New Scheme of Intermittent Benznidazole Administration in Patients Chronically Infected with Trypanosoma cruzi: Clinical, Parasitological, and Serological Assessment after Three Years of Follow-Up.

In a pilot study, we showed that the intermittent administration of benznidazole in chronic Chagas disease patients resulted in a low rate of treatment suspension and therapeutic failure, as assessed by quantitative PCR (qPCR) at the end of treatment. Here, a 3-year posttreatment follow-up study of the same cohort of patients is presented. The treatment scheme consisted of 12 doses of benznidazole at 5 mg/kg of body weight/day in two daily doses every 5 days. Parasite load, Trypanosoma cruzi-specific antibodies, and serum chemokine levels were measured prior to treatment and after a median follow-up of 36 months posttreatment by DNA minicircle kinetoplastid and nuclear DNA satellite sequence qPCR methods, conventional serological techniques, a Luminex-based assay with recombinant T. cruzi proteins, and a cytometric bead array. At the end of follow-up, 14 of 17 (82%) patients had negative qPCR findings, whereas three of 17 (18%) had detectable nonquantifiable findings by at least one of the qPCR techniques. A decline in parasite-specific antibodies at 12 months posttreatment was confirmed by conventional serological tests and the Luminex assays. Monocyte chemoattractant protein 1 levels increased after treatment, whereas monokine induced by gamma interferon levels decreased. New posttreatment electrocardiographic abnormalities were observed in only one patient who had cardiomyopathy prior to treatment. Together, these data strengthen our previous findings by showing that the intermittent administration of benznidazole results in a low rate of treatment suspension, with treatment efficacy comparable to that of a daily dose of 5 mg/kg for 60 days.

Reporting of adverse reactions to benznidazole: does medical expertise matter?

This study evaluated and compared follow-up and adverse drug reaction (ADR) reporting for Chagas disease (CD) patients treated with benznidazole (BZN) by two health teams with different levels of experience, using medical records for 204 patients participating in the first year of a scaled-up public health program for CD case detection and treatment conducted at all 46 primary health care centers in La Plata district, Buenos Aires, Argentina, in 2014. Both teams were experienced in CD patient management and trained in BZN administration, and included senior physicians, but one team had no experience in administering BZN while the other team had three years of experience due to their participation in the program's pilot project. Patients with positive serology for CD were treated with 5 mg/kg/day of BZN for 60 days. Patients' median age was 35 years and 84.3% were female. There was a statistically significant difference in the number of ADRs reported by the experienced versus the inexperienced health teams (18 versus 44 respectively; P < 0.001). Health team experience in administering BZN to CD patients, and treatment duration, were significantly associated with reporting of ADRs (adjusted odds ratios (aORs) 0.340 (95% confidence interval (CI): 0.177-0.652) and 0.967 (CI: 0.942-0.993) respectively). ADR reporting increased with patient age, occurring at the highest frequency (42.9%) in people 50+ years old. All treatment discontinuations (nine) occurred in patients followed up by the inexperienced health team. Level of experience in BZN administration to CD patients was significantly and inversely associated with frequency of ADR reports: inexperienced health team members tended to report more.

