Chagas disease: an impediment in achieving the Millennium Development Goals in Latin America

Repurposing of rabeprazole as an anti-Trypanosoma cruzi drug that targets cellular triosephosphate isomerase

Trypanosoma cruzi is the causative agent of American trypanosomiasis, which mainly affects populations in Latin America. Benznidazole is used to control the disease, with severe effects in patients receiving this chemotherapy. Previous studies have demonstrated the inhibition of triosephosphate isomerase from T. cruzi, but cellular enzyme inhibition has yet to be established. This study demonstrates that rabeprazole inhibits both cell viability and triosephosphate isomerase activity in T. cruzi epimastigotes. Our results show that rabeprazole has an IC50 of 0.4 µM, which is 14.5 times more effective than benznidazole. Additionally, we observed increased levels of methyl-glyoxal and advanced glycation end products after the inhibition of cellular triosephosphate isomerase by rabeprazole. Finally, we demonstrate that the inactivation mechanisms of rabeprazole on triosephosphate isomerase of T. cruzi can be achieved through the derivatization of three of its four cysteine residues. These results indicate that rabeprazole is a promising candidate against American trypanosomiasis.

Iron Uptake Controls Trypanosoma cruzi Metabolic Shift and Cell Proliferation

(1) Background: Ionic transport in Trypanosoma cruzi is the object of intense studies. T. cruzi expresses a Fe-reductase (TcFR) and a Fe transporter (TcIT). We investigated the effect of Fe depletion and Fe supplementation on different structures and functions of T. cruzi epimastigotes in culture. (2) Methods: We investigated growth and metacyclogenesis, variations of intracellular Fe, endocytosis of transferrin, hemoglobin, and albumin by cell cytometry, structural changes of organelles by transmission electron microscopy, O₂ consumption by oximetry, mitochondrial membrane potential measuring JC-1 fluorescence at different wavelengths, intracellular ATP by bioluminescence, succinate-cytochrome c oxidoreductase following reduction of ferricytochrome c, production of H₂O₂ following oxidation of the Amplex^® red probe, superoxide dismutase (SOD) activity following the reduction of nitroblue tetrazolium, expression of SOD, elements of the protein kinase A (PKA) signaling, TcFR and TcIT by quantitative PCR, PKA activity by luminescence, glyceraldehyde-3-phosphate dehydrogenase abundance and activity by Western blotting and NAD⁺ reduction, and glucokinase activity recording NADP⁺ reduction. (3) Results: Fe depletion increased oxidative stress, inhibited mitochondrial function and ATP formation, increased lipid accumulation in the reservosomes, and inhibited differentiation toward trypomastigotes, with the simultaneous metabolic shift from respiration to glycolysis. (4) Conclusion: The processes modulated for ionic Fe provide energy for the T. cruzi life cycle and the propagation of Chagas disease.

Severe Chagas disease in Ecuador: a countrywide geodemographic epidemiological analysis from 2011 to 2021

Background

Chagas disease is a neglected and often forgotten tropical disease caused by the Trypanosoma cruzi. This parasite can be transmitted through the direct contact of human skin with feces and urine of the triatomine insect. According to the World Health Organization (WHO), an estimated 6-7 million people are infected worldwide, killing at least 14,000 every year. The disease has been reported in 20 of the 24 provinces of Ecuador, with El Oro, Guayas, and Loja being the most affected.

Methodology

We analyzed the morbidity and mortality rates of severe Chagas disease in Ecuador on a nationwide, population-based level. Hospitalization cases and deaths were also examined based on altitude, including low (< 2,500 m) and high (> 2,500 m) altitudes, according to the International Society. Data was retrieved from the National Institute of Statistics and Census hospital admissions and in-hospital mortality databases from 2011 to 2021.

Results

A total of 118 patients have been hospitalized in Ecuador since 2011 due to Chagas disease. The overall in-hospital mortality rate was 69.4% (N = 82). Men have a higher incidence rate (4.8/1,000,000) than women, although women have a significantly higher mortality rate than men (6.9/1,000,000).

Conclusion

Chagas disease is a severe parasitic condition that primarily affects rural and poorer areas of Ecuador. Men are more likely to be infected due to differences in work and sociocultural activities. Using average elevation data, we conducted a geodemographic analysis to assess incidence rates by altitude. Our findings indicate that the disease is more common at low and moderate altitudes, but recent increases in cases at higher altitudes suggest that environmental changes, such as global warming, could be driving the proliferation of disease-carrying vectors in previously unaffected areas.

Prevalence of zoonotic and non-zoonotic Rickettsia in horses: A systematic review and meta-analysis

In a broad sense, Rickettsiae are a group of microorganisms that can be transmitted mechanically or biologically to animals and humans. Rickettsioses are associated with hematic manifestations. Its prevalence in humans, dogs and other animals has been widely explored, but not in equine species. To determine the prevalence of Rickettsia infection in horses. A systematic review of the literature was carried out in five databases for the proportion of horses infected with Rickettsia, defined by molecular and immunological techniques. A meta-analysis was performed using a random-effects model to calculate the pooled prevalence and 95% confidence intervals (CI). The Cochran's Q test and the I² statistic were used to assess the between-study-heterogeneity. The pooled prevalence of Rickettsia in equines was 37.0% (95% CI: 26.0%-47.0%), with significant heterogeneity among studies (I² = 98.12%). In the subgroup analysis, the prevalence of Rickettsia in horses was found to be 24.0% (95%CI: 10.0%-41.0%) for IFI, 47.0% (95%CI: 30.0%-64.0%) for IFA, 14.0% (95%CI: 11.0%-17.0%) for IFAT and 39.0% (95%CI: 0.0%-95.0%) for PCR. There was a high prevalence of Rickettsia among horses, with some of the species being zoonotic, with their corresponding implications for humans, which increasingly are in close contact with equines, particularly horses and their ticks, posing a risk for spillover and transmission.

