Action of Trypanosoma rangeli in infections with virulent Trypanosoma cruzi populations

In experimental murine infections with Trypanosoma rangeli it has been observed development immune response to Trypanosoma cruzi. The aim of the present work was to analyze the result of antigenic stimuli and the protective effect with T. rangeli in T. cruzi infections. Mice groups immunized with metacyclic trypomastigotes of T. rangeli (Choach -2V strain), derived from haemolymph and salivary gland and reinfected with T. cruzi virulent populations (Tulahuen strain, SA strain and Dm28c clone) from infected in vitro cells, showed decrease severity of disease outcomes, low parasitemia levels and 100% survival of all mice immunized, in comparison with groups infected only with T. cruzi populations, which demonstrated tissue affection, high parasitemia levels and the death of all animals. The above mentioned data contribute to understand the biological behaviour of T. cruzi and T. rangeli and their interaction with vertebrate host.     

Population distribution and zoonotic potential of gastrointestinal helminths of wild rats Rattus rattus and R. norvegicus from Jamaica

The population distribution and zoonotic potential of gastrointestinal helminths in a naturally infected population of wild rats (Rattus rattus and Rattus norvegicus) in Jamaica are described. One hundred and thirty (29.7%) of 437 rats captured in the study were infected: 104 (35%) of 297 R. rattus compared with 26 (18.6%) of 140 R. norvegicus. Nine species of gastrointestinal helminths were recovered: Raillietina sp. (0.2%), Trichuris sp. (0.2%), Rictularia sp. (0.7%), Syphacia obvelata (1.1%), Strongyloides ratti (1.4%), Hymenolepis diminuta (3.8%), Protospirura muricola (4.3%), Moniliformis moniliformis (11.2%), and Nippostrongylus brasiliensis (14.2%). In a logistic model, the single risk factor identified for both M. moniliformis and P. muricola was R. rattus, compared with R. norvegicus (OR = 8.369 and 9.714, respectively). In comparison, the risk factor predicted for infection with N. brasiliensis was the northeastern section of Jamaica (OR = 11.000) compared with western Jamaica. Rictularia sp. represents a new geographic distribution record for the Caribbean region. Hymenolepis diminuta, M. moniliformis, Raillietina sp., and Rictularia sp. are potentially zoonotic, but only human infection with H. diminuta has been previously reported in the Caribbean.     

Trypanosoma (Herpetosoma) rangeli Tejera, 1920: an updated review

Trypanosoma rangeli, a parasite generally considered non-pathogenic for man, is the second species of human trypanosome to be reported from the New World. The geographical distribution of T. rangeli often overlaps with that of T. cruzi, the same vertebrate and invertebrate hosts being infected. Their differentiation thus becomes of real, practical importance, particularly as they share approximately half the antigenic determinants recognized by the humoral response. Little is known about the life cycle of T. rangeli in the vertebrate host, although thousands of human and wild animal infections have been reported. Recent studies have revealed 2 major phylogenetic lineages in T. rangeli having different characteristics, thus leading to better understanding of the epidemiology and interactions with this parasite's vertebrate hosts and triatomine vectors. Based on further genetic characterization analysis, the authors have proposed 2 alternative hypotheses and consider that T. rangeli could have had clonal evolution or have been subjected to speciation processes.     

Household risk factors for Trypanosoma cruzi seropositivity in two geographic regions of Ecuador

Few studies on the relationship between environmental factors and Trypanosoma cruzi transmission have been conducted in Ecuador. We conducted a cross-sectional study of household risk factors for T. cruzi seropositivity in 2 distinct geographical regions of Ecuador. Exposure information was collected via household surveys, and subjects were tested for serological evidence of T. cruzi infection. In total, 3,286 subjects from 997 households were included. In the coastal region, factors associated with seropositivity were living in a house with a palm roof (odds ratio [OR] = 2.63, 95% confidence interval, [1.61. 4.27]), wood walls (OR = 5.75 [2.04, 16.18]), or cane walls (OR = 2.81 11.31, 6.04]), and the presence of firewood in the peridomicile (OR = 2.48 [1.54, 4.01]). Accumulation of trash outside the home was associated with a reduced risk of seropositivity (OR = 0.25 [0.12, 0.51]). In the Andean region, living in a house with adobe walls was the only factor predictive of T. cruzi seropositivity. In conclusion, risk factors for T. cruzi transmission in Ecuador varied by geographic region, probably because of differing behavior of the triatomine vector species in each region. An understanding of the transmission dynamics of T. cruzi in a particular area is necessary for the development of effective Chagas disease control strategies in those areas.     

