Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondônia, Brazil

The present study assessed the prevalence of anti-Leishmania spp. antibodies in dogs from the city of Monte Negro, State of Rondônia, Brazil. ELISA (NE > 3) and IFAT (>1:40) were used to evaluate 161 serum samples collected from rural dogs from Monte Negro. Forty-five (27.9%) dogs were positive by ELISA tests and five (3.1%) were positive by IFAT. The present study showed for the first time the frequency of exposure to Leishmania spp. in dogs in the State of Rondônia, Amazon Region.

Quantum and pseudoclassical descriptions of nonrelativistic spinning particles in noncommutative space

We construct a nonrelativistic wave equation for spinning particles in the noncommutative space (in a sense, a theta modification of the Pauli equation). To this end, we consider the nonrelativistic limit of the theta-modified Dirac equation. To complete the consideration, we present a pseudoclassical model (a la Berezin-Marinov) for the corresponding nonrelativistic particle in the noncommutative space. To justify the latter model, we demonstrate that its quantization leads to the theta-modified Pauli equation. We extract theta-modified interaction between a nonrelativistic spin and a magnetic field from such a Pauli equation and construct a theta modification of the Heisenberg model for two coupled spins placed in an external magnetic field. In the framework of such a model, we calculate the probability transition between two orthogonal Einstein-Podolsky-Rosen states for a pair of spins in an oscillatory magnetic field and show that some of such transitions, which are forbidden in the commutative space, are possible due to the space noncommutativity. This allows us to estimate an upper bound on the noncommutativity parameter.

The development of social tourism in Brazil

This article reflects on the origins and development of social tourism in Brazil, with particular reference to the socio-economic conditions in the country. It discusses the theoretical conceptualisation of social tourism and its implementations in the non-European context. The case study presented here is based on a secondary bibliographical research of existing definitions and an in-depth analysis of the political conditions that have framed its development. More particularly, this article will discuss public initiatives since the Labour Party gained power in Brazil in 2003. Apart from public sector involvement in social tourism, this article also examines the role of the third sector in provision. The example of Social Service of Commerce will be presented. This article will conclude by evaluating the phenomenon of social tourism in Brazil, highlighting where progress has been made and which are the key challenges that need to be overcome.

Epidemiology and control of frontier malaria in Brazil: lessons from community-based studies in rural Amazonia

We describe the epidemiology of malaria in a frontier agricultural settlement in Brazilian Amazonia. We analysed the incidence of slide-confirmed symptomatic infections diagnosed between 2001 and 2006 in a cohort of 531 individuals (2281.53 person-years of follow-up) and parasite prevalence data derived from four cross-sectional surveys. Overall, the incidence rates of Plasmodium vivax and P. falciparaum were 20.6/100 and 6.8/100 person-years at risk, respectively, with a marked decline in the incidence of both species (81.4 and 56.8%, respectively) observed between 2001 and 2006. PCR revealed 5.4-fold more infections than conventional microscopy in population-wide cross-sectional surveys carried out between 2004 and 2006 (average prevalence, 11.3 vs. 2.0%). Only 27.2% of PCR-positive (but 73.3% of slide-positive) individuals had symptoms when enrolled, indicating that asymptomatic carriage of low-grade parasitaemias is a common phenomenon in frontier settlements. A circular cluster comprising 22.3% of the households, all situated in the area of most recent occupation, comprised 69.1% of all malaria infections diagnosed during the follow-up, with malaria incidence decreasing exponentially with distance from the cluster centre. By targeting one-quarter of the households, with selective indoor spraying or other house-protection measures, malaria incidence could be reduced by more than two-thirds in this community. (C) 2010 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Naturally Acquired Antibodies to Plasmodium vivax Duffy Binding Protein (DBP) in Rural Brazilian Amazon

Duffy binding protein (DBP), a leading malaria vaccine candidate, plays a critical role ill Plasmodium vivax erythrocyte invasion. Sixty-eight of 366 (18.6%) subjects had IgG anti-DBP antibodies by enzyme-linked immunosorbent assay (ELISA) in a community-based cross-sectional survey ill the Brazilian Amazon Basin. Despite Continuous exposure to low-level malaria transmission, the overall seroprevalence decreased to 9.0% when the Population was reexamined 12 months later. Antibodies from 16 of 50 (360%) Subjects who were ELISA-positive at the baseline were able to inhibit erythrocyte binding to at least one of two DBP variants tested. Most (13 of 16) of these subjects still had inhibitory antibodies when reevaluated 12 months later. Cumulative exposure to malaria was the strongest predictor of DBP seropositivity identified by Multiple logistic regression models in this population. The poor antibody recognition of DBP elicited by natural exposure to P. vivax in Amazonian populations represents a challenge to be addressed by vaccine development strategies.

