Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use.

BACKGROUND: Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE: To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS: A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS: Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS: Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.

Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use

BACKGROUND Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.

Experimental hut to study the indoor behaviour and effects of insecticide-treated bednets on phlebotomine sand flies (Diptera: Psychodidae).

INTRODUCTION: Behavioural effects of insecticides on endophagic phlebotomine sand fly vectors of Leishmania are poorly understood mainly because of the lack of an experimental hut (EH) in which to study them. OBJECTIVE: To build an EH to evaluate the effects of long-lasting insecticide-treated nets (LLINs) on Lutzomyia longiflocosa. METHODS: The study had two phases: (1) Laboratory experiments using tunnel tests to select the traps for the EH; and (2) EH construction and evaluation of the effects of deltamethrin and lambda-cyhalothrin LLINs on L. longiflocosa females inside the EH. FINDINGS: Phase 1: The horizontal-slit trap was the best trap. This trap collected the highest percentage of sand flies, and prevented them from escaping. Therefore, this trap was used in the EH. Phase 2: The main effects of LLINs on L. longiflocosa in the EH were: landing inhibition, inhibition from entering the bednet, induced exophily, and high mortality (total and inside exit traps). CONCLUSIONS: The EH was effective for evaluating the effects of LLINs on endophagic sand flies. Although both types of LLINs showed high efficacy, the lambda-cyhalothrin-treated LLIN performed better. This is the first report of induced exophily in sand flies.

Experimental hut to study the indoor behaviour and effects of insecticide-treated bednets on phlebotomine sand flies (Diptera: Psychodidae)

BACKGROUND Behavioural effects of insecticides on endophagic phlebotomine sand fly vectors of Leishmania are poorly understood mainly because of the lack of an experimental hut (EH) in which to study them. OBJECTIVE To build an EH to evaluate the effects of long-lasting insecticide-treated nets (LLINs) on Lutzomyia longiflocosa. METHODS The study had two phases: (1) Laboratory experiments using tunnel tests to select the traps for the EH; and (2) EH construction and evaluation of the effects of deltamethrin and lambda-cyhalothrin LLINs on L. longiflocosa females inside the EH. FINDINGS Phase 1: The horizontal-slit trap was the best trap. This trap collected the highest percentage of sand flies, and prevented them from escaping. Therefore, this trap was used in the EH. Phase 2: The main effects of LLINs on L. longiflocosa in the EH were: landing inhibition, inhibition from entering the bednet, induced exophily, and high mortality (total and inside exit traps). CONCLUSIONS The EH was effective for evaluating the effects of LLINs on endophagic sand flies. Although both types of LLINs showed high efficacy, the lambda-cyhalothrin-treated LLIN performed better. This is the first report of induced exophily in sand flies.

Entering and exiting behaviour of the phlebotomine sand fly Lutzomyia longiflocosa (Diptera: Psychodidae) in rural houses of the sub-Andean region of Colombia

The present study identified the entering and exiting sites for Lutzomyia longiflocosa in rural houses of the sub-Andean region in Colombia. Entering sites were identified with sticky traps set up outside the bedrooms, around the eave openings, and with cage traps enclosing the slits in the doors and windows inside the bedrooms. Exiting sites were identified by releasing groups of females indoors. These females were blood fed and marked with fluorescent powders. Females were recaptured with the trap placement described above but set up on the opposite sides of the openings. In the entering experiment, a significantly higher number of females were captured in the sticky traps at the zone nearest the eave openings (n = 142) than those captured in the other zones of the trap (n = 52); similarly, a higher number of females were captured on the front side of the house (n = 105) than at the rear side (n = 37). Only two females were collected in the cage trap. In the exiting experiment, at the ceiling, the highest percentage (86.2%) of females was recaptured with sticky traps nearest the eave openings and on the front side of the house (70.0%). Seven females were collected in the cage trap. Lu. longiflocosa entered and exited houses primarily through the eave openings in a non-random pattern in relation to the sides of the house.

Entering and exiting behaviour of the phlebotomine sand fly Lutzomyia longiflocosa (Diptera: Psychodidae) in rural houses of the sub-Andean region of Colombia.

