ABSTRACT
We assessed whether fluralaner administered to outbred healthy dogs reduced or supressed site infestation and abundance of pyrethroid-resistant populations of Triatoma infestans Klug (Heteroptera: Reduviidae). We conducted a placebo-controlled before-and-after efficacy trial in 28 infested sites in Castelli (Argentine Chaco) over 10 months. All 72 dogs initially present received either an oral dose of fluralaner (treated group) or placebo (control group) at month 0 posttreatment (MPT). Preliminary results justified treating all 38 control-house dogs with fluralaner 1 month later, and 71 of 78 existing dogs at 7 MPT. Site-level infestation and triatomine abundance were evaluated using timed manual searches with a dislodging aerosol. In the fluralaner-treated group, infestation dropped significantly from 100% at baseline to 19% over 6-10 MPT whereas mean abundance fell highly significantly from 5.5 to 0.8-0.9 triatomines per unit effort. In the placebo group, site infestation and mean abundance remained stable between 0 and 1 MPT, and strongly declined after fluralaner administration from 13.0-14.7 - triatomines at 0-1 MPT to 4.0-4.2 over 6-10 MPT. Only one of 81 noninfested sites before fluralaner treatment became infested subsequently. Fluralaner significantly reduced the site-level infestation and abundance of pyrethroid-resistant T. infestans and should be tested more widely in Phase III efficacy trials.
Subject(s)
Pyrethrins , Insecticide Resistance , Chagas Disease , Vector Control of Diseases , IsoxazolesABSTRACT
Triatoma infestans, the main vector in the Gran Chaco region, may competitively displace other sympatric species such as Triatoma sordida. We conducted a three-year longitudinal study of site- and house-level infestation and abundance of triatomine bugs before and after an area-wide insecticide spraying campaign followed by sustained vector surveillance in a well-defined rural section of the Argentine Chaco encompassing 368411 houses. Here, we tested whether insecticide applications targeting and virtually suppressing T. infestans reduced the abundance of T. sordida and modified its habitat occupancies, and whether their joint spatial distribution was random, aggregated or uniform, and varied over time. Systematic timed-manual searches of 18,031 sites yielded 2,226 T. sordida over seven postintervention surveys. Triatoma sordida failed to colonize human sleeping quarters after interventions, and its prime and secondary habitats remained virtually unmodified. Residual insecticide spraying and seasonality best described variations in the house-level abundance of T. sordida as determined using a generalized estimating equation model. Two-species foci occurred in 3.2% of sites ever positive for any species. The habitat-adjusted relative odds of catching one species was 10.8 times greater when the other species was present, with no evidence of heterogeneity among ORs, suggesting no antagonistic interactions throughout the follow-up. The spatial occurrence of both species was significantly aggregated within 300500â¯m before and after interventions, and was random at broader spatial scales. The habitat occupancies of T. sordida may be used as a proxy for potential infestation with T. infestans and to guide targeted vector control actions.
ABSTRACT
Peri-urban infestations with triatomine bugs, their sources and their dynamics have rarely been investigated. Here, we corroborated the reported occurrence of Triatoma infestans in a peri-urban area and in neighbouring rural houses in Pampa del Indio, in the Argentine Chaco, and identified its putative sources using spatial analysis and demographic questionnaires. Peri-urban householders reported that 10% of their premises had triatomines, whereas T. infestans was collected by timed manual searches or community-based surveillance in only nine (3%) houses. Trypanosoma cruzi-infected T. infestans and Triatoma sordida were collected indoors only in peri-urban houses and were infected with TcV and TcI, respectively. The triatomines fed on chickens, cats and humans. Peri-urban infestations were most frequent in a squatter settlement and particularly within the recently built mud houses of rural immigrants, with large-sized households, more dogs and cats and more crowding. Several of the observed infestations were most likely associated with passive bug transport from other sources and with active bug dispersal from neighbouring foci. Thus, the households in the squatter settlement were at a greater risk of bug invasion and colonisation. In sum, the incipient process of domestic colonisation and transmission, along with persistent rural-to-urban migratory flows and unplanned urbanisation, indicate the need for active vector surveillance and control actions at the peri-urban interface of the Gran Chaco.