Seroprevalence of anti-Leishmania spp. antibodies in rural dogs from the city of Monte Negro, State of Rondonia, Brazil

The present study assessed the prevalence of anti-Leishmania spp antibodies in dogs from the city of Monte Negro, State of Rondonia, Brazil ELISA (NE >= 3) and IFAT (>= 1 40) were used to evaluate 161 serum samples collected from rural dogs from Monte Negro Forty-five (27 9%) dogs were positive by ELISA tests and five (3 1%) were positive by IFAT The present study showed for the first time the frequency of exposure to Leishmania spp in dogs in the State of Rondonia, Amazon Region

Recurrent Parasitemias and Population Dynamics of Plasmodium vivax Polymorphisms in Rural Amazonia

Clinical trials documented alarming post-treatment Plasmodium vivax recurrence rates caused by recrudescence of surviving asexual blood stages, relapse from hypnozoites, or new infections. Here we describe high rates of P vivax recurrence (26-40% 180 days after treatment) in two cohorts of rural Amazonians exposed to low levels of malaria transmission after a vivax malaria episode treated with chloroquine-primaquine. Microsatellite analysis of 28 paired acute infection and recurrence parasites showed only two pairs of identical haplotypes (consistent with recrudescences or reactivation of homologous hypnozoites) and four pairs of related haplotypes (sharing alleles at 11-13 of 14 microsatellites analyzed). Local isolates of P vivax were extraordinarily diverse and rarely shared the same haplotype, indicating that frequent recurrences did not favor the persistence or reappearance of clonal lineages of parasites in the Population. This fast haplotype replacement rate may represent the typical population dynamics Of neutral polymorphisms in parasites from low-endemicity areas.

Population dynamics of genetically diverse Plasmodium falciparum lineages: community-based prospective study in rural Amazonia

Temporal changes in the prevalence of antigenic variants in Plasmodium falciparum populations have been interpreted as evidence of immune-mediated frequency-dependent selection, but evolutively neutral processes may generate similar patterns of serotype replacement. Over 4 years, we investigated the population dynamics of P. falciparum polymorphisms the community level by using 11 putatively neutral microsatellite markers. Plasmodium falciparum Populations were less diverse than sympatric P. vivax isolates, with less multiple-clone infections, lower number of alleles per locus and lower Virtual heterozygosity, but both species showed significant multilocus linkage disequilibrium. Evolutively neutral P. falciparum polymorphisms showed a high turnover rate, with few lineages persisting for several months in the population. Similar results had previously been obtained, in the same community, for sympatric P. vivax isolates. In contrast, the prevalence of the 2 dimorphic types of a major antigen, MSP-2, remained remarkably stable throughout the Study period. We Suggest that the relatively fast turnover of parasite lineages represents the typical population dynamics of neutral polymorphisms in small populations, with clear implications for the detection of frequency-dependent selection of polymorphisms.

Human toxocariasis in rural Brazilian Amazonia: Seroprevalence, risk factors, and spatial distribution

This population-based cross-sectional study of 403 rural settlers in Brazilian Amazonia revealed an overall rate of IgG seropositivity to Toxocara canis excretory-secretory larval antigen of 26.8% (95% confidence interval [CI], 22.5-31.4%). Multilevel logistic regression analysis identified current infection with hookworm (odds ratio [OR], 2.32; 95% CI, 1.11-4.86) and residence in the most recently occupied sectors of the settlement (OR, 1.81.; 95%CI, 1.3-2.52) as significant risk factors for Toxocara seropositivity; age > 14 years (OR, 0.46; 95% CI, 0.28-0.73) and the presence of cats in the household (OR, 0.57; 95% CI, 0.32-1.02) appeared to be protective. Two significant high-prevalence clusters were detected in the area, together comprising 38.9% of the seropositive subjects; households in the clusters had slightly lower socioeconomic status and were less likely to have cats as pets. The obstacles for controlling human toxocariasis in this and other tropical rural settings are discussed.

