Age and socio-economic status affect dengue and COVID-19 incidence: spatio-temporal analysis of the 2020 syndemic in Buenos Aires City.

In early 2020, Argentina experienced the worst dengue outbreak in its history, concomitant with first-to-date increasing COVID-19 cases. Dengue epidemics in temperate Argentina have already been described as spatially heterogeneous; in the previous 2016 outbreak, transmission occurred 7.3 times more frequently in slums compared to the rest of Buenos Aires City (CABA). These informal settlements have deficient sanitary conditions, precarious housing and high incidence of social vulnerabilities. The purpose of this work was to study the spatio-temporal patterns of the 2020 dengue epidemic in CABA in relation to socio-economic living conditions of its inhabitants and its interaction with the onset of COVID-19. The study considered the period between Jan 1st and May 30th 2020. Dengue and COVID-19 databases were obtained from the National Health Surveillance System; each record was anonymized and geo-localized. The city was divided according to census tracts and grouped in four socio-economic strata: slums, high, mid and low residential. An aligned-rank transform ANOVA was performed to test for differences in the incidence of dengue and COVID-19, and age at death due to COVID-19, among socio-economic strata, four age categories and their interaction. The incidence by cluster was calculated with a distance matrix up to 600 m from the centroid. Spatial joint dengue and COVID-19 risk was estimated by multiplying the nominal risk for each disease, defined from 1 (low) to 5 (high) according to their quantiles. During the study period, 7,175 dengue cases were registered in CABA (incidence rate 23.3 cases per 10,000 inh), 29.2% of which occurred in slums. During the same period, 8,809 cases of COVID-19 were registered (28.6 cases per 10,000 inh); over half (51.4%) occurred in slums, where the median age of cases (29 years old) was lower than in residential areas (42 years old). The mean age of the deceased was 58 years old in slums compared to 79 years old outside. The percentage of deaths in patients under 60 years old was 56% in slums compared to 8% in the rest of the city. The incidence of both diseases was higher in slums than in residential areas for most age categories. Spatial patterns were heterogeneous: dengue presented higher incidence values in the southern sector of the city and the west, and low values in highly urbanized quarters, whereas COVID-19 presented higher values in the east, south, high populated areas and slums. The lowest joint risk clusters were located mainly in high residential areas, whereas high joint risk was observed mainly in the south, some western clusters, the historical part of the city and center north. The social epidemiological perspective of dengue and COVID-19 differed, given that socio environmental heterogeneity influenced the burden of both viruses in a different manner. Despite the overwhelming effect of the COVID-19 pandemic, health care towards other diseases, especially in territories with pre-existing vulnerabilities, should not be unattended.

Culicidae assemblages of artificial containers and possible biotic interactions affecting Aedes albopictus (Diptera: Culicidae) in Argentina.

In Argentina, the distribution of Aedes albopictus (Skuse) is limited to two provinces with a subtropical climate and few records. This study aims to describe and compare assemblies of Culicidae that breed in artificial containers in two areas with different degrees of urbanisation where Ae. albopictus is present and to evaluate possible biotic interactions. We sampled container larval habitats of an urban (Eldorado city) and a rural environment (Colonia Aurora village). We performed generalized linear mixed models to evaluate which variables (containers characteristics or environment) are associated with the presence and abundance of Ae. albopictus, Aedes aegypti Linneaus and Culex quinquefasciatus Say, and the presence of mosquito predators (Lutzia bigoti (Bellardi) and Toxorhynchites spp.). Also, the relationship between the most abundant species was quantified in each environment using Hurlbert's C8 association coefficient. Ae. aegypti was the most abundant species in the urban environment, while Cx. quinquefasciatus and Ae. albopictus were the most abundant in the rural area. Predators were more present in the rural environment and affected the abundance of Aedes mosquitoes. Regarding the C8 index, Ae. aegypti was negatively associated with Ae. albopictus in the urban area, whereas in the rural area these species presented a significantly positive relationship. These results show that in urban environments the high abundance of Ae. aegypti could be affecting the Asian tiger mosquito as evidenced by local studies of food larval competition. Also a greater presence of predators could be affecting Ae. albopictus in rural environments.

First report on knockdown resistance mutations in wild populations of Aedes aegypti from Argentina determined by a novel multiplex high-resolution melting polymerase chain reaction method.

