Association between environmental gradient of anthropization and phenotypic plasticity in two species of triatomines.

BACKGROUND: Triatoma garciabesi and T. guasayana are considered secondary vectors of Trypanosoma cruzi and frequently invade rural houses in central Argentina. Wing and head structures determine the ability of triatomines to disperse. Environmental changes exert selective pressures on populations of both species, promoting changes in these structures that could have consequences for flight dispersal. The aim of this study was to investigate the relationship between a gradient of anthropization and phenotypic plasticity in flight-related traits. METHODS: The research was carried out in Cruz del Eje and Ischilín departments (Córdoba, Argentina) and included 423 individuals of the two species of triatomines. To measure the degree of anthropization, a thematic map was constructed using supervised classification, from which seven landscapes were selected, and nine landscape metrics were extracted and used in a hierarchical analysis. To determine the flight capacity and the invasion of dwellings at different levels of anthropization for both species, entomological indices were calculated. Digital images of the body, head and wings were used to measure linear and geometric morphometric variables related to flight dispersion. One-way ANOVA and canonical variate analysis (CVA) were used to analyze differences in size and shape between levels of anthropization. Procrustes variance of shape was calculated to analyze differences in phenotypic variation in heads and wings. RESULTS: Hierarchical analysis was used to classify the landscapes into three levels of anthropization: high, intermediate and low. The dispersal index for both species yielded similar results across the anthropization gradient. However, in less anthropized landscapes, the density index was higher for T. garciabesi. Additionally, in highly anthropized landscapes, females and males of both species exhibited reduced numbers. Regarding phenotypic changes, the size of body, head and wings of T. garciabesi captured in the most anthropized landscapes was greater than for those captured in less anthropized landscapes. No differences in body size were observed in T. guasayana collected in the different landscapes. However, males from highly anthropized landscapes had smaller heads and wings than those captured in less anthropized landscapes. Both wing and head shapes varied between less and more anthropogenic environments in both species. CONCLUSIONS: Results of the study indicate that the flight-dispersal characteristics of T. garciabesi and T. guasayana changed in response to varying degrees of anthropization.

Socio-environmental factors associated with the occurrence of triatomines (Hemiptera: Reduviidae) in an endemic municipality in northern Minas Gerais, Brazil.

Triatomines are the vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. The study aimed to evaluate the association between sociodemographic and environmental factors, and changes in land use and cover, with the occurrence and abundance of triatomines by census sectors in an endemic municipality of northern Minas Gerais, Brazil. The study was conducted in Montes Claros, located in the north of Minas Gerais, Brazil. The entomological data used in the study were collected by active surveillance in the rural area from 2015 to 2019 and by passive surveillance in the urban area from 2009 to 2019. Data on sociodemographic and environmental factors and changes in land use and land cover were obtained from the urban and rural census sectors. A total of 1404 triatomines, belonging to eight species, were captured in domiciles in the rural area (2015-2019) and 277 triatomines in domiciles in the urban area (2009-2019) of the municipality of Montes Claros. The variables the number of domiciles, household economic income, pavement, NDVI, deforestation, unchanged, and anthropic proved to be positively associated with the occurrence and/or number of triatomines in census sectors, within the models. The occurrence of triatomines in the domestic environment of the municipality of Montes Claros should be considered a public health problem, as it suggests a potential risk of establishment and transmission of T. cruzi to domestic animals, farm animals, and humans.

Ecomorphological variation of the Triatoma guasayana wing shape in semi-arid Chaco region.