Vaccination with Trypanosoma rangeli modulates the profiles of immunoglobulins and IL-6 at local and systemic levels in the early phase of Trypanosoma cruzi experimental infection

In America, there are two species of Trypanosoma that can infect humans: Trypanosoma cruzi, which is responsible for Chagas disease and Trypanosoma rangeli, which is not pathogenic. We have developed a model of vaccination in mice with T. rangeli epimastigotes that protects against T. cruzi infection. The goal of this work was to study the pattern of specific immunoglobulins in the peritoneum (the site of infection) and in the sera of mice immunized with T. rangeli before and after challenge with T. cruzi. Additionally, we studied the effects triggered by antigen-antibodies binding and the levels of key cytokines involved in the humoral response, such as IL-4, IL-5 and IL-6. The immunization triggered the production of antibodies reactive with T. cruzi in peritoneal fluid (PF) and in serum, mainly IgG1 and, to a lesser magnitude, IgG2. Only immunized mice developed specific IgG3 antibodies in their peritoneal cavities. Antibodies were able to bind to the surface of the parasites and agglutinate them. Among the cytokines studied, IL-6 was elevated in PF during early infection, with higher levels in non-immunized-infected mice. The results indicate that T. rangeli vaccination against T. cruzi infection triggers a high production of specific IgG isotypes in PF and sera before infection and modulates the levels of IL-6 in PF in the early periods of infection.     

Triatomines involved in domestic and wild Trypanosoma cruzi transmission in Concepción, Corrientes, Argentina

An entomological and serological survey was performed in three localities of the Department of Concepción, Province of Corrientes, Argentina in 1998 and 1999, to identify triatomines species involved in domestic and wild transmission of Chagas disease. Triatomines were collected by man/hour capture in 32 houses randomly selected and 44 nearby outdoor ecotopes. Trypanosoma cruzi infection in triatomines was assessed by direct microscopic observation (400x) of feces and polymerase chain reaction. Serological techniques used for people were Indirect Hemagglutination Test and Indirect Fluorescent Test. Triatomines were collected in 28.1% of the houses and 31.8% of the wild biotopes. Triatoma infestans (Klug 1834) was exclusively found indoors and T. cruzi infected 60% of them. Triatoma sordida (St?l 1859) was mainly found in extradomestic ecotopes where trypanosome infection rate reached 12.7%. Serological study of 98 local people showed that 29.6% were seroreactive; most of their houses were closed to wild biotopes colonized by T. sordida. Results indicate that there is an active T. infestans mediated transmission of Chagas disease in this zone that yields important human prevalence and that the populations of T. sordida in wild biotopes not only sustain the wild T. cruzi cycle but also represent an actual risk for people living in the area.     

Experimental transmission of the parasitic flagellates Trypanosoma cruzi and Trypanosoma rangeli between triatomine bugs or mice and captive neotropical bats

Trypanosoma cruzi and Trypanosoma rangeli-like trypanosomes have been found in a variety of neotropical bat species. In this study, bats (Artibeus lituratus, Carollia perspicillata, Desmodus rotundus, Glossophaga soricina, Molossus molossus, Phyllostomus hastatus) were maintained under controlled conditions, and experiments were conducted to determine how they might become infected naturally with trypanosomes. All bats were first screened for existing infections by hemoculture and the examination of blood smears, and only apparently uninfected animals were then used in the experiments. Proof was obtained that the triatomine bug Rhodnius prolixus would readily feed upon some of the bats, and two species became infected after being bitten by bugs infected with T. rangeli. Some bats also became infected by ingesting R. prolixus carrying T. cruzi, or following subcutaneous or intragastic inoculation with fecal suspensions of R. prolixus containing T. cruzi. P. hastatus became infected after ingesting mice carrying T. cruzi. All of the bats studied inhabit roosts that may be occupied by triatomine bugs and, with the exception of D. rotundus, all also feed to at least some extent upon insects. These findings provide further evidence of how bats may play significant roles in the epidemiology of T. cruzi and T. rangeli in the New World tropics.     

