New host and locality records of coccidia (Apicomplexa: Eimeriidae) from rodents in the southwestern and western United States.

One hundred forty-seven murid and heteromyid rodents were collected from various sites in the southwestern and western United States (Arizona, Colorado, New Mexico, Texas, and Utah) and Baja California Norte, Mexico, and their feces were examined for coccidial parasites. Of these, 53 (36%) were infected with at least 1 coccidian; 45 of 53 (85%) of the infected rodents harbored only 1 species of coccidian. Infected rodents included: 10 of 22 (45%) Neotoma albigula, 3 of 11 (27%) Neotoma floridana, 2 of 14 (14%) Neotoma lepida, 15 of 29 (52%) Neotoma micropus, 5 of 8 (63%) Peromyscus crinitis, 6 of 6 (100%) Peromyscus difficilis, 1 of 2 (50%) Peromyscus eremicus, 9 of 34 (26%) Sigmodon hispidis, and 2 of 3 (67%) Sigmodon ochrognathus; 4 Neotoma cinerea, 3 Neotoma devia, 3 Neotoma mexicana, 1 Peromyscus maniculatus, 1 Onychomys leucogaster, 1 Onychomys torridus, 3 Chaetodipus fallax, and 2 Chaetodipus penicillatus were negative. Although no new species was found, the following coccidians were identified from infected rodents: Eimeria albigulae from N. albigula, N. floridana, and N. micropus, Eimeria antonellii from N. albigula and N. micropus, Eimeria ladronensis from N. albigula, N. floridana, N. lepida, and N. micropus, Eimeria arizonensis and Eimeria lachrymalis from P. crinitis and P. difficilis, Eimeria lachrymalis from P. eremicus, Eimeria tuskeegensis from S. ochrognathus, and Eimeria roperi, Eimeria sigmodontis, Eimeria tuskeegensis, Eimeria webbae, and an unidentified species of Eimeria from S. hispidis. This report documents 12 new host and several distributional records for Eimeria species from murid rodents in Arizona, Texas, and Utah.     

Reproducible and Predictable Yearly Pattern in the Incidence of Uterine Cervical Cancer

A yearly pattern in the occurrence of uterine cervical cancer (UCC), obtained from cytological examinations reported as type V (cases concluding a malignant alteration), has been previously shown for data obtained in the Monterrey Metropolitan Area (state of Nuevo Leon, Mexico) for a span of 10 years (1978-1987), with a peak of relative incidence in the month of February being highly stable for consecutive years. With the aim of extending and validating those results, we analyzed the monthly totals of positive detected cases of UCC in the states of Nuevo Leon, Chihuahua, Coahuila, and Tamaulipas (covering most of Northern Mexico) during the same period. To eliminate bias due to the seasonal variation in the number of screening smears, data were first expressed in relation to the number of cytological examinations done the same month. The least-squares fit of a 1 -year cosine curve to the data of relative incidence in the four states reveals a statistically significant yearly pattern (p = .008), with a maximum of relative incidence in February almost double that during the rest of the year. Results indicate that the relative incidence of UCC is higher than the yearly average during the winter, with secondary peaks in May and October. In view of the nonsi-nusoidal waveform in the incidence of UCC, we undertook a multiple-component analysis, allowing several cosine functions to be simultaneously fitted to the data. Results indicate that the yearly pattern in the relative incidence of UCC can be represented by a model that includes two components with periods of 12 and 4 months (p = .004). The same model can be documented as statistically significant independently for each of the four states. These results, summarizing over 2200 positive cases of UCC detected in more than 1,100,000 screening smears, are in full agreement with those found previously for part of the state of Nuevo Leon and reveal a highly stable and predictable yearly pattern of variation in the relative incidence of UCC in Northern Mexico. (Chronobiology International, 13(4), 305-316, 1996)     

Prevalence of infectious agents in free-ranging white-tailed deer in northeastern Mexico