Triatoma guasayana (Hemiptera, Reduviidae), considered a secondary vector of Chagas disease, invades rural dwellings through flight dispersal during the warm season in semi-arid Chaco of Argentina. The objective of this study was to define and compare morphometrics features in the relative body size and wing shape of T. guasayana related to temperature and rainfall between spring, summer and end of summer. A total of 188 adults were collected in rural communities in the northwest of the province of Córdoba (central Argentina). Relative body size [body length (mm) / wing length (mm)] and 11 landmarks on the right wing were recorded. The temperature ( °C) and precipitation (mm) data were extracted from the MODIS sensor and Terra Climate dataset, respectively. Correlations between climatic variables and morphological variation were analyzed using Partial Least Square (PLS). Males at the end of summer were smaller than those at spring or summer (F = 4.48; df = 2; p = 0.01), whereas females were similar in relative body size at all seasons (F = 0.76; df = 2; p = 0.47). The PLS in males showed a correlation between wing shape and temperature (r = 0.48; p = 0.03) and precipitation (r = 0.50; p = 0.02) while in females only the temperature was the correlation significant (r = 0.35; p = 0.03). Triatoma guasayana has elongated and thin wings in spring that become short and wide at the end of summer. The morphotype of early summer could allow sustained long-duration flights, while the morphotype of end of summer would be related to short flights, correlated with the dispersive behavior of the species. The results in this study suggest that wing morphology of T. guasayana has phenotypic plasticity, and that temperature and rainfall could be considered modulator factors during the developmental stage.

Histology of folicular development of hybrids between Triatoma infestans Klug, 1864 and Triatoma platensis Neiva, 1913 (Hemiptera: Heteroptera) / HISTOLOGÍA DEL DESARROLLO FOLICULAR DE HÍBRIDOS ENTRE Triatoma infestans Klug, 1864 Y Triatoma platensis Neiva, 1913 (HEMIPTERA: HETEROPTERA)

ABSTRACT Triatoma infestans and Triatoma platensis are interfertile species that frequently share ecotopes and produce natural fertile hybrids. Interspecific crossing allows the production of more suitable hybrid genotypes capable of colonizing new habitats. Therefore, studies of reproductive aspects in hybrids are of great importance. In this sense, oogenesis, a process that involves the development of the oocyte and allows the formation of viable eggs, is a relevant aspect. In this study, histological aspects focused on the follicular development of experimental hybrids were characterized. To do this, the ovaries of35 hybrid females were removed, paraffin-embedded and stained with hematoxylin-eosin. The development of the follicular epithelium and the oocyte in the stages of previtellogenesis and vitellogenesis were characterized, finding that the oogenesis of the hybrid females is well defined producing viable eggs and that the changes occurred at the histological level resemble those registered in T. infestans.

RESUMEN Triatoma infestans y Triatoma platensis son especies interfértiles que en ocasiones comparten ecotopos y producen híbridos fértiles naturales. El cruzamiento interespecífico podría permitir la producción de genotipos híbridos capaces de colonizar nuevos hábitats. Por ello, los estudios de aspectos reproductivos sobre estos organismos son de gran importancia. En este sentido la oogénesis, proceso que implica el desarrollo del ovocito y permite la formación de huevos viables, es un aspecto relevante. En este estudio se caracterizaron aspectos histológicos enfocados en el desarrollo folicular de híbridos experimentales. Para ello, se extrajeron los ovarios de 35 hembras híbrido, se embebieron en parafina y colorearon con hematoxilina-eosina. Se caracterizó el desarrollo del epitelio folicular y del ovocito en las etapas de previtelogénesis y vitelogénesis, encontrándose que la oogénesis de las hembras híbrido se encuentra bien definida produciendo huevos viables y que los cambios ocurridos a nivel histológico se asemejan a los registrados en T. infestans.

Triatominae of the semi-arid Chaco in central Argentina.

The epidemiological scenario in central Argentinian Chaco region shows persistence of Triatoma infestans domestic populations in endemic areas, with control interventions historically affected by the economic instability of the region. Considering this situation, we aimed to (i) update the information regarding to the diversity of triatomines present in domestic, peridomestic and sylvatic environments in departments historically endemic of the Chaco region, (ii) to report the occurrence of secondary vectors of Chagas disease invading domestic environments and (iii) to discuss the possible sources of dispersal of these sylvatic species towards anthropic habitats. Between November 2017 and March 2020, we visited fourteen rural communities of northwest Córdoba province (central Argentina). Entomological data were collected through community vector surveillance in domiciles, active search in peridomiciles and the use of light and yeast traps in sylvatic environments. Seven Triatominae species were captured invading domiciles (T. guasayana, T. garciabesi, T. platensis, T. delpontei, T. breyeri, Panstrongylus guentheri and T. infestans). T. guasayana and T. garciabesi were the species with the highest number of captures. The 32% of the peridomiciles registered infestation with T. infestans (n â€‹= 355), mostly in chicken coops and goat pens. In sylvatic environments, T. garciabesi, T. guasayana, T. infestans and P. guentheri were collected. Only one adult specimen of T. infestans was positive for the presence of Trypanosoma cruzi. Our results suggest that the persistence of T. infestans populations in peridomiciles continues to be a serious challenge for control programs, whereas the finding of secondary vectors of Chagas disease actively invading domiciles emphasizes the need to implement new strategies for entomological surveillance.

