Spatial patterns associated with the distribution of immature stages of Aedes aegypti in three dengue high-risk municipalities of Southwestern Colombia.

Aedes aegypti mosquitoes are the main vector of human arbovirosis in tropical and subtropical areas. Their adaptation to urban and rural environments generates infestations inside households. Therefore, entomological surveillance associated with spatio-temporal analysis is an innovative approach for vector control and dengue management. Here, our main aim was to inspect immature pupal stages in households belonging to municipalities at high risk of dengue in Cauca, Colombia, by implementing entomological indices and relating how they influence adult mosquitos' density. We provide novel data for the geographical distribution of 3,806 immature pupal stages of Ae. aegypti. We also report entomological indices and spatial characterization. Our results suggest that, for Ae. aegypti species, pupal productivity generates high densities of adult mosquitos in neighbouring households, evidencing seasonal behaviour. Our dataset is essential as it provides an innovative strategy for mitigating vector-borne diseases using vector spatial patterns. It also delineates the association between these vector spatial patterns, entomological indicators, and breeding sites in high-risk neighbourhoods.

Spatial patterns associated with the distribution of immature stages of Aedes aegypti in three high-risk dengue municipalities of Southwestern Colombia / Patrones espaciales asociados a la distribución de estadios inmaduros de Aedes aegypti en tres municipios de alto riesgo para el departamento del Cauca, Colombia

Aedes aegypti mosquitoes are the main vector of human arbovirosis in tropical and subtropical areas.  Its adaptation to urban and rural environments generates infestations inside households. Therefore, entomological surveillance in association with spatio-temporal analysis is an innovative approach to vector control and dengue management. The main aim was to inspect immature pupal stages in households belonging to municipalities at high risk of dengue in Cauca, Colombia by implementing entomological indices and relating how they influence adult mosquito density. Here, we provide novel data for the geographical distribution of 3,806 immature pupal stages of Ae. aegypti. We also report entomological indices and spatial characterization. The results suggest that for Ae. aegypti species, pupal productivity generates high densities of adults in neighbouring households, evidencing seasonal behaviour. This dataset is of great importance as it provides an innovative strategy for vector-borne disease mitigation using vector spatial patterns and their association with entomological indicators and breeding sites in high-risk neighbourhoods.

Los mosquitos Aedes aegypti son el principal vector de las arbovirosis humanas en zonas tropicales y subtropicales. Su adaptación a entornos urbanos y rurales genera infestaciones en el intradomicilio de las viviendas. De aquí que, la vigilancia entomológica en asociación con el análisis espacial y el análisis espacio-temporal sean un enfoque innovador para el control de vectores y la gestión del dengue.El objetivo principal de la investigación fue realizar una comparación de la vigilancia entomológica, mediante el uso de índices cuantitativos de pupas y de adultos en tres municipios de alto riesgo de dengue Patía (El Bordo), Miranda y Piamonte del departamento del Cauca, con el fin de examinar cómo influye la productividad de pupas, entre índices entomológicos, en la densidad de mosquitos adultos y otros patrones espaciales y temporales. Ae. aegypti , sus índices entomológicos y su caracterización espacial. Los resultados sugieren que, para las especies de Ae. aegypti , la productividad de pupas genera altas densidades de adultos en las viviendas vecinas, evidenciando un comportamiento estacional.Estos resultados son de gran importancia ya que proporciona una estrategia innovadora para la mitigación de enfermedades transmitidas por vectores utilizando patrones espaciales de los vectores y su asociación con indicadores entomológicos y lugares de cría en barrios de alto riesgo para la transmisión del dengue.

Spatial Analysis of Dengue Clusters at Department, Municipality and Local Scales in the Southwest of Colombia, 2014-2019.

Dengue is an arbovirus transmitted by mosquitoes of the genus Aedes and is one of the 15 main public health problems in the world, including Colombia. Where limited financial resources create a problem for management, there is a need for the department to prioritize target areas for public health implementation. This study focuses on a spatio-temporal analysis to determine the targeted area to manage the public health problems related to dengue cases. To this end, three phases at three different scales were carried out. First, for the departmental scale, four risk clusters were identified in Cauca (RR ≥ 1.49) using the Poisson model, and three clusters were identified through Getis-Ord Gi* hotspots analysis; among them, Patía municipality presented significantly high incidence rates in the time window (2014-2018). Second, on the municipality scale, altitude and minimum temperature were observed to be more relevant than precipitation; considering posterior means, no spatial autocorrelation for the Markov Chain Monte Carlo was found (Moran test ˂ 1.0), and convergence was reached for b1-b105 with 20,000 iterations. Finally, on the local scale, a clustered pattern was observed for dengue cases distribution (nearest neighbour index, NNI = 0.202819) and the accumulated number of pupae (G = 0.70007). Two neighbourhoods showed higher concentrations of both epidemiological and entomological hotspots. In conclusion, the municipality of Patía is in an operational scenario of a high transmission of dengue.