Spatial epidemiology and adaptive targeted sampling to manage the Chagas disease vector Triatoma dimidiata

Widespread application of insecticide remains the primary form of control for Chagas disease in Central America, despite only temporarily reducing domestic levels of the endemic vector Triatoma dimidiata and having little long-term impact. Recently, an approach emphasizing community feedback and housing improvements has been shown to yield lasting results. However, the additional resources and personnel required by such an intervention likely hinders its widespread adoption. One solution to this problem would be to target only a subset of houses in a community while still eliminating enough infestations to interrupt disease transfer. Here we develop a sequential sampling framework that adapts to information specific to a community as more houses are visited, thereby allowing us to efficiently find homes with domiciliary vectors while minimizing sampling bias. The method fits Bayesian geostatistical models to make spatially informed predictions, while gradually transitioning from prioritizing houses based on prediction uncertainty to targeting houses with a high risk of infestation. A key feature of the method is the use of a single exploration parameter, α, to control the rate of transition between these two design targets. In a simulation study using empirical data from five villages in southeastern Guatemala, we test our method using a range of values for α, and find it can consistently select fewer homes than random sampling, while still bringing the village infestation rate below a given threshold. We further find that when additional socioeconomic information is available, much larger savings are possible, but that meeting the target infestation rate is less consistent, particularly among the less exploratory strategies. Our results suggest new options for implementing long-term T. dimidiata control.

Effective public health interventions for the control and elimination of neglected tropical diseases require an efficient use of resources while still causing long-term disease reduction at the community level. To use resources to best effect, areas most in need of control efforts must be identified. However, strategies for correctly identifying these areas are rarely known due to the complex environmental, biological, and cultural factors shaping disease spread. In turn, incorrect prioritization of control targets can cause the intervention to have no lasting effect. We address this tradeoff between efficiency and efficacy by adapting control priorities throughout an intervention, targeting areas of high uncertainty during the initial stages while shifting to areas of greatest risk at later stages. In the context of controlling Triatoma dimidiata, the primary vector of Chagas disease in several countries in Latin America, our methods provide a means of targeting only a subset of homes for insecticide and housing improvements, while still reducing a village’s overall infestation rate below the critical threshold.

Chagas disease in the context of the 2030 agenda: global warming and vectors

The 2030 Agenda for Sustainable Development is a plan of action for people, planet and prosperity. Thousands of years and centuries of colonisation have passed the precarious housing conditions, food insecurity, lack of sanitation, the limitation of surveillance, health care programs and climate change. Chagas disease continues to be a public health problem. The control programs have been successful in many countries in reducing transmission by T. cruzi; but the results have been variable. WHO makes recommendations for prevention and control with the aim of eliminating Chagas disease as a public health problem. Climate change, deforestation, migration, urbanisation, sylvatic vectors and oral transmission require integrating the economic, social, and environmental dimensions of sustainable development, as well as the links within and between objectives and sectors. While the environment scenarios change around the world, native vector species pose a significant public health threat. The man-made atmosphere change is related to the increase of triatomines’ dispersal range, or an increase of the mobility of the vectors from their sylvatic environment to man-made constructions, or humans getting into sylvatic scenarios, leading to an increase of Chagas disease infection. Innovations with the communities and collaborations among municipalities, International cooperation agencies, local governmental agencies, academic partners, developmental agencies, or environmental institutions may present promising solutions, but sustained partnerships, long-term commitment, and strong regional leadership are required. A new world has just opened up for the renewal of surveillance practices, but the lessons learned in the past should be the basis for solutions in the future.

Serological screening for Chagas disease in an endemic region of Northern Minas Gerais, Brazil: the SaMi-Trop project

Chagas disease (CD) is still a neglected disease. Infected individuals are diagnosed late, being treated in worse clinical conditions. Thus, this study aimed to analyze the prevalence and the factors associated with new confirmed cases of CD identified by serological screening in an endemic region of Minas Gerais State, Brazil. This is an analytical cross-sectional study with data from a project of the Research Center in Tropical Medicine of Sao Paulo- Minas Gerais (SaMi-Trop) conducted in two municipalities. Data collection included a questionnaire with closed questions, a venous blood collection and an ELISA serological test for CD. A total of 2,038 individuals with no previous diagnosis of CD participated in the study. The result of the serological test for CD was adopted as the dependent variable. The independent variables addressed personal issues, health conditions and lifetime housing. A descriptive analysis of individual variables was performed. Subsequently, a bivariate analysis was performed using the Pearson’s chi-square test. Households sheltering individuals positive for CD were georeferenced, and the analysis of spatial distribution was performed using the quartic function to estimate the density of the nucleus. Among the participants, 188 (9.2 %) were positive for CD. The profile of participants with CD was associated with place of residence, age, relative/family member with CD and living conditions. It is noteworthy that there are still patients with CD who are unaware of their diagnosis in both, rural and urban areas.

