Agenda Nacional de Investigación en Salud Pública / National Agenda for Research in Public Health

El 2 de diciembre de 2019 se presentó la Agenda Nacional de Investigación en Salud Pública en el Ministerio de Salud de Argentina. El establecimiento de prioridades en una Agenda Nacional de Investigación en Salud Pública es un proceso sistemático, participativo y reflexivo, que permite guiar la investigación hacia problemas relevantes, prevalentes y emergentes de la población, orientar los recursos hacia los temas priorizados, fortalecer y/o crear grupos, centros y redes de investigación para la salud pública, mejorar las capacidades para el desarrollo de investigación de calidad e incrementar la evidencia local para la toma de decisiones a fin de mejorar la salud de la población y los sistemas sanitarios en el marco de los Objetivos de Desarrollo Sustentable 2030. Como metodología para la elaboración de la Agenda se eligió el Método Delphi modificado por la Organización Panamericana de la Salud (OPS). En la elaboración de esta herramienta participaron la Dirección de Investigación para la Salud (DIS) del Ministerio de Salud de la Nación, a través de la Red Ministerial de Investigación en Salud (REMINSA), y la OPS. A lo largo de todo el proceso se consideró imprescindible lograr una amplia participación de actores de los niveles provinciales y nacionales, y de los sectores público y privado. La presencia de una Agenda Nacional de Investigación en Salud Pública permitirá generar investigación científica nacional y regional, e implementar políticas y recomendaciones que impacten en la salud de las poblaciones

CSV-ARG, Estudio multi-céntrico de validación de una escala de detección temprana de deterioro en pacientes internados / CSV-ARG, multicenter study of validation of an early detection scale of deterioration in hospitalized patients

Introducción: La detección precoz de un paciente con riesgo de deterioro, y la intervención temprana por un equipo de salud competente en el manejo de la vía aérea ha demostrado reducir la mortalidad intrahospitalaria. El NEWS (National Early Warning Score, Reino Unido) clasifica a los pacientes según su probabilidad de deterioro dentro de las siguientes doce horas; en baja (0-1), moderada (2-4) y alta posibilidad de deterioro (5-13), a partir de cuatro signos vitales: frecuencias cardíaca y respiratoria, temperatura y presión arterial sistólica sumados a la saturación de oxígeno y el estado de conciencia. Fue generada a partir de una gran base de datos de signos vitales obtenidos de manera electrónica en pacientes internados en Inglaterra. En las instituciones de nuestro país, los signos vitales son tomados manualmente y hay una percepción generalizada de que estos o "están mal tomados" o no se los ubica dentro del centro de la toma de decisiones. Objetivos: El objetivo de este estudio fue, a partir de signos vitales tal como se toman en nuestro medio, realizar una validación de la capacidad de discriminación de la escala NEWS de eventos severos durante la internación. Diseño, materiales y métodos: Ocho instituciones de la ciudad de Buenos Aires y del área metropolitana participaron recolectando de manera consecutiva los seis parámetros vitales que componen la escala NEWS en los pacientes internados, tal como se toman en las salas de internación, además de datos demográficos, presencia de comorbilidades, eventos de gravedad durante la internación como sepsis, trombo embolismo de pulmón, shock hipovolémico, distrés respiratorio, insuficiencia respiratoria, trastorno de la conciencia y muerte sin evento previo. Los datos se ingresaron a una base de datos virtual calculándose el puntaje de la escala NEWS. Se analiza en este primer trabajo las características de la población con medidas de tendencia central y de dispersión estándares según la distribución de los valores. Mediante regresión logística se analizó la capacidad del primer NEWS al ingreso de predecir un evento independientemente de la edad, el sexo y la presencia de comorbilidades. Resultados: Entre el 1 de enero de 2015 hasta el 31 de julio ingresaron en el estudio 1705 pacientes de nueve Instituciones del área metropolitana, 869 eran mujeres (51%), rango de edad 18 a 100. Un 10% de los pacientes presentó algún evento grave, y la mortalidad global fue de 3,5%. El 90% de los pacientes fue clasificado al ingreso como NEWS de bajo grado de deterioro (0-4), el 5% riesgo moderado (5-6) y el 5% de riesgo alto (mayor a 7). El valor de NEWS, al ingreso de la internación y tal como se toman los signos vitales en nuestro medio, predice el riesgo de presentar un evento severo durante la internación, independientemente de la edad, sexo y la presencia de comorbilidades. Discusión: En este estudio pudimos demostrar que los signos vitales, tomados de manera manual calculando la escala NEWS, es un excelente predictor de la ocurrencia de eventos durante la internación. En próximos análisis evaluaremos la capacidad de discriminación y la capacidad de predecir eventos entre 12 y 24 horas posteriores a la toma. (AU)

