Trypanosoma cruzi TcIII / Z3 genotype as agent of an outbreak of Chagas disease in the Brazilian Western Amazonia

Chagas’ disease is an emerging and neglected disease in the Brazilian Amazon region, where T. cruzi I predominates among the acute cases of the disease; and T. cruzi III/Z3, a population cluster from sylvatic areas of the Amazon basin, is rarely associated with human infections. On 23rd April 2007, the Foundation for Health Surveillance of the State of Amazonas, Brazil reported an outbreak of acute Chagas disease in the municipality of Coari on the Solimões River banks. Fresh blood examination confirmed the infection in 25 patients. Parasite culture in LIT medium was successful for 18 isolates. Molecular characterization was performed by PCR of the non‐transcribed spacer of the mini‐exon and by sequencing of the mitochondrial cytochrome c oxidase subunit II (COII) gene. The T. cruzi isolates were all from genotype Z3, and sequencing revealed that all isolates had equal COII sequences compatible with TcIII type, suggesting a single source of infection. To our knowledge, this is the first outbreak of acute cases caused uniquely by the genotype TcIII/Z3. Wild vectors harbouring TcIII stocks contribute to transmission when the triatomine species reaches human food chain or when humans invade the forest environment, where sylvatic cycle constitutes a reservoir of parasites that might be associated with specific epidemiological and clinical traits of the emergent Chagas disease in the Amazon.     

Inconclusive results in conventional serological screening for Chagas' disease in blood banks: evaluation of cellular and humoral response

Objective To find the most reliable screening method for Trypanosoma cruzi infection in blood banks. Material and methods Epidemiological data, lymphoproliferation assay, parasitological, conventional serological tests: immunofluorescence, haemagglutination, ELISA with epimastigote and trypomastigote antigens and reference serological tests: trypomastigote excreted‐secreted antigens (TESA) blot and chemiluminescent ELISA assay with mucine from trypomastigote forms were applied to individuals with inconclusive serology, non‐chagasic individuals and chronic chagasic patients. Results TESA blot had the best performance when used as a single test in all the groups. In the inconclusive group 20.5% of individuals were positive for TESA blot, 23.3% for either lymphoproliferation or TESA blot, and 17.8% for lymphoproliferation only. Positive lymphoproliferation without detectable antibodies was observed in 5.47% of all inconclusive serology cases. Analysis of six parameters (three serological assays, at least one parasitological test, one lymphoproliferation assay and epidemiological data) in the inconclusive group showed that diagnosis of Chagas’ disease was probable in 15 patients who were positive by two or more serological tests or for whom three of those six parameters were positive. Conclusion TESA blot is a good confirmatory test for Chagas’ disease in the inconclusive group. Although lymphoproliferation suggests the diagnosis of Chagas’ disease in the absence of antibodies when associated with a high epidemiological risk of acquiring Chagas’ disease, the data from this study and the characteristics of the lymphoproliferation assay (which is both laborious and time‐consuming) do not support its use as a confirmatory test in blood‐bank screening. However, our findings underscore the need to develop alternative methods that are not based on antibody detection to improve the diagnosis when serological tests are inconclusive.     

Myocardial scars correlate with eletrocardiographic changes in chronic Trypanosoma cruzi infection for dogs treated with Benznidazole