The present study identified the entering and exiting sites for Lutzomyia longiflocosa in rural houses of the sub-Andean region in Colombia. Entering sites were identified with sticky traps set up outside the bedrooms, around the eave openings, and with cage traps enclosing the slits in the doors and windows inside the bedrooms. Exiting sites were identified by releasing groups of females indoors. These females were blood fed and marked with fluorescent powders. Females were recaptured with the trap placement described above but set up on the opposite sides of the openings. In the entering experiment, a significantly higher number of females were captured in the sticky traps at the zone nearest the eave openings (n = 142) than those captured in the other zones of the trap (n = 52); similarly, a higher number of females were captured on the front side of the house (n = 105) than at the rear side (n = 37). Only two females were collected in the cage trap. In the exiting experiment, at the ceiling, the highest percentage (86.2%) of females was recaptured with sticky traps nearest the eave openings and on the front side of the house (70.0%). Seven females were collected in the cage trap. Lu. longiflocosa entered and exited houses primarily through the eave openings in a non-random pattern in relation to the sides of the house.

[KIR-HLA class i and pulmonary tuberculosis in the Amerindian population in Chaco, Argentina]. / KIR-HLA clase i y tuberculosis pulmonar en población amerindia del Chaco, Argentina.

INTRODUCTION: The susceptibility to pulmonary tuberculosis (TB) is multifactorial, thus genetic factors such as HLA and immunoglobulins-like killer receptors (KIR) could be predisposed to the development of the disease. Aim To evaluate whether any HLA classi allele and its combination with KIR could be related to the development of TB in the Wichi Amerindian community in north-eastern Argentina. METHODS: A cohort study was conducted that included 18 families, 35 individuals affected with TB, 84 cohabiting families, and 63 controls of the same ethnic group. A and B loci of HLA classi were typed by generic PCR followed by reverse hybridization (Dynal), locus C by PCR-SSOP. KIR receptors were studied using sequence specific PCR. RESULTS: There was a highly significant association with allele B*35:19/47 in TB vs. household contacts [Pc=0.0051] and vs. controls [Pc=0.0033], and with allele HLA-C*03 in TB vs. household contacts [Pc=0.014] and vs. controls [Pc=0.0033]. KIR receptors had shown increased KIR2DL3/KIR2DL3 frequency in combination with the C1 group of HLA-C (P=.018). HLA-C*03 belongs to C1 group, and this combination could have a strong inhibitory action on the infected cell. CONCLUSION: HLA-B35:19/47-C*03 haplotype could be a susceptibility factor to TB and KIR2DL3-HLA-C1 combination have an inhibitory capacity on NK cells, and might contribute to the course of the infection by Mycobacterium tuberculosis.

[Field efficacy of repellent formulation containing para-menthane-3,8-diol and lemongrass against Culicoides pachymerus (Diptera: Ceratopogonidae) in Colombia]. / Eficacia en campo de un repelente a base de para-mentano-3,8-diol y aceite de limonaria contra Culicoides pachymerus (Diptera: Ceratopogonidae) en Colombia.

INTRODUCTION: Culicoides pachymerus is a major pest species for the inhabitants of the western Boyacá province of Colombia. OBJECTIVE: The effect of a repellent lotion based on p-menthane-3,8-diol (16%) and lemongrass oil (2%) was evaluated against the bites of C. pachymerus. MATERIALS AND METHODS: The repellent lotion was compared simultaneously with a control (no treatment) by human landing catches of C. pachymerus on the forearms of paired volunteers situated near human dwellings. Protection percentage and protection time for 3 to 6 h after repellent application was calculated. The test was repeated ten times. RESULTS: Only two females of C. pachymerus were collected on arms with the repellent treatment. In contrast, the mean biting rate in the untreated control was 47.7 midges/person/10 min. Mean protection percentage of the repellent was 100% up to 4 h and 99.5% up to 5 h. Protection time was 332.2 and 338.2 min in the two replicates where bites of C. pachymerus were confirmed. In the remaining eight replicates protection time exceeded the test duration. CONCLUSION: The repellent showed high efficacy against C. pachymerus, up to 5 h post-application.

Breeding sites of Culicoides pachymerus Lutz in the Magdalena River basin, Colombia.

The breeding sites of Culicoides pachymerus are described for the first time in western Boyacá Province, Colombia, where this species is a public health problem. In addition to being a nuisance due to its enormous density and its high biting rates, C. pachymerus cause dermatological problems in the human population. Analysis of microhabitats by the sugar flotation technique and the use of emergence traps allowed us to recover 155 larvae of Culicoides spp and 65 adults of C. pachymerus from peridomiciliary muddy substrates formed by springs of water and constant rainwater accumulation. These important findings could aid in the design of integrated control measures against this pest.