Background: Early warning scores at hospital settings have shown to reduce hospital mortality. The NEWS (National Early Warning Score, UK), classifies patients as per their risk to deteriorate in three categories, low risk (0-2), moderate risk (3-4) and high risk (5-13). The scale uses four vital signs, heart rate, respiratory rate, temperature and systolic arterial pressure, plus oxygen saturation and conscious state. It was developed and validated using a large database of electronic captured vital signs in England. In Argentina, most of the vital signs are taken manually. (AU)

El cabello, fuente de información del estado de salud / The hair, source of health information

El cabello y especialmente el localizado en la cabeza provee importante información sobre posibles exposiciones ambientales y/o laborales a diferentes elementos. El pelo puede ser considerado como un producto excretor, y su estudio reflejaría el metabolismo de minerales en el cuerpo. Nuestro propósito en el presente estudio es conocer si datos existentes dan información poblacional sobre la presencia de elementos tóxicos o no a través del análisis del cabello humano. RESULTADOS: Fue analizada la información proveniente de 241 muestras de cabello, de los cuales 163 (67,6%) corresponden al sexo femenino y 78 (32,4%) al masculino. Fueron analizados 22 elementos esenciales y 17 elementos de tóxicos. Entre los elementos esenciales presentaron resultados elevados Calcio (Ca), Magnesio (Mg), Manganeso (Mn), Molibdeno (Mo), Vanadio (V), Estroncio (Sr) y Circonio (Zr); entre los elementos tóxicos tuvieron valores elevados Aluminio (Al), Arsénico (As), Bario (Ba), Bismuto (Bi), Cadmio (Cd), Níquel (Ni), Plomo (Pb), Mercurio (Mg), Plata (Ag), Estaño (Sn). CONCLUSIÓN. Nuestro estudio muestra a nivel poblacional, no individual, puntos de alerta por la carencia o exceso de algunos elementos analizados debiéndose continuar con estudios locales interdisciplinarios en los cuales exista información sobre enfermedades, hábitos alimentarios, hábitos tóxicos, actividad laboral y exposición ambiental a los diferentes elementos. (AU)

Hair, especially localized in the head, provides important information on possible environmental and/or labor exposures to different elements. Hair can be considered as an excretory product, and its study would reflect the metabolism of minerals in the body. Our purpose in this study was to determine whether existing population data provide information on the presence of toxic and non-toxic elements by analizing human hair. RESULTS: We analyzed information from 241 hair samples, of which 163 (67.6%) are from females and 78 (32.4%) are from males. There were analyzed 22 essential elements and 17 toxic elements. Among the essential elements that had elevated results there were: Calcium (CA), magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), strontium (Sr) and zirconium (Zr); among the toxic elements, those with higher values were: Aluminum (Al), arsenic (As), barium (BA), bismuth (Bi), Cadmium (Cd), Nickel (Ni), lead (Pb), Mercury (Mg), silver (Ag), tin (Sn). CONCLUSION. Our study shows at population level, not individual, warning points due to the lack or excess of some elements analyzed. It is reccommended to continue the research with local interdisciplinary studies which include information on diseases, eating habits, toxic habits, work activity and environmental exposure to different elements. (AU)

Evaluación del impacto de la participación comunitaria en la vigilancia de Chagas / Evaluation of the impact of community participation in the surveillance of Chagas