Subject(s)
Animals , Cats , Dogs , Humans , Chagas Disease/prevention & control , Endemic Diseases/statistics & numerical data , Insect Vectors/physiology , Suburban Population/statistics & numerical data , Triatoma/parasitology , Argentina , Crowding , Chagas Disease/epidemiology , Chickens/parasitology , Disease Notification/statistics & numerical data , Emigration and Immigration/statistics & numerical data , Family Characteristics , Feeding Behavior/physiology , Housing , Insect Control/statistics & numerical data , Multivariate Analysis , Rural Population/statistics & numerical data , Socioeconomic Factors , Surveys and Questionnaires , Triatoma/physiology , Trypanosoma cruzi/parasitologyABSTRACT
Certifying the absence of Chagas disease transmission by native vectors lacks scientific grounds and weakens long-term control-surveillance systems to the detriment of people living under risk conditions. Instead, a regular "certification of good practice" (including vector control-surveillance, case detection/patient care and blood safety) could help achieve sustained disease control.
Subject(s)
Animals , Humans , Certification , Chagas Disease/prevention & control , Insect Control/standards , Insect Vectors , Triatominae , Latin America , Pan American Health Organization , Population Surveillance , World Health OrganizationABSTRACT
Sustainability has become a focal point of the international agenda. At the heart of its range of distribution in the Gran Chaco Region, the elimination of Triatoma infestans has failed, even in areas subject to intensive professional vector control efforts. Chagas disease control programs traditionally have been composed of two divorced entities: a vector control program in charge of routine field operations (bug detection and insecticide spraying) and a disease control program in charge of screening blood donors, diagnosis, etiologic treatment and providing medical care to chronic patients. The challenge of sustainable suppression of bug infestation and Trypanosoma cruzi transmission can be met through integrated disease management, in which vector control is combined with active case detection and treatment to increase impact, cost-effectiveness and public acceptance in resource-limited settings. Multi-stakeholder involvement may add sustainability and resilience to the surveillance system. Chagas vector control and disease management must remain a regional effort within the frame of sustainable development rather than being viewed exclusively as a matter of health pertinent to the health sector. Sustained and continuous coordination between governments, agencies, control programs, academia and the affected communities is critical.
Subject(s)
Animals , Humans , Chagas Disease/prevention & control , Insect Vectors , Insect Control/methods , National Health Programs , Triatominae , Argentina , Chagas Disease/transmissionABSTRACT
We assessed the distribution of Trypanosoma cruzi infection in peridomestic triatomines collected manually at a district-wide scale in rural villages around Olta, Western Argentina, and typed the isolated strains according to their pathogenicity to laboratory mice. Of 1623 triatomines examined, only 14 (0.9 percent) were infected with T. cruzi based on microscopical examination of feces. The prevalence of T. cruzi infection was 0.8 percent in Triatoma infestans, 2.3 percent in T. guasayana, and nil in T. garciabesi, T. platensis, and T. eratyrusiformis. Local transmission occurred in kitchens, store-rooms and goat corrals or nearby, though at very low levels. T. cruzi was detected by at least one parasitological method in 11 (79 percent) of 14 microscope-positive bugs. Hemoculture was the most sensitive method (67 percent) followed by culture of organ homogenates, histopathology or xenodiagnosis of inoculated suckling mice (55-58 percent), and culture of microscope-positive bug feces (46 percent). The evidence suggests that most of the isolated T. cruzi strains would be myotropic type III. Our study establishes for the first time that peridomestic, microscope-positive T. guasayana nymphs were actually infected with T. cruzi, and may be implicated as a putative secondary vector of T. cruzi in domestic or peridomestic sites.