El presente estudio evaluó y comparó el seguimiento y la notificación de reacciones adversas medicamentosas (RAM) en pacientes con enfermedad de Chagas tratados con benznidazol por dos equipos de salud con diferentes niveles de experiencia, mediante el uso de los expedientes médicos de 204 pacientes que participaron en el primer año de un programa de salud pública ampliado para la detección de casos de enfermedad de Chagas y su tratamiento, realizado en los 46 centros de atención primaria de salud del distrito de La Plata (Buenos Aires) en el 2014. Ambos equipos tenían experiencia en la atención de pacientes con enfermedad de Chagas, estaban capacitados en la administración de benznidazol e incluían médicos experimentados, pero uno de los equipos nunca había usado benznidazol, mientras que el otro tenía tres años de experiencia por su participación en el proyecto piloto del programa. Los pacientes con pruebas serológicas positivas para la enfermedad de Chagas recibieron 5 mg/kg/día de benznidazol durante 60 días. La mediana de edad de los pacientes era de 35 años y 84,3% eran mujeres. Hubo una diferencia estadísticamente significativa entre el número de reacciones adversas medicamentosas notificadas por el equipo de salud experimentado y el equipo sin experiencia (18 y 44, respectivamente; P<0.001). Tanto la experiencia de los equipos de salud en la administración de benznidazol a los pacientes con enfermedad de Chagas como la duración del tratamiento se asociaron significativamente con la notificación de reacciones adversas medicamentosas (razones de posibilidades ajustadas, 0,340; intervalo de confianza de 95% [IC]: 0,177­0,652; y 0,967, IC: 0,942­0,993, respectivamente). La notificación de reacciones adversas medicamentosas aumentó a mayor edad de los pacientes; la frecuencia máxima (42,9%) se observó en las personas mayores de 50 años. Todas las interrupciones del tratamiento (nueve) fueron en pacientes atendidos por el equipo de salud sin experiencia. El nivel de experiencia en la administración de benznidazol a los pacientes con enfermedad de Chagas mostró una asociación significativa e inversa con la frecuencia de notificación de reacciones adversas medicamentosas: los miembros del equipo de salud sin experiencia tendieron a notificar más reacciones.

Neste estudo foram analisados e comparados dados notificados de reação adversa medicamentosa e de acompanhamento de pacientes com doença de Chagas tratados com benznidazol (BZN) por dois grupos de profissionais da saúde com níveis de experiência distintos. Os dados foram obtidos dos prontuários médicos de 204 pacientes que participaram do primeiro ano de um programa expandido de saúde pública para detecção de casos e tratamento da doença de Chagas implantado nas 46 unidades básicas de saúde do distrito de La Plata em Buenos Aires, Argentina, em 2014. Ambos os grupos eram formados por médicos mais graduados e profissionais com experiência na conduta de pacientes com doença de Chagas e capacitados em administrar BZN, porém um dos grupos era inexperiente em administrar BZN enquanto o outro contava com experiência de três anos por ter participado do projeto-piloto do programa. Os pacientes com sorologia positiva para doença de Chagas foram tratados com 5 mg/kg/dia de BZN por 60 dias. A mediana de idade foi 35 anos e 84,3% dos pacientes eram do sexo feminino. Verificou-se uma diferença estatisticamente significativa no número de reações adversas medicamentosas notificadas pelo grupo experiente em relação ao grupo inexperiente (18 vs. 44, respectivamente; P < 0.001). Ter experiência em administrar BZN aos pacientes com doença de Chagas e a duração do tratamento foram fatores significativamente associados à notificação de reação adversa medicamentosa (razão de chances ajustada [aOR] 0,340, intervalo de confiança de 95% [IC 95%] 0,177­0,652 e aOR 0,967, IC 95% 0,942­0,993, respectivamente). A notificação de reação adversa medicamentosa aumentou de acordo com a idade do paciente, ocorrendo com maior frequência (42,9%) nos pacientes acima de 50 anos. Os 9 casos de interrupção do tratamento ocorreram em pacientes acompanhados pelo grupo inexperiente. O nível da experiência em administrar BZN aos pacientes com doença de Chagas teve uma associação significativa e inversa com a frequência de notificação de reação adversa medicamentosa: os integrantes do grupo inexperiente tenderam a notificar mais.

New Scheme of Intermittent Benznidazole Administration in Patients Chronically Infected with Trypanosoma cruzi: a Pilot Short-Term Follow-Up Study with Adult Patients.