BACKGROUND: The mosquito Aedes aegypti is an urban vector of dengue and other arboviruses. During epidemics of these viruses, pyrethroid insecticides are used for the control of adult mosquitoes. The worldwide resistance of Ae. aegypti to these insecticides is a cause of failure of vector control campaigns. The primary target of pyrethroids is the voltage-gated sodium channel. Point mutations in the gene coding for this channel, called knockdown resistance (kdr) mutations, are associated with pyrethroid resistance. Two kdr mutations, V1016I and F1534C, have increased in frequency in natural populations of Ae. aegypti in the Americas during the last decade. Their association with pyrethroid resistance has been largely demonstrated in field populations throughout the Americas, and in in vitro assays. Diagnostics for kdr polymorphism allow early detection of the spread of insecticide resistance, which is critical for timely decisions on vector management. Given the importance of resistance management, high-throughput methods for kdr genotyping are valuable tools as they can be used for resistance monitoring programs. These methods should be cost-effective, to allow regional-scale surveys. Despite the extensive presence of Ae. aegypti and incidence of dengue in Argentina, the presence, abundance, and distribution of kdr mutations in populations of this mosquito have yet to be reported for the country. METHODS: Aedes aegypti samples were collected as immature stages or adults from Buenos Aires Metropolitan Area and northern localities of Tartagal (Salta Province) and Calilegua (Jujuy Province). Immature stages were maintained in the laboratory until they developed into adults. A high-resolution melting assay, based on an analysis of melting temperatures, was developed for the simultaneous genotyping of V1016I and F1534C kdr mutations. We used this method to infer the presence and frequencies of kdr alleles in 11 wild populations from Argentina. RESULTS: We demonstrated the presence of kdr mutations in Ae. aegypti in Argentina in regions where this species is under different selection pressures due to the use of pyrethroids. The populations under analysis are located in geographically distant regions of the species' distribution in Argentina: the northern provinces of Salta and Jujuy and the Buenos Aires Metropolitan Area. Higher frequencies of resistant-associated alleles were detected in the northern region. We report a multiplex high-throughput assay based on a high-resolution melting polymerase chain reaction method for the simultaneous genotyping of V1016I and F1534C kdr mutations. This assay was shown to be cost-effective, and thus provides an interesting molecular tool for kdr genotyping in A. aegypti control campaigns. CONCLUSIONS: We report, to the best of our knowledge for the first time, the presence of kdr mutations in populations of Ae. aegypti from geographically distant locations of Argentina that differ with respect to their epidemiological situation and history of mosquito control. We have developed a high-throughput method for the genotyping of kdr mutations in Ae. aegypti from the Americas. Given its affordability and short running time, this method can be used in control campaigns to monitor the presence and spread of kdr alleles. The information provided here is relevant for the rational design of control strategies in the context of integrated vector management.

Population dynamics of Nyssomyia whitmani (Diptera: Psychodidae) in domestic and peridomestic environments in Northeast Argentina, a tegumentary leishmaniasis outbreak area.

In the present study, the temporal dynamics of the main vector of Leishmania braziliensis, Nyssomyia whitmani, was measured by monthly captures of phlebotominae sandflies during 5 consecutive years (from 2011 to 2016) in the Paranaense region of South America. The captures were performed in environments where the human-vector contact risk is high: domiciliary and peridomiciliary environments in a rural area endemic of tegumentary leishmaniasis. Nyssomyia whitmani was recorded as the dominant species of the phlebotominae ensemble in all domiciliary and peridomiciliary environments (House, Chicken Shed, Pigsty, and Forest Edge). Using generalized additive models, intra- and interannual fluctuations were observed, modulated by meteorological variables such as the minimum temperature and the accumulated precipitation 1 wk prior to capture. The installation of a pigsty by the farmer during the study period allowed us to observe and describe the so-called "pigsty effect" where the Ny. whitmani population was spatially redistributed, turning the pigsty as the environment that obtained the highest phlebotominae record counts, thus maintaining the farm overall abundance, supporting the idea that the environmental management of the peridomicile could have an impact on the reduction of epidemiological risk by altering the spatial distribution of the phlebotominae ensemble in the environments.

Abundance of Lutzomyia longipalpis and Nyssomyia whitmani, the Leishmania spp. vectors in northeastern of Argentina: Are spatial and temporal changing patterns consistence?

Lutzomyia longipalpis and Nyssomyia whitmani were incriminated as vectors of Leishmania sp. Spatial heterogeneity together with seasonal changes in abundance constitute important elements for the understanding of the dynamics of vector populations, and there are fundamental for the development of adequate prevention and control strategies. The aim of this work was to compare the spatial and seasonal abundance of Lu. longipalpis and Ny. whitmani at a city spatial scale between two periods separated by three years. To study the spatial distribution, we compared the abundance distribution of these species at two warm times, 2011 with 2014. Respect to inter-annual seasonal abundance changes, we compared the four seasons of the year between two periods (2011-2012 vs 2014-2016). The spatial distribution for both species were found to be distributed mainly in the same areas of the city in both periods. We change for: Respect to the seasonal pattern of abundance, we observed that seasonal patterns showed changes between periods. Our study defines the 'where' and 'when' implement the actions to mitigate leishmaniasis cases.

