Risk factors, representations and practices associated with emerging urban human visceral leishmaniasis in Posadas, Argentina.

INTRODUCTION: Visceral leishmaniasis is an often overlooked disease with high lethality rates about which there is need of additional local studies to inform the design of effective control strategies. The urbanization of its transmission has already been verified in America, with domestic dogs being the primary reservoirs and vectors of the disease. Socio-economic conditions, demographics and practices of domestic groups typically present in urban settings may play a specific role in the transmission of the infection, which is still poorly understood.  OBJECTIVE: To analyze the sociodemographic characteristics, risk factors and overall practices concerning prevention and coping strategies of visceral leishmaniasis, in both human beings and canines.  MATERIALS AND METHODS: This study utilized a cross-sectional case-control design. Cases were defined as a domestic group where the Public Health Ministry had at least one record of a member with human visceral leishmaniasis. Control cases were defined as a domestic group without a clinical record of the disease. The populations were characterized demographically and socially using primary information sources. Measures of household quality and a ranking of knowledge and attitudes towards visceral leishmaniasis were constructed, and practices associated with the presence, and the risk for canine visceral leishmaniasis were described.  RESULTS: Low household quality (p≤0.001), a member of the domestic group out of the household after 6:00 pm (OR=4.4; 95% CI: 1.69-12.18), the uncontrolled racial breeding of dogs (OR=15.7; 95% CI: 3.91-63.2), and the presence of infected dogs infected in the household (OR=120.3; 95% CI: 18.51-728.3) were variables positively associated with the risk of infection.  CONCLUSION: We observed certain social risk factors, primarily low household quality and overcrowding, associated with structural poverty that could increase human-vector contact probability. The most important risk factor for human visceral leishmaniasis was the possession of infected dogs in the household.

An rK28-Based Immunoenzymatic Assay for the Diagnosis of Canine Visceral Leishmaniasis in Latin America.

Direct observation of Leishmania parasites in tissue aspirates has shown low sensitivity for the detection of canine visceral leishmaniasis (VL). Therefore in the last quarter century immunoenzymatic tests have been developed to improve diagnosis. The purpose of this study was to develop a fast recombinant K28 antigen, naked-eye qualitative enzyme-linked immunosorbent assay (VL Ql-ELISA) and a quantitative version (VL Qt-ELISA), and to display it in a kit format, whose cutoff value (0.156) was selected as the most adequate one to differentiate reactive from nonreactive samples. Considering 167 cases and 300 controls, sensitivity was 91% for both assays and specificity was 100% and 98.7% in Ql-ELISA and Qt-ELISA, respectively. Positive predictive values were 100% and 97.4% for Ql-ELISA and Qt-ELISA, respectively, and negative predictive values were 95.2% for both ELISAs. Reagent stability, reliability studies, including periodic repetitions and retest of samples, cutoff selection, and comparison of rK28 ELISAs with rK39 immunochromatographic test, were the international criteria that supported the quality in both kits. The performance of both ELISA kits in this work confirmed their validity and emphasized their usefulness for low-to-medium complexity laboratories.

Factores de riesgo, representaciones y prácticas asociadas con la leishmaniasis visceral humana en un foco urbano emergente en Posadas, Argentina / Risk factors, representations and practices associated with emerging urban human visceral leishmaniasis in Posadas, Argentina

Introducción. La leishmaniasis visceral es una enfermedad desatendida de alta letalidad que amerita que se profundice en los estudios locales para diseñar estrategias efectivas de control. En América, su transmisión ya se ha evidenciado en las zonas urbanas, en donde el reservorio principal es el perro doméstico. Las condiciones socioeconómicas, así como las representaciones y las prácticas de los grupos domésticos podrían desempeñar un papel crucial y poco conocido en su transmisión. Objetivo. Analizar las representaciones y las prácticas de prevención y afrontamiento de la leishmaniasis visceral humana y canina, así como los factores socioeconómicos de riesgo. Materiales y métodos. Se hizo un estudio transversal de casos y controles. Se definió´caso´ como un grupo doméstico en el que, al menos, un integrante tuviera antecedentes de leishmaniasis visceral humana y hubiera sido notificado por el Ministerio de Salud Pública. El´control´ se definió como un grupo doméstico sin integrantes con antecedentes de la enfermedad. A partir de la información primaria, se caracterizó demográfica y socialmente a la población, se estableció la calidad de las viviendas, se hizo una clasificación de los conocimientos y las actitudes en torno a la enfermedad, y se describieron las prácticas asociadas al riesgo y la presencia de leishmaniasis visceral canina. Resultados. La mala calidad de la vivienda (p=0,001), las personas del grupo doméstico que permanecían fuera de esta después de las 18 horas (razón de momios, OR ( odds ratio) =4,5; IC 95% 1,69-12,18), la reproducción sin control de la raza canina (OR=15,7; IC 95% 3,91-63,2) y la presencia de leishmaniasis visceral canina en el domicilio (OR=120,3; IC 95% 18,51-728,3), se asociaron positivamente o incrementaron el riesgo de contraer leishmaniasis visceral humana. Conclusión. Se observó que la pobreza estructural constituía un factor social determinante del riesgo, y que aumentaba la probabilidad de contacto entre humanos y vectores por la mala calidad de la vivienda y el hacinamiento. El factor de riesgo más importante para la leishmaniasis visceral humana fue la tenencia en el domicilio de perros con la enfermedad.