Predominance of Trypanosoma rangeli infection in children from a Chagas disease endemic area in the west-shore of the Panama canal

A total of 206 serum samples from children (3-14 years old) living in the Amador County (La Chorrera District, Province of Panama) were screened by indirect immunofluorescence antibody test (IFAT) for the presence of antibodies against Trypanosoma cruzi. Positive sera were confirmed by recombinant enzyme-linked immunosorbent assay (ELISA) and Western blot analysis. The presence of blood trypanosomes was investigated by hemoculture and subsequently identify by a duplex polymerase chain reaction (PCR) followed by dot blot hybridization. The results indicated a prevalence of 9.7% for trypanosome infections, a seroprevalence of 2.9% against T. cruzi and a predominance of T. rangeli infection (6.8%). The immunological and clinical implications of these findings are discussed.     

Epidemiology of Chagas disease in Ecuador. A brief review

Chagas disease is a complex public health problem that has been underestimated in Ecuador. Here we review the relevant published information, and present unpublished and new data that help to understand the current Chagas disease epidemiological situation and its evolution in the country. Three main characteristics have been identified: (i) persistence of Trypanosoma cruzi transmission in already known foci; (ii) a marked endemicity in some urban areas of Guayaquil; and (iii) the transformation of new Amazon foci into truly endemic areas. The situation in other suspect areas remains uncertain. Five Triatominae species have been implicated in the transmission of T. cruzi to people in Ecuador (Triatoma dimidiata, Rhodnius ecuadoriensis, R. pictipes, R. robustus and Panstrongylus geniculatus), but some others may also play a role in some areas (P. rufotuberculatus, P. howardi, T. carrioni and P. chinai). Other Triatominae reported seem to have little or no epidemiological relevance (T. venosa, T. dispar, Eratyrus mucronatus, E. cuspidatus, P. lignarius and Cavernicola pilosa). High frequency of acute cases and severe chronic disease has been observed. Although cardiomyopathy is more frequent, serious digestive disease is also present. It is estimated that around 120,000-200,000 people may be infected. 2.2 to 3.8 million people are estimated to live under transmission risk conditions.     

Prevalence and molecular phylogenetic characterization of Trypanosoma (Megatrypanum) minasense in the peripheral blood of small neotropical primates after a quarantine period

Neotropical primates of the Cebidae and Callitrichidae, in their natural habitats, are frequently infected with a variety of trypanosomes including Trypanosoma cruzi, which causes a serious zoonosis, Chagas' disease. The state of trypanosome infection after a 30-day quarantine period was assessed in 85 squirrel monkeys (Saimiri sciureus) and 15 red-handed tamarins (Saguinus midas), that were wild-caught and exported to Japan as companion animals or laboratory animals, for biomedical research, respectively. In addition to many microfilariae of Mansonella (Tetrapetalonema) mariae at a prevalence of 25.9%, and Dipetalonema caudispina at a prevalence of 3.5%, a few trypomastigotes of Trypanosoma (Megatrypanum) minasense were detected in Giemsa-stained thin films of blood from 20 squirrel monkeys at a prevalence of 23.5%. Although few T. minasense trypomastigotes were found in Giemsa-stained blood films from tamarins, a buffy-coat examination detected trypanosomes in 12 red-handed tamarins (80.0%), and PCR amplification of a highly variable region of the small subunit ribosomal RNA genes (SSU rDNA) for Trypanosoma spp. detected the infection in 14 of the 15 tamarins (93.3%). Nucleotide sequences of the amplicons were identical for trypanosomes from tamarins and squirrel monkeys, indicating a high prevalence but low parasitemia of T. minasense in imported Neotropical nonhuman primates. Based on the SSU rDNA and 5.8S rDNA, the molecular phylogenetic characterization of T. minasense indicated that T. minasense is closely related to trypanosomes with Trypanosoma theileri-like morphology and is distinct from Trypanosoma (Tejeraia) rangeli, as well as from T. cruzi. Using some blood samples from these monkeys, amplification and subsequent sequencing of the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene fragments detected 4 trypanosome genotypes, including 2 types of T. cruzi clade, 1 type of T. rangeli clade, and 1 T. rangeli-related type, but failed to indicate its phylogenetic position based on the gGAPDH gene. Furthermore, species ordinarily classified in the Megatrypanum by morphological criteria do not form a clade in any molecular phylogenetic trees based on rDNA or gGAPDH genes.     