Orbital Cellulitis in Chagas Disease: An Unusual Presentation

Chagas disease is an inflammatory, infectious disease caused by the parasite Trypanosoma cruzi found in the feces of the triatomine bug, which can cause a sudden, brief acute illness, or it may become a long-lasting chronic condition. Chagas disease is common in South America and Central America, however, the constantly expanding global community has brought Chagas disease to the forefront of non-endemic areas, particularly the United States and Europe. The authors present a case of a 47-year-old healthy farmer diagnosed with a right orbital cellulitis refractory to systemic antibiotics. Based on clinical symptoms, the patient's medical/demographical history and a proper differential diagnosis, an acute phase of Chagas disease was diagnosed. After antiparasitic treatment, the patient had a proper recovery and continued with a regular follow-up to monitor the possible development of a chronic phase.

A ferric reductase of Trypanosoma cruzi (TcFR) is involved in iron metabolism in the parasite

Trypanosoma cruzi is a parasitic protozoan that infects various species of domestic and wild animals, triatomine bugs and humans. It is the etiological agent of American trypanosomiasis, also known as Chagas Disease, which affects about 17 million people in Latin America and is emerging elsewhere in the world. Iron (Fe) is a crucial micronutrient for almost all cells, acting as a cofactor for several metabolic enzymes. T. cruzi has a high requirement for Fe, using heminic and non-heminic Fe for growth and differentiation. Fe occurs in the oxidized (Fe³⁺) form in aerobic environments and needs to be reduced to Fe²⁺ before it enters cells. Fe-reductase, located in the plasma membranes of some organisms, catalyzes the Fe³⁺⇒ Fe²⁺ conversion. In the present study we found an amino acid sequence in silico that allowed us to identify a novel 35 kDa protein in T. cruzi with two transmembrane domains in the C-terminal region containing His residues that are conserved in the Ferric Reductase Domain Superfamily and are required for catalyzing Fe³⁺ reduction. Accordingly, we named this protein TcFR. Intact epimastigotes from the T. cruzi DM28c strain reduced the artificial Fe³⁺-containing substrate potassium ferricyanide in a cell density-dependent manner, following Michaelis-Menten kinetics. The TcFR activity was more than eightfold higher in a plasma membrane-enriched fraction than in whole homogenates, and this increase was consistent with the intensity of the 35 kDa band on Western blotting images obtained using anti-NOX5 raised against the human antigen. Immunofluorescence experiments demonstrated TcFR on the parasite surface. That TcFR is part of a catalytic complex allowing T. cruzi to take up Fe from the medium was confirmed by experiments in which DM28c was assayed after culturing in Fe-depleted medium: (i) proliferation during the stationary growth phase was five times slower; (ii) the relative expression of TcFR (qPCR) was 50% greater; (iii) intact cells had 120% higher Fe-reductase activity. This ensemble of results indicates that TcFR is a conserved enzyme in T. cruzi, and its catalytic properties are modulated in order to respond to external Fe fluctuations.

In Search of Congenital Chagas Disease in the Sierra Nevada de Santa Marta, Colombia

Chagas disease remains a major impediment to sustainable socioeconomic development in Latin America. Transplacental transmission explains the persistence of transmission in urban areas, in non-endemic regions, and in areas with an established interrupted vectorial transmission. One of every five cases of congenital Chagas disease in the world occurs in Colombia and Venezuela. The massive migration of impoverished populations from neighboring Venezuela has worsened the situation creating a humanitarian crisis in Northeastern Colombia, including the Sierra Nevada de Santa Marta. The prevalence of Chagas infection among pregnant women in these areas is higher than the national average, and the public health resources are insufficient. This perspective discusses the associated increased morbidity and mortality of congenital Chagas in this region, where stigmatization contributes to the impression among health authorities and the general population that it affects indigenous communities only. The monitoring and control of congenital Chagas disease in the Sierra Nevada of Santa Marta is a public health necessity that demands urgent and effective interventions.

A deadly feast: Elucidating the burden of orally acquired acute Chagas disease in Latin America - Public health and travel medicine importance

Over the past two decades, several countries in Latin American, particularly Brazil, Venezuela, and Colombia, have experienced multiple outbreaks of oral Chagas disease. Transmission occurs secondary to contamination of food or beverages by triatomine (kissing bug) feces containing infective Trypanosoma cruzi metacyclic trypomastigotes. Orally transmitted infections are acute and potentially fatal. Oral Chagas transmission carries important clinical implications from management to public health policies compared to vector-borne transmission. This review aims to discuss the contemporary situation of orally acquired Chagas disease, and its eco-epidemiology, pathogenesis, and clinical management. We also propose preventive public health interventions to reduce the burden of disease and provide important perspectives for travel medicine. Travel health advisors need to counsel intending travellers to South America on avoidance of "deadly feasts" - risky beverages such as fruit juices including guava juice, bacaba, babaçu and palm wine (vino de palma), açai pulp, sugar cane juice and foodstuffs such as wild animal meats that may be contaminated with T. cruzi.