Subject(s)
Animals , Mice , Chagas Disease/veterinary , Insect Vectors/parasitology , Triatoma/parasitology , Trypanosoma cruzi/isolation & purification , Argentina , Chagas Disease/parasitology , Chagas Disease/pathology , Feces/parasitology , Insect Vectors/classification , Rural Population , Triatoma/classificationSubject(s)
Humans , Psychodidae , Chagas Disease/epidemiology , Argentina , Environmental Hazards , Risk AssessmentABSTRACT
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 per cent in 664 T. infestans, 0,7 per cent in 268 T.guasayana, and 0.2 per cent 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 per cent to 1.5 per cent 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 per cent to 4.6 per cent in bedrooms, as well as a fall from 6 per cent to 1.8 per cent 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 abundat species, but it was strongly associated with chickens and showed little tendency to invade bedrooms
Durante los cinco años posteriores a una fumigación masiva con deltametrina realizada en 1992 y seguida de fumigaciones selectivas, se investigó la prevalencia de la infección por Trypanosoma cruzi en Triatoma infestans, Triatoma guasayana y Triatoma sordida en Amamá y otras poblaciones rurales vecinas del noroeste de Argentina. Los triatómidos fueron recogidos en los domicilios y en el área peridoméstica por los propios residentes y por personal experto. Durante el quinquenio 19931997, la prevalencia de T. cruzi fue de 2,4% en 664 T. infestans, de 0,7% en 268 T. guasayana y de 0,2% en 832 T. sordida. La infección por T. cruzi se detectó con mayor frecuencia en las chinches adultas y en los triatómidos recogidos en los domicilios. T. guasayana y T. sordida fueron, respectivamente, ninfas y adultos recogidos en el área peridoméstica. Durante el período de vigilancia, la prevalencia de la infección por T. cruzi en T. infestans disminuyó de 7,7% en 1993 a 1,5% en 1997, aunque este cambio no fue estadísticamente significativo. La comparación de las tasas de infección de T. infestans antes del programa de control (1992) y durante el período de vigilancia (19931997) reveló una disminución altamente significativa, de 49% a 4,6%, en los dormitorios y también en las áreas peridomésticas (de 6% a 1,8%). Debido a su infección por T. cruzi y a su frecuente invasión de las áreas domésticas con ataques a los humanos y a los perros, T. guasayana parecía estar implicado como vector secundario de T. cruzi en las áreas domésticas y peridomésticas durante el período de vigilancia. T. sordida fue la especie más abundante, pero estaba estrechamente asociada a los pollos y mostró escasa tendencia a invadir los dormitorios
Subject(s)
Animals , Triatoma , Chagas Disease , Efficiency, Organizational , Pest Control, Biological , ArgentinaABSTRACT
We tested experimentally the effects of the presence of non-susceptible hosts on the infectin with Trypanosoma cruzi of the vector Triatoma infestans. The experiment consisted in two treatments: with chickens, including two chickens (non-susceptible hosts) and two infected guinea pigs (susceptible hosts), and without chickens, including only two infected guinea pigs. The hosts were held unrestrained in individual metal cages inside a closed tulle chamber. A total of 200 uninfected T. infestand third instar nymphs were liberated in each replica, collected on day 14, and examined for infection and blood meal sources on day 32-36. The additional presence of chickens relative to infected guinea pigs: (a) significantly modified the spatial distribution of bugs; (b) increased significantly the likelihoods of having a detectable blood meal on any host and molting to the next instar; (c) did not affect the bugs ' probability of death by predation; and (d) decreased significantly the overall percentage of T. infestand infected with T. cruzi. The bugs collected from inside or close to the guinea pigs ' cages showed a higher infection rate (71-88 por cento) than those collected from the chickens ' cages (22-32 por cento). Mixed blood meals on chickens and guinea pigs were detedted in 12-21 por cento of bugs. Although the presence of chickens would decrease the overall percentage of infected bugs in short term experiments, the high rate of host change of T. infestans would make this difference fade out if longer exposure times had been provided.
