Chagas Disease In Chile Research Articles

1386. Chagas Disease in Chile: an Old and Forgotten

Abstract Background Chagas disease (ChD) affects 8-10 million people worldwide. In Chile there are 98,000 people affected. Most endemic region is the middle northern part of the country, but not present south of the central areas. Significant interruption of vector transmission was achieved in the late 1900s. Since 2008, blood products for transfusions are screened universally, and since 2014 ChD serology testing has been implemented in all pregnant women, focusing efforts on prevention of vertical transmision, the most important form of contagion at present. Being a referal center, we describe the demographic and clinical presentation as well as the treatment offered to the ChD referred patients. Methods Descriptive, retrospective study of patients with ChD referred to the San Borja Arriarán Hospital between january 2009 and march 2023. Demographic and clinical variables were analyzed: likely transmission mechanism, reason for testing, classification up on admission, diagnostic laboratory tests, treatment and reported adverse drug reaction (ADRs) Results T. cruzi infection was diagnosed in 234 patients, 74% women. The median age in years was 47; 70% Chileans nationals, the majority living in the Metropolitan Region (Fig 1). Among foreigners, the majority were form Bolivian. 76% had no associated comorbidity. Blood donation was the main form of detection (42 %), followed by pregnancy and family history study (Fig 2). Vector transmission was estimated in 50% of the cases; 84% were classified on admission as an indeterminate chronic disease; 42% patients received treatment, all with nifurtimox; 60% of them presented ADRs, more frequently during the first two weeks of treatment initiation. Most ADRs were gastrointestinal (anorexia, nausea and vomiting) (Fig 3); treatment was discontinued 20% of patients. Age and sex were not associated to higher rate of ADRs. Conclusion ChD continues to be endemic in Chile. Screening in blood donors and pregnant women is the main approach to diagnosis. The importance of its detection in pregnancy is both, the prevention of vertical transmission and the opportunity for early curative treatment. The incidence of ADRs is lower than that described in other series; a small percentage of these cases led to the discontinuation of treatment. Disclosures All Authors: No reported disclosures

Utility of prenatal screening for Congenital Chagas Disease in Chile

Chagas Disease is a pathology caused by the parasite Trypanosoma cruzi. It is considered a public health issue, especially its congenital transmission, not only in endemic countries but also in non endemic ones, being the main form of transmission in Chile. Objectives: To describe a congenital Chagas Disease case and to report about the usefulness of prenatal screening for Chagas Disease. Cli nical Case: A 29-week preterm newborn of a multiparous mother with Chagas Disease detected in the perinatal screening of current pregnancy. Due to history of Trypanosoma cruzi, PCR was performed on the 4th day of life resulting undetectable. At the 6th and the 8th week of life, a macular erythema tous rash and fever and respiratory distress were observed, respectively, both self-limited. At the 8th week of life, as a routine prematurity follow-up, a fundus examination was performed which showed bilateral retinal granulation, therefore, a TORCH study was performed with a negative result. Also, in this same week, a second Trypanosoma cruzi PCR was performed, with a positive result. Lab tests reported visualization of trypomastigotes, confirming the Congenital Chagas Disease diagnosis. The patient was treated with Nifurtimox, presenting an adverse reaction at 35 days of treatment with neu tropenia, vomiting, and poor weight gain. The treating drug was replaced by Benznidazole, achieving 60 days of treatment. At 22 months of chronologic age, the patient has remained asymptomatic. Con clusions: It is necessary to increase efforts in prevention, early detection, and study of direct relatives. This report is an example of the usefulness of Chagas disease prenatal screening for the detection and early treatment of new cases.

Changes in Age and Geographic Distribution of the Risk of Chagas Disease in Chile from 1989 to 2017.