El objetivo del presente estudio es efectuar el análisis del impacto de la vigilancia en sus diferentes modalidades en el control de la infección por T. cruzi y la densidad vectorial (Triatoma infestans). Material y métodos: El trabajo fue desarrollado en el Departamento de Capayán, en la provincia de Catamarca, Argentina. Se seleccionaron aleatoriamente 5 comunidades rurales y 3 comunidades peri-urbanas para desarrollar el estudio. Indicadores utilizados: a) infestación domiciliaria en los meses 24, 48 y 96; y b) Infección por T.cruzi de menores de 14 años. Resultados: Se observa persistencia de triatomineos durante el periodo de seguimiento y cuando se comparan los datos del estudio de base (2007) con los obtenidos en el año 2009 y 2012 existe significancia estadística (p <0.04) entre áreas. Se capturaron 1.89 insectos/intradomicilio en áreas con vigilancia activa versus 5.21 insectos/intradomicilio en áreas donde la misma no existió. Se demuestra la existencia de infecciones recientes en niños menores de 4 años e hijos de mujeres negativas para T. cruzi en áreas sin vigilancia activa (3 niños). Conclusión: En la presente investigación se demuestra el impacto de la vigilancia activa en sus diferentes modalidades por la no existencia de casos nuevos vectoriales en el período de seguimiento. (AU)

The aim of this study is to perform the analysis of the impact of surveillance in its various forms in the control of infection by T. cruzi and vector density (Triatoma infestans). Material and Methods: The work was developed in the Department of Capayán, in the Province of Catamarca, Argentina. Eight rural communities were selected to develop the study. Indicators used: a) house infestation in 24 months, 48 and 96; b) T. cruzi infection in children under 14 years. Results: Persistence of triatomine It is observed during the monitoring period as the baseline study (2007) thus obtained in 2009 compared to 2012 there is statistical significance (p <0.04) between areas. 1.89 insect / intradomicile were captured in areas with active surveillance versus 5.21 insect/intradomicile in areas where it did not exist. The existence of recent infections in children under four years of negative women and children for T. cruzi in areas without active surveillance (3 children) is demonstrated. Conclusion: In this research, the impact of active surveillance in its various forms by Vector exists no new cases in the follow-up period shown. (AU)

Las decisiones políticas y su influencia en los programas de salud / Political decisions and their influence on health programs

El objetivo de este trabajo es analizar la evolución epidemiológica de cuatro enfermedades de importancia sanitaria para Argentina y observar el impacto que diferentes decisiones político / administrativos / técnicas han tenido en su desarrollo histórico epidemiológico. Analizamos la evolución histórica del Paludismo, Enfermedad de Chagas, Fiebre Hemorrágica Argentina (Virus Junín) y Dengue, asociándolos a los diferentes períodos administrativos de gobierno. La incidencia y prevalencia de estas enfermedades se dan fundamentalmente en jurisdicciones que tienen los PBI más bajos, índices generales de educación y desarrollo en los percentiles inferiores y, por lo tanto, las intervenciones dependen fundamentalmente del financiamiento y de la estructura federal. Argentina logró el control de las poblaciones del Aedes aegipty en 1965 y con ello, la suspensión de la ocurrencia de casos de Fiebre Amarilla. Hoy el vector está distribuido más allá de sus fronteras originales produciendo epidemias de Dengue y la retransmisión de Fiebre Amarilla. En Paludismo, de más de 100.000 casos anuales ocurridos durante toda la primera mitad del siglo pasado, se logró bajar la incidencia a poco más de 400 casos en pocos años. Hoy está siendo una amenaza en amplias zonas del Norte y el Litoral de Argentina. De controlar la transmisión vectorial de Chagas, que de unos pocos casos notificados en áreas determinadas en 1996, hoy el número de Chagas agudos vectoriales no deja de aumentar año a año. La excusa más extendida para justificar estos cambios es el calentamiento global, pero podemos afirmar con los datos de nuestro estudio, que mejorando el ambiente político, paso crítico, se pueden alcanzar muchos de los objetivos que han quedado postergados en el área de la salud pública de Argentina. Los argentinos podríamos tener una mejor salud de la que actualmente tenemos si hubiera existido continuidad y estabilidad de las acciones que se desarrollaron en los últimos 60 años. (AU)