Subject(s)
Animals , Chagas Disease/prevention & control , Clinical Trial , Guinea Pigs/parasitology , Triatoma/parasitology , Triatominae/parasitology , Trypanosoma cruzi , Behavior, Animal , Chickens , Insect VectorsABSTRACT
Las campañas de control de Triatoma infestans, el principal vector del Trypanosoma cruzi, se han basada solamente en el uso de insecticidas con poder residual y concibieron al sistema como homogéneo. La reinfestación generalmente se inicia en focos residuales peridomiciliarios o en focos pro-existentes que escapan al rociado por diversas causas. Desde estos focos los adultos de T. infestans activamente invaden otros sitios, o son transportados pasivamente en objetos o productos desde comunidades infestadas. En ausencia de rociados adicionales luego de la fase de ataque, la reinfestación domiciliaria se expandió exponencialmente para retornar a sus niveles pre-rociado en 3-4 años en Amamá, Santiago del Estero. Sin embargo, la tasa de recuperación de la abundancia de T. infestans fue mucho menor que la predicha por un simple modelo matemático. La reinfestación no avanzó homogéneamente dentro de la comunidad. Dos estudios longitudinales en Santiago del Estero revelaron que la presencia de un peridomicilio infestado por T. infestans aumentó el riesgo de reinfestación del domicilio respectivo. Los sitios "clave" donde la reinfestación se inició tempranamente fueron los corrales de cabras u ovejas, los corrales de cerdos, los gallineros, y los depósitos. La reinfestación del peridomicilio problamente sea el resultado de múltiples factores, tales como la degradación del insecticida por los agentes climáticos, y la mayor superficie y disponibilidad de refugios y hospedadores que cuenta el peridomicilio respecto al domicilio. Dicha heterogeneidad ambiental genera heterogeneidad de efectos de los insecticidas y aumenta la probabilidad de persistencia de T. infestans aún bajo control químico. Varios estudios muestran que la vigilancia sostenida luego de la fase de ataque disminuye abruptamente la colonización domiciliaria y el porcentaje de T. infestans infectados por T. cruzi, e interrumpe la aparición de nuevos casos locales de niños infectados. La eliminación sostenida de T. infestans requiere un enfoque que no se centre sólo en los insecticidas sino que incluya al ambiente y los pobladores en su escenario político y social.
Subject(s)
Humans , Animals , Insect Control/methods , Triatoma , Argentina , Population Surveillance/methods , Rural PopulationABSTRACT
La transmisión vertical de Trypanosoma cruzi ha ido aumentado su importancia relativa a medida que la transmisión vectorial y transfusional han sido y son crecientemente controladas. La transmisión vertical de T. cruzi no puede ser prevenida, pero el diagnóstico y tratamiento oportuno de la infección congénita alcanza curas cercanas al 100 por ciento. En la Argentina, el Subprograma de Control de la Mujer Embarazada estudió 58 196 mujeres de 13 provincias en 1997 y halló un 9 pro ciento con seropositividad a T. cruzi. A pesar de tan altas tasas de prevalencia maternal por T. cruzi, sólo una pequeña proporción de los recién nacidos vivos de madre infectada contrae la infección. La probabilidad de transmisión vertical fue del 1.9 por ciento (rango: 0.1 por ciento al 3.5 por ciento) en estudios realizados en los '70, y del 2.5 por ciento (rango: 0.7 por ciento al 10.4 por ciento) en otros realizados en los '70-'80. Otros estudios recientes en Argetina estimaron la probabilidad de transmisión en 2.6 por ciento - 6.7 por ciento, pero estudios en Paraguay