate between rejection and infection in the heart. Accurate diagnosis of rejection and infection is absolutely crucial, however, as the respective treatments are completely different. Using microarrays, we analyzed gene expression in 76 cardiac biopsies from 40 heart recipients undergoing rejection, no rejection, or Trypanosoma cruzi infection. We found a set of genes whose expression patterns were typical of acute rejection, and another set of genes that discriminated between rejection and T cruzi infection. These sets revealed acute rejection episodes up to 2 weeks earlier, and trypanosome infection up to 2 months earlier than did histological evaluation. When applied to raw data from other institutions, the 2 sets of predictive genes were also able to accurately pinpoint acute rejection of lung and kidney transplants, as well as bacterial infections in kidneys. In addition to their usefulness as diagnostic tools, the data suggest that there are similarities in the biology of the processes involved in rejection of different grafts and also in the tissue responses to pathogens as diverse as bacteria and protozoa.  (+info)

Endogenous glucocorticoids cause thymus atrophy but are protective during acute Trypanosoma cruzi infection. (52/251)

The cytokine-mediated stimulation of the hypothalamus-pituitary-adrenal (HPA) axis is relevant for survival during bacterial endotoxemia and certain viral infections. However, only limited information is available regarding the effects of endogenous glucocorticoids on parasite diseases. We have studied this issue using, as a model, C57Bl/6 and Balb/c mice infected with Trypanosoma cruzi, the causal agent of Chagas' disease. These two mouse strains differ in the susceptibility to infection with the parasite. An intense stimulation of the HPA-axis was observed 3 weeks after infection in both strains, but glucocorticoid levels were already increased two- to threefold in the less susceptible Balb/c strain during the first week. Blockade of glucocorticoid receptors with the glucocorticoid antagonist RU486, starting on day 10 after infection, partially reversed the thymic atrophy and decreased the number of CD4(+)CD8(+) thymocytes without affecting parasitemia and the number of inflammatory foci in the heart. However, tumor necrosis factor-alpha blood levels were increased in infected mice of both strains treated with RU486. Furthermore, the blockade of glucocorticoid receptors accelerated death in C57Bl/6J mice and increased lethality to 100% in Balb/c mice. The results obtained represent the first evidence that an endocrine host response that is coupled to the immune process can strongly affect the course of a parasite infection.  (+info)

Interspecific transfer of bacterial endosymbionts between tsetse fly species: infection establishment and effect on host fitness. (53/251)

Tsetse flies (Glossina spp.) can harbor up to three distinct species of endosymbiotic bacteria that exhibit unique modes of transmission and evolutionary histories with their host. Two mutualist enterics, Wigglesworthia and Sodalis, are transmitted maternally to tsetse flies' intrauterine larvae. The third symbiont, from the genus Wolbachia, parasitizes developing oocytes. In this study, we determined that Sodalis isolates from several tsetse fly species are virtually identical based on a phylogenetic analysis of their ftsZ gene sequences. Furthermore, restriction fragment-length polymorphism analysis revealed little variation in the genomes of Sodalis isolates from tsetse fly species within different subgenera (Glossina fuscipes fuscipes and Glossina morsitans morsitans). We also examined the impact on host fitness of transinfecting G. fuscipes fuscipes and G. morsitans morsitans flies with reciprocal Sodalis strains. Tsetse flies cleared of their native Sodalis symbionts were successfully repopulated with the Sodalis species isolated from a different tsetse fly species. These transinfected flies effectively transmitted the novel symbionts to their offspring and experienced no detrimental fitness effects compared to their wild-type counterparts, as measured by longevity and fecundity. Quantitative PCR analysis revealed that transinfected flies maintained their Sodalis populations at densities comparable to those in flies harboring native symbionts. Our ability to transinfect tsetse flies is indicative of Sodalis ' recent evolutionary history with its tsetse fly host and demonstrates that this procedure may be used as a means of streamlining future paratransgenesis experiments.  (+info)