Objectives The cardiac form of Chagas disease is evidenced by a progressive cardiac inflammation that leads to myocarditis, fibrosis and electrocardiographic (ECG) conduction abnormalities. Considering these characteristics, the aim of this study was to prospectively evaluate the early ECG changes in dogs that were experimentally inoculated with Benznidazole (Bz)‐susceptibly (Berenice‐78) and Bz‐resistant (VL‐10, and AAS) Trypanosoma cruzi strains and, later, evaluate the efficacy of Bz treatment for preventing these ECG alterations. Methods Electrocardiographic changes of treated and untreated animals were prospectively evaluated for up to 270 days after infection, at which point collagen (right atrium) quantification was performed. Results All infected dogs had a high intensity of heart fibrosis (4616.00 ± 1715.82 collagen/74931 μm² in dogs infected with Berenice‐78 strain, 5839.2 ± 1423.49 collagen/74931 μm² in infected by AAS and 6294.40 ± 896.04 collagen/74931 μm² in animals infected with VL‐10 strain), while 78.57% of all infected dogs showed ECG alterations. Bz Therapy reduced or prevented fibrosis in Bz‐susceptible Berenice‐78 (2813.00 ± 607.13 collagen/74931 μm²) and Bz‐resistant AAS strains (4024 ± 1272.44 collagen/74931 μm²), coincident with only 10% de ECG alterations at 270 days. However, in those animals infected with a Bz‐resistant VL‐10 strain, specific treatment did not alter collagen deposition (6749.5 ± 1596.35 collagen/74931 μm²) and there was first atrioventricular block and chamber overload at 120 and 270 days after infection, with 75% abnormal ECG exams. Conclusions These findings indicate that an effective antiparasitic treatment in the early stage of Chagas disease can lead to a significant reduction in the frequency and severity of the parasite‐induced cardiac disease, even if parasites are not completely eliminated.     

CHICKEN COOPS,Triatoma dimidiata INFESTATION AND ITS INFECTION WITH Trypanosoma cruzi IN A RURAL VILLAGE OF YUCATAN, MEXICO

This study longitudinally investigated the association between Triatoma dimidiata infestation, triatomine infection with Trypanosoma cruzi and household/backyard environmental characteristics in 101 homesteads in Molas and Yucatan, Mexico, between November 2009 (rainy season) and May 2010 (dry season). Logistic regression models tested the associations between insect infestation/infection and potential household-level risk factors. A total of 200 T. dimidiata were collected from 35.6% of the homesteads, mostly (73%) from the peridomicile. Of all the insects collected, 48% were infected with T. cruzi. Infected insects were collected in 31.6% of the homesteads (54.1% and 45.9% intra- and peridomiciliary, respectively). Approximately 30% of all triatomines collected were found in chicken coops. The presence of a chicken coop in the backyard of a homestead was significantly associated with both the odds of finding T. dimidiata (OR = 4.10, CI 95% = 1.61-10.43, p = 0.003) and the presence of triatomines infected with T. cruzi (OR = 3.37, CI 95% = 1.36-8.33, p = 0.006). The results of this study emphasize the relevance of chicken coops as a putative source of T. dimidiata populations and a potential risk for T. cruzi transmission.     

Is Rhodnius robustus (Hemiptera: Reduviidae) responsible for Chagas disease transmission in Western Venezuela?

We present evidence for the putative role of Rhodnius robustus as extradomestic vector of Chagas disease in Western Venezuela. First, we assessed the validity of this triatomine species by genetic characterization in relation with some other species of the prolixus group. Random amplified polymorphic DNA data showed a clear separation between this species and R. prolixus and indicated a probable genetic heterogeneity within R. robustus. Faeces and gut contents were microscopically examined in 54 of 137 R. robustus collected in palm trees. According to this morphological examination, 18% were positive for Trypanosoma cruzi, 11% harboured T. rangeli and 11% showed mixed infection. Five of the seven samples examined gave a polymerase chain reaction major band of 270 bp specific of T. cruzi. The hybridization probes showed that R. robustus may transmit clones 20 and 39 (or genetically related ones) in Venezuela. Such a transmission might occur when, in absence of domestic R. prolixus and attracted by artificial light, R. robustus enters houses and feeds on humans, or when people are bitten outdoors. The lack of bugs inside houses could mean that the insects leave houses after feeding, or die without reproducing there.     

Seroprevalence of Trypanosoma cruzi in kidney transplant donors and recipients in Mexico City

Infectious diseases are common causes of morbidity and mortality among kidney transplant recipients. Chagas disease (CD) has been recognized as an emerging infectious complication of transplantation caused by the parasite Trypanosoma cruzi. CD is prevalent in Mexico, particularly in the southern coastal region. The impact on Mexican kidney transplant programs has not been previously studied prospectively. From 2009 through 2010, serum samples from 59 kidney transplant donors and 405 renal transplant recipients were screened for antibodies against T. cruzi. Serum was initially screened using a locally developed ELISA test; positive results were confirmed by an indirect immunofluorescense test, in accordance with Panamerican Health Organization/World Health Organization guidelines. None of the donors were seropositive for T. cruzi, while 8 (1.97%) kidney transplant recipients were confirmed to be seropositive for T. cruzi. None of them have developed clinical manifestations of CD, although specific screening of recipients was not performed. A prospective study is planned to define the epidemiology and outcome of CD among kidney transplant donors and recipients in Mexico more thoroughly.     