The taxonomic position and evolutionary relationships of Trypanosoma rangeli.

This paper presents a re-evaluation of the taxonomic position and evolutionary relationships of Trypanosoma (Herpetosoma) rangeli based on the phylogenetic analysis of ssrRNA sequences of 64 Trypanosoma species and comparison of mini-exon sequences. All five isolates of T. rangeli grouped together in a clade containing Trypanosoma (Schizotrypanum) cruzi and a range of closely related trypanosome species from bats [Trypanosoma (Schizotrypanum) dionisii, Trypanosoma (Schizotrypanum) vespertilionis] and other South American mammals [Trypanosoma (Herpetosoma) leeuwenhoeki, Trypanosoma (Megatrypanum) minasense, Trypanosoma (Megatrypanum) conorhini] and an as yet unidentified species of trypanosome from an Australian kangaroo. Significantly T. rangeli failed to group with (a) species of subgenus Herpetosoma, other than those which are probably synonyms of T. rangeli, or (b) species transmitted via the salivarian route, although either of these outcomes would have been more consistent with the current taxonomic and biological status of T. rangeli. We propose that use of the names Herpetosoma and Megatrypanum should be discontinued, since these subgenera are clearly polyphyletic and lack evolutionary and taxonomic relevance. We hypothesise that T. rangeli and T. cruzi represent a group of mammalian trypanosomes which completed their early evolution and diversification in South America.     

A mathematical epidemiological model of gram-negative Bartonella bacteria: does differential ectoparasite load fully explain the differences in infection prevalence of Rattus rattus and Rattus norvegicus?

We postulate that the large difference in infection prevalence, 24% versus 5%, in R. norvegicus and R. rattus, respectively, between these two co-occurring host species may be due to differences in ectoparasite and potential vector infestation rates. A compartmental model, representative of an infectious system containing these two Rattus species and two ectoparasite vectors, was constructed and the coefficients of the forces of infection determined mathematically. The maximum difference obtained by the model in the prevalence of Bartonella in the two Rattus species amounts to 4.6%, compared to the observed mean difference of 19%. Results suggest the observed higher Bartonella infection prevalence in Rattus norvegicus compared to Rattus rattus, cannot be explained solely by higher ectoparasite load. The model also highlights the need for more detailed biological research on Bartonella infections in Rattus and the importance of the flea vector in the spread of this disease.     

Epidemiology of Chagas disease in non-endemic countries: the role of international migration