The political decision and their influence on health programs development. The objective of this work is to analyze the epidemiological evolution of four diseases in the course of different governmental administrations. We analyzed the historical evolution of the Paludismo, Chagas' disease, Argentine Hemorrhagic Fever (Junín Virus) and Dengue. The incidence and prevalence of these diseases occur fundamentally in jurisdictions that have the lowest GDP, education indices and human development are in the lower percentiles and therefore the interventions depend fundamentally on the financing and federal structures. In the analysis of the Argentina diseases profit the control of the Aedes aegipty vector of Yellow Fever and Dengue was controlled in 1965 and the suspension of the occurrence of Yellow Fever was achieved, today, the vector is distributed beyond its original borders producing epidemics of Dengue and the broadcasting of the Yellow Fever. In Paludismo of more than 100,000 cases occurred during the first half of the last century we were able to lower it to a little more of 400 cases in a short period of time, and today is being a threat in wide zones of the Northwest and the Northeast of Argentina. From almost controlling the Chagas vector transmission in 1996, when only a few cases were reported; today, the amount of acute cases rises to nearly more than 60 cases reported per year. The extended excuse of these occurrence is the global warming and we can affirm without being mistaken, with the data of our study, that improving the political atmosphere, will help to achieve many of the objectives that have been delayed in the area of public health in Argentina. We, Argentineans, could have a better health than we have at the moment if it had existed continuity and stability in the actions that were developed in the last 60 years. (AU)

Effect on seroprevalence of anti-poliovirus antibodies and on vaccination coverage of the implementation of a DTwP-IPV-Hib vaccination programme in a South American city.

Vaccination coverage and seroprevalence of poliovirus antibodies were assessed in Argentinean children (aged 8-12 and 19-21 months) living in Cordoba City pre-/post-implementation of a DTwP-IPV-Hib vaccination programme, and compared to those of controls from neighbouring populations receiving a full oral poliovirus vaccine schedule. Vaccination coverage was higher in control areas pre-intervention; this increased post-intervention in Cordoba (>90%) but not in control areas. Poliovirus types 1 and 2 seroprotection rates were >97% in all groups pre-/post-intervention. Type 3 seroprotection rates were generally lower, but increased post-intervention in Cordoba becoming significantly higher than control rates. Anti-type 1 and 3 antibody titres increased twofold and sevenfold, respectively, post-intervention, whereas anti-type 2 antibody titres decreased ~40% in the 8-12 months group. All titres increased in the 19-21 months post-intervention group. The introduction of a three-dose primary DTwP-IPV-Hib schedule maintained protection against poliovirus types 1 and 2, and increased protection against type 3, while vaccine coverage in the study area increased.

Effects of partial housing improvement and insecticide spraying on the reinfestation dynamics of Triatoma infestans in rural northwestern Argentina.

The long-term effects on domiciliary reinfestation by Triatoma infestans of smoothing the plaster of indoor walls prior to insecticide application (in Amamá village) relative to only insecticide application (in Trinidad-Mercedes villages) were evaluated in rural northwestern Argentina from 1992 to 1997. All domestic and peridomestic areas of each house were sprayed with 2.5% suspension concentrate deltamethrin at 25 mg/m(2) in October 1992, and infestations were assessed by various methods every 6 months. Domiciliary infestation decreased from 72-88% in 1992 to 6-17% in late 1995, to increase moderately thereafter without returning to baseline rates. Peridomestic sites were the first in becoming reinfested, and reached more abundant T. infestans populations than domiciliary areas. Domiciliary infestation rates and bug abundances were not significantly different between communities during surveillance. Domiciliary infestation rates in well-plastered houses were very low (5-9%) and approximately stable until 1996, but in houses with regular or bad plaster they consistently increased from 5 to 19-21% in both communities. Logistic multiple regression analysis showed that the likelihood of domestic infestation assessed through householders' collections was significantly and positively associated with the occurrence of an infested peridomestic site in the respective house, the occurrence of high-density domestic infestations before interventions, and well-plastered walls in 1996. Combining insecticide spraying and partial improvement of walls controlled domestic infestations and transmission of Trypanosoma cruzi effectively, but was not sufficient to eliminate T. infestans from the study area or increase the effectiveness of careful chemical control.

Peridomestic distribution of Triatoma garciabesi and Triatoma guasayana in north-west Argentina.