Hindgut microbiota in laboratory-reared and wild Triatoma infestans

Triatomine vectors transmit Trypanosoma cruzi, the etiological agent of Chagas disease in humans. Transmission to humans typically occurs when contaminated triatomine feces come in contact with the bite site or mucosal membranes. In the Southern Cone of South America, where the highest burden of disease exists, Triatoma infestans is the principal vector for T. cruzi. Recent studies of other vector-borne illnesses have shown that arthropod microbiota influences the ability of infectious agents to colonize the insect vector and transmit to the human host. This has garnered attention as a potential control strategy against T. cruzi, as vector control is the main tool of Chagas disease prevention. Here we characterized the microbiota in T. infestans feces of both wild-caught and laboratory-reared insects and examined the relationship between microbial composition and T. cruzi infection using highly sensitive high-throughput sequencing technology to sequence the V3-V4 region of the 16S ribosomal RNA gene on the MiSeq Illumina platform. We collected 59 wild (9 with T. cruzi infection) and 10 lab-reared T. infestans (4 with T. cruzi infection) from the endemic area of Arequipa, Perú. Wild T. infestans had greater hindgut bacterial diversity than laboratory-reared bugs. Microbiota of lab insects comprised a subset of those identified in their wild counterparts, with 96 of the total 124 genera also observed in laboratory-reared insects. Among wild insects, variation in bacterial composition was observed, but time and location of collection and development stage did not explain this variation. T. cruzi infection in lab insects did not affect α- or β-diversity; however, we did find that the β-diversity of wild insects differed if they were infected with T. cruzi and identified 10 specific taxa that had significantly different relative abundances in infected vs. uninfected wild T. infestans (Bosea, Mesorhizobium, Dietzia, and Cupriavidus were underrepresented in infected bugs; Sporosarcina, an unclassified genus of Porphyromonadaceae, Nestenrenkonia, Alkalibacterium, Peptoniphilus, Marinilactibacillus were overrepresented in infected bugs). Our findings suggest that T. cruzi infection is associated with the microbiota of T. infestans and that inferring the microbiota of wild T. infestans may not be possible through sampling of T. infestans reared in the insectary.

Chagas disease in humans is caused by the parasite Trypanosoma cruzi and it is endemic to the Americas. Poor populations are most at risk. The parasite infects an estimated six million people of 21 endemic countries in the Americas, with 30,000 new infections yearly. The main mode of transmission is vector-borne by triatomine bugs, which tend to live in close association with humans. The main Chagas disease vector in the Southern Cone of South America, where the highest burden of disease exists, is Triatoma infestans. As blood-sucking insects, triatomines become infected when they bite a T. cruzi-positive human and once infected they transmit the parasites in their feces. Controlling the vector populations is the main strategy of Chagas disease transmission reduction efforts. Microbiota-mediated methods to control this vector-borne disease are now being explored to determine whether microbes typically found in the vectors’ gut have a detrimental effect on T. cruzi and how they may be used to modify the vector and curb the ability for T. cruzi to be transmitted to humans. To advance this new field, we first must gain better knowledge of the gut microbiota of triatomines. Our study is the first to use sensitive high-throughput methods to study the gut microbes of T. infestans, using both laboratory-reared and wild insects. We have found that the microbial composition of T. infestans in the laboratory does not reflect the complete collection of gut microbes of wild T. infestans and inferring the gut microbiota profile of wild insects through studying lab insects alone may not be possible. We also found evidence that in wild insects T. cruzi affects the composition of the gut microbiota and identified some bacterial taxa which may be important in modulating the T.infestans-T.cruzi relationship.

Mechanistic Insights into the Anti-angiogenic Activity of Trypanosoma cruzi Protein 21 and its Potential Impact on the Onset of Chagasic Cardiomyopathy

Chronic chagasic cardiomyopathy (CCC) is arguably the most important form of the Chagas Disease, caused by the intracellular protozoan Trypanosoma cruzi; it is estimated that 10-30% of chronic patients develop this clinical manifestation. The most common and severe form of CCC can be related to ventricular abnormalities, such as heart failure, arrhythmias, heart blocks, thromboembolic events and sudden death. Therefore, in this study, we proposed to evaluate the anti-angiogenic activity of a recombinant protein from T. cruzi named P21 (rP21) and the potential impact of the native protein on CCC. Our data suggest that the anti-angiogenic activity of rP21 depends on the protein's direct interaction with the CXCR4 receptor. This capacity is likely related to the modulation of the expression of actin and angiogenesis-associated genes. Thus, our results indicate that T. cruzi P21 is an attractive target for the development of innovative therapeutic agents against CCC.

Mutagenic and Cytotoxicity LQB 123 Profile: Safety and Tripanocidal Effect of a Phenyl-t-Butylnitrone Derivative

The therapeutic options for Chagas disease are limited and its treatment presents a number of drawbacks including toxicity, drug resistance, and insufficient effectiveness against the chronic stage of the disease. Therefore, new therapeutical options are mandatory. In the present work, we evaluated the effect of a phenyl-tert-butylnitrone (PBN) derivate, LQB 123, against Trypanosoma cruzi forms. LQB 123 presented a trypanocidal effect against bloodstream trypomastigotes (IC50 = 259.4 ± 6.1 μM) and intracellular amastigotes infecting peritoneal macrophages (IC50 = 188.2 ± 47.5 μM), with no harmful effects upon the mammalian cells (CC50 values greater than 4 mM), resulting in a high selectivity index (CC50/IC50 > 20). Additionally, metacyclic trypomastigotes submitted to LQB 123 presented an IC50 of about 191.8 ± 10.5 μM and epimastigotes forms incubated with different concentrations of LQB 123 presented an inhibition of parasite growth with an IC50 of 255.1 ± 3.6 μM. Finally, we investigated the mutagenic potential of the nitrone by the Salmonella/microsome assay and observed no induction of mutagenicity even in concentrations as high as 33000 μM. Taken together, these results present a nonmutagenic compound, with trypanocidal activity against all relevant forms of T. cruzi, offering new insights into CD treatment suggesting additional in vivo tests.