Larval Competition Between Aedes albopictus and Aedes aegypti (Diptera: Culicidae) in Argentina: Coexistence and Implications in the Distribution of the Asian Tiger Mosquito.

Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) are worldwide vectors of dengue and yellow fever viruses. These species coexist in many countries and the biotic interactions between them can influence their abundances and distributions. In Argentina, Ae. aegypti is widely distributed in the north and center regions of the country, with temperate and subtropical climate, while both are sympatric only in the northeastern area of the subtropical region. Interspecific and intraspecific larval competition for food was evaluated to assess if their interaction influences on patterns of abundance and distribution. Finite rates of increase and survivorship for each species were estimated and the effects of mosquito density ratio and detritus availability were determined. The Lambda (λ´) index of population performance of both showed there is no competitive exclusion pattern. However, survival of Ae. albopictus was negatively affected by the presence of Ae. aegypti. These results suggest one possible explanation for the codominance pattern of both species display in rural regions of the southernmost distribution of Ae. albopictus in South America. They also show Ae. aegypti as a potential biotic barrier for the expansion of Ae. albopictus as was reported in regions of the United States.

Peridomestic natural breeding sites of Nyssomyia whitmani (Antunes and Coutinho) in an endemic area of tegumentary leishmaniasis in northeastern Argentina.

The scarce information about breeding sites of phlebotomines limits our understanding of the epidemiology of tegumentary leishmaniasis. Identifying the breeding sites and seasons of immature stages of these vectors is essential to propose prevention and control strategies different from those targeting the adult stage. Here we identified the rural breeding environments of immature stages of Ny. whitmani, vector species of Leishmania braziliensis in the north of Misiones province, Argentina; then we determined and compared the environmental and structural characteristics of those sites. We also identified the season of greatest emergence and its relationship with adult abundance. During a first collection period, between 28 and 48 emergence traps were set continuously for 16 months in six environments of the farm peridomicile and domicile: below house, chicken shed, experimental chicken shed, forest edge, pigsty and under fruit tree. Traps were checked and rotated every 40 nights. A total of 146 newly emerged individuals were collected (93.8% of them were Ny. whitmani), totaling an effort of 23,040 emergence trap-nights. The most productive environments were chicken shed and below house, and the greatest emergence was recorded in spring and summer. During a second collection period, emergence traps and light traps for adult capture were placed in the chicken shed and below house environments of eight farms. Emergence traps were active continuously during spring, summer, and early autumn. Environmental and structural characteristics of each environment were recorded. A total of 84 newly emerged phlebotomines (92.9% Ny. whitmani; 72,144 emergence trap-nights) and 13,993 adult phlebotomines (147 light trap-nights) were recorded in the chicken shed and below house environments. A positive correlation was also observed between trap success of newly emerged phlebotomines and of adults after 120 days. A high spatial variability was observed in the emergence of Ny. whitmani, with the number of newly emerged individuals being highest in soils of chicken sheds with the highest number of chickens and closest to forest edge. Moreover, below house was found to be as important as chicken sheds as breeding sites of Ny. whitmani. Management of the number of chickens in sheds, soil moisture and pH, and the decision of where to localize the chicken sheds in relation to the houses and the forest edge, might contribute to reduce the risk of human vector exposure and transmission of Leishmania.

Multiscale environmental determinants of Leishmania vectors in the urban-rural context.

BACKGROUND: In South America, cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL) are emerging diseases, expanding in the border area of Argentina, Brazil and Paraguay. Outbreaks of CL were reported since the 1990s, with Nyssomyia whitmani as the main vector in this region. Regarding VL, urban reports started in 2010 with Lutzomyia longipalpis as the main vector. The aim of this study was to evaluate environmental determinants related to the main vectors of leishmaniasis, to contribute to the prevention and control response to the emergence of VL and CL in the Argentina-Brazil-Paraguay border region. METHODS: The cross-sectional survey includes two cities and two close rural areas in the Argentinean Northeast Region, between November 2014 and January 2015, with a total of 95 sampling sites. REDILA-BL traps were set for three consecutive nights, and a total of 68 meso- and microscale environmental and landscape characteristics were surveyed. The association between vector abundance with different variables was evaluated using a generalized linear model with zero-inflated negative binomial distribution. We analyzed females for detection of Leishmania DNA. RESULTS: The analysis for Lu. longipalpis indicates an excess of absences when the mean NDWI around the sites were higher. The abundance of Lu. longipalpis at mesoscale level was higher when more urban services were present, and when blood sources such as chickens or dogs at the microscale level were present. For Ny. whitmani, no variable was found to be associated with the absences, while its abundance increased in association with the following variables: percentage of tree cover, presence of garbage collection service, hosted people and, at microscale, the presence of poultry. Leshmania infantum DNA was detected in 2/49 (4%) Lu. longipalpis. CONCLUSIONS: The abundance of both species is influenced by variables at different scales, their influence probably has a hierarchy and they are acting on different aspects of the biology of these vectors. The urban spatial segregation of Lu. longipalpis and the peri-urban and rural segregation of N. whitmani increase the risk of VL and CL. The selection of the better variables for each scale will allow the design of appropriate control strategies depending on species.