The interruption of vector-borne transmission of Chagas disease was certified in Chile in 1999. Our goal was to determine the effects of the interruption of vector transmission on the age and spatial distributions of the risk of Chagas disease. We analyzed cases of Chagas disease by age and sex between 1989 and 2017, from notified disease reports of the Ministry of Health. Bayesian risk maps were constructed using the Besag-York-Mollie model. The reported cases of Chagas disease had a mean age of 45.9 ± 17.6 years. Small changes in the age distribution were found among different periods (χ215 = 602.4, p < 0.001). These were explained mainly by numbers lower than those expected in age groups 0-39 years in the 2011-2017 period. Part of the observed reduction in the proportion of individuals in the lower strata could be explained by the aging of the Chilean population. An increase of reported cases was detected after the interruption of vector-borne transmission (F1,327 = 4.24, p < 0.04), with regional differences (F14,1308 = 4.35, p < 0.001). The regions of the north-central area that have the highest burden of Chagas tended to decrease the relative risk, while the regions of the south tended to increase and small risk areas appear in zones where there are no insect vectors. There is still no clear evidence of a reduction in the reported cases in Chile. This could be explained mainly by an improvement in the detection of cases, but it cannot be ruled out that vector transmission still exists. The changes in distribution suggest potential impact from human internal migration and blood transfusion. This study provides strong evidence supporting the idea that entomological surveillance and long-term follow-up of Chagas disease need to be maintained after certification of interruption in endemic countries.

Epidemiology of Chagas disease: high mortality and incidence rate, Coquimbo Region

Chagas disease in Chile has increased in research, especially in pregnant women and donors in general, but remains neglected in Latin America. The environmental epidemiology of the vector points out the Coquimbo region is a greatest risk area. To analyze the time series of mortality and incidence rate Chagas disease national; regional and communal according to age. Population-based study, time series of mortality (1997 to 2017) and incidence rate (2011 to 2017), country, region and 15 communes. Use of gross and adjusted rates, calculating ch2, T test, ANOVA, p value < 0.05. Mortality; 49.37% (668) of the National deaths (1353) were Coquimbo region's residents, mainly male patients and over 60 years old people with cardiac and digestive complications, residents from Salamanca, Combarbalá and Illapel. Incidence: Of 6.173 accumulated cases, 6% are under 20 years old, higher incidence of women (61.4%) with an average age of 50 years old versus 56 years old men (T test = 29.19 p-value = 0.000), residents from Ovalle, Andacollo, Monte Patria and Illapel. Half of Chagas' disease deaths reside in the Coquimbo region, new cases, under 20 years old, are 6%.

Potential impact of climate change on the geographical distribution of two wild vectors of Chagas disease in Chile: Mepraia spinolai and Mepraia gajardoi

BackgroundMepraia gajardoi and Mepraia spinolai are endemic triatomine vector species of Trypanosoma cruzi, a parasite that causes Chagas disease. These vectors inhabit arid, semiarid and Mediterranean areas of Chile. Mepraia gajardoi occurs from 18° to 25°S, and M. spinolai from 26° to 34°S. Even though both species are involved in T. cruzi transmission in the Pacific side of the Southern Cone of South America, no study has modelled their distributions at a regional scale. Therefore, the aim of this study is to estimate the potential geographical distribution of M. spinolai and M. gajardoi under current and future climate scenarios.MethodsWe used the Maxent algorithm to model the ecological niche of M. spinolai and M. gajardoi, estimating their potential distributions from current climate information and projecting their distributions to future climatic conditions under representative concentration pathways (RCP) 2.6, 4.5, 6.0 and 8.5 scenarios. Future predictions of suitability were constructed considering both higher and lower public health risk situations.ResultsThe current potential distributions of both species were broader than their known ranges. For both species, climate change projections for 2070 in RCP 2.6, 4.5, 6.0 and 8.5 scenarios showed different results depending on the methodology used. The higher risk situation showed new suitable areas, but the lower risk situation modelled a net reduction in the future potential distribution areas of M. spinolai and M. gajardoi.ConclusionsThe suitable areas for both species may be greater than currently known, generating new challenges in terms of vector control and prevention. Under future climate conditions, these species could modify their potential geographical range. Preventive measures to avoid accidental human vectorial transmission by wild vectors of T. cruzi become critical considering the uncertainty of future suitable areas projected in this study.