There is a clinical need to test new schemes of benznidazole administration that are expected to be at least as effective as the current therapeutic scheme but safer. This study assessed a new scheme of benznidazole administration in chronic Chagas disease patients. A pilot study with intermittent doses of benznidazole at 5 mg/kg/day in two daily doses every 5 days for a total of 60 days was designed. The main criterion of response was the comparison of quantitative PCR (qPCR) findings prior to and 1 week after the end of treatment. The safety profile was assessed by the rate of suspensions and severity of adverse effects. Twenty patients were analyzed for safety, while qPCR was tested for 17 of them. The average age was 43 ± 7.9 years; 55% were female. Sixty-five percent of treated subjects showed detectable qPCR results prior to treatment of 1.45 (0.63 to 2.81) and 2.1 (1.18 to 2.78) parasitic equivalents per milliliter of blood (par.eq/ml) for kinetoplastic DNA (kDNA) qPCR and nuclear repetitive sequence satellite DNA (SatDNA) qPCR, respectively. One patient showed detectable PCR at the end of treatment (1/17), corresponding to 6% treatment failure, compared with 11/17 (65%) patients pretreatment (P = 0.01). Adverse effects were present in 10/20 (50%) patients, but in only one case was treatment suspended. Eight patients showed mild adverse effects, whereas moderate reactions with increased liver enzymes were observed in two patients. The main accomplishment of this pilot study is the promising low rate of treatment suspension. Intermittent administration of benznidazole emerges a new potential therapeutic scheme, the efficacy of which should be confirmed by long-term assessment posttreatment.

Mother-to-child Chagas disease transmission: The challenge of detection and prevention in areas without the risk of vectorial transmission.

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi. Although it is endemic in many Latin American (LA) countries, mother-to-child transmission has caused it to expand to other countries and continents. In places where vector transmission is controlled or absent, the epidemiological importance of T. cruzi transmission of the infected mother to her child during pregnancy or childbirth (i.e., perinatal CD) increases. In countries where CD is not endemic, CD screening should be performed in pregnant or fertile women who are native to LA countries or whose mothers are native to LA countries. Diagnosis is established by detecting anti-T. cruzi IgG antibodies in a serum or plasma sample. Antiparasitic treatment cannot be offered during pregnancy, and since the majority of infected newborns are asymptomatic at birth, a diagnosis is made by direct observation or concentration (microhematocrit) or by using molecular testing techniques. Once the infected child receives a diagnosis, it is essential to offer treatment (benznidazole/nifurtimox) as soon as possible, with good tolerance and effectiveness in the first year of life. Even if the diagnosis is negative at birth, the newborn must be followed up for at least the first 9 months of life.

Zoonotic Cycle of American Trypanosomiasis in an Endemic Region of the Argentine Chaco, Factors That Influenced a Paradigm Shift.

Trypanosoma cruzi, the causative agent of Chagas disease (American trypanosomiasis), is a highly complex zoonosis that is present throughout South America, Central America, and Mexico. The transmission of this disease is influenced by various factors, including human activities like deforestation and land use changes, which may have altered the natural transmission cycles and their connection to the environment. In this study conducted in the Argentine Chaco region, we examined the transmission dynamics of T. cruzi by collecting blood samples from wild and domestic animals, as well as triatomine bugs from human dwellings, across five sites of varying anthropic intervention. Samples were analyzed for T. cruzi infection via qPCR, and we additionally examined triatomines for bloodmeal analysis via NGS amplicon sequencing. Our analysis revealed a 15.3% infection rate among 20 wild species (n = 123) and no T. cruzi presence in 9 species of domestic animals (n = 1359) or collected triatomines via qPCR. Additionally, we found chicken (34.28%), human (21.59%), and goat (19.36%) as the predominant bloodmeal sources across all sites. These findings suggest that anthropic intervention and other variables analyzed may have directly impacted the spillover dynamics of T. cruzi's sylvatic cycle and potentially reduced its prevalence in human habitats.

Evaluation and validation of a PrintrLab-based LAMP assay to identify Trypanosoma cruzi in newborns in Bolivia: a proof-of-concept study.