llegaron a estimar un 10.5 por ciento por PCR o serodiagnóstico. La técnica del microhematocrito es el método parasitológico de elección para el diagnóstico de la infección congénita. El serodiagnóstico rutinario que detecta IgG contra T. cruzi sólo es útil luego de los 6 meses de edad del bebé. La detección de IgM específica mediante antígenos recombinantes y el PCR constituyen excelentes alternativas, pero resta considerar su factibilidad desde un punto de vista operacional y de costo-efectividad en las áreas endémicas afectadas. En un proyecto piloto realizado en la Maternidad Nuestra Señora de la Merced en la ciudad de Tucumán entre 1992-1994, la mayoría de los casos congénitos fueron asintomáticos y se los diagnosticó mediante el microhematocrito, pero hubo un número de casos que sólo pudieron ser detectados más tardiamente como producto del seguimiento parasitológico y/o serológico. De un total de 32 niños infectados por T. cruzi tratados con nifurtimox o benznidazol, 30 negativizaron su microhematocrito y serodiagnóstico entre 6 meses y 2 años post-tratamiento. La magnitud de la transmisión congénita, y la morbilidad y mortalidad asociada a ella, justifican con creces el esfuerzo necesario para detectar la infección por T. cruzi en las madres y sus bebés....
Subject(s)
Humans , Female , Pregnancy , Infant, Newborn , Infant , Child, Preschool , Chagas Disease/congenital , Chagas Disease/prevention & control , Communicable Disease Control , Argentina , Chagas Disease/transmission , Infectious Disease Transmission, VerticalABSTRACT
El objetivo del estudio fue identificar el origen y estudiar la dinámica de la reinfestación por Triatoma infestans ocurrida después de rociar con deltametrina el domicilio y peridomicilio de 94 casas de tres comunidades rurales el noroeste argentino. La efectividad del rociamiento se evaluó inmediatamente después y al segundo mes de rociar las viviendas. Además, se detectaron y rociaron 5 focos residuales peridomiciliarios y 3 preexistentes que no habían sido rociados. Para monitorizar la reinfestación, se colocaron biosensores en los domicilios, se solicitó a cada familia que capturase triatominos y los guardara en bolsas de plástico, y se buscaron triatominos en domicilios y peridomicilios usando un aerosol para desalojar a los insectos de sus refugios. Solo se realizaron rociamientos selectivos donde se encontró alguna colonia de T. infestans. Durante 30 meses de seguimiento, el porcentaje de casas donde se capturó algún T. infestans osciló entre 3% y 9%. En 6 casas se capturaron T. infestans en más de una evaluación. El número de peridomicilios infestados (19) fue el doble que el de domicilios (9). Solo se detectaron colonias de T. infestans en peridomicilios. La cifra de T. infestans capturados en peridomicilios fue seis veces más alta que la de los domicilios. Las gallinas fueron el hospedador más frecuentemente asociado con los focos peridomiciliarios. El peridomicilio constituyó el origen y la principal fuente de reinfestación. Para reducir la velocidad de reinfestación y la frecuencia de rociamientos es preciso combinar medidas de manejo ambiental y control químico en los peridomicilios: reducir los refugios para triatominos; restringir la cría de aves a estructuras no colonizables por triatominos; aplicar un insecticida menos degradable por agentes climáticos o realizar un segundo rociamiento de 6 a 12 meses después del primero, y emplear un dispositivo para detectar tempranamente la presencia de T. infestans en peridomicilios
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.