Effects of climate change on reproductive number of Chagas disease

Reproductive number (R0)-maps estimate risk zones of vector-borne diseases and geographical distribution changes under climate change. To map R0 aiming to estimate the epidemiological risk of Chagas disease in Chile, its distribution and possible changes due to the global climate change. We used a relationship between R0 and entomological parameters of vectors as function of environmental variables, to map the risk of Chagas disease in Chile, under current and projected future environmental conditions. We obtained a geographical R0 estimation of Chagas disease in Chile. The highest R0averages correspond to the Central-Northern regions of Chile. T. cruzi transmission area could increase in the future due to climate changes. Independent of the future condition, both for optimistic and pessimistic climate change scenarios, the area of potential risk for Chagas disease transmission would increase. The estimated R0 values suggest that, if a control of T. infestans is not maintained, Chagas disease endemic status will persist or increase, independently of the climate change scenarios. Mapping R0 values is an effective method to assess the risk of Chagas disease. The eventual increase in the transmission area of the disease is worrisome.

Effects of atmospheric oscillations on infectious diseases: the case of Chagas disease in Chile.

BACKGROUND Currently, there is an increasing global interest for the study of how infectious diseases could be linked to climate and weather variability. The Chagas disease was described in 1909 by Carlos Chagas, and is caused by the flagellate protozoan Trypanosoma cruzi. The Chagas disease is considered one of the biggest concerns in public health in Latin America. In Chile, the main vectors involved in the transmission of T. cruzi are arthropods of the Triatominae subfamily. Moreover, another main transmission way is through of vectors by fecal-urine way, however, oral way also has been described among others transmission form.OBJECTIVES In order to get understand outbreaks of Chagas-disease, we search for possible relationships between the frequency of cases in the Chilean population and atmospheric oscillations.METHODS We explored the two most important atmospheric oscillations in the Southern Hemisphere: southern oscillation index (SOI) and Antarctic oscillation (AAO), during the available years with official data. Because the number of migrant people born outside from Chile increasing significantively between 2014 and 2018, we used for the analysis two different periods from data available official data: (i) 2001 to 2014, (ii) 2001 to 2017.FINDINGS For both periods we observed a significant and positive relation between AAO one year before. However, for the 2001 to 2014 period positive SOI one year before, which is related with La Niña phases, was the more important variable.MAIN CONCLUSIONS The Chagas disease frequency per year in Chile was found to depend mainly on SOI in previous year, whose values can be determined one year in advance. Therefore, it is possible to partially forecast annual frequency patterns. This could have important applications in public health strategies and for allocating resources for the management of the disease.

Modeling Chagas disease in Chile: From vector to congenital transmission

Chagaś disease is a human health problem in Latin America. It is highly prevalent in northern Chile between the Arica-Parinacota and Coquimbo regions, with reported incidence of 3–11/100000 inhabitants and mortality of 0.3–0.4/100000. The interruption of vector transmission was reported in 1999 by means of the elimination of the primary vector, Triatoma infestans, from human dwellings, thus the epidemiologic dynamics of this disease should be modified. Here we model the dynamics of Chagaś disease based on previous models for vector and congenital transmission, propose a model that includes both transmission forms and perform simulations. We derive useful relationships for the reproductive number (R0) showing that it may be expressed as the sum of the vector (R0V) and congenital (R0C) contributions. The vector contribution is larger than the congenital one; without the former Chagaś disease vanishes exponentially in two to three generations. Sensitivity analyses showed that the main parameters that intervene are the human bite rate, the density of vectors per human and the mortality rate of the insect vectors. Our model showed that the success of the eradication of Chagaś disease is based on the interruption of domestic transmission. Once this is obtained, the control strategies should focus on avoiding the domiciliation of wild vectors, re-colonization by the primary vector, and an adequate coverage of congenital case treatment.