Introduction: Visceral leishmaniasis is an often overlooked disease with high lethality rates about which there is need of additional local studies to inform the design of effective control strategies. The urbanization of its transmission has already been verified in America, with domestic dogs being the primary reservoirs and vectors of the disease. Socio-economic conditions, demographics and practices of domestic groups typically present in urban settings may play a specific role in the transmission of the infection, which is still poorly understood. Objective: To analyze the sociodemographic characteristics, risk factors and overall practices concerning prevention and coping strategies of visceral leishmaniasis, in both human beings and canines. Materials and methods: This study utilized a cross-sectional case-control design. Cases were defined as a domestic group where the Public Health Ministry had at least one record of a member with human visceral leishmaniasis. Control cases were defined as a domestic group without a clinical record of the disease. The populations were characterized demographically and socially using primary information sources. Measures of household quality and a ranking of knowledge and attitudes towards visceral leishmaniasis were constructed, and practices associated with the presence, and the risk for canine visceral leishmaniasis were described. Results: Low household quality (p=0.001), a member of the domestic group out of the household after 6:00 pm (OR=4.4; 95% CI: 1.69-12.18), the uncontrolled racial breeding of dogs (OR=15.7; 95% CI: 3.91-63.2), and the presence of infected dogs infected in the household (OR=120.3; 95% CI: 18.51-728.3) were variables positively associated with the risk of infection. Conclusion: We observed certain social risk factors, primarily low household quality and overcrowding, associated with structural poverty that could increase human-vector contact probability. The most important risk factor for human visceral leishmaniasis was the possession of infected dogs in the household.

A Novel Molecular Test to Diagnose Canine Visceral Leishmaniasis at the Point of Care.

Dogs are the principal reservoir hosts of zoonotic visceral leishmaniasis (VL) but current serological methods are not sensitive enough to detect all subclinically infected animals, which is crucial to VL control programs. Polymerase chain reaction (PCR) methods have greater sensitivity but require expensive equipment and trained personnel, impairing its implementation in endemic areas. We developed a diagnostic test that uses isothermal recombinase polymerase amplification (RPA) to detect Leishmania infantum. This method was coupled with lateral flow (LF) reading with the naked eye to be adapted as a point-of-care test. The L. infantum RPA-LF had an analytical sensitivity similar to real time-PCR, detecting DNA of 0.1 parasites spiked in dog blood, which was equivalent to 40 parasites/mL. There was no cross amplification with dog or human DNA or with Leishmania braziliensis, Leishmania amazonensis, or Trypanosoma cruzi. The test also amplified Leishmania donovani strains (N = 7). In a group of clinically normal dogs (N = 30), RPA-LF detected more subclinical infections than rK39 strip test, a standard serological method (50% versus 13.3% positivity, respectively; P = 0.005). Also, RPA-LF detected L. infantum in noninvasive mucosal samples of dogs with a sensitivity comparable to blood samples. This novel molecular test may have a positive impact in leishmaniasis control programs.