The objectives of this study were to determine the prevalence of antibodies against brucellosis, leptospirosis, infectious bovine rhinotracheitis virus, and bovine viral diarrhea virus (BVDV) in white-tailed deer (Odocoileus virginianus) in northeastern Mexico. Deer (n=521) were captured from helicopter using a netgun on 15 ranches covering 62,114 ha in the states of Coahuila, Nuevo Leon, and Tamaulipas during spring 2004. The prevalence of antibodies against Leptospira, infectious bovine rhinotracheitis, BVDV, and brucellosis were 5.6, 41.1, 63.5, and 0%, respectively, indicating that white-tailed deer and cattle may share disease agents when cohabiting in northeastern Mexico.     

Histotropism and pathogenicity of Trypanosoma cruzi in albino mice (NHI) isolated from triatomines in Nuevo Leon, Mexico]

The neolonese strain of Trypanosoma cruzi was obtained from deyections of nosed bugs (Triatoma gerstaeckeri) which were caught in General Teran and Dr. Coss, Nuevo Leon. This strain was kept alive for passing it from mouse-triatomines and vice versa. Posteriorly, nests of amastigotes were found in skeletal and myocardial muscle fibers from albinous mouse Mus musculus NHI by using light microscopy and electron microscopy. In consequence, the parasitic element was classified as a myotropic strain, although it was observed in less amount in liver, kidney and spleen. Main pathological changes observed were intersticial inflammation, disruption of muscle fibers, myocarditis, mitochondrial alteration and cytoplasmic vacuolation.     

Trypanosoma cruzi: surface charge and freeze-fracture of amastigotes

Amastigotes of Trypanosoma cruzi, within vertebrate cells or isolated from the supernatant of vertebrate cell cultures (L-A9 fibroblast or J774G8 macrophage-like cell lines), possess glycoproteins or glycolipids on the cell surface according to the periodic acid-thiosemicarbazide-silver proteinate technique used in association with electron microscopy. The cell surface of isolated amastigotes is negatively charged, as evaluated by the binding of cationic particles (colloidal iron hydroxyde at pH 1.8 and cationized ferritin at pH 7.2) as well as by direct measurement of cellular electrophoretic mobility. Amastigotes (Y strain) isolated from the spleen of infected mice and amastigotes (Y and CL strains) from the supernatant of cell cultures previously infected with T. cruzi have the same mean electrophoretic mobility (-0.85 micron sec-1 V-1 cm). It is intermediate between the epimastigote and the trypomastigote forms (determined previously). Sialic acid is the important component responsible for the negative surface charge, as determined by the use of neuraminidase. Thus, it is possible to use the mean electrophoretic mobility as an indicator for identifying amastigotes of T. cruzi.     

Myxobacters from Arid Mexican Soil

Myxobacters were found to be common inhabitants of the arid soils from the Monterrey, Nuevo Leon, Mexico, area. Thirteen species of the genera Myxococcus, Archangium, Cystobacter, Stigmatella, Polyangium, and Chondromyces were isolated on a mineral salts agar supplemented with bakers' yeast and filter paper. Greater species diversity per soil sample was found in the region receiving 400 to 800 mm of annual rainfall as compared with soils from an area having only 200 to 400 mm of rainfall.     

Trypanosoma cruzi: description of a highly purified surface antigen defined by human antibodies

A glycoprotein of 25,000 daltons (G25) purified from T. cruzi extracts is recognized by serum antibodies of Chagas' disease patients. These human antibodies were isolated by affinity chromatography and were used to demonstrate that G25 antigenic determinants are i) represented at the parasite surface, and ii) are expressed in all developmental stages of the parasite's life cycle, as well as in several T. cruzi strains. This antigen-antibody system may be useful for the diagnosis of Chagas' disease because antibodies to radiolabeled G25 are found in the serum of 96.5% of 173 chagasic patients from different endemic areas, but are not found in the serum from other individuals. Taken collectively, the data suggest that antibodies to G25 define highly conserved determinants of the species T. cruzi. Moreover, its remarkable immunogenicity to infected humans offers an opportunity to investigate the role of specific immunologic responses in the pathogenicity of Chagas' disease.     