Feeding profile of Mepraia spinolai, a sylvatic vector of Chagas disease in Chile

American trypanosomiasis is a chronic disease transmitted mainly by vectors. The hematophagous triatomine vectors transmit Trypanosoma cruzi to a wide variety of mammals, which usually are their food source. This study determined the feeding profile of Mepraia spinolai, a sylvatic triatomine vector, present in endemic areas of Chile. Vectors were captured in the north-central area of Chile. Samples of intestinal contents were analyzed by an Enzyme-linked immunosorbent assay (ELISA) that identifies and discriminates the presence of serum antigens from Homo sapiens and nine animal species (Canis familiaris, Felis catus, Capra hircus, Mus musculus, Gallus gallus, Octodon degus, Thylamys elegans, Phyllotis darwini and Oryctolagus cuniculus). Our data indicate the most frequent feeding source in this area was P. darwini, followed by O. degus, O. cuniculus, M. musculus, G. gallus, T. elegans, C. familiaris, F. catus and C. hircus. Mixed food sources were also identified.

Temporal variation in Trypanosoma cruzi lineages from the native rodent Octodon degus in semiarid Chile

Chagas disease is a zoonosis caused by the protozoan parasite Trypanosoma cruzi and transmitted by triatomine insects to several mammalian species acting as reservoir hosts. In the present study, we assess T. cruzi-prevalence and DTU composition of the endemic rodent Octodon degus from a hyper-endemic area of Chagas disease in Chile. Parasite detection is performed by PCR assays on blood samples of individuals captured in the austral summers of 2010–2013. The infection level in rodents differed in the summers of these four years between 18% and 70%. Overall, infected O. degus showed similar T. cruzi-DTU composition (TcI, TcII, TcV and TcVI lineages) among years, corresponding to single and mixed infection, but the relative importance of each DTU changed among years. In 2013, we detected that only three out of the four T. cruzi-DTU found in O. degus were present in the endemic triatomine Mepria spinolai. We suggest that O. degus, an abundant long-lived rodent, is an important native reservoir of T. cruzi in the wild transmission cycle of Chagas disease and it is able to maintain all the T. cruzi-DTUs described in semiarid Chile.

Mannose-Binding Lectin and Toll-Like Receptor Polymorphisms and Chagas Disease in Chile

Mannose-binding lectin (MBL) and Toll-like receptor (TLR) polymorphisms may influence susceptibility and manifestation of Trypanosoma cruzi infection. In northern Chile, we examined 61 asymptomatic patients with chronic Chagas disease (CD), 64 patients with chronic Chagas cardiomyopathy (CCC), and 45 healthy individuals. Low-producer MBL2*B genotypes were more common in CD patients (48%) than healthy individuals (31%; adjusted odds ratio = 2.3, 95% confidence interval = 1.01-5.4, P = 0.047) but did not differ with manifestation. In contrast, the heterozygous Toll-like receptor 4 (TLR4)-deficiency genotype D299G/T399I occurred more frequently in asymptomatic (14.8%) than CCC patients (3.1%; P = 0.02). TLR1-I602S, TLR2-R753Q, TLR6-S249P, and MAL/TIRAP-S180L did not associate with CD or CCC. These findings support the complement system to be involved in defense against Trypanosoma cruzi infection and indicate that curbed TLR4 activation might be beneficial in preventing CCC.

Field assessment of Trypanosoma cruzi infection and host survival in the native rodent Octodon degus

Chagas disease is a zoonosis caused by the flagellated parasite Trypanosoma cruzi and transmitted by triatomine insects to several mammalian species acting as reservoir hosts. In the present study, we assess T. cruzi-prevalence, survivorship and T. cruzi-infection rate of the endemic rodent Octodon degus from a hyper-endemic area of Chagas disease in Chile. Parasite detection is performed by PCR assays on blood samples of individuals captured in austral summer of 2010, and on non-infected individuals recaptured in 2011 as well as on new captures. Results show a high infection level in this species (up to 70%). Infected O. degus have the same chance of surviving to the next reproductive season as uninfected individuals, irrespective of sex. We suggest that O. degus, an abundant long-lived rodent with high dispersal capability, could be considered an important native reservoir of T. cruzi in the wild transmission cycle of Chagas disease in Chile.