The Reduviid bugs Triatoma garciabesi Carcavallo et al. (Hemiptera: Reduviidae: Triatominae), previously known as T. sordida Ståhl in the semi-arid chaco region, and T. guasayana Wygodzinsky & Abalos, vectors of Trypanosoma cruzi Chagas (Kinetoplastida: Trypanosomatidae), were found to occupy wide but different ranges of ecotopes in the peridomestic environment. At Amamá and nearby rural villages in north-western Argentina, a combined total of 1233 specimens were collected from 325/2314 (14%) sites surveyed at 6-monthly intervals from November 1994 to November 1996. Triatoma garciabesi and T. guasayana displayed a significantly different distribution among peridomestic ecotopes. Triatoma garciabesi predominated over T. guasayana in the prevalence of infested sites, the number of colonies and the number of bugs collected. For T. garciabesi, the predominant ecotopes most likely to yield T. garciabesi repeatedly were the rugged bark of Prosopis alba or P. nigra (Fabaceae) trees, where chickens roosted, and chicken coops. For T. guasayana the main ecotopes were goat or sheep corrals, piled materials and orchard fences. Triatoma garciabesi and T. guasayana were collected concurrently from the same site on 9/2314 (0.4%) occasions, and on different dates at the same site on 12 (0.5%) occasions. The observed low frequency of mixed populations (< 1%) was not significantly different from that expected from a hypothesis of independence. Triatoma garciabesi clearly outnumbered T. guasayana in four of the nine mixed populations, none of which persisted as such. Neither T. garciabesi nor T. guasayana colonized human habitations, even in the absence of T. infestans (formerly the predominant domestic vector of T. cruzi in this area), a situation that apparently has not changed in the last 50 years in northern Argentina.

Congenital transmission of Trypanosoma cruzi: an operational outline for detecting and treating infected infants in north-western Argentina.

We designed a set of procedures for first-line local health services to detect and treat the congenital transmission of Trypanosoma cruzi at a province-wide scale, and field-tested the programme in the province of Tucumán, northwestern Argentina, from 1992 to 1994. The programme consists of routine screening of pregnant women for seroreactivity to T. cruzi, serological and parasitological follow-up of the newborn at least twice during the first year of age, treatment of the infected infants, and evaluation of the outcome. 927 (5.5%) of 16 842 pregnant women were seroreactive to T. cruzi by indirect haemagglutination assay and ELISA. Twenty-one (6.7%) of 315 newborns to seroreactive mothers were diagnosed as infected with T. cruzi parasites microhaematocrit concentration before 30 days of age. Five newborns who initially tested negative had a T. cruzi infection detected by microhaematocrit and/or serological techniques at 3 or 6 months of age. Thus, congenital infection was diagnosed in 26 (7.1%) infants born to seroreactive women and residing in houses free of triatomine bugs. Four of 6 infants born to seroreactive mothers died during the first year of age and had some evidence of T. cruzi infection; one of the deaths was attributed to T. cruzi based on clinical evidence. After specific treatment with nifurtimox or benznidazole, 30 of 32 infants remained parasitologically and serologically negative. This study shows the feasibility of controlling the incidence of congenitally acquired T. cruzi infections at a province-wide scale by means of a specific screening programme at first-line health services level.

Small-scale field trial of a sensing device for detecting peridomestic populations of Triatoma infestans (Hemiptera: Reduviidae) in northwestern Argentina.

Two prototypes of sensing devices for detecting peridomestic populations of Triatoma infestans Klug were tested in paired trials with bamboo canes in Amamá and nearby rural villages under triatomine surveillance. In infested peridomestic structures housing domestic animals, 1-2 pairs of numbered devices were placed per test site, left for 3-9 nights, and inspected for evidence of infestation. Prototype A was a black plastic cylinder 19 cm high and 10 cm diameter, with a screw cap on the top, 2 openings in the bottom, and a removable central structure made of resistant plastic coated with leather. Prototype B had square leather pieces rolled into cylinders instead of the central structure. Prototype A was significantly more sensitive than the bamboo cane with pleated paper inside in 13 test sites in which 20 pairs were tried. In a smaller series involving 7 pairs, prototype B also detected infestations more frequently than the cane. Triatomine feces were the signs most frequently recorded by both prototypes, whereas the bamboo canes recorded no feces. Ten T. infestans and 1 Triatoma guasayana Wygodzinsky & Avalos were collected from the prototypes placed on the ground or walls, not beneath the thatched roofs of the animal shelters, whereas only 3 T. infestans were collected from the canes. This study describes an effective sensing device for detecting T. infestans populations in outdoor animal shelters and provides quantitative field data on its performance.

Trypanosoma cruzi infection in Triatoma infestans and other triatomines: long-term effects of a control program in rural northwestern Argentina.