Breeding sites of Culicoides pachymerus Lutz in the Magdalena River basin, Colombia

The breeding sites of Culicoides pachymerus are described for the first time in western Boyacá Province, Colombia, where this species is a public health problem. In addition to being a nuisance due to its enormous density and its high biting rates, C. pachymerus cause dermatological problems in the human population. Analysis of microhabitats by the sugar flotation technique and the use of emergence traps allowed us to recover 155 larvae of Culicoides spp and 65 adults of C. pachymerus from peridomiciliary muddy substrates formed by springs of water and constant rainwater accumulation. These important findings could aid in the design of integrated control meas-ures against this pest.

Diagnóstico preliminar de la molestia sanitaria causada por Culicoides (Diptera: Ceratopogonidae) / Culicoides biting nuisance (Diptera: Ceratopogonidae) in the province of Boyacá, Colombia

Introducción. Los habitantes del occidente del departamento de Boyacá han reportado molestia sanitaria y problemas dermatológicos ocasionados por la constante picadura de insectos del género Culicoides. Objetivo. Identificar el área de Boyacá afectada por Culicoides, determinar las especies antropofílicas involucradas y su abundancia. Materiales y métodos. Se solicitó información sobre la molestia sanitaria y el registro decasos dermatológicos asociados a la picadura de Culicoides a las autoridades de salud de los municipios que por sus reportes previos o por sus características geográficas se consideraron como potencialmente afectados. En los municipios que informaron sufrir la problemática, se realizó un muestreo entomológico con atrayente humano afuera de las viviendas. Resultados. Se confirmó la gravedad de la molestia en el área rural de nueve municipios ubicados en el flanco occidental de la Cordillera Oriental. Aunque los registros epidemiológicos fueron fragmentados, se estableció que en seis municipios el 11,4 por ciento de los casos (n=2.472) dedermatitis reportados entre el 2003 y el 2005 fueron atribuidos a la picadura de Culicoides. Los resultados entomológicos mostraron que la especie dominante fue Culicoides pachymerus, 99,3 porcentaje de las 3.389 hembras recolectadas, con tasas de picadura (promedios geométricos) por municipio de hasta 52 hembras/persona en 5 minutos. Mediante análisis multivariado, se encontró que la abundancia de esta especie se relaciona negativamente con la altitud. Conclusiones. Por su dominancia y altas tasas de picadura, C. pachymerus es muy probablemente la especie responsable de la molestia sanitaria y los problemas dermatológicos causados por Culicoides en el departamento de Boyacá.

[Preliminary evaluation of the Culicoides biting nuisance (Diptera: Ceratopogonidae) in the province of Boyacá, Colombia]. / Diagnóstico preliminar de la molestia sanitaria causada por Culicoides (Diptera: Ceratopogonidae) en el departamento de Boyacá, Colombia.

INTRODUCTION: Inhabitants in the western border of Boyacá province have reported high nuisance levels and dermatologic problems caused by the intensely irritating bites of the very small flies of the genus Culicoides. OBJECTIVE: A survey was carried out to locate the affected area, identify the anthropophylic Culicoides species and estimate its abundance in Boyacá. MATERIALS AND METHODS: Nuisance reports and clinical records of dermatologic cases associated with Culicoides bites were requested from health authorities in counties where nuisance reports had been received or which had geographical features apparently favorable for Culicoides infestations. An outdoors entomological survey using human landing catches was undertaken in areas reporting a pest problem. RESULTS: Culicoides infestations were confirmed as a serious nuisance problem in the rural areas of nine counties located in the western foothills of the Eastern Range of the Colombian Andes. Although available epidemiological records were fragmented, it was established that in six counties 11.4% of the dermatitis cases (total=2,472 cases) reported between 2003 and 2005 were attributed to the Culicoides bites. The entomological survey identified Culicoides pachymerus as the dominant species, 99.3% of 3,389 caught females. Biting rates in the most intensely affected areas reach a geometric mean of 52 females/person per 5 minutes. Multivariate analysis indicated that abundance of C. pachymerus had a negative relationship with altitude. CONCLUSIONS: Based on its dominance and high biting rates, C. pachymerus is probably the species responsible for the high nuisance levels caused by Culicoides bites and the associated dermatological pathology, within the study area.