Human infection with the protozoa Trypanosoma cruzi extends through North, Central, and South America, affecting 21 countries. Most human infections in the Western Hemisphere occur through contact with infected bloodsucking insects of the triatomine species. As T. cruzi can be detected in the blood of untreated infected individuals, decades after infection took place; the infection can be also transmitted through blood transfusion and organ transplant, which is considered the second most common mode of transmission for T. cruzi. The third mode of transmission is congenital infection. Economic hardship, political problems, or both, have spurred migration from Chagas endemic countries to developed countries. The main destination of this immigration is Australia, Canada, Spain, and the United States. In fact, human infection through blood or organ transplantation, as well as confirmed or potential cases of congenital infections has been described in Spain and in the United States. Estimates reported here indicates that in Australia in 2005-2006, 1067 of the 65,255 Latin American immigrants (16 per 1000) may be infected with T. cruzi, and in Canada, in 2001, 1218 of the 131,135 immigrants (9 per 1000) whose country of origin was identified may have been also infected. In Spain, a magnet for Latin American immigrants since the 2000, 6141 of 38,777 to 339,954 [corrected] legal immigrants in 2003 (25 per 1000), could be infected. In the United States, 56,028 to 357,205 of the 7,20 million, legal immigrants (8 to 50 per 1000), depending on the scenario, from the period 1981-2005 may be infected with T. cruzi. On the other hand, 33,193 to 336,097 of the estimated 5,6 million undocumented immigrants in 2000 (6 to 59 per 1000) could be infected. Non endemic countries receiving immigrants from the endemic ones should develop policies to protect organ recipients from T. cruzi infection, prevent tainting the blood supply with T. cruzi, and implement secondary prevention of congenital Chagas disease.     

Antigenic make-up of Trypanosoma cruzi culture forms: identification of a specific component.

A comparison of Trypanosoma cruzi water soluble antigens with those of stercorarian and salivarian trypanosomes, and Leishmania using immunoprecipitation in gels and immunoelectrophoresis, with the aid of hyperimmune rabbit serum and heterologous adsorptions showed the following. 1) There is a high complexity of soluble antigens of T. cruzi and T. rangeli. 2) At the intraspecific level our results demonstrated the antigenic stability of T. cruzi when maintained in vitro, and that there was quantitative antigenic consistency of the culture forms of different strains of T. cruzi from diverse geographic and parasite sources. At the interspecific level, the antigenic relationships between T. cruzi and the other Trypanosomatidae were established, as follows: 6/10ths of the antigens are shared by stercorarian species (T. dionisii, T. rangeli); 4/10ths by a salivarian trypanosome (T. brucei); and 3/10ths by Leishmania (L. donovani, L. mexicana). 3) Among the 4/10ths of antigenic components specific to T. cruzi, one component was characterized by its antigenicity and immunogenicity in natural and experimental infections, and in immunization experiments; this component was specific to T. cruzi when compared to the other Trypanosomatidae antigens.     

Vertical transmission of Trypanosoma cruzi in the Province of Choapa, IV Region, Chile: Preliminary Report (2005-2008)

Congenital Chagas disease acquired special importance in Chile after the certification of the control of Triatoma infestans and transmission by blood donors affected with Trypanosoma cruzi. In order to establish adequate protocols for intervention and control in infected mother-neonate pairs in endemic zones of Chagas disease, we present partial results (2005-2008) of a pilot project which is being carried out in the Province of Choapa, IV Region, Chile, whose objectives are: determine the current prevalence of the disease in pregnant women, estimate the incidence of vertical transmission of T. cruzi to newborns, determine the lineages of the parasite present in mothers who do and do not transmit the disease, determine the prevalence of Chagas disease in maternal grandmothers of neonates and study placental histopathology. Preliminary results indicated that in this study period, 3.7% of the women who gave birth in the Province have Chagas disease and 2.5% of their newborns were infected. The most frequent T. cruzi genotypes found in mothers studied during pregnancy were TCI and TCIId, either alone or in mixed infections. A high percentage (74.3%) of the grandmothers studied was infected with the parasite. In 29 placentas from mothers with Chagas disease we observed edema, necrosis, fibrinoid deposits and slight lymphoplasmocyte infiltration. In three placentas we found erythroblastosis and in one of them amastigote forms of T. cruzi; this was one of the cases of congenital infection. The evaluation of the diagnostic and control protocols generated will allow us to determine if it has been possible to modify the natural history of vertical transmission of T. cruzi in Chile.     