Publishing data to support the fight against human vector-borne diseases.

Vector-borne diseases are responsible for more than 17% of human cases of infectious diseases. In most situations, effective control of debilitating and deadly vector-bone diseases (VBDs), such as malaria, dengue, chikungunya, yellow fever, Zika and Chagas requires up-to-date, robust and comprehensive information on the presence, diversity, ecology, bionomics and geographic spread of the organisms that carry and transmit the infectious agents. Huge gaps exist in the information related to these vectors, creating an essential need for campaigns to mobilise and share data. The publication of data papers is an effective tool for overcoming this challenge. These peer-reviewed articles provide scholarly credit for researchers whose vital work of assembling and publishing well-described, properly-formatted datasets often fails to receive appropriate recognition. To address this, GigaScience's sister journal GigaByte partnered with the Global Biodiversity Information Facility (GBIF) to publish a series of data papers, with support from the Special Programme for Research and Training in Tropical Diseases (TDR), hosted by the World Health Organisation (WHO). Here we outline the initial results of this targeted approach to sharing data and describe its importance for controlling VBDs and improving public health.

Pintomyia evansi (Diptera: Psychodidae) larvae susceptibility to hydrated lime under laboratory conditions.

This study evaluated the effect of Calcium hydroxide (Ca(OH)2 Mg(OH)2) on third stages Pi. evansi larvae mortality under experimental laboratory conditions. Three treatments containing a mixture of phlebotomine natural breeding soil (substrate) and Calcium hydroxide at different concentrations were used: Treatment 1 (T1), 1 kg of substrate mixed with 56.2 g of lime; Treatment 2 (T2), 1 kg of substrate mixed with 62.5 g of lime; and Treatment 3 (T3), 1 kg of substrate mixed with 70 g of lime. in addition, a sample of substrate without lime was used as a control for each treatment. The mortality in T1 was 1% at 24 h and 12% at 48 h, reaching a maximum of 56% at 72 h of exposure. For T2, mortality was progressive, starting with 12% at 12 h, 36% at 24 h, 52% at 48 h, and 100% at 72 h; while T3 showed mortality percentages of 94% and 100% between 12 and 24 h of exposure. Therefore, T3 was the most effective to according to the Kaplan-Meier survival analysis. This study showed that treatments over 62 g of Calcium hydroxide per 1 kg of substrate offer a starting point for immature stage control under laboratory conditions. With these results, we propose to evaluate the cost-effectiveness and feasibility of the application, of the latter concentration, under field conditions in urban environments for its application in vector control programs.

Arbovirus vectors in municipalities with a high risk of dengue in Cauca, Southwestern Colombia.

The Culicidae family has two of the most important disease vector genus: Aedes spp. and Culex spp. Both of these are involved in the transmission of arboviruses. Here, we provide novel data for the geographical distribution of 2,383 specimens in the Culicidae family. We also report the percentage of houses infested with these vectors, and Shannon and Simpson diversity indices in three municipalities located in Cauca, Colombia. This dataset is relevant for research on vector-borne diseases because Aedes spp. can transmit arboviruses such as dengue, Zika and chikungunya, and Culex spp. is a well-known vector of West Nile virus and Venezuelan equine encephalitis.

Development of Lutzomyia evansi immature stages in peridomiciliary environment in a leishmaniasis urban focus in the Colombian Caribbean.

In the Caribbean region of Colombia, Lutzomyia evansi is recognized as the vector for Leishmania infantum and Leishmania braziliensis. Identifying breeding sites and surveying abundance of immature phlebotomine sand flies in urban foci of leishmaniasis are useful tool to design new vector control strategies. The objective of this study was to describe the natural breeding sites of Lu. evansi in peridomiciliary vegetation in a peri-urban area of the Colombian Caribbean region. Between 2013 and 2015, 466 microhabitats were sampled, collecting 621 kg of soil samples. The explored microhabitats were bases and tree holes, fallen trees, animal caves, leaf litter, domestic animal shelters, and the inside of dwellings. The immature phlebotomines were recovered by direct search under the stereoscope and incubation of soil samples. In total, 103 microhabitats, associated with 17 arboreal species, were identified as natural breeding sites. Of 422 immature sandflies detected, 98.6% were found in soils at the base of the trees. Eight species of the genus Lutzomyia were identified, of which Lu. evansi (52.6%) was the most abundant, followed by Lu. rangeliana, Lu. cayennensis cayennensis, Lu. atroclavata, Lu. micropyga, Lu. trinidadensis, Lu. dubitans and Lu. gomezi. The arboreal species Cordia alba was the most used by phlebotomines for the development of their immature stages. From 63 natural breeding sites identified 268 immatures were recovered including 176 Lu. evansi. The accumulated precipitation showed correlation (R2 = 0.643, p = 0.013) with the abundance of developmental stages, which increased in September and October. The natural breeding sites of Lu. evansi exhibited a local pattern of occurrence dependent on rainfall. The physicochemical analysis of the soil samples showed that the natural sites for C. alba were categorized as fertile loam soils. This is the first systematic study that estimates the temporal variation of immature sand flies in peridomiciliary vegetation in a peri-urban focus of leishmaniasis in Colombia.