Modelling the effect of density vegetation coverage and the occurrence of peridomestic infestation by Triatoma infestans in rural houses of northwest of Córdoba, Argentina.

To better understand the dispersion strategies of Triatoma infestans (Klug) (Hemiptera: Reduviidae, Triatominae), we evaluated the spatial effect of infested peridomicile and density vegetation cover in a historically endemic area for Chagas disease. The study was conducted in rural houses of the northwest of Córdoba province, Argentine, during 2012-2013. Active search of triatomines were made in domicile and peridomicile habitats. To characterize vegetation coverage, a thematic map was obtained considering five types of vegetation cover (closed/open forest, closed/open shrubland and cultural land). From each house we extracted the area of vegetation coverage, housing density and infested peridomiciles density. We used generalized linear models to evaluate the effect of these variables on the occurrence of infested peridomicile. According to our results, the probability of a peridomicile to be infested increases by 1.34 (95%CI [0.98; 1.90]) times more when peridomicile structures are in environments with higher housing density and by 1.25 (95%CI [0.84; 1.88]) more times when houses are surrounded by open shrublands. Among the multiple ecological determinants of peridomestic infestation, the influence of vegetation cover has been poorly studied. In this study we discussed the effect of the vegetation as a potential modulator of the dispersion strategies of T. infestans.

Effect of habitat fragmentation on rural house invasion by sylvatic triatomines: A multiple landscape-scale approach.

After the decrease of the relative importance of Triatoma infestans, a number of studies reported the occurrence of sylvatic triatomines dispersing actively to domestic environments in the dry western Chaco Region of Argentina. Anthropic modification of the landscape is mentioned as one of the main causes of the increase in domicile invasion. The aim of this study was to describe the occurrence and frequency of sylvatic triatomines invading rural houses, and to evaluate the effect of habitat fragmentation and other ecological factors on the invasion of rural houses in central Argentina. We hypothesized that the decrease in food sources and the loss of wild ecotopes, as a consequence of habitat fragmentation, increase the chances of invasion by triatomines. The entomological data was collected by community-based vector surveillance during fieldwork carried out between 2017-2020, over 131 houses located in fourteen rural communities in the northwest of Córdoba Province (central Argentina). We used generalized linear models to evaluate the effect of (i) the environmental anthropic disturbance in the study area, (ii) the composition and configuration of the landscape surrounding the house, (iii) the spatial arrangement of houses, (iv) and the availability of artificial refuges and domestic animals in the peridomicile, on house invasion by triatomines. We report the occurrence of seven species of triatomines invading rural houses in the study area -T. infestans, T. guasayana, T. garciabesi, T. platensis, T. delpontei, T. breyeri and P. guentheri-. Study data suggest that invasion by triatomines occurs with higher frequency in disturbed landscapes, with houses spatially isolated and in proximity to subdivided fragments of forest. The availability of domestic refuges in the peridomestic structures as well as the presence of a higher number of domestic animals increase the chances of invasion by triatomines.

Dynamics of feeding and defecation behavior of Triatoma infestans hybrids.

Triatoma platensis is occasionally found coexisting with Triatoma infestans in chicken coops in Argentina. Some authors have reported the presence of hybrid specimens of both species in chicken coops and other peridomestic habitats. Given the coexistence of T. infestans with T. platensis and the possibility of generating fertile hybrids, it is important to evaluate the vectorial competence of these hybrids. The objective of this study was to record the dynamics of feeding-defecation behavior in fifth-stage nymphs and adults of hybrids between both species and to compare it with T. platensis and T. infestans. Three experimental groups were formed separated by stage and sex: Hybrid group, T. infestans group, and T. platensis group. During feeding, the following variables were recorded for each group: (i) blood meal size, (ii) feeding time, (iii) number of defecations during feeding, and (iv) number of defecations at 10 and 30 min after feeding. The results indicate that adults and fifth-instar nymphs of hybrids have a feeding and defecation behavior similar to T. infestans: they achieve feeding in a short time and first defecation occurs during or just after feeding. Nevertheless, hybrid's ingestion of blood occurs at higher velocity and they require higher blood intake to provoke early defecations. Considering the blood ingestion velocity, the amount of blood ingested, and the short time required for the production of the first defecation, the results of this study suggest that hybrid can be a competent Trypanosoma cruzi vector.