The resistance of fasting and nutritional aspects of Triatoma lecticularia (Stal, 1859) (Hemiptera, Reduviidae, Triatominae)

The resistance to fasting of Triatoma lecticularia was studied in all phases of the life cycle and the insect weighed in different nutritional situations (fed, not fed, death after starvation). The temperature and humidity levels were also recorded. The nymphal phases showed increasing resistance to fasting as demonstrated by the following averages (days) 1st 45.84; 2nd 61; 3rd 88.74; 4th 123.44; 5th 162.30. Upon the adult phase, the averages were similar to those of the 3rd stage for the male insects 88.94 and for the females 83.66. The weighing technique allowed for the measurement of the quantity of blood ingested, the weight loss during the fast and the percentage weight loss as related to the initial weight. The species is found in the Neartic region where it has been found infected with Trypanosoma cruzi and is associated with the terrestrial rodents Neotoma micropus Baird and Spermophilus variagatus (Erxelebem).     

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.     

Immunological characterization of antigens released by Trypanosoma cruzi-infected cells.

Chagas' disease, caused by Trypanosorna cruzi, is characterized by the appearance of pathological lesions in the heart and other tissues during the chronic phase. The mechanisms responsible for such damage are still unclear. In the vertebrate host, T. cruzi replicates intracellularly before transforming from amastigotes into trypomastigotes. The infected host cell then lyses, releasing the cytoplasmic contents and the parasites that shed membrane glycoproteins soon after release. The sum of all these components we have termed released antigen (Rag). We characterized antigens, released in vitro by fibroblasts infected with T. cruzi, obtained by concentrating conditioned serum-free culture media. The results demonstrate that Rag contains a complex protein mixture including stage-specific T. cruzi antigens (Ssp-1, -2, -4), glucose-regulated protein (Grp) 78h, and peptides recognized by the monoclonal antibody 2B10. These peptides exhibit neuraminidase activity and are expressed by intracellular and 10-20% of released trypomastigotes. Additionally, Rag is recognized by sera from T. cruzi-infected mice and human chagasic patients. Rag also stimulates in vitro production of interferon-gamma by splenocytes from resistant C57B1/6 and susceptible BALB/c infected mice and interleukin-4 by splenocytes from BALB/c infected mice. Altogether these results indicate that Rag is immunologically relevant and could contribute to pathogenesis of T. cruzi infection.     

A role for protease activity and host-cell permeability during the process of Trypanosoma cruzi egress from infected cells

The mechanism by which Trypanosoma cruzi egresses from infected cells at the end of the intracellular replication cycle is not understood. This study explored the role of T. cruzi-derived proteases and host-cell membrane permeability during the parasite's egress process. Treatment with a fluoromethyl ketone, known to inhibit the parasite's major protease, significantly reduced parasite egress. In addition, in the late stages of intracellular infection, cells infected with T. cruzi showed increased permeability as evidenced by dye exclusion tests. Furthermore, parasites could be antibody stained inside host cells without chemical permeabilization of the plasma membrane. These results suggest that in advanced stages of the intracellular cycle of T. cruzi, the host cells lose membrane integrity. Previous studies in our laboratory have found that antibodies present in sera of mice chronically infected with T. cruzi (antiegressin) bind the surface of infected cells and reduce parasite egress. In agreement with these reports, western blot analysis showed that several proteins in infected cell membrane extracts reacted with antibodies from infected mouse serum. The findings reported herein might have implications in the process of T. cruzi egress, as well as in the mechanism of action of antiegressin.     

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.     