Performance of rapid tests for canine visceral leishmaniasis diagnosis in Argentina.

To diagnose dogs infected by Leishmania infantum rK39 rapid diagnosis test is widely used in the Americas, while dual path platform (DPP) was recently adopted by Brazil. In this study we assessed the performance of rK39-RDT and DPP tests in recent urban transmission scenarios of Argentina. The sensitivity and specificity were evaluated with a sera panel and field samples, taken as true infected those from parasitological and/or PCR positive tests. Since none of these tests can be taken as a gold standard, the performance was also evaluated using Latent Class Analysis, a statistical modeling technique which allows to estimating sensitivity and specificity defining a latent class variable as the reference standard. The sensitivity of both tests in the panel was around 92% (symptomatic dogs 96%, asymptomatic 83%), while the sensitivity in field samples of rK39-RDT was 77%, and DPP 98% (mean in symptomatic dogs 89%, asymptomatic 82%). The specificity was similar for both tests and samples, around 98%. Therefore, these tests are acceptable for program dog population-based studies, as spatial stratification, focus intervention and follow up, and they could be used for individual screening and confirmation of clinical presumptive diagnosis in polysymptomatic dogs. The inability to discriminate between immunity and actual infectiousness suggest that a combination with other non-immunological based tests will be required for highly sensitive/specific diagnosis in order to targeting control measures in individual reservoirs from public health perspective, as for individual management from animal health perspective.

Para diagnosticar perros infectados por Leishmania infantum, en las Américas se utiliza ampliamente la prueba rápida rK39, mientras que DPP fue adoptado recientemente por Brasil. En este estudio se evaluó el desempeño de las pruebas rK39-RDT y DPP en escenarios de transmisión urbana reciente en Argentina. La sensibilidad y especificidad se evaluaron con un panel de sueros y muestras de campo, considerando muestras infectadas verdaderas aquellas con pruebas parasitológicas y/o de PCR positivas. Como ninguna de estas pruebas puede considerarse estándar de oro, el desempeño también se evaluó mediante análisis de clases latentes, una técnica de modelado estadístico que permite estimar sensibilidad y especificidad definiendo una variable de clase latente como estándar. La sensibilidad de ambas pruebas en el panel fue de alrededor del 92% (perros sintomáticos 96%, asintomáticos 83%), mientras que la sensibilidad en muestras de campo fue rK39-RDT: 77%, y DPP 98% (media en perros sintomáticos 89%, asintomáticos 82%). La especificidad fue similar para ambas pruebas y muestras, cerca de 98%. Por lo tanto, estas pruebas son aceptables para estudios programáticos caninos de base-poblacional, como estratificación espacial, intervención de foco y seguimiento, y podrían utilizarse para el tamizaje individual y la confirmación del diagnóstico clínico presuntivo en perros poli-sintomáticos. La incapacidad de discriminar entre inmunidad e infectividad real sugiere que se requerirá una combinación con otras pruebas, de base no inmunológica, para un diagnóstico suficientemente sensible/específico que permita definir las medidas de control en reservorios individuales, tanto para salud pública, como para la gestión individual en salud animal.

Performance of rapid tests for canine visceral leishmaniasis diagnosis in Argentina

To diagnose dogs infected by Leishmania infantum rK39 rapid diagnosis test is widely used in the Americas, while dual path platform (DPP) was recently adopted by Brazil. In this study we assessed the performance of rK39-RDT and DPP tests in recent urban transmission scenarios of Argentina. The sensitivity and specificity were evaluated with a sera panel and field samples, taken as true infected those from parasitological and/or PCR positive tests. Since none of these tests can be taken as a gold standard, the performance was also evaluated using Latent Class Analysis, a statistical modeling technique which allows to estimating sensitivity and specificity defining a latent class variable as the reference standard. The sensitivity of both tests in the panel was around 92% (symptomatic dogs 96%, asymptomatic 83%), while the sensitivity in field samples of rK39-RDT was 77%, and DPP 98% (mean in symptomatic dogs 89%, asymptomatic 82%). The specificity was similar for both tests and samples, around 98%. Therefore, these tests are acceptable for program dog population-based studies, as spatial stratification, focus intervention and follow up, and they could be used for individual screening and confirmation of clinical presumptive diagnosis in polysymptomatic dogs. The inability to discriminate between immunity and actual infectiousness suggest that a combination with other non-immunological based tests will be required for highly sensitive/specific diagnosis in order to targeting control measures in individual reservoirs from public health perspective, as for individual management from animal health perspective.