Subject(s)
Triatoma/parasitology , Pest Control , Fumigation/statistics & numerical data , Argentina , Evaluation of Results of Preventive Actions/methodsABSTRACT
Flight activity and invasion of houses by Triatoma sordida and T. guasayana were studied in the Province of Santiago del Estero, Argentina. Spontaneous findings of both species in houses were recorded from 1982 to 1989. Light trap collections were performed in 1982, 1983 and 1984, at the woods surrounding the settlements of Amamá (43 houses) and Trinidad (19 houses). Most of the 101 triatomines collected, were unfed and negative for Trypanosoma cruzi. T. guasayana predominated over T. sordida, and both appeared on the lighted screens between 19-31 min (mean 24) after dusk and the catch time was 30-45 min. Although entomological evaluation of 41 houses at Amamá performed in September 1985, just before insecticidal spraying, showed that Triatoma infestans predominated, adults of T. guasayana were collected in sleeping places, in 7 houses (17%). Most triatomines invading houses from then up to 1990 were flying T. guasayana (20/27) and females outnumbered males. Three non infected T. guasayana females were fed on man and two T. guasayana males positive for "T. cruzi like" trypanosomes were unfed. Therefore, visiting hungry adults could transmit T. cruzi to people and introduce wild parasites to the domestic cycle. T. guasayana stands as the main potential substitute of T. infestans in the studied area, and it might play there the same role as T. sordida in Brazil
Subject(s)
Humans , Triatoma/parasitology , Trypanosoma cruzi , ArgentinaSubject(s)
Dogs , Animals , Male , Female , Perianal Glands/parasitology , Trypanosoma cruzi/isolation & purificationABSTRACT
cross-sectional survey of 20 households was conducted at Amama (Santiago del Estero Province, Argentina), an área where active Trypanosoma cruzi transmission was occurring and where no official insecticide applications agains Chagas' disease vector had been made. The survey sought to collect data on the numbers of Triatoma infestans vectors present, the intensity of T. cruzi transmission to dogs and children, and relationships between the presence of infected household dogs and T. cruzi infection among children. Bugs were collected with forceps and flashlights by two-man teams and later by spraying the walls and roofs of the study houses with a synthetic pyrethrin solution. Blood samples, obtained from all members of each study household and from household pets, were tested serologically for T. cruzi; in addition, study subjects were tested for T. Cruzi by xenodiagnosis. The bug collection effort found relatively few Tr. infectans (less than 15 per house) in about a quarter of the study households, and relatively high densities (over 50 bugs) in all but one of the rest. Similarly, less than 16 T. cruzi infected vectors were found in six study homes, while most of the rest yielded at least 40. Statistically significant differences were found between the T, cruzi infection rates of both children and dogs in low-risk and high-risk settings. Examination of the collected information also suggests
Subject(s)
Pest Control , Triatoma , Trypanosoma cruzi , Argentina , Rural PopulationABSTRACT
Foi realizada em 1984 uma nova pesquisa epidemiológica dos cäes domésticos e seguimento dos indivíduos que apresentaram parasitemia dois anos antes a fim de compreender a relaçäo entre a parasitemia e a idade dos cäes, empregando para isso técnicas sorológicas e xenodiagnóstico. A persistência da parasitemia foi independente ou pouco relacionada à idade, confirmando assim o padräo observado em 1982. Da mesma maneira, nos cäes soropositivos näo se registrou nenhuma diminuiçäo significativa com respeito a idade em: a) a probabilidade de descobrir parasitas por meio de um seguimento durante 2 anos; b) sua capacidade de infecçäo para a ninfas de 3ª e 4ª fase de T. infestans, medido pela porcentagem de barbeiros infectados que se observou em cada um dos xenodiagnósticos dos cäes. A capacidade infectante dos cäes soropositivos foi aproximadamente constante ao longo da vida, e significativamente maior