A simplified method for sample collection and DNA isolation for polymerase chain reaction detection of Trypanosoma rangeli and Trypanosoma cruzi in triatomine vectors

Due to the overlapping distribution of Trypanosoma rangeli and T. cruzi in Central and South America, sharing several reservoirs and triatomine vectors, we herein describe a simple method to collect triatomine feces and hemolymph in filter paper for further detection and specific characterization of these two trypanosomes. Experimentally infected triatomines feces and hemolymph were collected in filter paper and specific detection of T. rangeli or T. cruzi DNA by polymerase chain reaction was achieved. This simple DNA collection method allows sample collection in the field and further specific trypanosome detection and characterization in the laboratory.     

Experimental transmission of Trypanosoma cruzi through the genitalia of albino mice

Trypanosoma cruzi is usually transmitted by contact with the excreta of infected Triatominae; among non-vectorial infections, direct transmission through coitus has been proposed. We investigated this possibility by instilling, through the external meatus of the vagina and the penis of previously anesthetized NMRI albino mice, blood of mice infected with strains isolated from Didelphis marsupialis (opossum, strain CO57), Rattus rattus (rat, strain CO22) and human (strain EP). Some animals were allowed to copulate the same day of the instillation. In other experiments, the strains were inoculated in the scrotum. To determine the effect of immunosuppression, some mice were treated with cyclophosphamide 30 days post-instillation. Controls were instilled orally and ocularly. Vaginal instillation with strain CO22 produced systemic infection with tropism to the heart, skeletal muscle, skin, duodenum, pancreas, ovary and sternum. Scrotal inoculation with strain EP likewise invaded liver, spleen, lung, lymph nodes and urogenital organs; while strain CO57 invaded skeletal and cardiac muscle, pancreas, testis, and vas deferens. Penile infection with strain CO22 was detected by xenodiagnosis. Immunosuppression did not increase parasitemia of vaginally infected mice or controls. Mating did not produce infection. Our results show that contact of blood trypomastigotes of T. cruzi with genital mucosa can produce blood and tissue infections. These results are discussed in relation to reports of frequent experimental tropism of T. cruzi toward urogenital organs.     

Resolution of multiclonal infections of Trypanosoma cruzi from naturally infected triatomine bugs and from experimentally infected mice by direct plating on a sensitive solid medium

The isolation of biological clones of Trypanosoma cruzi by microscopically dispensing individual organisms or by serial dilution is laborious and time consuming. The inability to resolve mixed T. cruzi infections, from vectors and hosts, and to isolate clones of slow growing genotypes by efficient plating on solid media, has hindered characterisation studies and downstream applications. We have devised and validated a sensitive, solid medium plating technique for rapid in vitro isolation of clones representative of all the recognised T. cruzi lineages (TCI, TCIIa-e), including the slow growing strain CANIII (TC IIa) and Trypanosoma rangeli, with high plating efficiencies. Furthermore, the method is effective for the isolation of clones directly from silvatic triatomine bugs and from experimentally infected mice harbouring mixed infections, allowing resolution of multiclonal infections from varied sources.     

High infection rates of Triatoma dimidiata are associated with low levels of Trypanosoma cruzi seroprevalence in Pedro Carbo, Ecuador. Use of a tc24 gene-based PCR approach

In control programs for vectorial transmission of Chagas' disease, conventional microscopic procedures are generally performed to determine baseline levels of infectivity of vectors. Reported here are data using Polymerase Chain Reaction in the detection of Trypanosoma cruzi in Triatoma dimidiata, one of the principal vectors of Chagas' disease in Ecuador. The microscopy and PCR techniques showed a high percentage of vector infection in Pedro Carbo, province of Guayas (Ecuador), with 44.16% and 46.13% positive insects, respectively. This contrasted with the very low Chagas seropositivity recorded (0.5%). Since T. dimidiata was the only vector of the Chagas' disease found in Pedro Carbo and looking at the vector behavior, our data suggest that despite the high T. dimidiata infection, the low Chagas seropositivity detected is closely associated with the epidemiological and ecological context of T. dimidiata in Pedro Carbo.     

Prevalence of Trypanosoma lewisi in Rattus norvegicus from Belo Horizonte,State of Minas Gerais,Brazil

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).