Para diagnosticar perros infectados por Leishmania infantum, en las Américas se utiliza ampliamente la prueba rápida rK39, mientras que DPP fue adoptado recientemente por Brasil. En este estudio se evaluó el desempeño de las pruebas rK39-RDT y DPP en escenarios de transmisión urbana reciente en Argentina. La sensibilidad y especificidad se evaluaron con un panel de sueros y muestras de campo, considerando muestras infectadas verdaderas aquellas con pruebas parasitológicas y/o de PCR positivas. Como ninguna de estas pruebas puede considerarse estándar de oro, el desempeño también se evaluó mediante análisis de clases latentes, una técnica de modelado estadístico que permite estimar sensibilidad y especificidad definiendo una variable de clase latente como estándar. La sensibilidad de ambas pruebas en el panel fue de alrededor del 92% (perros sintomáticos 96%, asintomáticos 83%), mientras que la sensibilidad en muestras de campo fue rK39-RDT: 77%, y DPP 98% (media en perros sintomáticos 89%, asintomáticos 82%). La especificidad fue similar para ambas pruebas y muestras, cerca de 98%. Por lo tanto, estas pruebas son aceptables para estudios programáticos caninos de base-poblacional, como estratificación espacial, intervención de foco y seguimiento, y podrían utilizarse para el tamizaje individual y la confirmación del diagnóstico clínico presuntivo en perros poli-sintomáticos. La incapacidad de discriminar entre inmunidad e infectividad real sugiere que se requerirá una combinación con otras pruebas, de base no inmunológica, para un diagnóstico suficientemente sensible/específico que permita definir las medidas de control en reservorios individuales, tanto para salud pública, como para la gestión individual en salud animal.

Detección de bacterias de los géneros Ehrlichia Anaplasma y Rickettsia en garrapatas rhipicephalus Sanguineus sl en Pergamino Argentina / Detection of Bacteria of the Genera Ehrlichia, Anaplasma and Rickettsia in Rhipicephalus sanguineus s.l Ticks in the City of Pergamino, Argentina

Las rickettsiosis, ehrlichiosis y anaplasmosis son causadas por bacterias gramnegativas intracelulares obligadas y transmitidas por artrópodos. El objetivo de este trabajo fue determinar especies de garrapatas presentes en caninos de la ciudad de Pergamino y detectar presencia de patógenos de los géneros Ehrlichia, Anaplasma y Rickettsia. MÉTODOS: Se estudiaron 21 garrapatas Rhipicephalus sanguineus s.l obtenidas de caninos de diferentes ambientes de la ciudad de Pergamino. Las muestras fueron analizadas mediante PCR, amplificando un fragmento del gen gltA para Rickettsia spp. y del 16SrRNA para los géneros Ehrlichia/Anaplasma. RESULTADOS: Se detectó positividad a Rickettsia spp. en el 4,76%, identificándose por secuenciación a la especie Rickettsia massiliae. Para la familia Anaplasmataceae se detectó positividad para Ehrlichia canis (23,8%) y Anaplasma platys (19,04%). CONCLUSIONES: Se trata del primer reporte de patógenos de interés zoonótico y/o veterinario pertenecientes a los géneros Rickettsia, Ehrlichia y Anaplasma en garrapatas Rh. sanguineus s.l para el norte de la provincia de Buenos Aires

Descripción del Primer Brote de Dengue en la Ciudad de Santo Tomé, Corrientes, 2016 / Description of the First Dengue Outbreak in the City of Santo Tomé, Corrientes, 2016