que a registrada para as crianças no presente estudo, e para os agrupamentos humanos pesquisados por outros investigadores. Assim sendo e considerando as altas freqüências de alimentaçäo no cäo que säo observados nas populaçöes pelo T. infestans, espera-se que o cäo contribua para o total de barbeiros infectados existentes nas áreas rurais da Argentina. Esta característica deveria ser suficiente para incriminar definitivamente os reservatórios caninos como um fator de risco para as pessoas residentes na mesma casa. A alta intensidade da parasitemia registrada entre os cäes na presente pesquisa poderia estar relacionada com a acentuada desnutriçäo característica dos cäes nas áreas rurais pobres da Argentina, o que poderia afetar a capacidade do hospedeiro para controlar a infecçäo
Subject(s)
Dogs , Animals , Chagas Disease/transmission , Dog Diseases/parasitology , Trypanosoma cruzi/parasitology , ArgentinaABSTRACT
Levou-se a cabo numa área rural da Argentina uma pesquisa epidemiológica dos cäes associados ao domicílio, com vistas a caracterizar sua dinâmica populacional as infecçöes naturais pelo T. cruzi empregando técnicas sorológicas e xenodiagnóstico. A estruturas de idades da populaçäo mostrou que os indivíduos participam no ciclo doméstico da transmissäo uma média de 4 anos; a proporçäo de sexos por grupos etários sugeriu uma mortalidade diferencial para as fêmeas. especialmente nas cadelas. Achou-se uma prevalência geral de infecçäo de 84%, crescendo desde 69% em cäes 1 ano até 100% nos maiores de 3 anos, indicando alta eficiência de transmissäo do T. cruzi aos cäes na qual a infecçäo congênita ou pelo leite pode estar implicada. A sorologia mostrou concordancia de 98% com os xenodiagnósticos positivos. A parasitemia näo diminuiu com a idade em cäes seropositivos <- 10 anos. Ao menos os 50% dos reservatórios achavam-se estreitamente associados as moradas da gente. A estreita associaçäo trófica entre os cäes e T. infestans; a persistência da parasitemia nos reservatórios; a alta eficiência de transmissäo do parasito a este; padröes de exposiçäo do hospedeiro adequados; e altas taxas de recrutamento de indivíduos suscetíveis qualificam o cäo como hospedeiro amplificador da doença de Chagas nas áreas rurais do centro e norte da Argentina. Os programas rurais de atençäo primária da saúde vieram estimular a introduçäo de medidas dirigidas a diminuir o contacto cäo-barbeiro para ser executadas em concexäo à luta química contra os vetores na Argentina
Subject(s)
Dogs , Animals , Male , Female , Chagas Disease/veterinary , Disease Reservoirs , Dog Diseases/parasitology , Argentina , Chagas Disease/diagnosis , Chagas Disease/transmission , Serologic TestsABSTRACT
Foi determinada a prevalência da infecçäo por T. cruzi nos humanos, cäes e gatos, pertencentes a 47 rancherías em três povoados rurais; Guanaco Muerto (Córdoba). La Invernada e Amamás (Santiago del Estero), mediante reaçöes serológicas e xenodiagnóstico. Foram examinadas 245 pessoas, 123 cäes e 14 gatos. A taxa de prevalência na populaçäo foi entre 58,7% (GM) e 49,6% (LI). Foram detectados 76% de cäes infectados, o que resultou significativamente superior aos 51% encontrados nos humanos. As porcentagens de cäes (64,2%) e gatos (63,6%) com parasitemia foram significativamente superiores à correspondente aos humanos (12,5%). Se bem que 79% dos gatos estavam infectados, sua pequena quantidade e seus hábitos de perambulaçäo determinam que sua participaçäo na transmissäo doméstica do T. cruzi seja restrita. Näo obstante existir em média um maior número de humanos que de cäes em cada lar, tanto de sujeitos säos como infectados (6,5 vs. 3,3 e 3,4 vs. 2,4, respectivamente), foram detectados - também na média - mais cäes que humanos com parasitemia em cada casa (2,1 vs 1,0). As altas porcentagens de cäes infectados e com parasitemia, além do hábito de repouso intra-domiciliário - o qual ocasiona estreito contacto entre eles e os barbeiros - determinam que os cäes sejam os principais provedores de parasitos à disposiçäo para a transmissäo, e os hospedeiros mais importantes para manutençäo da doença de Chagas na Regiäo do Chago Argentino