Interferon-γ and other inflammatory mediators in cardiomyocyte signaling during Chagas disease cardiomyopathy

Chagas disease cardiomyopathy(CCC), the main consequence of Trypanosoma cruzi(T.cruzi) infection, is an inflammatory cardiomyopathy that develops in up to 30% of infected individuals. The heart inflammation in CCC patients is characterized by a Th1 T cell-rich myocarditis with increased production of interferon(IFN)-γ, produced by the CCC myocardial infiltrate and detected at high levels in the periphery. IFN-γ has a central role in the cardiomyocyte signaling during both acute and chronic phases of T.cruzi infection. In this review, we have chosen to focus in its pleiotropic mode of action during CCC, which may ultimately be the strongest driver towards pathological remodeling and heart failure. We describe here the antiparasitic protective and pathogenic dual role of IFN-γ in Chagas disease.     

Oral transmission of Chagas disease from a One Health approach: A systematic review

Objective

To analyse acute Chagas disease (CD) outbreaks through a qualitative systematic review and discuss the determinants for its prevention and control.

Methods

Review of studies in which clinical cases of oral transmission were confirmed by parasitological and/or serological tests that included an epidemiological investigation of sources of infection, vectors and reservoirs.

Results

Thirty-two outbreaks (1965–2022) were analysed. The main foods involved in oral transmission outbreaks are homemade fruit juices. Different species of vectors were identified. Reservoirs were mainly dogs, rodents and large American opossums (didelphids).

Conclusion

Under a One Health approach, environmental changes are one of the factors responsible of the rise of oral transmission of CD. Entomological surveillance of vectors and control of the changes in wild and domestic reservoirs and reinforcement of hygiene measures around food in domestic and commercial sites are needed.     

Metabolic,mental health,behavioural and socioeconomic characteristics of migrants with Chagas disease in a non‐endemic country

Objectives Chronic Chagas disease causes cardiopathy in 20–40% of the 8–10 million people affected. The prevalence of atherogenic factors increases rapidly in Latin America. Somatic, mental, behavioural and social characteristics of the 80 000 Latino migrants with Chagas disease in Europe are not known. We postulate that they may accumulate these factors for poor health – notably cardiovascular‐outcomes. Methods This study took place at the Geneva University Hospitals in 2011. Latin American migrants with Chagas disease diagnosed in Geneva since 2008 were contacted. Interviews and blood tests assessed behavioural, socioeconomic, metabolic and cardiovascular factors. Results One hundred and thirty‐seven patients (women: 84.7%; median age: 43 years) with chronic Chagas disease were included in the study. The majority were Bolivians (94.2%), undocumented (83.3%), uninsured (72.3%) and living below the Swiss poverty line (89.1%). Prevalence of obesity was 25.5%, of hypertension 17.5%, of hypercholesterolemia 16.1%, of impaired fasting glucose 23.4%, of diabetes 2.9%, of metabolic syndrome 16.8%, of anxiety 58.4%, of depression 28.5%, of current smoking 15.4% and of sedentary lifestyle 62.8%. High (>10%) 10‐year cardiovascular risk affected 12.4%. Conclusions Latin American migrants with Chagas disease accumulate pathogenic chronic conditions of infectious, non‐transmissible, socioeconomic and behavioural origin, putting them at high risk of poor health, notably cardiovascular, outcomes. This highlights the importance of screening for these factors and providing interventions to tackle reversible disorders; facilitating access to care for this hard‐to‐reach population to prevent delays in medical interventions and poorer health outcomes; and launching prospective studies to evaluate the long‐term impact of these combined factors on the natural course of Chagas disease.