Argentina sufrió diferentes brotes de dengue en las regiones más cálidas durante el verano de 2016. En la ciudad de Santo Tomé (Corrientes) se produjo el primer brote. En este marco, el objetivo del trabajo fue evaluar la distribución temporal y espacial de los casos de dengue en Santo Tomé, así como las acciones adoptadas para interrumpir la transmisión. MÉTODOS: Los casos sospechosos fueron detectados por el personal sanitario, se confirmaron las muestras por análisis serológico y se georreferenció cada caso positivo, que fue clasificado como autóctono o importado. Las acciones de prevención fueron: bloqueo larval; control focal y rociado espacial; evaluación de larvicidas; descacharrado; charlas, capacitaciones y asamblea barrial. RESULTADOS: De 148 pacientes sospechosos se confirmaron 52 entre las semanas epidemiológicas 3 y 22. La cepa circulante fue DENV 1. El 46% (24/52) de los casos fueron autóctonos y se concentraron en el barrio Sarmiento. El 21% (140/655) de las viviendas presentaron criaderos de culícidos, de los cuales el 84% (210/251) resultó positivo para Ae. aegypti. DISCUSIÓN: Santo Tomé tuvo todas las condiciones para que se registrara el brote de dengue: población susceptible, presencia del vector y arribo de casos importados. Si bien la distribución de casos fue homogénea durante todo el brote, en el barrio Sarmiento se vio una clara circulación viral, que pudo ser controlada mediante una tarea interdisciplinaria de acción y prevención

Update on the distribution of Aedes albopictus (Diptera: Culicidae) in Misiones, Argentina.

The Asian tiger mosquito ( Aedes albopictus, Diptera: Culicidae) has spread rapidly in the last 30 years from its native region in Southeast Asia. In Argentina, studies on its potential distribution suggest that this species could be found in temperate zones of the province of Buenos Aires. However, since its initial detection in 1998 Ae. albopictus is bounded to the subtropical province of Misiones. To evaluate the presence and abundance of Ae. albopictus in the Northeast of Argentina, we preliminarily evaluated the presence of this vector by analyzing its presence in tires of 20 cities belonging to the province of Misiones and four cities in Northern Corrientes, and then performed an evaluation of the vector in the towns where the vector was detected. Aedes albopictus was present only in two cities of Misiones: Eldorado and Colonia Aurora. Aedes aegypti and Ae . albopictus accounted for 86% of the individuals collected in the domiciles of both towns. In Colonia Aurora both species were in similar abundances suggesting a co-dominance. The present study extends the austral distribution of Ae. albopictus in Argentina to the city of Colonia Aurora where the highest abundance recorded in Argentina was detected. Nevertheless, the reasons of its bounded distribution in the region are not known.

Identificación de los escenarios epidemiológicos de la enfermedad de Chagas en áreas de nulo riesgo de transmisión vectorial de Trypanosoma cruzi / Identification of the epidemiological scenarios of the disease of Chagas in areas with no risk of vector transmission of Trypanosoma cruzi

La enfermedad de Chagas congénita se refiere a la transmisión de Trypanosoma cruzi de una generación a la siguiente, incluyendo la transmisión prenatal, perinatal y posnatal. Constituye la primera forma de aparición de nuevos casos en nuestro país y es la única forma de transmisión que puede ocurrir en todas las provincias de Argentina, donde se estima que el 4% de las mujeres embarazadas están infectadas. Este estudio tuvo como objetivo conocer la situación epidemiológica de la infección connatal de la enfermedad de Chagas en las zonas de nulo riesgo de transmisión vectorial (Buenos Aires, Chubut, Santa Cruz y Tierra del Fuego). Así como identificar los saberes y prácticas del personal de salud en relación al diagnóstico de Chagas en personas embarazadas y su descendencia, con el fin de identificar nuevos escenarios epidemiológicos y compartir estrategias para detectar niños y niñas tempranamente y permitirles el acceso oportuno al tratamiento en estas áreas del país. En relación a la nueva coyuntura transitada desde el 2019 al 2021 inclusive, se planificó el desarrollo de una encuesta vía web al personal sanitario de las provincias en estudio y, de modo complementario, realizar entrevistas a distancia a los actores esenciales en sus niveles de atención (3 niveles de atención sanitaria y los dos niveles de gestión nacional y provincial). De los resultados de las encuestas y las entrevistas, se desprende la necesidad de avanzar en una capacitación, la misma se estructuró con modalidad de taller, para abordar las dificultades que surgieron en las instancias previas e introducir conceptos y visiones que permitan realizar un abordaje integral del Chagas congénito/connatal. Esta actividad final se desarrollará en el mes de septiembre de 2021, por lo cual los resultados no podrán ser presentados en este informe. Este proyecto llegó a poner de manifiesto ciertas deficiencias en la formación de los profesionales, y principalmente la postergación del Chagas en los sistemas, implicando la descoordinación y desconocimientos entre niveles de responsabilidades, la falta de recursos así como el desconocimiento y/o desinterés. Si bien estas cuestiones son conocidas en la práctica, mediante el trabajo realizado en este proyecto se visibilizaron estas cuestiones, que son claramente relevantes para que los circuitos de atención y cuidado funcionen y tengan una actitud pro-activa, actitud necesaria al tratarse la transmisión vertical de Chagas

Presence of Lutzomyia longipalpis and Nyssomyia whitmani in Entre Rios, Argentina.