Characterization of melanic and non-melanic forms in domestic and peridomestic populations of Triatoma infestans (Hemiptera: Reduviidae).

BACKGROUND: Melanic (dark) morphs have been barely reported in peridomestic and sylvatic conditions for Triatoma infestans, the most important vector of Chagas disease in the Southern Cone of South America. Adults with dark and small yellow markings on the connexivum were collected after manual searches conducted by technical personnel in 62 domiciliary units in Cruz del Eje, Córdoba Province, Argentina. The last community-wide insecticide spraying campaign before the study had been conducted three years earlier. We investigated if there was a measurable color morph variation (melanic and non-melanic) in wings and connexivum; we determined infestation, distribution of melanic and non-melanic forms, and correspondence of colorimetric variation with variations in morphology (wing size and shape and body length), development (wing fluctuating asymmetry), physiology (nutritional status) or behaviour (flight initiation). RESULTS: Forty-nine females, 54 males and 217 nymphs were collected in 24 domiciliary units. House infestation and colonization were 53% and 47%, respectively. Most of the T. infestans individuals (83.2%) were collected in chicken coops; intradomicile infestation was recorded in only one case. The chromatic cluster analysis showed two well-defined groups: melanic and non-melanic. The melanic group included 17 (35%) females and 25 (46%) males. Peridomestic infestation was lower for melanic than for non-melanic adults. Melanic morphs were collected in houses from several localities. Sexual dimorphisms were confirmed by morphometric measurements. Body length was large in melanic adults (P < 0.01 only for males). Differences between groups were significant for wing size and shape, but not for weight or weight/body length ratio. Melanic females and males showed significantly higher fluctuating asymmetry (FA) indices than their non-melanic counterparts. CONCLUSIONS: This is the second report of melanic forms of T. infestans in domestic and peridomestic habitats in the Dry Chaco region of Argentina. Although non-melanic adults exhibited a higher infestation rate, melanic adults were widespread in the area and were collected in the infested domicile and in most types of peridomestic annexes. Differences in morphometric variables between groups might be due to different ecological adaptations. The higher FA levels observed in melanic individuals suggest a higher developmental instability and a selective advantage of non-melanic individuals in domestic and peridomestic habitats.

Factors associated with the presence of triatomines in rural areas of south Argentine Chaco.

INTRODUCTION: The domestic and peridomestic presence of Triatoma infestans depends on several factors, such as human behavior, vector behavior, ecology, and the environment. METHODS: This work was conducted in 139 domiciliary units, where triatomines were captured and risk factors in domiciles and peridomicilies were recorded. Household dwellers were interviewed to obtain information about practices regarding this disease and entomological indicators were calculated. RESULTS: Infestation indices were 59.7% for house compounds, 4.3% for domestic areas and 58.3% for the peridomestic areas. Intradomicile infestation was significantly associated with housing characteristics. The presence of chicken coops in peridomicilies was associated with an increased risk of infestation. Of the respondents, 80% did not recognize the importance of the peridomiciliary structures for triatomine control and had infested peridomicilies. CONCLUSIONS: The results show the importance of peridomiciles as refuge sites for Triatominae bugs; however, household dwellers do not perceive peridomiciles as areas that favor the presence of vectors. Actions for raising awareness about factors that favor the presence of triatomines are needed to improve the conditions of peridomiciliary environments.