The prevalence of Trypanosoma cruzi infection in Triatoma infestans, Triatoma guasayana, and Triatoma sordida was evaluated in Amamá and other neighboring rural villages in northwestern Argentina for five years after massive spraying with deltamethrin in 1992 and selective sprays thereafter. Local residents and expert staff collected triatomines in domiciliary and peridomestic sites. During 1993-1997, the prevalence of T. cruzi was 2.4% in 664 T. infestans, 0.7% in 268 T. guasayana, and 0.2% in 832 T. sordida. T. cruzi infection was more frequently detected in adult bugs and in triatomines collected at domiciliary sites. The infected T. guasayana and T. sordida were nymphs and adults, respectively, captured at peridomestic sites. The prevalence of T. cruzi infection in T. infestans decreased from 7.7% to 1.5% during the surveillance period, although that change was not statistically significant. Comparison of T. infestans infection rates before the control program and during surveillance showed a highly significant decrease from 49% to 4.6% in bedrooms, as well as a fall from 6% to 1.8% in peridomestic sites. Because of its infection with T. cruzi and frequent invasion of domiciliary areas and attacks on humans and dogs, T. guasayana appeared implicated as a putative secondary vector of T. cruzi in domestic and peridomestic sites during the surveillance period. T. sordida was the most abundant species, but it was strongly associated with chickens and showed little tendency to invade bedrooms.

Monitoring house reinfestation by vectors of Chagas disease: a comparative trial of detection methods during a four-year follow-up.

Domestic reinfestations by triatomine bugs were monitored after application of deltamethrin and apparent elimination of Triatoma infestans in Amama and other nearby rural villages, north-west Argentina, from 1992 to 1996. The five methods used were sensor boxes, sheets of pink typing-paper, timed manual catches by a skilled three-person team aided by a flushing-out agent, collections by house-dwellers, and knockdown using insecticide fumigant canisters. In bedrooms, house-dwellers collected T. infestans significantly more frequently than the flushing-out method, but the reverse occurred in peridomestic sites. Both methods and sensor boxes revealed the frequent invasion of adult Triatoma guasayana and T. infestans, but neither T. guasayana nor Triatoma sordida colonized bedroom areas in spite of their rising abundance in nearby peridomestic sites. Sensor boxes were significantly more sensitive than the matched paper-sheets in three of five cross-sectional surveys. On average, each box recorded 2.0-3.2 times more triatomine fecal smears than each paper sheet. The frequency of dejecta in sensor boxes correlated positively with the proportion of houses where T. infestans, T. guasayana or T. sordida were captured by any method in bedroom areas. Triatomine fecal smears in sensor boxes were the earliest and most frequent sign of domiciliary infestation, followed by dwellers' collections of adult bugs. Analyzing the data prospectively, we provide a quantitative, predictive understanding of detection methods and review the validity and interpretation of the different signs of infestation obtained. The most sensitive and cost-effective combination of detection methods for vector surveillance in domestic areas was the use of sensor boxes and house-dwellers collections.

Risk of death due to chronic chagasic cardiopathy.

In this longitudinal study 5,710 people were included. The inclusion criteria were two positive serological results for Trypanosoma cruzi infection, 15 and 50 years old and no other demonstrable disease at the time of study. In the five year follow up 1,117 patients were lost. The follow up involved yearly evaluation of serology, clinical examination, X-ray of thorax, and ECG, for 4,593 patients and 263 were contacted at home because they did not assist for their clinical consultant. Time average of follow up was 5.3 years. Eighty nine (1.5%) of the 4,593 patients died during the follow-up period, 63 (71%) by cardiac insufficiency (CI) and 26 (29%) by severe ventricular arrhythmias. Diagnosis of cardiomegaly was present in all the patients with diagnosis of CI and in 15 (5%) of the patients with diagnosis of arrhythmias. The ECG alterations of these patients show 61 right bundle branch block (RBBB), associated or not with left anterior hemiblock (LAHB), 47 pathological Q wave and 70 primary repolarization alterations; 61 had polyfocal ventricular arrhythmia. The death rate was similar in the sexes and was more frequent between 40 and 50 years of age. Information on 1,380 recuperated patients shows that 15 died with no previous symptoms and without medical assistance and were interpreted as sudden death. The latest ECG in three follow-up of these patients indicates (before death) that only one had normal study and 14 presented 12 RBBB; 9 LAHB; 7 isolated ventricular arrhythmia; 10 repolarize alterations; 2 pathological Q wave, 10 patients of them with RBBB and repolarize alterations. In all the cases we had people between 35 and 43 years old, 9 men and 6 women. This study shows that in Chagas disease is possible to differentiate two risk groups. A low risk death group that have normal ECG and clinical evaluation during the follow up, and a high risk group associate ECG with RBBB and primary alterations of repolarization and/or inactivation zones with not annual clinical evaluation.