A galactosyl(alpha 1-3)mannose epitope on phospholipids of Leishmania mexicana and L. braziliensis is recognized by trypanosomatid-infected human sera. (54/251)

An immunoglobulin M antibody reactive with galactosyl(alpha 1-3)mannose [Gal(alpha 1-3)Man] residues present on phospholipids extracted from Leishmania mexicana and L. braziliensis was found to be present in high titer in the serum of every normal individual studied. Periodate oxidation, acid hydrolysis, or acetylation suppressed immunoreactivity, suggesting that an oligosaccharide chain was responsible for antibody binding. Interaction occurs only with alpha-Gal terminal residues, since treatment of purified glycophospholipids with alpha-galactosidase but not with beta-galactosidase abolished it. Antibody bound to galactosyl(alpha 1-3)galactose-linked synthetic antigens but did not bind to the same residues present in rabbit, rat, and guinea pig erythrocytes or in murine laminin. Antigen-antibody binding was strongly blocked with Gal(alpha 1-3)Man and Gal(beta 1-4)Man. These results plus inhibition studies with several oligosaccharides suggest that they are indeed different from antibodies against the galactosyl(alpha 1-3)galactose residue. Anti-Gal(alpha 1-3)Man antibody values were significantly elevated in 89% of patients with diffuse cutaneous leishmaniasis, 84% of patients with localized cutaneous leishmaniasis, 69% of patients with mucocutaneous leishmaniasis, and 44 and 62% of patients with Trypanosoma cruzi or T. rangeli infection, respectively, but not in patients with 15 other different infectious and inflammatory diseases. Anti-Gal(alpha 1-3)Man antibody readily absorbed to American Leishmania and Trypanosoma culture forms, suggesting a surface membrane localization of reactive epitope. Gal(alpha 1-3)Man-bearing glycophospholipid was easily extracted from American Leishmania promastigotes and T. cruzi trypomastigotes as well as from American Trypanosoma culture forms. The possibility that this antibody arises against parasitic glycophospholipid-linked Gal(alpha 1-3)Man terminal residues is proposed.  (+info)

Polymerase chain reaction detection and serologic follow-up after treatment with benznidazole in Bolivian children infected with a natural mixture of Trypanosoma cruzi I and II. (55/251)

Thirty-five Bolivian children (5-10 years of age) seropositive for infection with T. cruzi underwent specific chemotherapy with benznidazole. Before treatment, 57.1% had a positive parasitologic diagnosis. Some patients presented an early conversion by polymerase chain reaction of blood samples, while others were still positive four and seven months after the end of the treatment, which indicated an absence of parasite clearance. Strain typing showed that most patients were infected by a mixture of clones I and II of T. cruzi. Serologic conversion in conventional tests and antibodies to shed acute-phase antigen were observed in two and four patients, respectively. For the other patients, the average rate of antibody decay was half the initial rate. The parasitologic and serologic data indicated that chemotherapy acts throughout the course of infection in a long-lasting process in which the decrease of specific antibody production is related to the reduction of the live parasite load.  (+info)

Short report: Human trypanosomiasis caused by Trypanosoma evansi in a village in India: preliminary serologic survey of the local population. (56/251)

After discovery of the first recorded case of human infection with Trypanosoma evansi, serologic screening of 1,806 persons from the village of origin of the patient in India was performed using the card agglutination test for trypanosomiasis and T. evansi. A total of 410 (22.7%) people were positive by whole blood, but only 81 were confirmed positive by serum. However, no trypanosomes were detected in the blood of 60 people who were positive at a high serum dilution. The results probably indicate frequent exposure of the human population to T. evansi in the study area, which suggests frequent vector transmission of parasites to humans. Although T. evansi is not infective for humans, a follow-up of seropositive persons is required to observe the evolution of human infection with this parasite.  (+info)