Health Care Seeking Behavior of Persons with Acute Chagas Disease in Rural Argentina: A Qualitative View

Chagas disease (CD) is a tropical parasitic disease largely underdiagnosed and mostly asymptomatic affecting marginalized rural populations. Argentina regularly reports acute cases of CD, mostly young individuals under 14 years old. There is a void of knowledge of health care seeking behavior in subjects experiencing a CD acute condition. Early treatment of the acute case is crucial to limit subsequent development of disease. The article explores how the health outcome of persons with acute CD may be conditioned by their health care seeking behavior. The study, with a qualitative approach, was carried out in rural areas of Santiago del Estero Province, a high risk endemic region for vector transmission of CD. Narratives of 25 in-depth interviews carried out in 2005 and 2006 are analyzed identifying patterns of health care seeking behavior followed by acute cases. Through the retrospective recall of paths for diagnoses, weaknesses of disease information, knowledge at the household level, and underperformance at the provincial health care system level are detected. The misdiagnoses were a major factor in delaying a health care response. The study results expose lost opportunities for the health care system to effectively record CD acute cases.

A Critical Assessment of Officially Reported Chagas Disease Surveillance Data in Mexico

OBJECTIVE

Chagas disease, a disease caused by Trypanosoma cruzi, disproportionately affects poor people throughout Latin America. In Mexico, assessments of officially reported burden have not been previously reported. To evaluate discontinuity between surveillance data and data from other sources, we used data from the Mexican Ministry of Health to describe the distribution of reported Chagas disease over time in Mexico and compare it with estimates from the literature.

METHODS

We summarized age and sex differences for Chagas cases and mortality for 1995-2013 and 1982-2010, respectively. We examined the spatial distribution of Chagas disease over time with respect to disease burden. We further compared officially reported figures with estimates from the literature.

RESULTS

Among 6,494 officially reported cases, rates of Chagas disease were highest in adults aged 25-44 years (47.3%). Mortality was highest in adults aged ≥45 years (423/495, 85.5%). The data indicated increasing temporal trends for incidence and mortality. The greatest burden occurred in southern states, with increasing spatial distribution over time. Fewer than 900 cases and 40 deaths were officially reported annually, in contrast to estimates from the literature of approximately 69,000 new cases and 25,000 deaths annually.

CONCLUSION

While increasing trends in officially reported data have been observed, large discrepancies in case estimates compromise our understanding of Chagas disease epidemiology. Reported cases based on current practices are not enough to correctly assess the Chagas disease burden and spatial distribution in Mexico. Understanding the true epidemiology of this disease will lead to more focused and successful control and prevention strategies to decrease disease burden.

Course of Chronic Trypanosoma cruzi Infection after Treatment Based on Parasitological and Serological Tests: A Systematic Review of Follow-Up Studies

Background

Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi (T. cruzi). It is endemic in Latin American countries outside the Caribbean. The current criterion for cure in the chronic phase of the disease is the negativization of at least two serological tests such as enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IIF) and indirect hemagglutination assay (IHA). The serological evolution of treated subjects with chronic T. cruzi infection is variable. Treatment failure is indicated by a positive parasitological and/or molecular test (persistence of parasitemia).

Objectives

To summarize the pattern of response to treatment of parasitological, molecular and serological tests performed during the follow-up of subjects with chronic T. cruzi infection.

Methods

Electronic searches in relevant databases and screening of citations of potentially eligible articles were accomplished. Organizations focusing on neglected infectious diseases were asked for help in identifying relevant studies.

Included studies were randomized controlled trials (RCTs), quasi-RCTs, and cohort studies involving adults and children with chronic infection who received trypanocidal treatment (benznidazole or nifurtimox) and were followed over time. The assessment of risk of bias was performed separately for each study design. The Cochrane Collaboration’s tool and the guidelines developed by Hayden et al. were used. Two reviewers extracted all data independently. A third review author was consulted in case of discordant opinion.

Additional analyses were defined in ad-hoc basis. Scatter plots for percentage of positive parasitological and molecular tests and for negative serological tests were developed by using the lowess curve technique. Heterogeneity was measured by I².

The protocol was registered in PROSPERO, an international prospective register of systematic review protocols (Registration Number CRD42012002162).

Results

Out of 2,136 citations screened, 54 studies (six RCTs and 48 cohort studies) were included. The smoothed curves for positive xenodiagnosis and positive polymerase chain reaction (PCR) were characterized by a sharp decrease at twelve month posttreatment. Afterwards, they reached 10–20% and 40% for xenodiagnosis and PCR, respectively. The smoothed curves for negative conventional serological tests increased up to 10% after 48 months of treatment. In the long-term, the rate of negativization was between 20% and 45%.

The main sources of bias identified across cohort studies were the lack of control for confounding and attrition bias. In general, RCTs were judged as low risk of bias in all domains. The level of heterogeneity across included studies was moderate to high.

Additional analysis were incomplete because of the limited availability of data. In this regard, the country of origin of study participants might affect the results of parasitological and molecular tests, while the level of risk of bias might affect serological outcomes. Subgroup analysis suggested that seronegativization occurs earlier in children compared to adults.