Immunologic and molecular identification of Babesia bovis and Babesia bigemina in free-ranging white-tailed deer in northern Mexico

The suitability of white-tailed deer (Odocoileus virginianus) as hosts for the cattle ticks Rhipicephalus (Boophilus) microplus and Rhipicephalus (Boophilus) annulatus, has been well documented. These ticks have a wide host range, and both transmit Babesia bovis and Babesia bigemina, the agents responsible for bovine babesiosis. Although this disease and its vectors have been eradicated from the United States and some states in northern Mexico, it still is a problem in other Mexican states. It is not known if wild cervids like white-tailed deer can act as reservoirs for bovine babesiosis. The purpose of this study was to determine if B. bovis and B. bigemina or antibodies against them occur in white-tailed deer in the states of Nuevo Leon and Tamaulipas, Mexico. Twenty blood samples from white-tailed deer from two ranches were collected and tested with a nested polymerase chain reaction (nested PCR) and indirect immunofluorescence antibody test (IFAT) for B. bovis and B. bigemina. Eleven samples were positive for B. bigemina and four for B. bovis by nested PCR; amplicon sequences were identical to those reported in GenBank for B. bovis (Rap 1) and B. bigemina. Results of the IFA test showed the presence of specific antibodies in serum samples. This is the first report of the presence of B. bovis and B. bigemina in white-tailed deer using these techniques and underscores the importance of cervids as possible reservoirs for bovine babesiosis.     

People Out of Place: Unquiet Immigrants

Legalizing Moves: Salvadoran Immigrants' Struggle for U.S. Residency . Susan Bibler Coutin. Ann Arbor: University of Michigan Press, 2003. 228 pp.
The Maya of Morganton: Work and Community in the Nuevo New South . Leon Fink. Chapel Hill: University of North Carolina Press, 2003. 254 pp.
The Children of NAFTA: Labor Wars on the U.S./Mexico Border . David Bacon. Berkeley: University of California Press, 2004. 348 pp.     

Characterization of TcSTI-1, a homologue of stress-induced protein-1, in Trypanosoma cruzi

The life cycle of the protozoan Trypanosoma cruzi exposes it to several environmental stresses in its invertebrate and vertebrate hosts. Stress conditions are involved in parasite differentiation, but little is known about the stress response proteins involved. We report here the first characterization of stress-induced protein-1 (STI-1) in T. cruzi (TcSTI-1). This co-chaperone is produced in response to stress and mediates the formation of a complex between the stress proteins HSP70 and HSP90 in other organisms. Despite the similarity of TcSTI-1 to STI-1 proteins in other organisms, its expression profile in response to various stress conditions, such as heat shock, acidic pH or nutrient starvation, is quite different. Neither polysomal mRNA nor protein levels changed in exponentially growing epimastigotes cultured under any of the stress conditions studied. Increased levels of TcSTI-1 were observed in epimastigotes subjected to nutritional stress in the late growth phase. Co-immunoprecipitation assays revealed an association between TcSTI-1 and TcHSP70 in T. cruzi epimastigotes. Immunolocalization demonstrated that TcSTI-1 was distributed throughout the cytoplasm and there was some colocalization of TcSTI-1 and TcHSP70 around the nucleus. Thus, TcSTI-1 associates with TcHSP70 and TcSTI-1 expression is induced when the parasites are subjected to stress conditions during specific growth phase.     

Resistance of Trypanosoma cruzi to blood clearance induced by acute-phase immune mouse serum.