Cambio organizacional en el Estado Local como estrategia para enfrentar la emergencia de Leishmaniasis Visceral en la ciudad de Posada, Misiones: 2006-2011 / Organizational Change in Local State as a strategy to tackle the emergence of Visceral Leishmaniasis in the city of Posada, Misiones: 2006-2011

La problemática epidemiológica representada por la aparición de casos autóctonos de Leishmaniasis Visceral Humana (LVH) en la ciudad de Posadas/Provincia de Misiones - República Argentina, a partir de 2006 y el accionar de la Municipalidad de Posadas orientado a hacer frente a esa enfermedad emergente, demarca un contexto particular para intentar estudiar en profundidad lógicas organizativas y de gestión de las instituciones de salud a partir de un escenario de crisis. ¿Qué condiciones, desarrollo y resultados ha implicado la estrategia del sistema sanitario local (municipal) para enfrentar la emergencia en la población humana de una enfermedad parasitaria de carßcter endémica y de transmisión vectorial como el representado por la LV, por cierto, sin antecedentes para la ciudad?. ¿Cómo ha evolucionado esa respuesta a lo largo de los últimos seis a±os?. Frente a esas preguntas y problemas que formulamos, este documento apunta a presentar las respuestas elaboradas a partir de un estudio de tipo descriptivo cuanti-cualitativo y longitudinal cuya principal estrategia de producción de datos fue la colecta, sistematización y anßlisis de información primaria, y en menor medida, secundaria en el ßmbito del Estado local, particularmente de la Secretaría de Calidad de Vida de la Municipalidad de Posadas, ciudad capital de la provincia...

The epidemiological problem represented by the appearance of native cases of human Visceral Leishmaniasis (HVL) in the city of Posadas, Misiones Province - Argentine Republic since 2006 and the actions of the municipality of Posadas aimed to address this emerging disease, defines a particular context to try studying in depth the organizational logic and management of health institutions during a crisis scenario. What conditions, development and results have involved the strategy of the local (municipal) health system to confront the emergency in the human population of a parasitic disease of endemic characteristics and vector transmitted such as that of VL, certainly unprecedented for the city? How has that response evolved over the past six years? Faced with those questions and problems that we formulated, this document aims to provide answers elaborated from a qualitative, quantitative and longitudinal descriptive study whose main strategy of data production was the collection, systematization and analysis of primary data, and to a lesser extent, secondary in the realm of local State, particularly the Secretary of Quality of Life of Posadas municipality, capital city of the province...

Leishmaniasis visceral: contribución a su control mediante el fortalecimiento del diagnóstico del reservorio canino en Posadas, Misiones, Argentina / Visceral leishmaniasis: control contribution by strengthening the diagnosis of dog reservoir in the city of Posadas, Misiones, Argentina

INTRODUCCION: La leishmaniasis visceral (LV) es una enfermedad emergente en Argentina. En 2006 se describió el primer caso autóctono en Posadas (Misiones), ciudad que se convirtió en epicentro de la LV.OBJETIVO: Determinar la prevalencia de la LV canica (LVC) y fortalecer su diagnóstico en Posadas.METODOS: Con un criterio entomológico, la ciudad de Posadas se dividió en islas de alta densidad (IAD) e islas de baja densidad (IBD) de flebótomos. Se seleccionó, de forma arbitraria y mediante imágenes satelitales, la manzana situada más al norte y más al sur de cada IAD e IBD. Se realizó un diseño observacional prospectivo, y se estudió a todos los perros de las manzanas seleccionadas. Se consideró un N inicial de 400 animales para detectar una diferencia de al menos 7% con una potencia de 0,90 y un nivel de 0,05 respecto de la prevalencia global supuesta del 20%. Se tomaron muestras de sangre, punción de ganglios linfáticos y raspado de piel. El estudio incluyó además un test serológico rápido (rK39 canino) y frotis de las muestras para búsqueda parasitológica, que se procesaron y evaluaron en el Instituto Municipal de Salud Animal de Posadas y en el Instituto Nacional de Parasitología Fatala Chabén.RESULTADOS: De los 182 animales evaluados, 33 fueron positivos para LVC, con una prevalencia global del 18,1%. En IAD la prevalencia fue 22% y en IBD, 13,4%. Los estudios parasitológicos fueron positivos en el 10% de los caninos en IAD y 1,2% en IBD. La LVC fue asintomática u oligosintomática, con una presentación más frecuente en IAD. La rK39 tuvo una sensibilidad del 90,3% y una especificidad del 98,9%.CONCLUSIONES: El análisis serológico con antígeno rK39 fue siempre más sensible que la búsqueda parasitológica para el diagnóstico. La LVC parece tener menor prevalencia en relación con estudios previos, quizás debido a diferentes medidas de control realizadas en el Municipio de Posadas.