Conclusions

We acknowledge that there is a dynamic pattern of response based on parasitological, molecular and serological tests in subjects chronically infected with T. cruzi after treatment. Our findings suggest a trypanocidal effect in the long-term follow-up.

Further research is needed to explore potential sources of heterogeneity and to conduct reliable subgroup analysis.

MODELING PARASITE REDUCTION MECHANISMS IN CHAGAS DISEASE

Various procedures have been proposed to reduce parasitemia during Chagas disease. Here we analyze in detail models developed to predict the possible outcomes of two of these treatments. The model solutions reproduce available experimental population data and can be used as tools to help researchers to find a cure or, at least, an optimal treatment to reduce cardiac cell damage. In particular, we study how the phase diagram describing the infection outcome is modified by the application of the ganglioside GM1, finding the optimum concentration of the drug in terms of the parameters characterizing its influence on the parasite-host interaction. We also investigate the use of the non-pathogenic parasite T. rangeli to reduce T. cruzi load in a mixed infection, finding that this method is not effective against all T. cruzi strains. Furthermore, we compare phase portraits of the evolution of the disease for a single and a mixed infection, and evaluate the cell damage as a function of the time elapsed between both infections, remarking on the temporary protective effect of the reaction to T. rangeli.

Chagas' disease: an emergent urban zoonosis. The caracas valley (Venezuela) as an epidemiological model

The unprecedented emergence of important public health and veterinary zoonoses is usually a result of exponential population growth and globalization of human activities. I characterized Chagas’ disease as an emergent zoonosis in the Caracas Valley (Venezuela) due to the following findings: the presence of reservoirs (Didelphis marsupialis, Rattus rattus) and vectors (Panstrongylus geniculatus, Panstrongylus rufotuberculatus) infected with Trypanosoma cruzi in urbanized or marginalized areas; the elevated contact between P. geniculatus and human beings detected by parasitological and molecular examinations of triatomine feces demonstrated the possibility of transmission risks; a study of outbreaks of urban Chagas’ disease reported the first proven case of oral transmission of T. cruzi to human beings; the risk of transmission of glandular metacyclic stages from marsupials by experimental ocular and oral instillation; mice genitalia infected with T. cruzi contaminated blood resulted in the formation of amastigotes very close to the lumen suggesting that there may be a possibility of infection via their release into the urine and thence to the exterior; the ubiquitous histotropism and histopathology of T. cruzi was demonstrated using a mouse model; the presence of experimental T. cruzi pseudocysts in adipose, bone-cartilage, and eye tissue indicated a potential risk for transplants. Socio-sanitary programs that include improvements in housing, vector control, and access to medical treatment, as well as strategies aimed at combating social inequalities, poverty, and underdevelopment should be undertaken in those areas where zoonoses are most prevalent. Disciplines, such as Ecology, Epidemiology, Medical Entomology, Human and Veterinary Medicine, Environmental Studies, Public Health, Social and Political Studies, Immunology, Microbiology, and Pharmacology could all provide important contributions that aim to reduce the occurrence of factors governing the spread of emergent diseases.

House-level risk factors for Triatoma dimidiata infestation in Colombia

In Colombia, the main vectors of Trypanosoma cruzi, the causative agent of Chagas disease, are Rhodnius prolixus and Triatoma dimidiata. T. dimidiata is present in the east region of Colombia as domestic, peridomestic, and sylvatic populations, resulting in difficulties for its control. A cost-effective way to prioritize houses for treatment is to stratify houses based on risk factors. In this study, risk factors were evaluated for potential associations with domicile infestation of T. dimidiata. There was an increased likelihood of domestic infestation associated with the presence of mixed roofs (odds ratio [OR] = 36.14, 95% confidence interval [95% CI] = 12.21-106.97), cats (OR = 3.94, 95% CI = 1.36-11.38), rock piles (OR = 5.28, 95% CI = 1.64-16.98), and bushes with height above 10 m (OR = 11.21, 95% CI = 2.08-60.45). These factors could be used to target surveillance and control of T. dimidiata to houses with an increased risk of being infested.

Fatal chagas disease among solid-organ transplant recipients in Colombia

Chagas disease continues to cause substantial morbidity and mortality in endemic areas in Latin America. Although there have been some well documented successes in halting the transmission of Chagas disease through preventive interventions to decrease vector-borne and blood-transfusion cases, this parasitic infection continues to be transmitted through these routes in some areas as well through perinatal and foodborne routes. In addition, transmission through solid-organ transplantation has been described in nonendemic settings due to the increasing globalization of Chagas disease to the United States of America, Europe, and other areas. Because there has been a concomitant increase in the number of solid-organ transplantations performed in Latin American settings endemic for American trypanosomiasis, there is increasing concern for the potential reactivation of Trypanosoma cruzi in a previously infected recipient and as a result of aggressive immunosuppression; or via transmission from organs donated by a latently infection donor transplanted onto an uninfected recipient. In this study, we report 2 cases of Chagas disease reactivation in 2 solid-organ transplant recipients in Northeastern Colombia, and we discuss the implications for screening as a crucial strategy for preventing transmission in endemic settings.