BACKGROUND: Vertical transmission of Trypanosoma cruzi represents approximately 20% of new Chagas disease cases. Early detection and treatment for women of childbearing age and newborns is a public health priority, but the lack of a simple and reliable diagnostic test remains a major barrier. We aimed to evaluate the performance of a point-of-care loop-mediated isothermal amplification (LAMP) assay for the detection of T cruzi. METHODS: In this proof-of-concept study, we coupled a low-cost 3D printer repurposed for sample preparation and amplification (PrintrLab) to the Eiken T cruzi-LAMP prototype to detect vertically transmitted T cruzi, which we compared with standardised PCR and with the gold-standard algorithm (microscopy at birth and 2 months and serological study several months later). We screened pregnant women from two hospitals in the Bolivian Gran Chaco province, and those who were seropositive for T cruzi were offered the opportunity for their newborns to be enrolled in the study. Newborns were tested by microscopy, LAMP, and PCR at birth and 2 months, and by serology at 8 months. FINDINGS: Between April 23 and Nov 17, 2018, 986 mothers were screened, among whom 276 were seropositive for T cruzi (28·0% prevalence, 95% CI 25·6-31·2). In total, 224 infants born to 221 seropositive mothers completed 8 months of follow-up. Congenital transmission was detected in nine of the 224 newborns (4·0% prevalence, 1·9-7·5) by direct microscopy observation, and 14 more cases were diagnosed serologically (6·3%, 3·6-10·3), accounting for an overall vertical transmission rate of 10·3% (6·6-15·0; 23 of 224). All microscopy-positive newborns were positive by PrintrLab-LAMP and by PCR, while these techniques respectively detected four and five extra positive cases among the remaining 215 microscopy-negative newborns. INTERPRETATION: The PrintrLab-LAMP yielded a higher sensitivity than microscopy-based analysis. Considering the simpler use and expected lower cost of LAMP compared with PCR, our findings encourage its evaluation in a larger study over a wider geographical area. FUNDING: Inter-American Development Bank.

A standardized clinical database for research in Chagas disease: The NHEPACHA network.

The NHEPACHA Iberoamerican Network, founded on the initiative of a group of researchers from Latin American countries and Spain, aims to establish a research framework for Chagas disease that encompasses diagnosis and treatment. For this purpose, the network has created a questionnaire to gather relevant data on epidemiological, clinical, diagnostic, and therapeutic aspects of the disease. This questionnaire was developed based on a consensus of expert members of the network, with the intention of collecting high-quality standardized data, which can be used interchangeably by the different research centers that make up the NHEPACHA network. Furthermore, the network intends to offer a clinical protocol that can be embraced by other researchers, facilitating comparability among published studies, as well as the development of therapeutic response and progression markers.

The first record of Lutzomyia longipalpis in the Argentine northwest.

In 2004, the urban presence of Lutzomyia longipalpis was recorded for the first time in Formosa province. In 2006, the first autochthonous case of human urban visceral leishmaniasis (VL) was recorded in Misiones in the presence of the vector, along with some canine VL cases. After this first case, the vector began to spread primarily in northeast Argentina. Between 2008-2011, three human VL cases were reported in Salta province, but the presence of Lu. longipalpis was not recorded. Captures of Phlebotominae were made in Tartagal, Salta, in 2013, and the presence of Lu. longipalpis was first recorded in northwest Argentina at that time. Systematic sampling is recommended to observe the distribution and dispersion patterns of Lu. longipalpis and consider the risk of VL transmission in the region.

Risk Stratification to Guide Prevention and Control Strategies for Arboviruses Transmitted by Aedes aegypti.