To investigate functional changes in Trypanosoma cruzi parasites induced during their interaction with the vertebrate host, we compared the blood clearance profiles of blood forms isolated from infected normal mice (Reg-Tc) or from infected mice immunodepressed after treatment with cyclophosphamide (Cy-Tc). Parasite blood numbers were measured at various time intervals in animals injected intravenously (i.v.) with 1-2 x 10(6) T. cruzi of either isolate. In the absence of added immune sera (spontaneous clearance), Reg-Tc and Cy-Tc were cleared from blood at similar rates. However, when acute immune mouse serum (Ac-IMS) was injected i.v. 2 min after inoculation of parasites, a significant proportion of Cy-Tc only was cleared from the blood an hour later, whereas Reg-Tc were not, their clearance profile being identical to that observed in mice injected with normal mouse serum. Cy-Tc susceptibility to Ac-IMS was not the result of a toxic effect of cyclophosphamide over T. cruzi as parasites recovered from animals immunodepressed by irradiation before infection were cleared similarly by acute serum. Contrary to Ac-IMS, chronic immune mouse serum induced similar rates of disappearance of Reg-Tc and Cy-Tc from blood. Our results suggest the occurrence of T. cruzi selection or modification during the acute phase, which leads to an increased parasite resistance to the clearance properties of acute-phase antibodies.     

Mapping of the distribution of Trypanosoma cruzi infection among small wild mammals in a conservation unit and its surroundings (Northeast-Brazil)

Maps are a useful tool that permits correlation of landscapes with hotspots of parasite transmission. Here, they were used as a tool for geovisualization to evaluate variables involved in the transmission of Trypanosoma cruzi among small wild mammals in an area endemic for Chagas disease, the "Serra da Capivara" National Park (PARNA) and its surroundings in Piauí State, Northeast Brazil. The implementation of a Geographical Information System (GIS) allowed the observation that a previously noted aggregated distribution of Triatoma sordida and Triatoma brasiliensis, T. cruzi prevalence and infection pattern of small wild mammals was directly or indirectly influenced by the local relief and human action. Small mammalian species diversity was higher in mesic refugia inside the park and in its buffer zone and lower in the disturbed area by anthropic activities. Didelphis albiventris was more abundant in the areas affected by human action. Thrichomys laurentius demonstrated to be an eclectic species and a competent reservoir of T. cruzi, being infected in all study areas. Small wild mammals infected with the TCII genotype of T. cruzi were localized only in the buffer zone of PARNA while TCI infected specimens were found in both areas, inside the PARNA and its buffer zone. The impact of biodiversity loss on the transmission cycle of T. cruzi in the wild environment was discussed.     

Chagas cardiomyopathy manifestations and Trypanosoma cruzi genotypes circulating in chronic Chagasic patients

Chagas disease caused by Trypanosoma cruzi is a complex disease that is endemic and an important problem in public health in Latin America. The T. cruzi parasite is classified into six discrete taxonomic units (DTUs) based on the recently proposed nomenclature (TcI, TcII, TcIII, TcIV, TcV and TcVI). The discovery of genetic variability within TcI showed the presence of five genotypes (Ia, Ib, Ic, Id and Ie) related to the transmission cycle of Chagas disease. In Colombia, TcI is more prevalent but TcII has also been reported, as has mixed infection by both TcI and TcII in the same Chagasic patient. The objectives of this study were to determine the T. cruzi DTUs that are circulating in Colombian chronic Chagasic patients and to obtain more information about the molecular epidemiology of Chagas disease in Colombia. We also assessed the presence of electrocardiographic, radiologic and echocardiographic abnormalities with the purpose of correlating T. cruzi genetic variability and cardiac disease. Molecular characterization was performed in Colombian adult chronic Chagasic patients based on the intergenic region of the mini-exon gene, the 24Sα and 18S regions of rDNA and the variable region of satellite DNA, whereby the presence of T.cruzi I, II, III and IV was detected. In our population, mixed infections also occurred, with TcI-TcII, TcI-TcIII and TcI-TcIV, as well as the existence of the TcI genotypes showing the presence of genotypes Ia and Id. Patients infected with TcI demonstrated a higher prevalence of cardiac alterations than those infected with TcII. These results corroborate the predominance of TcI in Colombia and show the first report of TcIII and TcIV in Colombian Chagasic patients. Findings also indicate that Chagas cardiomyopathy manifestations are more correlated with TcI than with TcII in Colombia.