Factors associated with the presence of triatomines in rural areas of south Argentine Chaco

Abstract INTRODUCTION: The domestic and peridomestic presence of Triatoma infestans depends on several factors, such as human behavior, vector behavior, ecology, and the environment. METHODS: This work was conducted in 139 domiciliary units, where triatomines were captured and risk factors in domiciles and peridomicilies were recorded. Household dwellers were interviewed to obtain information about practices regarding this disease and entomological indicators were calculated. RESULTS: Infestation indices were 59.7% for house compounds, 4.3% for domestic areas and 58.3% for the peridomestic areas. Intradomicile infestation was significantly associated with housing characteristics. The presence of chicken coops in peridomicilies was associated with an increased risk of infestation. Of the respondents, 80% did not recognize the importance of the peridomiciliary structures for triatomine control and had infested peridomicilies. CONCLUSIONS: The results show the importance of peridomiciles as refuge sites for Triatominae bugs; however, household dwellers do not perceive peridomiciles as areas that favor the presence of vectors. Actions for raising awareness about factors that favor the presence of triatomines are needed to improve the conditions of peridomiciliary environments.

Evaluación de la asociación amoxicilina/sulbactam frente a amoxicilina/sulbactam más gentamicina en niños con peritonitis de origen apendicular / Evolution of tje association amoxicillin/sulbactam to a amoxicillin/sulbactam more gentamicins in childs with peritonitis of apendicular origin

La apendicitis complicada y la no complicada siguen teniendo una alta incidencia en la población pediátrica. La mortalidad en este grupo de pacientes está dada principalmente por sus complicaciones infecciosas, entre las cuales destacan por su frecuencia, la infección de herida operatoria y los abscesos residuales intraperitoneales. La selección apropiada de antibióticos logra reducir considerablemente el porcentaje de estas complicaciones. Objetivos: Comparar la eficacia clínica de amoxicilina/sulbactam frente a amoxicilina/sulbactam más gentamicina en pacientes con peritonitis de origen apendicular. Material y Métodos: El estudio fue de carácter prospectivo, abierto, aleatorizado, realizado en el periodo comprendido entre mayo de 2000 y abril de 2001 que incluyó pacientes de 12 meses a 15 años de edad. Fueron asignados al azar en dos grupos, para recibir ya sea amoxicilina/sulbactam (GrupoA) o amoxicilina/sulbactam más gentamicina (Grupo B). La técnica quirúrgica fue básicamente la misma en todos los pacientes. Resultados: 104 pacientes fueron incluidos en el estudio; 56 pacientes en en Grupo A y 48 pacientes en el Grupo B. La edad promedio+-DS fue de 8.89 +- 0.82 años vs. 7.31 +- 0.67 años. El tratamiento fue clínicamente satisfactorio en 47 de 56 pacientes (84 porcientos) en el Grupo A y en 39 de los 48 pacientes (81 porcientos) en el Grupo B (p=0.9). La presencia de accesos residuales intraperitoneales se observó en 1 de 56 pacientes (2 porcientos) enel Grupo A y en 2 de 48 pacientes (4 porcientos) en el Grupo B (p=0.5). La incidencia de infección de la herida operatoria fue similar en ambos grupos de pacientes (14 porcientos) (p=0.8). Conclusiones: Estos resultados sugieren que amoxicilina/sulbactam puede ser una opción efectiva en el tratamiento de niños con peritonitis de origen apendicular. La utilización de gentamicina asociada a la amoxicilina/sulbactam no demostró reducir la incidencia de abscesos residuales intraperitoneales, ni de infección de la herida operatoria

Problemas y alternativas de solución a la seguridad social en México: una perspectiva desde los sindicatos y los trabajadores / Solution of alternate and problems a the social security in México: a perspective from the workers and the labor

Esta trabajo muestra la perspectiva del sector trabajador sobre el sistema de seguridad laboral y social en México, es un aporte preliminar a la comprensión del problema y sus alternativas de solución, basado en lo abordado en el taller: Elaboración de Propuestas Sindicales de Mejoría y Transformación de los sistemas de salud y seguridad social de México. Se extrajeron cinco problemas específicos desarrollados en el taller, tales como: La modernización productiva y Nuevos Problemas de salud del Trabajo en la Industria Química. Los riesgos de los trabajadores de la slud, en particular, de las enfermeras. La modernización y salud laboral en el transporte. Los riesgos laborales en la Industria del Transporte