Ampliación de la distribución de Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) en el departamento de Caldas: potencial aumento del riesgo de leishmaniasis visceral / Expansion of the distribution of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) in the department of Caldas: Increased risk of visceral leishmaniasis

Introducción. Diversos estudios a nivel taxonómico y molecular sugieren que Lutzomyia longipalpis, principal vector de la leishmaniasis visceral en Latinoamérica, es un complejo de especies con amplia distribución a lo largo del continente y con adaptaciones a diferentes hábitats. Objetivo. Realizar vigilancia entomológica en el área de influencia de la hidroeléctrica Miel I. Materiales y métodos. Se utilizaron trampas adhesivas en una intersección de 400 km, aproximadamente, para la captura de insectos, los cuales fueron identificados con la clave taxonómica de Young y Duncan. Resultados. En este estudio se reporta la presencia de Lu. longipalpis en los municipios de Norcasia a una altitud de 392 msnm y en Marquetalia a 1.387 msnm; es el primer reporte a esta altura para esta especie en Colombia. Conclusiones. Se sugiere que la ampliación de la distribución geográfica y altitudinal de Lu. longipalpisen el país podría estar relacionada con la existencia del complejo de especies Lu. longipalpis, o a factores ambientales como el aumento de temperatura debido al cambio climático global que viene sucediendo en las últimas décadas. Esta última hipótesis sugeriría que se están creando nuevos hábitats propicios para el establecimiento de Lu. longipalpis, lo cual genera un nuevo riesgo epidemiológico de posibles nuevos focos de leishmaniasis visceral en el país.

Introduction: Diverse taxonomical and molecular studies suggest that Lutzomyia longipalpis, main vector of visceral leishmaniasis in Latin America, is a complex of species widely distributed throughout the continent and adapted to different habitats. Objective: To carry out entomological surveillance in the area of influence of the Miel I Hydroelectric Plant. Materials and methods: Adhesive traps were used in a transect covering an area of approximately 400 km for the capture of insects, which were then identified using the Young and Duncan taxonomical key. Results: This study reports the presence of Lutzomyia longipalpis in the municipalities of Norcasia at an altitude of 392 masl, and in Marquetalia at 1,387 masl. Conclusions: We suggest that the increase in the geographical and altitudinal distribution could be related to the existence of the Lu. longipalpis species complex, or to environmental factors, such as the rise in temperature due to global climate changes, which create the establishment of Lu. longipalpis, generating a new epidemiological risk for new visceral leishmaniasis foci in the country.

[Expansion of the distribution of Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) in the department of Caldas: Increased risk of visceral leishmaniasis]. / Ampliación de la distribución de Lutzomyia longipalpis (Lutz & Neiva, 1912) (Diptera: Psychodidae) en el departamento de Caldas: potencial aumento del riesgo de leishmaniasis visceral.

INTRODUCTION: Diverse taxonomical and molecular studies suggest that Lutzomyia longipalpis , main vector of visceral leishmaniasis in Latin America, is a complex of species widely distributed throughout the continent and adapted to different habitats. OBJECTIVE: To carry out entomological surveillance in the area of influence of the Miel I Hydroelectric Plant. MATERIALS AND METHODS: Adhesive traps were used in a transect covering an area of approximately 400 km for the capture of insects, which were then identified using the Young and Duncan taxonomical key. RESULTS: This study reports the presence of Lutzomyia longipalpis in the municipalities of Norcasia at an altitude of 392 masl, and in Marquetalia at 1,387 masl. CONCLUSIONS: We suggest that the increase in the geographical and altitudinal distribution could be related to the existence of the Lu. longipalpis species complex, or to environmental factors, such as the rise in temperature due to global climate changes, which create the establishment of Lu. longipalpis , generating a new epidemiological risk for new visceral leishmaniasis foci in the country.

Environmental risk factors for the incidence of American cutaneous leishmaniasis in a sub-Andean zone of Colombia (Chaparral, Tolima).