Strategies for the prevention of arboviral diseases transmitted by Aedes aegypti have traditionally focused on vector control. This remains the same to this day, despite a lack of documented evidence on its efficacy due to a lack of coverage and sustainability. The continuous growth of urban areas and generally unplanned urbanization, which favor the presence of Ae. aegypti, demand resources, both material and human, as well as logistics to effectively lower the population's risk of infection. These considerations have motivated the development of tools to identify areas with a recurrent concentration of arboviral cases during an outbreak to be able to prioritize preventive actions and optimize available resources. This study explores the existence of spatial patterns of dengue incidence in the locality of Tartagal, in northeastern Argentina, during the outbreaks that occurred between 2010 and 2020. Approximately half (50.8%) of the cases recorded during this period were concentrated in 35.9% of the urban area. Additionally, an important overlap was found between hotspot areas of dengue and chikungunya (Kendall's W = 0.92; p-value < 0.001) during the 2016 outbreak. Moreover, 65.9% of the cases recorded in 2022 were geolocalized within the hotspot areas detected between 2010 and 2020. These results can be used to generate a risk map to implement timely preventive control strategies that prioritize these areas to reduce their vulnerability while optimizing the available resources and increasing the scope of action.

Chagas prevention and control in an endemic area from the Argentinian Gran Chaco Region: Data from 14 years of uninterrupted intervention.

BACKGROUND: Chagas Disease (ChD) is a Neglected Tropical Disease (NTD) affecting 6 to 7 million people worldwide, mostly from Latin America. In Argentina, a national control program has been implemented since 1962, yet there are still an estimated 1.6 million infected individuals. Control programs were based almost exclusively on entomological surveillance and chemical control of households and were not continuous given a lack of coordination and resources. Argentina´s ChD program was originally vertical and centralized; later, it was partially and, in general, unsuccessfully transferred to the provinces. Herein, we describe the implementation of a control program for ChD with an ecohealth approach in rural settlements around the city of Añatuya, Santiago del Estero. METHODS: The program included yearly household visits for entomological surveillance and control, health promotion workshops, and structural house improvements. Improved structures included internal and external walls and roofs, as well as the construction of water wells and latrines, and the organization and improvement of peri-domestic structures. Activities were carried out by specifically trained personnel except for house improvements, which were performed by the community, under technical guidance and provision of materials. Data was collected using standardized questionnaires for household characterization, entomological infestation status and chemical control activities. RESULTS: This program was continuously implemented since 2005 with high community participation and adherence, incorporating 13 settlements and 502 households. During the surveillance phase, 4,193 domiciliary inspections were performed, and both the intra- and peri-domestic infestation rate were reduced from 17.9% to 0.2% (P < 0.01) and from 20.4% to 3%, respectively. Additionally, 399 households were structurally improved. CONCLUSION: The program is still ongoing and, after 14 years of implementation, has built social networks and collaboration between implementers and beneficiaries with a reduction of T. infestans infestation in the intra- and peri-domicile. This reduction, especially inside the household, has enabled access to diagnosis and treatment of the population, with minimal risk of re-infection.

A multidisciplinary, collaborative, inter-agency and comprehensive approach for the control of Chagas Disease as a public health problem in Guatemala.

The Pan American Health Organization (PAHO) has defined Chagas Disease hotspots in Central America associated with the vector Triatoma spp. Triatoma dimidiata is a native vector adapted to multiple environments, including intra-domestic and peri-domestic habitats. A multi-institutional project named "Alliances for the elimination of Chagas in Central America" was created to help reduce the incidence of the disease in the region. Activities performed in the field as part of the project included aspects of vector surveillance and control, improvement of houses, diagnosis and treatment of individuals, health promotion, training of human resources and identification of access barriers to diagnosis and treatment. As a base line study, eleven villages, comprised of 1,572 households, were entomologically evaluated (83.4% overall participation); five were found to have very high infestation rates (>20%), three had high infestation rates (8-20%) and three had low-infestation rates (<8%), coinciding with the category of infestation-risk of the houses within each village. Serological tests were carried out in 812 people (>80% participation) in two of the 11 villages and none of the 128 children tested, less than 5 years of age, were positive for Trypanosoma cruzi infection. Community participation in all the activities was high (>70%). The collaboration between several subnational, national, and international institutions, each with specific roles, promoted community participation in the activities of vector control and patient care, thus, establishing a baseline to continue implementing and monitoring project progress.