Effect of knowledge and economic status on sandfly control activities by householders at risk of cutaneous leishmaniasis in the subandean region of Huila department, Colombia / Efecto del conocimiento y nivel socioeconómico sobre las actividades de control realizadas por la población en riesgo de adquirir leishmaniasis cutánea en la región subandina del departamento del Huila, Colombia

Introducción. Las medidas de control vectorial en el ámbito familiar pueden ser estimuladas por campañas de promoción en salud que tengan en cuenta los conocimientos y actitudes de la población con énfasis en vacíos claves en el conocimiento. Objetivos. Describir las prácticas de control para flebótomos realizadas por las familias en un área endémica de leishmaniasis cutánea en el departamento del Huila, Colombia, y determinar cómo estas prácticas son influenciadas por las actitudes, conocimientos y el estatus socioeconómico. Materiales y métodos. Se aplicó un cuestionario a nivel familiar para recolectar información sobre: demografía, estatus socioeconómico, conocimientos sobre leishmaniasis cutánea y sobre los flebótomos y su papel en la transmisión, y la práctica de actividades de control. La abundancia intradomiciliar de flebótomos fue estimada con trampas de luz. Resultados. De 249 entrevistados, 86 por ciento conocían la leishmaniasis cutánea y 98 por ciento los flebótomos. 35 por ciento de los entrevistados que conocían la leishmaniasis cutánea practicaron medidas para su control. Estas prácticas fueron mayores, 32 por ciento, en las familias que conocían que los flebótomos transmiten la LC. Sin embargo, 82 por ciento de los entrevistados practicaron medidas de control para los flebótomos, y estas prácticas estuvieron significativamente asociadas con altas abundancias de flebótomos. Las medidas de control practicadas incluyeron humazo, toldillos, fumigación intradomiciliar con insecticidas o con sustancias no insecticidas. Las familias que usaron medidas de costo alto (toldillos e insecticidas) tenían el estatus económico más alto. Conclusiones. Los programas de educación en salud deben considerar que la molestia sanitaria causada por los flebótomos puede iniciar la práctica de medidas de control y que el conocimiento del papel de los flebótomos en la Transmisión puede aumentar estas actividades. Los resultados con relación al estatus socioeconómico in...

Introduction. Householder vector control measures can be encouraged by health promotion campaigns which take into account peoples’ attitudes and focus on key gaps in knowledge. Objectives. To describe household sandfly control practices in an endemic area of cutaneous leishmaniasis in the department of Huila, Colombia, and determine how these are influenced by attitudes, knowledge and socioeconomic status. Materials and methods. A household questionnaire was applied to collect information on: demography, socioeconomic status, knowledge of cutaneous leishmaniasis and of sandflies and their role in transmission, and the control activities practiced. Indoor sandfly abundance was estimated by light trap collections. Results. Amongst 249 interviewees, 86% knew about cutaneous leishmaniasis and 98% sand flies. 35% of interviewees who knew about cutaneous leishmaniasis practiced measures with the purpose of its control. This practice was higher amongst the 32% who knew that sand flies transmit cutaneous leishmaniasis. However, 82% of interviewees practiced sand fly control measures, and these were significantly associated with high sand fly abundance. Measures included smoke, bednets, and house spraying with insecticide or non-insecticidal substances. Householders using the high cost measures (bednets and insecticide) had the highest economic status. Conclusions. Health education programmes should note that sand fly nuisance can initiate control measures, but that knowledge of the role of sand flies in transmission could enhance activities. The socioeconomic findings indicate that targeted bednet subsidies could reduce inequities in health status amongst cutaneous leishmaniasis endemic communities.

[Lutzomyia longiflocosa as suspected vector of cutaneous leishmaniasis in a focus of cutaneous leishmaniasis on the sub-andean region of Tolima department, Colombia, and the knowledge on sandflies by the inhabitants]. / Lutzomyia longiflocosa, posible vector en un foco de leishmaniasis cutánea en la región subandina del departamento del Tolima, Colombia, y el conocimiento que tiene la población sobre este insecto.