Household prevalence of seropositivity for Trypanosoma cruzi in three rural villages in northwest Argentina: environmental, demographic, and entomologic associations.

Environmental, demographic, and entomologic variables were analyzed by logistic multiple regression analysis for their association with the likelihood of being seropositive for Trypanosoma cruzi in three highly infested rural villages of northwest Argentina. The prevalence of seropositivity for T. cruzi, as determined by the composite results of three serologic tests, was 34% among 338 persons in 1992. The strongest positive predictors of the adjusted odds of being infected were the household number of dogs, the density of T. cruzi-infected Triatoma infestans in bedroom areas, and each person's age. Dwellers from houses with roofs made completely or partly with a grass called simbol, or which used insecticides rudimentarily and nonsystematically, had a significantly lower odds of being seropositive for T. cruzi than residents from other types of dwellings. The adjusted odds of infection also increased with the number of T. cruzi-infected dogs or cats and the presence of chickens in bedroom areas. No significant effects on the adjusted odds of infection of a community-wide deltamethrin spraying carried out in one of the villages seven years before were detected. Socioeconomic indicators, such as domiciliary area, and numbers of corrals and livestock, were inversely related to being infected. Our study identified several manageable variables suitable for control actions, most of them not examined before in univariate or multivariate analyses. Environmental management based on low-cost housing with appropriate local materials and removal of domestic animals from domiciliary areas have a crucial role to play in the control of Chagas' disease in rural areas.

Factors limiting the domestic density of Triatoma infestans in north-west Argentina: a longitudinal study.

Reported are the environmental and demographic risk factors associated with the domestic infestation and density of Triatoma infestans in three heavily infested rural villages in Santiago del Estero Province, Argentina. In a one-factor unadjusted analysis, the number of T. infestans captured per person-hour was associated significantly and negatively with the use of domestic insecticides by householders, type of thatch used in the roofs and the age of the house; and positively with the following: degree of cracking of the indoor walls and presence of hens nesting indoors. In one model, using multiple linear regression and a backward stepwise elimination procedure, most of the variation in the overall abundance of T. infestans was explained by insecticide use and the presence of hens nesting indoors; in another model using the same procedure it was explained by insecticide use, bug density in 1988 and previous spraying with deltamethrin in 1985. Variations in bug density per capture stratum (household goods, beds, walls and roof) were explained by the bug density in other strata and by one or two of the following risk factors: hens nesting indoors, type of roof, presence of cracks in the walls and number of people living in the house. Bug density might be locally controlled by the availability of refuges in the roofs and walls, by the presence of hens nesting indoors and by the use of domestic insecticides. Certain local materials, such as a grass known as simbol, could be successfully used in rural housing improvement programmes aimed at reducing the availability of refuges for insects in the roof.

Influence of humans and domestic animals on the household prevalence of Trypanosoma cruzi in Triatoma infestans populations in northwest Argentina.

In three rural villages of northwest Argentina, the overall proportion of domiciliary Triatoma infestans infected with Trypanosoma cruzi was 49% among 1,316 bugs individually examined for infection in March and October 1992). Most of the variation among individual households in the proportion of infected triatomines was explained by variations among houses in the proportion of bugs that fed on dogs or cats, the prevalence of infected dogs or cats, and the proportion of bugs that fed on humans, according to a logistic multiple regression analysis. The effects of human infection rates on bug infection rates were not statistically significant. After adjusting for the effects of other predictors, the presence of chickens in bedroom areas had negative and significant effects on the proportion of infected Triatoma infestans, and positive and significant effects on the number of T. cruzi-infected triatomines collected per person-hr per house. Dog or cat infection rates and the proportion of bugs that fed on dogs or cats and on chickens explained 80% of the total variance of infected-bug numbers in a linear multiple regression model. This is the first study to use detailed field data to show that variations in triatomine infection rates depend on bug host feeding patterns and dog or cat infection rates, while the presence of chickens in bedroom areas exerts opposite effects on the proportion and number of infected triatomines. Domestic animals play a crucial role in the domiciliary transmission of T. cruzi.