The objective of this study was to evaluate the presence of Lutzomyia longipalpis in the Argentine city of Concordia, in the province of Entre Rios, without record of this species despite previous samplings, but with canine cases of visceral leishmaniasis and Lu. longipalpis reports both, from Northern Argentine localities and from the city of Salto, Uruguay, located just across the river and the international border. This study confirms the presence of Lu. longipalpis and Nyssomyia whitmani, related to the risk of visceral and tegumentary leishmaniasis, respectively, in Concordia-Entre Rios. The presence of Lu. longipalpis confirms the ongoing dispersal along the Uruguay river basin. The presence of these species in the study area alerts about the risk of transmission of Leishmania spp.

Respuesta doméstica a las recomendaciones sanitarias de intervención sobre ambiente y perros en una localidad con transmisión de leishmaniasis visceral (Pto. Iguazú, Argentina, 2014­2016) / Domestic response to intervention based on health recommendations on the environment and dogs in a locality with transmission of visceral leishmaniosis (Pto. Iguazú, Argentina, 2014-2016)

Introducción: La leishmaniasis visceral (LV) es una enfermedad parasitaria emergente en Argentina. En Puerto Iguazú, frontera con Brasil y Paraguay, en 2010 se registró presencia del vector y casos caninos; y en 2014-2015 dos casos humanos. Objetivo: Este artículo tiene como objetivo analizar los cambios en el nivel micro escala después de dar a conocer a los convivientes el diagnóstico de LV canina (LVC), informándoles estrategias de manejo ambiental para reducir el contacto con el vector. Método: Es una investigación descriptiva, que indagó en dos momentos (2014 y 2016) una muestra no probabilística distribuida en base al criterio de mejor escenario para la presencia del vector (n = 55) en la que se seleccionaron, luego de un primer rastrillaje entomológico y de diagnóstico veterinario, puntos de muestreo con presencia de vectores y al menos un perro con LVC (n = 6/55). Resultados: Un único hogar implementó las modificaciones sugeridas. Esos cambios no resultaron suficientes para controlar la transmisión. La hipótesis es que las medidas de control requieren intervención a meso escala (el vecindario y no el domicilio), atendiendo al radio real de dispersión de vectores. Conclusiones: El riesgo de infección humana por LV se relaciona con el modo de vida, incluyendo las relaciones interespecie. Las relaciones humano-perro combinan especismo y poshumanismo, acotando la efectividad de la "tenencia responsable" como modelo de vínculo saludable.

Introduction: Visceral leishmaniasis (VL) is an emerging parasitic disease in Argentina. In Puerto Iguazú, border with Brazil and Paraguay, vector and canine cases were registered in 2010; and in 2014 and 2015 there were two human cases. Objective: The objective of this article is to analyze changes at the micro-scale level after informing the cohabitants of the diagnosis of canine LV (LVC), letting them know the environmental management strategies to reduce contact with the vector. Method: It is a descriptive researh, which investigated in two moments (2014 and 2016) a non-probabilistic sample distributed based on the criterion of the best scenario for the presence of the vector (n = 55). Sampling points with the presence of vectors and at least one dog with LVC (n = 6/55) were selected, after a first entomological and veterinary diagnosis raking. Results: A single household implemented the suggested modifications. The changes were not enough to control the transmission. The hypothesis is that the control measures require intervention at a meso-scale (the neighborhood instead of the home), taking into account the real radius of vector dispersion. Conclusions: The risk of human infection due to VL is related to the way of life, including interspecies relationships. The human-dog relationships combine speciesism and post-humanism, which limits the effectiveness of "responsible ownership" as model of a healthy bond.

Evaluación de insecticida en terreno para el control del vector del dengue / Evaluation of an insecticide in the field for the control of the dengue vector