Risk factors for dengue virus infection in rural Amazonia: Population-based cross-sectional surveys

A comparison of dengue virus (DENV) antibody levels in paired serum samples collected from predominantly DENV-naive residents in an agricultural settlement in Brazilian Amazonia (baseline seroprevalence, 18.3%) showed a seroconversion rate of 3.67 episodes/100 person-years at risk during 12 months of follow-up. Multivariate analysis identified male sex, poverty, and migration from extra-Amazonian states as significant predictors of baseline DENY seropositivity, whereas male sex, a history of clinical diagnosis of dengue fever, and travel to an urban area predicted subsequent seroconversion. The laboratory surveillance of acute febrile illnesses implemented at the study site and in a nearby town between 2004 and 2006 confirmed 11. DENV infections among 102 episodes studied with DENV IgM detection, reverse transcriptase-polymerise chain reaction, and virus isolation; DENV-3 was isolated. Because DENV exposure is associated with migration or travel, personal protection measures when visiting high-risk urban areas may reduce the incidence of DENV infection in this rural population.

A Community-based Survey of Human Toxoplasmosis in Rural Amazonia: Seroprevalence, Seroconversion Rate, and Associated Risk Factors

IgG antibodies to Toxoplasma gondii were detected in, March-April 2004, in 65.8% (95% confidence interval, 60.8-70.8%) of 342 systematically sampled subjects 5-90 years of age (87.5% of the eligible) living in a rural settlement in Amazonia, with a seroconversion rate of 9% over I year of follow-up of 99 seronegative subjects. Multiple logistic regression analysis identified age as the only significant independent predictor of seropositivity at the baseline. Each additional year of age increases the odds of being seropositive by 6%, and 76.8% of the subjects are expected to be seropositive at 30 years of age. A single high-prevalence spatial cluster, comprising 11.9% of the seropositive subjects, was detected in the area; households in the cluster were less likely to have dogs as pets and their heads had a lower education level, when compared with households located outside the cluster. The challenges for preventing human toxoplasmosis in tropical rural settings are discussed.

Total absolute horospherical curvature of submanifolds in hyperbolic space

We study the horospherical geometry of submanifolds in hyperbolic space. The main result is a formula for the total absolute horospherical curvature of M, which implies, for the horospherical geometry, the analogues of classical inequalities of the Euclidean Geometry. We prove the horospherical Chern-Lashof inequality for surfaces in 3-space and the horospherical Fenchel and Fary-Milnor`s theorems.

Horo-tight spheres in hyperbolic space

We study horo-tight immersions of manifolds into hyperbolic spaces. The main result gives several characterizations of horo-tightness of spheres, answering a question proposed by Cecil and Ryan. For instance, we prove that a sphere is horo-tight if and only if it is tight in the hyperbolic sense. For codimension bigger than one, it follows that horo-tight spheres in hyperbolic space are metric spheres. We also prove that horo-tight hyperspheres are characterized by the property that both of its total absolute horospherical curvatures attend their minimum value. We also introduce the notion of weak horo-tightness: an immersion is weak horo-tight if only one of its total absolute curvature attends its minimum. We prove a characterization theorem for weak horo-tight hyperspheres.

3-manifolds in Euclidean space from a contact viewpoint

We study the geometry of 3-manifolds generically embedded in R(n) by means of the analysis of the singularities of the distance-squared and height functions on them. We describe the local structure of the discriminant (associated to the distribution of asymptotic directions), the ridges and the flat ridges.

Dirac equation in noncommutative space for hydrogen atom

We consider the energy levels of a hydrogen-like atom in the framework of theta-modified, due to space noncommutativity, Dirac equation with Coulomb field. It is shown that on the noncommutative (NC) space the degeneracy of the levels 2S(1/2), 2P(1/2) and 2P(3/2) is lifted completely, such that new transition channels are allowed. (C) 2009 Elsevier B.V. All rights reserved.