Corrigendum: Risks for Child Cognitive Development in Rural Contexts.

[This corrects the article DOI: 10.3389/fpsyg.2018.02735.].

Impact of a public health intervention for active surveillance and mitigation of SARS-CoV-2 in a district from Buenos Aires province, Argentina: a descriptive epidemiological study.

BACKGROUND: The first case of SARS-CoV-2 was reported in Argentina on 3 March 2020. Measures to limit the spread of the virus were implemented, including complete lockdown (26 March). Nonetheless, the virus spread throughout the country, with a first peak of almost a million cases in October. On 30 November, the government's recommendation switched from social, preventive and compulsory isolation, to social, preventive and compulsory distancing. OBJECTIVES: To describe a tailored public health strategy to mitigate the spread of SARS-CoV-2 and determine its behaviour in San Antonio de Areco district from Buenos Aires province (Argentina) through a private-public association. DESIGN, SETTING AND PARTICIPANTS: Surveillance of the virus was performed with the local healthcare system, through early identification of cases and the systematic study of each infected individual and contact, regardless of symptomatology, using telemedicine and a COVID-19-specific outpatient clinic. Real-time PCR was used for detection using both individual and pooled samples, with a 12-hour turnaround time. RESULTS: Up to 30 November, a total of 2426 suspected cases were analysed and 578 were confirmed. Surveillance of health personnel and at-risk populations proved effective, mitigating viral spread. Pooling samples allowed reduction of operator time, helped reduce costs, and allowed detection of both symptomatic and asymptomatic cases. CONCLUSION: After 8 months of protocol implementation, the strategy to intensively survey groups at higher epidemiological risk and the systematic search for asymptomatic cases with the incorporation of pooled PCR for diagnosis, in combination with individual testing, is an efficient and viable option in populations with similar characteristics, in the frame of social isolation.

Development and Evaluation of a Three-Dimensional Printer-Based DNA Extraction Method Coupled to Loop Mediated Isothermal Amplification for Point-of-Care Diagnosis of Congenital Chagas Disease in Endemic Regions.

Vertical transmission of Trypanosomacruzi is the cause of congenital Chagas disease, a re-emerging infectious disease that affects endemic and nonendemic regions alike. An early diagnosis is crucial because prompt treatment achieves a high cure rate, precluding evolution to symptomatic chronic Chagas disease. However, early diagnosis involves low-sensitive parasitologic assays, making necessary serologic confirmation after 9 months of life. With the aim of implementing early diagnostic strategies suitable for minimally equipped laboratories, a T. cruzi-loop-mediated isothermal amplification (LAMP) prototype was coupled with an automated DNA-extraction device repurposed from a three-dimensional printer (PrintrLab). The whole process takes <3 hours to yield a result, with an analytical sensitivity of 0.1 to 2 parasite equivalents per milliliter, depending on the T. cruzi strain. Twenty-five blood samples from neonates born to seropositive mothers were tested blindly. In comparison to quantitative real-time PCR, the PrintrLab-LAMP dual strategy showed high agreement, while both molecular-based methodologies yielded optimal sensitivity and specificity with respect to microscopy-based diagnosis of congenital Chagas disease. PrintrLab-LAMP detected all 10 congenitally transmitted T. cruzi infections, showing promise for point-of-care early diagnosis of congenital Chagas disease.

Real-time polymerase chain reaction based algorithm for differential diagnosis of Kinetoplastidean species of zoonotic relevance.