INTRODUCCIÓN Las enfermedades transmitidas por insectos vectores, como el dengue y la enfermedad de Chagas, registran cada año miles de defunciones. El control de las poblaciones de los vectores es la principal herramienta para prevenir estas enfermedades. En este marco, existen protocolos para la evaluación de insecticidas en terreno que no se adaptan a las diversas realidades sociales, climáticas y ambientales que presenta nuestro país. OBJETIVO Se proponen dos objetivos; 1) Diseñar protocolos de evaluación de insecticidas en terreno para el control de los vectores del dengue y la enfermedad de Chagas con adaptaciones a la heterogeneidad de la región; y 2) evaluar la eficacia en terreno de un insecticida con efecto larvicida y adulticida para el control de las poblaciones de Ae. aegypti. METODOS Se diseñaron protocolos para la evaluación de insecticidas contra las poblaciones de Ae. aegypti y T. infestans. Además, se evaluó el efecto larvicida y adulticida de un producto contra Ae. aegypti en Santo Tomé (Corrientes). Para ello se estimó la supervivencia de adultos, mortalidad de estadios preimaginales, porcentaje de emergencia e indicadores entomológicos de la población local de forma semanal en viviendas de dos áreas de la ciudad. En una se aplicó el producto mediante máquina UBV y la otra fue considerada como control. RESULTADOS Se generaron dos protocolos para la evaluación de insecticidas en terreno; uno para Ae. aegypti y otro para T. infestans. En la evaluación sobre Ae. aegypti, se observó un incremento del 24,06% de mortalidad total de los estados preimaginales y una disminución del 29,32% de la emergencia de los adultos. Solo la cantidad de adultos y el índice de Breteau de los índices entomológicos presentaron una merma en las semanas posteriores al tratamiento. DISCUSIÓN El producto evaluado mostró una elevada eficacia. Sin embargo un incremento de los índices en la semanas subsiguientes al tratamiento sugieren la implementación de técnicas de control adicionales en el tiempo

Environmental suitability for Lutzomyia longipalpis in a subtropical city with a recently established visceral leishmaniasis transmission cycle, Argentina

BACKGROUND Visceral leishmaniasis (VL) is an endemic disease in northeastern Argentina including the Corrientes province, where the presence of the vector and canine cases of VL were recently confirmed in December 2008. OBJECTIVES The objective of this study was to assess the modelling of micro- and macro-habitat variables to evaluate the urban environmental suitability for the spatial distribution of Lutzomyia longipalpis presence and abundance in an urban scenario. METHODS Sampling of 45 sites distributed throughout Corrientes city (Argentina) was carried out using REDILA-BL minilight traps in December 2013. The sampled specimens were identified according to methods described by Galati (2003). The analysis of variables derived from the processing of satellite images (macro-habitat variables) and from the entomological sampling and surveys (micro-habitat variables) was performed using the statistical software R. Three generalised linear models were constructed composed of micro- and macro-habitat variables to explain the spatial distribution of the abundance of Lu. longipalpis and one composed of micro-habitat variables to explain the occurrence of the vector. FINDINGS A total of 609 phlebotominae belonging to five species were collected, of which 56% were Lu. longipalpis. In addition, the presence of Nyssomyia neivai and Migonemya migonei, which are vectors of tegumentary leishmaniasis, were also documented and represented 34.81% and 6.74% of the collections, respectively. The explanatory variable normalised difference vegetation index (NDVI) described the abundance distribution, whereas the presence of farmyard animals was important for explaining both the abundance and the occurrence of the vector. MAIN CONCLUSIONS The results contribute to the identification of variables that can be used to establish priority areas for entomological surveillance and provide an efficient transfer tool for the control and prevention of vector-borne diseases.

Environmental suitability for Lutzomyia longipalpis in a subtropical city with a recently established visceral leishmaniasis transmission cycle, Argentina.

BACKGROUND: Visceral leishmaniasis (VL) is an endemic disease in northeastern Argentina including the Corrientes province, where the presence of the vector and canine cases of VL were recently confirmed in December 2008. OBJECTIVES: The objective of this study was to assess the modelling of micro- and macro-habitat variables to evaluate the urban environmental suitability for the spatial distribution of Lutzomyia longipalpis presence and abundance in an urban scenario. METHODS: Sampling of 45 sites distributed throughout Corrientes city (Argentina) was carried out using REDILA-BL minilight traps in December 2013. The sampled specimens were identified according to methods described by Galati (2003). The analysis of variables derived from the processing of satellite images (macro-habitat variables) and from the entomological sampling and surveys (micro-habitat variables) was performed using the statistical software R. Three generalised linear models were constructed composed of micro- and macro-habitat variables to explain the spatial distribution of the abundance of Lu. longipalpis and one composed of micro-habitat variables to explain the occurrence of the vector. FINDINGS: A total of 609 phlebotominae belonging to five species were collected, of which 56% were Lu. longipalpis. In addition, the presence of Nyssomyia neivai and Migonemya migonei, which are vectors of tegumentary leishmaniasis, were also documented and represented 34.81% and 6.74% of the collections, respectively. The explanatory variable normalised difference vegetation index (NDVI) described the abundance distribution, whereas the presence of farmyard animals was important for explaining both the abundance and the occurrence of the vector. MAIN CONCLUSIONS: The results contribute to the identification of variables that can be used to establish priority areas for entomological surveillance and provide an efficient transfer tool for the control and prevention of vector-borne diseases.