INTRODUCCION: Visceral leishmanisis (VL) is an emerging disease in Argentina. The first autochthonous case was described in 2006 in a chld from Posadas (Misiones), the city which turned out to be the focus of VL.OBJECTIVE: To determine the prevalence of canine VL (CVL) and improve its diagnosis in Posadas.METHODS: According to entomological criteria, Posadas was divided in high density islands (HDI) and low density islands (LDI) of sandfly. Randomly and with satellite images, the northernmost and southernmost blocks of each HDI and LDI were selected. A prospective, experimental design was performed, studying all the dogs in the selected blocks. There was an initial sample of 400 animals to detect a difference of at least 7%, with a power of 0.90 and a level of 0.05, compared to the supposed prevalence of 20%. Blood samples were taken, with puncture of lymph nodes and skin scraping. The study also included a (canine rK39) rapid test for serological assessment adn sample smears for parasitological search. Samples were processed and evaluated in the Posadas institute of animal health (I.MU.S.A) and the Fatala Chabén National Institute of Parasitology.RESULTS: CVL was assessed in 33/182 animals with an overall prevalence of 18.1%. In HDI, the prevalence was 22%; in LDI, it was 13.4%. Parasitological studies were positive in 10% (HDI) and 1.2% (LDI). The CVL had a nonspecific clinical presentation; canines were asimptomatic or oligosymptomatic, with a higher trend in HDI. The rK39 had a sensitivity of 90.3% and a specificity of 98.9%.CONCLUSIONS: The antigen rK39 was always more sensitive than the search for parasites for the diagnosis of CVL. The disease appears to be less prevalent comapring to previous studies, perhaps due to different control measures performed in the Municipality of Posadas.

Leishmaniasis visceral: contribución a su control mediante el fortalecimiento del diagnóstico del reservorio canino en Posadas, Misiones, Argentina / Visceral leishmaniasis: control contribution by strengthening the diagnosis of dog reservoir in the city of Posadas, Misiones, Argentina

INTRODUCCION: La leishmaniasis visceral (LV) es una enfermedad emergente en Argentina. En 2006 se describió el primer caso autóctono en Posadas (Misiones), ciudad que se convirtió en epicentro de la LV.OBJETIVO: Determinar la prevalencia de la LV canica (LVC) y fortalecer su diagnóstico en Posadas.METODOS: Con un criterio entomológico, la ciudad de Posadas se dividió en islas de alta densidad (IAD) e islas de baja densidad (IBD) de flebótomos. Se seleccionó, de forma arbitraria y mediante imágenes satelitales, la manzana situada más al norte y más al sur de cada IAD e IBD. Se realizó un diseño observacional prospectivo, y se estudió a todos los perros de las manzanas seleccionadas. Se consideró un N inicial de 400 animales para detectar una diferencia de al menos 7% con una potencia de 0,90 y un nivel de 0,05 respecto de la prevalencia global supuesta del 20%. Se tomaron muestras de sangre, punción de ganglios linfáticos y raspado de piel. El estudio incluyó además un test serológico rápido (rK39 canino) y frotis de las muestras para búsqueda parasitológica, que se procesaron y evaluaron en el Instituto Municipal de Salud Animal de Posadas y en el Instituto Nacional de Parasitología Fatala Chabén.RESULTADOS: De los 182 animales evaluados, 33 fueron positivos para LVC, con una prevalencia global del 18,1%. En IAD la prevalencia fue 22% y en IBD, 13,4%. Los estudios parasitológicos fueron positivos en el 10% de los caninos en IAD y 1,2% en IBD. La LVC fue asintomática u oligosintomática, con una presentación más frecuente en IAD. La rK39 tuvo una sensibilidad del 90,3% y una especificidad del 98,9%.CONCLUSIONES: El análisis serológico con antígeno rK39 fue siempre más sensible que la búsqueda parasitológica para el diagnóstico. La LVC parece tener menor prevalencia en relación con estudios previos, quizás debido a diferentes medidas de control realizadas en el Municipio de Posadas.

INTRODUCCION: Visceral leishmanisis (VL) is an emerging disease in Argentina. The first autochthonous case was described in 2006 in a chld from Posadas (Misiones), the city which turned out to be the focus of VL.OBJECTIVE: To determine the prevalence of canine VL (CVL) and improve its diagnosis in Posadas.METHODS: According to entomological criteria, Posadas was divided in high density islands (HDI) and low density islands (LDI) of sandfly. Randomly and with satellite images, the northernmost and southernmost blocks of each HDI and LDI were selected. A prospective, experimental design was performed, studying all the dogs in the selected blocks. There was an initial sample of 400 animals to detect a difference of at least 7%, with a power of 0.90 and a level of 0.05, compared to the supposed prevalence of 20%. Blood samples were taken, with puncture of lymph nodes and skin scraping. The study also included a (canine rK39) rapid test for serological assessment adn sample smears for parasitological search. Samples were processed and evaluated in the Posadas institute of animal health (I.MU.S.A) and the Fatala Chabén National Institute of Parasitology.RESULTS: CVL was assessed in 33/182 animals with an overall prevalence of 18.1%. In HDI, the prevalence was 22%; in LDI, it was 13.4%. Parasitological studies were positive in 10% (HDI) and 1.2% (LDI). The CVL had a nonspecific clinical presentation; canines were asimptomatic or oligosymptomatic, with a higher trend in HDI. The rK39 had a sensitivity of 90.3% and a specificity of 98.9%.CONCLUSIONS: The antigen rK39 was always more sensitive than the search for parasites for the diagnosis of CVL. The disease appears to be less prevalent comapring to previous studies, perhaps due to different control measures performed in the Municipality of Posadas.