Temporal Variation ofTrypanosoma cruziInfection in Native Mammals in Chile

In the present study, we compared Trypanosoma cruzi infection in four native mammals from a hyperendemic area of Chagas disease in Chile for two different periods to assess the occurrence of interannual variation (1999-2000 vs. 2005-2006). Parasite detection in mammals is performed by polymerase chain reaction assays and confirmed by Southern blot analysis and hybridization test with a universal probe. Results showed significant differences in the levels of T. cruzi infection between the compared periods. We suggest that the major El Niño event occurred in 1997-1998, a large-scale global climatic fluctuation, could be indirectly explaining the extremely high T. cruzi infection in 1999-2000 by means of a time-lag response of the wild transmission cycle of Chagas disease in semiarid Chile after the irruption of small rodent populations.

Molecular Epidemiology of Chagas Disease in the Wild Transmission Cycle: The Evaluation in the Sylvatic Vector Mepraia spinolai from an Endemic Area of Chile

The sylvatic transmission cycle of Chagas disease in Chile is composed of wild mammals and insects of the genus Mepraia. We determined infection rates and Trypanosoma cruzi genotypes in Mepraia spinolai. We collected 227 insects from two ecologically contrasting areas to assess T. cruzi infection. Polymerase chain reaction (PCR)-amplified minicircle DNAs were characterized by Southern blot and hybridization tests with genotype-specific probes. Infection in insects from the more fertile area was almost 2-fold higher than in the poorer area. The genotype TCI was the most prevalent and other genotypes such as TCIIb, TCIId, and TCIIe were found at lower rates. The areas differed in their genotype distribution but not in their genotype diversity. We suggest that the difference in abundance and richness of mammals between the areas may be producing the detected infection levels in vectors. Our results are compared with those reported for mammals from the same area.

European Rabbits (Oryctolagus cuniculus) are Naturally Infected with Different Trypanosoma cruzi Genotypes

Trypanosoma cruzi, the etiologic agent of Chagas disease, presents a complex life cycle, cycling between reduviid vectors and wild and domestic mammals. The European rabbit is an introduced species in America, but its role as reservoir in the wild transmission cycle of Chagas disease remains unknown. We used polymerase chain reaction, Southern blot, and hybridization tests to detect infection and characterize genotypes in rabbits from a hyperendemic area of Chagas disease in Chile. Results show 38% of infection with different genotypes. We provide evidence that rabbits are naturally infected with T. cruzi, which may have important epidemiologic consequences for the wild transmission cycle.

Blood host sources of Mepraia spinolai (Heteroptera: Reduviidae), wild vector of chagas disease in Chile.

There are two vectors of the Chagas' disease in Chile: Triatoma infestans Klug the domestic vector and Mepraia spinolai Porter the sylvatic vector. The alimentary profile of M. spinolai has been poorly studied. In this work we study the participation of humans, goats, dogs, cats, rodents, rabbits, birds (hens) and reptiles in the diet of M. spinolai by analyzing the intestinal content through immunoradiometric assay. To put our results in a general context, we also compared the diet with that described for T. infestans. In decreasing order, we detected blood of rabbits, dogs, goats, rodents, humans, and birds (hens). There were 12.3% of insects infected with T. cruzi, but this fact was not significant for diet variance. In warm weather there was a larger diversity of alimentary sources than in a cold one. The niche breadth increased from 0.029 in cold weather to 0.464 in warm weather. The niche overlap of T. infestans and M. spinolai was 0.23.