Evaluation of dogs as sentinels of the transmission of Trypanosoma cruzi in a rural area of north-western Argentina.

Dogs, the main domestic reservoirs of Trypanosoma cruzi in the Argentine chaco, may be useful as sentinels of vector-mediated transmission of Trypanosoma cruzi in control programmes if canine infections acquired by all other routes could be excluded. In the present study, in the province of Santiago del Estero, Argentina, the dog populations in the neighbouring villages of Amamá, Trinidad, Mercedes, Villa Matilde and Pampa Pozo were studied immediately before spraying of residual insecticides (in 1992 in Amamá, Trinidad and Mercedes and 1993-1994 in the other villages) and twice during a subsequent programme of triatomine surveillance (in 1994 and 1996). Overall seropositivity for Trypanosoma cruzi infection (i.e. the proportion of dogs found positive by at least two different serological tests in any one survey) steadily declined from 65% (54/83) in 1992 to 39% (70/182) in 1994 and 15% (36/237) in 1996. No seroconversion was detected between the 1994 and 1996 surveys in any dog aged > 2 years. However, among the dogs aged < 2 years (which were born after virtual elimination of Triatoma infestans from the villages), seropositivity fell from 15% (12/81) in 1994 to 5% (6/131) in 1996. Thirteen demographic, behavioural and entomological variables were analysed by logistic multiple-regression analysis for their association with seropositivity in dogs born locally during the surveillance programme. The total number of Triatoma guasayana collected in the bedroom areas of the owner's house, having a mother which was seropositive for Trypanosoma cruzi, and the number of seropositive dogs with which it cohabited were all found to be significant predictors of seropositivity in any dog. The results are the first indication that Triatoma guasayana is the vector responsible for the new cases of Trypanosoma cruzi infection seen in dogs in domestic or peridomestic sites during the surveillance programme.

Factors that make difficult the implementation of an integrated leprosy control programme in health zone II, Santa Fe Province, Argentina.

With the help of a pre-tested, structured questionnaire and participatory observation, effects of several variables that have a bearing on the process of integration were studied in Zone II of the Santa Fe Province of Argentina. Patient's knowledge and the presence of an NGO were identified as factors facilitating integration. The presence of a vertical programme staff and insufficient commitment towards integration were identified as factors hindering integration.

The role of the peridomiciliary area in the elimination of Triatoma infestans from rural Argentine communities.

The purpose of this study was to identify the origin of Triatoma infestans reinfestation and study its dynamics following spraying with deltamethrin inside and around 94 houses in three rural communities in northwestern Argentina. The effectiveness of the spraying was evaluated immediately after the houses were sprayed and two months later. In addition, five residual peridomiciliary foci were found and sprayed, as well as three preexisting ones that had not been sprayed. To monitor reinfestation, biosensors were placed in the houses and each family was also asked to capture triatomines and keep them in plastic bags; in addition, triatomines were searched for in and around houses, using an aerosol that dislodged them from their hiding places. Selective sprayings were carried out only where a colony of T. infestans was found. During the 30 months of follow-up, the percentage of houses in which any T. infestans were captured varied between 3% and 9%. In six houses, T. infestans were captured during more than one evaluation. The number of peridomiciliary areas found to be infested (19) was double the number of infested houses (9). Colonies of T. infestans were found only in the peridomiciliary areas, where the number of T. infestans captured was six times higher than in the houses. Chickens were the host most frequently associated with peridomiciliary foci. This area was the origin and principal source of reinfestation. To reduce the speed of reinfestation and the frequency with which sprayings are needed, the following environmental and chemical control methods must be combined in the peridomiciliary area: reduce the number of hiding places of triatomines; restrict the raising of birds to structures that cannot be colonized by triatomines; apply an insecticide that is less likely to be degraded by exposure to the elements, or perform a second spraying 6 to 12 months after the first; and employ a device for early detection of the presence of T. infestans around houses.