INTRODUCTION: Between 2003 and 2004 the largest epidemic of cutaneous leishmaniasis in Colombia (2,810 cases, with the highest incidence of 6,202 x 100,000 in 2004) occurred in the sub-Andean rural area of the municipalities of Chaparral and San Antonio in the department of Tolima. OBJECTIVE: The present study was carried out to identify suspected vectors and to establish the knowledge that the inhabitants have about sand flies in order to use this information for vector control. MATERIALS AND METHODS: 46 houses were sampled with CDC light traps set up indoors to establish the sand fly species composition, abundance and the percentage of infestation. Houses were examined during daylight to identify endophagy. A questionnaire was applied in order to estimate the knowledge about sand flies, their role in transmission and the sites and seasons of highest abundance. RESULTS: Three anthropophilic sand fly species of possible epidemiological importance were found. L. longiflocosa was the dominant sand fly species accounting for 81.7% (192 / 235) of all catches and infested the highest number of houses (41.7%). The other two species were L. columbiana and L. nuneztovari, with relative abundances of 3.4% and 2.1%, respectively, and house infestations of 13.0% and 6.5%, respectively. There was no evidence of endophilic behavior. Inhabitants recognized sand flies and their role in transmission. They identified the houses and the dry season as the site and time period of highest sand fly abundance. CONCLUSIONS: Based on its high anthropophily, predominance and apparent endophagic behavior, L. longiflocosa is the most probable vector of leishmaniasis indoors. L. columbiana and L. nuneztovari could be involved as secondary vectors outdoors. The importance of these findings on sand fly control is discussed.

Effect of knowledge and economic status on sandfly control activities by householders at risk of cutaneous leishmaniasis in the subandean region of Huila department, Colombia.

INTRODUCTION: Householder vector control measures can be encouraged by health promotion campaigns which take into account peoples' attitudes and focus on key gaps in knowledge. OBJECTIVES: To describe household sandfly control practices in an endemic area of cutaneous leishmaniasis in the department of Huila, Colombia, and determine how these are influenced by attitudes, knowledge and socioeconomic status. MATERIALS AND METHODS: A household questionnaire was applied to collect information on: demography, socioeconomic status, knowledge of cutaneous leishmaniasis and of sandflies and their role in transmission, and the control activities practiced. Indoor sandfly abundance was estimated by light trap collections. RESULTS: Amongst 249 interviewees, 86% knew about cutaneous leishmaniasis and 98% sand flies. 35% of interviewees who knew about cutaneous leishmaniasis practiced measures with the purpose of its control. This practice was higher amongst the 32% who knew that sand flies transmit cutaneous leishmaniasis. However, 82% of interviewees practiced sand fly control measures, and these were significantly associated with high sand fly abundance. Measures included smoke, bednets, and house spraying with insecticide or non-insecticidal substances. Householders using the high cost measures (bednets and insecticide) had the highest economic status. CONCLUSIONS: Health education programmes should note that sand fly nuisance can initiate control measures, but that knowledge of the role of sand flies in transmission could enhance activities. The socioeconomic findings indicate that targeted bednet subsidies could reduce inequities in health status amongst cutaneous leishmaniasis endemic communities.

Estudio preliminar de los flebótomos de Villeta y Quebradanegra, Cundinamarca: sus implicaciones en salud pública / Preliminar study of the flebotomines from Villeta and quebradanegra, Cundinamarca: its public healh implications

Con el fin de preseleccionar los posibles vectores de leishmaniasis cutánea en Villeta y su área rural más cercana, se hizo un reconocimiento de las especies del genero Lutzomyia. Los insectos se capturaron durante la noche con cebo humano, cebo animal, trampas shannon y trampas CDC y, durante el día, por aspiración directa en los sitios de reposo. Se encontraron ocho especies en los 497 insectos recolectados; las más abundates fueron Lu. ovallesi (48,7 por ciento), Lu. gomezi (38,5 por ciento) y Lu. lichyi (8 por ciento), Especies reconocidas como antropofílicas y con antecedentes de ser vectoras o posibles vectoras. Lu gomezi fue la especie más abundante en las capturas con cebo humano, con una fuerte tendencia peridomiciliaria por lo que podría estar implicada en la transmisión de leishmaniasis en toda el área de estudio. Lu ovallesi fue más abundante en los bosques poco intervenidos del área rural, por lo que es posible que juegue un papel como vector más importante en esta área. Lu. lichyi se presentó, principalmente, en el bosque aunque llegó hasta el peridomicilio. Finalmente, es necesario iniciar estudios detallados para aclarar el papel que, como vectores, puedan tener las especies de Lutzomyia antes mencionadas en Villeta y el área rural adyacente