Lutzomyia longipalpis behavior and control at an urban visceral leishmaniasis focus in Argentina / Comportamento e controle de Lutzomyia longipalpis em foco de leishmaniose visceral urbana na Argentina

During the earlier stages of visceral leishmaniasis transmission in Posadas City, Misiones, both the night activity and attraction to humans of Lutzomyia longipalpis were assessed, in order to provide preliminary recommendations. The impact of peridomestic deltamethrin spraying performed by local officials was also evaluated. Although Lu. longipalpis were found in traps located over a dog the entire night, 90 percent of the females were captured from 20.30h to 1.30h, and only landed on a human when he was at a distance of 1.5 m from the dog. Peridomestic spraying of deltamethrin (25 mg/m²) reduced the sand fly capture up to seven days post-intervention without dispersion in the border of the sprayed areas. These results support the recommendations about time-space focus of the protection measures: first half of the night, in the backyard, with pets and domestic animals kept at least 5 m from humans. The deltamethrin as it was used did not seem very effective in this scenario; neither did the eventual use of bed nets, at least in adults, due to the place/hour of sand fly higher activity. This study strengthens the need for a multidisciplinary approach to develop prevention strategies based both on biological and anthropological studies.

Durante os estádios precoces de transmissão da leishmaniose visceral na cidade de Posadas, Misiones, foi avaliada a atividade noturna da Lutzomyia longipalpis e a atração pelos seres humanos, para fornecer recomendações preliminares. O impacto do inseticida deltametrina peridoméstico, e a borrifação executada por funcionários locais, também foi avaliada. Embora existam Lu. longipalpis atingindo as armadilhas localizadas perto de um cão durante toda a noite, 90 por cento das fêmeas foram capturadas a partir das 20.30h até 1.30h, e só atinge seres humanos quando estão a 1,5 m do cão. A borrifação peridoméstica com deltametrina (25 mg/m²) reduziu a área de captura da mosca da areia, até sete dias após a intervenção, sem dispersão nas bordas das áreas pulverizadas. Estes resultados apóiam as recomendações sobre o tempo-espaço, das medidas de proteção: na primeira metade da noite, no quintal, com animais de estimação criados pelo menos a cinco metros de distância dos seres humanos. A deltametrina como ela é usada, não parece muito eficaz neste cenário, nem o eventual uso de mosquiteiros pelo menos em adultos, devido ao lugar/hora de mais alta atividade de vôo da Lu. longipalpis. Este estudo acentua a necessidade de abordagem multidisciplinar, para desenvolver estratégias de prevenção baseadas tanto em estudos biológicos como antropológicos.

Lutzomyia longipalpis behavior and control at an urban visceral leishmaniasis focus in Argentina.

During the earlier stages of visceral leishmaniasis transmission in Posadas City, Misiones, both the night activity and attraction to humans of Lutzomyia longipalpis were assessed, in order to provide preliminary recommendations. The impact of peridomestic deltamethrin spraying performed by local officials was also evaluated. Although Lu. longipalpis were found in traps located over a dog the entire night, 90% of the females were captured from 20.30h to 1.30h, and only landed on a human when he was at a distance of 1.5 m from the dog. Peridomestic spraying of deltamethrin (25 mg/m²) reduced the sand fly capture up to seven days post-intervention without dispersion in the border of the sprayed areas. These results support the recommendations about time-space focus of the protection measures: first half of the night, in the backyard, with pets and domestic animals kept at least 5 m from humans. The deltamethrin as it was used did not seem very effective in this scenario; neither did the eventual use of bed nets, at least in adults, due to the place/hour of sand fly higher activity. This study strengthens the need for a multidisciplinary approach to develop prevention strategies based both on biological and anthropological studies.