Kinetoplastids are a group of flagellated protozoa that infect a vast repertoire of mammals and insect vectors. From a zoonotic point of view, domestic animals are critical reservoirs for transmission of Kinetoplastidean parasites. Due to their proximity to humans, they assume substantial epidemiological importance in the context of these zoonoses and consequently in public health. Their reliable identification is relevant to understand their eco-epidemiological involvement in transmission cycles. This work aimed to develop an algorithm based on sequential Real-Time PCR (qPCR) assays targeted to different loci (24S alpha rDNA, ITS1 and Hsp70) allowing distinction among Trypanosoma cruzi, Trypanosoma rangeli, Trypanosoma evansi and Leishmania species in biological samples collected from mammalian reservoirs and triatomine vectors. The algorithm includes a first qPCR test targeted to endogenous genes conserved within mammals and within triatomine vectors as internal controls of DNA sample integrity and/or qPCR inhibition. This algorithm was evaluated in biological samples from domestic cattle (N = 14), dogs (N = 19) and triatomines (N = 19). Analytical sensitivity of 24S alpha rDNA for detection of T. rangeli was 10 fg of DNA, with a linear range between 10 fg and 10 ng. For T. cruzi it varied depending on the Discrete typing unit. The ITS1 qPCR showed an analytical sensitivity of 100 pg/reaction and 100 fg/reaction of Leishmania spp. and T. evansi DNAs. In mammal field samples, four T. cruzi 24S alpha rDNA sequences and fourteen ITS1 amplicons specific for T. evansi were detected. qPCR-HRM analysis directed to the Hsp70 gene diagnosed two dogs with Leishmania infantum infection. Among 19 triatomine field samples, T. cruzi was detected in five; T. rangeli in eight and one specimen showed a mixed infection. This diagnostic algorithm can provide more accurate records of kinetoplastidean infection burden in vectors and reservoirs, relevant to update current eco-epidemiological maps in co-endemic regions.

Risk map development for soil-transmitted helminth infections in Argentina.

BACKGROUND: Soil-transmitted helminths (STHs) comprise a group of helminth parasites that are included in the list of Neglected Tropical Diseases and require a passage through the soil to become infective. Several studies have detected that infection with STHs are associated with certain socioeconomic, environmental and soil characteristics. In Argentina, the presence of these parasites has been detected through a few point studies conducted in localities from 11 of the 23 provinces that comprise the country. METHODS/PRINCIPAL FINDINGS: The most important characteristics previously associated with the presence of STHs were identified and ranked through the use of an expert survey and the Analytical Hierarchy Process (AHP) in order to construct a risk map of STHs specific for Argentina. Prevalence data from previous studies was used to validate the generated risk map. The map shows that half of Argentina, from the Central provinces to the North, contains localities with the characteristics necessary for the development of these parasites. CONCLUSIONS/SIGNIFICANCE: The predicted map should serve as a useful tool for guiding the identification of survey areas for the generation of baseline data, detecting hotspots of infection, planning and prioritizing areas for control interventions, and eventually performing post-implementation surveillance activities.

Seroprevalence of the Strongyloides stercoralis Infection in Humans from Yungas Rainforest and Gran Chaco Region from Argentina and Bolivia.

The threadworm, Strongyloides stercoralis, is endemic in tropical and subtropical areas. Data on the prevalence and distribution of infection with this parasite species is scarce in many critical regions. We conducted a seroprevalence study of S. stercoralis infection in 13 locations in the Gran Chaco and Yungas regions of Argentina and Bolivia during the period 2010-2016. A total of 2803 human serum samples were analyzed by ELISA-NIE which has a sensitivity of 75% and specificity of 95%. Results showed that 551 (19.6%) of those samples were positive. The adjusted prevalence was 20.9%, (95% confidence interval (CI) 19.4%-22.4%). The distribution of cases was similar between females and males with an increase of prevalence with age. The prevalence in the different locations ranged from 7.75% in Pampa del Indio to 44.55% in Santa Victoria Este in the triple border between Argentina, Bolivia, and Paraguay in the Chaco region. Our results show that S. stercoralis is highly prevalent in the Chaco and Yungas regions, which should prompt prospective surveys to confirm our findings and the design and deployment of control measures.