Using the basic reproduction number to assess the effects of climate change in the risk of Chagas disease transmission in Colombia

The dynamics of vector-borne diseases has often been linked to climate change. However the commonly complex dynamics of vector-borne diseases make it very difficult to predict risk based on vector or host distributions. The basic reproduction number (R0) integrates all factors that determine whether a pathogen can establish or not. To obtain R0 for complex vector-borne diseases one can use the next-generation matrix (NGM) approach. We used the NGM to compute R0 for Chagas disease in Colombia incorporating the effect of temperature in some of the transmission routes of Trypanosoma cruzi. We used R0 to generate a risk map of present conditions and a forecast risk map at 20 years from now based on mean annual temperature (data obtained from Worldclim). In addition we used the model to compute elasticity and sensitivity indexes on all model parameters and routes of transmission. We present this work as an approach to indicate which transmission pathways are more critical for disease transmission but acknowledge the fact that results and projections strongly depend on better knowledge of entomological parameters and transmission routes. We concluded that the highest contribution to R0 comes from transmission of the parasites from humans to vectors, which is a surprising result. In addition,parameters related to contacts between human and vectors and the efficiency of parasite transmission between them also show a prominent effect on R0.

Bolivian migrants with Chagas disease in Barcelona, Spain: a qualitative study of dietary changes and digestive problems

Due to international migration, Chagas disease, endemic in Latin America, has become more common in non-endemic areas. Chronic Chagas disease can cause damage to the digestive system leading to constipation. However, a range of factors influences constipation and a better understanding of the role of non-Chagas related factors is required to improve management of Chagas-related digestive problems. This study explores perceptions of constipation and changes in food and exercise habits amongst Bolivians in Barcelona, Spain. Bolivian migrants attending the Tropical Medicine Unit (Hospital Clínic, Barcelona) were interviewed about their food habits in Spain and Bolivia, migratory experience, work and leisure activities. Chagas seropositive participants also received radiological examinations. Bolivian migrants experienced dietary changes, influenced by work-related factors, which included reductions in quantities of food and liquid consumed. Almost half the participants reported changes in digestive rhythm since arriving in Spain. Constipation, which was common, in some cases was only recounted during interviews. Bolivian migrants' constipation may be associated with chronic Chagas disease or migration-related dietary changes. Careful questioning using the Rome III criteria is however required to ensure its diagnosis. Radiological studies are also required to confirm the role of Chagas disease and identify potentially serious intestinal damage.

Chagas disease: an overview of clinical and epidemiological aspects

Chagas disease, caused by the parasite Trypanosoma cruzi, is a serious health problem in Latin America and is an emerging disease in non-endemic countries. In recent decades, the epidemiological profile of the disease has changed due to new patterns of immigration and successful control in its transmission, leading to the urbanization and globalization of the disease. Dilated cardiomyopathy is the most important and severe manifestation of human chronic Chagas disease and is characterized by heart failure, ventricular arrhythmias, heart blocks, thromboembolic phenomena, and sudden death. This article will present an overview of the clinical and epidemiological aspects of Chagas disease. It will focus on several clinical aspects of the disease, such as chronic Chagas disease without detectable cardiac pathology, as well as dysautonomia, some specific features, and the principles of treatment of chronic cardiomyopathy.

Oral transmission of Chagas disease: typing of Trypanosoma cruzi from five outbreaks occurred in Venezuela shows multiclonal and common infections in patients, vectors and reservoirs

In Venezuela six episodes of oral transmission of Chagas disease (OChD) have been described, being the one reported in 2007 with a total of 103 people infected the largest worldwide. This work shows the use of three molecular markers (mini-exon gene and domains 24Sα and 18S of the ribosomal RNA) to characterize the infecting Trypanosoma cruzi strain of patients, reservoirs and vectors involved in five of the six OChD outbreaks. For this, 28 T. cruzi isolates were characterized by PCR, and the products of these reactions cloned and sequenced to reveal the existence of different TcI SL-IR genotypes. We also describe a new PCR assay able to discriminate between TcIb and TcId parasite populations. In summary, we have identified mostly parasites with the TcId haplotype and multiclonal populations with predominance of haplotype TcId (65.2%). Additionally, populations of haplotypes TcIb, TcIa and mixtures (TcId+TcIb, TcId+TcIa, TcIb+TcIa) are recurrent in samples obtained from children. The analysis of the SL-IR motif showed two clones depicting a different motif that could be an evidence for a possible hybrid haplotype between TcIa and TcIb (haplotype TcIa/Ib). Interestingly, in a single patient haplotype differences between T.cruzi isolates obtained pre and post-treatment were found. In conclusion, our findings show that in order to understand the pathogenic mechanisms involved in the orally acquired Chagas disease there is a need to join efforts to study T. cruzi haplotypes, their tissue tropisms and their susceptibility to chemoteraphy.

Understanding chronic non-communicable diseases in Latin America: towards an equity-based research agenda

Although chronic non-communicable diseases are traditionally depicted as diseases of affluence, growing evidence suggests they strike along the fault lines of social inequality. The challenge of understanding how these conditions shape patterns of population health in Latin America requires an inter-disciplinary lens. This paper reviews the burden of chronic non-communicable diseases in the region and examines key myths surrounding their prevalence and distribution. It argues that a social justice approach rooted in the idea of health inequity needs to be at the core of research in this area, and concludes with discussion of a new approach to guide empirical research, the 'average/deprivation/inequality' framework.

Vaccines to combat the neglected tropical diseases

The neglected tropical diseases (NTDs) represent a group of parasitic and related infectious diseases such as amebiasis, Chagas disease, cysticercosis, echinococcosis, hookworm, leishmaniasis, and schistosomiasis. Together, these conditions are considered the most common infections in low- and middle-income countries, where they produce a level of global disability and human suffering equivalent to better known conditions such as human immunodeficiency virus/acquired immunodeficiency syndrome and malaria. Despite their global public health importance, progress on developing vaccines for NTD pathogens has lagged because of some key technical hurdles and the fact that these infections occur almost exclusively in the world's poorest people living below the World Bank poverty line. In the absence of financial incentives for new products, the multinational pharmaceutical companies have not embarked on substantive research and development programs for the neglected tropical disease vaccines. Here, we review the current status of scientific and technical progress in the development of new neglected tropical disease vaccines, highlighting the successes that have been achieved (cysticercosis and echinococcosis) and identifying the challenges and opportunities for development of new vaccines for NTDs. Also highlighted are the contributions being made by non-profit product development partnerships that are working to overcome some of the economic challenges in vaccine manufacture, clinical testing, and global access.

Screening for Chagas' disease in HIV-positive immigrants from endemic areas

Chagas' disease is an opportunistic infection in the setting of HIV/AIDS. The arrival of HIV-positive immigrants from endemic areas to non-endemic countries makes possible the detection of Chagas' disease in this group of patients. We describe the results of a screening programme conducted in the HIV-positive immigrant population arriving from endemic areas who attended the Tropical Medicine Unit of Hospital Universitario Central of Asturias during 2008. We determined anti-T. cruzi antibodies in all HIV patients arriving from endemic areas who were followed up. The ID-Chagas antibody test was used as a screening assay. The positive cases were confirmed with ELISA, IFAT and PCR. We analysed 19 HIV-positive immigrants, of which two (10·5%) had a positive antibody test for Chagas' disease confirmed. PCR was positive in both cases. There was no difference between the co-infected and the non-co-infected patients with respect to race, place of birth and residence, CD4+ cell count, and HIV viral load count. Direct microscopic examination of blood was negative in both positive cases. The positive patients were a man from Bolivia and woman from Paraguay. The overlap of HIV and T. cruzi infection occurs not only in endemic areas but also in non-endemic areas of North America and Europe where the diagnosis may be even more difficult due to low diagnostic suspicion. The implementation of screening programmes in this population group is needed for the early diagnostic of Chagas' disease.

Chagasic encephalitis in HIV patients: common presentation of an evolving epidemiological and clinical association

We present a case of chagasic meningoencephalitis reactivation in an HIV-infected woman with advanced immunosuppression. Prolonged survival was attained with antiparasitic therapy and secondary prophylaxis, in conjunction with the use of highly-active antiretroviral therapy. The geographic expansion of the HIV epidemic around the world coupled with global migration and international travel have created a favourable situation for Trypanosoma cruzi and HIV coinfection. The clinical manifestations of Chagas disease in HIV-positive people usually represent reactivation and not acute infection with T cruzi (coinfection). Symptomatic reactivation of chronic latent T cruzi infection can be triggered by severe immunosuppression associated with HIV infection. In this setting, Chagas disease reactivation often presents as meningoencephalitis resembling toxoplasma encephalitis. We review, in this Grand Round, the clinical manifestations, diagnostic approach, pathogenesis, natural history, treatment, prognosis, and prevention of Chagas disease reactivation among HIV-infected people with an emphasis on CNS manifestations.

Prizes and parasites: incentive models for addressing Chagas disease

Recent advances in immunology have provided a foundation of knowledge to understand many of the intricacies involved in manipulating the human response to fight parasitic infections, and a great deal has been learned from malaria vaccine efforts regarding strategies for developing parasite vaccines. There has been some encouraging progress in the development of a Chagas vaccine in animal models. A prize fund for Chagas could be instrumental in ensuring that these efforts are translated into products that benefit patients.

The neglected tropical diseases of Latin America and the Caribbean: a review of disease burden and distribution and a roadmap for control and elimination

The neglected tropical diseases (NTDs) represent some of the most common infections of the poorest people living in the Latin American and Caribbean region (LAC). Because they primarily afflict the disenfranchised poor as well as selected indigenous populations and people of African descent, the NTDs in LAC are largely forgotten diseases even though their collective disease burden may exceed better known conditions such as of HIV/AIDS, tuberculosis, or malaria. Based on their prevalence and healthy life years lost from disability, hookworm infection, other soil-transmitted helminth infections, and Chagas disease are the most important NTDs in LAC, followed by dengue, schistosomiasis, leishmaniasis, trachoma, leprosy, and lymphatic filariasis. On the other hand, for some important NTDs, such as leptospirosis and cysticercosis, complete disease burden estimates are not available. The NTDs in LAC geographically concentrate in 11 different sub-regions, each with a distinctive human and environmental ecology. In the coming years, schistosomiasis could be eliminated in the Caribbean and transmission of lymphatic filariasis and onchocerciasis could be eliminated in Latin America. However, the highest disease burden NTDs, such as Chagas disease, soil-transmitted helminth infections, and hookworm and schistosomiasis co-infections, may first require scale-up of existing resources or the development of new control tools in order to achieve control or elimination. Ultimately, the roadmap for the control and elimination of the more widespread NTDs will require an inter-sectoral approach that bridges public health, social services, and environmental interventions.