Evaluation and planning of Chagas control activities using geospatial tools.

Chagas continues to be a relevant public health problem in Latin America. In this work, we present a spatiotemporal analysis applied for the evaluation and planning of Chagas vector control strategies. We analysed the spatial distribution of the vector Triatoma infestans infestation related to ongoing control interventions cycles in rural communities near Añatuya, Santiago del Estero, Argentina. A geographical information system was developed for the spatial analysis obtaining, for each house, variables that describe the history of spraying and infestation at each time of interventions. Bi-dimensional histograms were used to describe the spatiotemporal pattern of these activities and peri-domestic infestation at the last intervention was modelled by a neural network model. We qualitatively evaluate control programmes considering the history of infestation and spraying from a spatiotemporal point of view, incorporating new ways of visualising this information. Predictions are based on novel, non-linear models and spatiotemporal indices, which should be useful for strategically allocating Chagas control resources in the future and thus help to better plan spraying strategies.

High effectiveness of an adulticide-larvicide formulation for field control of sandflies (Diptera: Psychodidae) in the city of Clorinda, Argentina.

In Argentina, Leishmania infantum (syn. L. chagasi) is the etiologic agent of human visceral leishmaniosis (HVL), and Lutzomyia longipalpis (Diptera: Psychodidae: Phlebotominae) is the main vector. The objective of this study was to evaluate the effectiveness and residual effect of two commercial insecticide formulations, one with permethrin and pyriproxyfen as active ingredients (Dragon Max®) and the other with only permethrin (Flop®) for the control of sandflies. Both formulations were applied in chicken coops and other surroundings structures of the peridomicile of urban houses in Clorinda, Formosa (Argentina). Entomological monitoring was carried out weekly for 44 weeks after the intervention. The results showed great effectiveness and residual effect up to 21 weeks post-intervention for Dragon Max®. This result could be explained by the excellent larvicidal activity of the Insect Growth Regulator (IGR) pyriproxyfen against the immature forms of phlebotomines and by the delay on the restoration of the natural threshold of the vector population in treated sites.

Use of rapid diagnostic tests (RDTs) for conclusive diagnosis of chronic Chagas disease - field implementation in the Bolivian Chaco region.

Chagas disease, caused by the parasite Trypanosoma cruzi, is the neglected tropical disease with a highest burden in Latin America. Its acute stage is mostly asymptomatic and goes unnoticed. Symptoms appear at the chronic stage, which is when diagnosis is usually made. This is based on the agreement of two conventional serological tests such as Enzyme-Linked Immunosorbent Assays (ELISAs). There are commercial kits with good sensitivity and specificity but their use is impractical in many highly endemic regions with poorly equipped laboratories. Luckily, several rapid diagnostic tests (RDTs) are available for the detection of anti-T. cruzi immunoglobulins. They are easy to operate, require no cold storage, provide fast turnaround of results, and some can work with a tiny volume of whole blood as sample. With the aim to field validate their use we compared an alternative algorithm based on a combination of RDTs with the standard based on ELISAs. In both cases a third test was available in case of discordance. RDTs were implemented by mobile teams in field campaigns to detect chronic T. cruzi-infections in the Chaco region of Bolivia. ELISAs were made in the reference laboratories located in the main hospitals of Yacuiba and Villa Montes, two major cities of the region. We enrolled 685 subjects who voluntarily participated in the study and had not been treated against the disease before. The agreement between the two main RDTs was 93.1% (638/685) (kappa index = 0.86; CI 95% 0.83-0.90). In comparison to the ELISAs algorithm, the combined use of the RDTs provided a sensitivity of 97.7% and a specificity of 96.1%. These results support the use of RDTs for the diagnosis of chronic Chagas disease in the studied region, and encourage their evaluation in other regions of Bolivia and other endemic countries.