Environmental risk factors for cutaneous leishmaniasis were investigated for the largest outbreak recorded in Colombia. The outbreak began in 2003 in Chaparral, and in the following five years produced 2,313 cases in a population of 56,228. Candidate predictor variables were land use, elevation, and climatic variables such as mean temperature and precipitation. Spatial analysis showed that incidence of cutaneous leishmaniasis was higher in townships with mean temperatures in the middle of the county's range. Incidence was independently associated with higher coverage with forest or shrubs (2.6% greater for each additional percent coverage, 95% credible interval [CI] = 0.5-4.9%), and lower population density (22% lower for each additional 100 persons/km(2), 95% CI = 7-41%). The extent of forest or shrub coverage did not show major changes over time. These findings confirmed the roles of climate and land use in leishmaniasis transmission. However, environmental variables were not sufficient to explain the spatial variation in incidence.

Clinical, parasitologic, and immunologic evolution in dogs experimentally infected with sand fly-derived Leishmania chagasi promastigotes.

Experimental infection of dogs with Leishmania infantum has yielded heterogeneous clinical, parasitologic, and immunologic results. We studied dogs infected with 10(5) or 10(4) sand fly-derived promastigotes delivered by the intradermal (ID) or intravenous (IV) routes. Total mortality over 1 year post-infection reached 23.8%. The mortality and proportion of sustained polysymptomatic dogs was highest in the IV-10(5) group. The early appearance of polysymptoms was associated with an increased risk of progression to death. Dissemination of the parasite to lymph nodes was faster, and the subsequent infectivity to sand flies higher, in the IV compared with ID-infected dogs. Parasite-specific IgG1 or IgG2 production was similar among the groups, but higher interferon-gamma (IFN-gamma) and interleukin-10 (IL-10) expression was associated with polysymptomatic dogs. On the basis of the data obtained from this study, a sample size analysis using different endpoints for future vaccine trials is described.

Leishmania (Viannia) braziliensis infection in two Colombian dogs: a note on infectivity for sand flies and response to treatment / Infección por Leishmania ( Viannia) braziliensis en dos perros colombianos: una nota sobre infectividad para flebótomos y respuesta al tratamiento

Introducción. A pesar de que la leishmaniasis cutánea canina ha sido reportada en varios focos de Sudamérica, no existe información publicada de Colombia. Objetivo. Se reportan dos casos hallados en la región de la costa Pacífica de este país, que se presentaron como una úlcera escrotal única en un perro y como dos úlceras en la cara externa de la oreja en un segundo individuo. Materiales y métodos. Los parásitos fueron aislados por cultivo en medio de Senekjie e identificados empleando anticuerpos monoclonales. La capacidad de los perros para transmitir parásitos a los flebótomos vectores ( Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia longipalpis, Lutzomyia youngi) se ensayó permitiendo que los insectos se alimentaran sobre el borde de las lesiones. Resultados. Ambos aislamientos se identificaron como Leishmania ( Viannia) braziliensis. No se detectaron infecciones durante la disección de los flebótomos alimentados. Una sola inyección peri- y sub-lesional de 1-2 ml de antimonio pentavalente en el perro con las lesiones auriculares resultó en la curación clínica a las 6 semanas post-tratamiento. Conclusiones. Estas observaciones sugieren que aunque los perros son susceptibles a L. braziliensis, su competencia como reservorio podría ser baja. Sin embargo, si estudios posteriores demuestran que los caninos tienen capacidad de reservorio para especies de L. Viannia, el tratamiento local de las lesiones podría ser una estrategia factible para disminuir el riesgo de infección humana en el peridomicilio, sin necesidad de sacrificar a los perros infectados.

Introduction. Although canine cutaneous leishmaniasis has been reported in several foci of South America, no published information from Colombia is available. Objective. We report on two cases found in the Pacific coast region of this country, which presented as a single scrotal ulcer in one dog, and two ulcers on the external surface of the ear in a second dog. Materials and methods. Parasites were isolated by culture in Senekjie’s culture medium and identified using monoclonal antibodies. The capacity of these dogs to transmit the parasites to sand fly vectors (Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia longipalpis, Lutzomyia youngi) was tested by allowing the flies to feed on the lesion borders. Results. Both isolates were identified as Leishmania (Viannia) braziliensis. No infections were detected upon dissection of engorged flies. A single peri-and sub-lesional injection of 1-2 ml of pentavalent antimony in the dog with ear lesions resulted in clinical cure 6 weeks post-treatment. Conclusions. These observations suggest that although dogs are susceptible to L. braziliensis, their reservoir competence could be low. However, if further studies indicate that canines are capable reservoir hosts of L. Viannia spp., the local treatment of lesions could become a feasible approach to diminish the risk of human infection in the peridomestic setting, without sacrificing infected dogs.

Evidence for leishmania (viannia) parasites in the skin and blood of patients before and after treatment.

BACKGROUND: American cutaneous leishmaniasis is considered to be a zoonotic disease transmitted by sand flies that feed on infected sylvatic mammals. However, the "domestication" of transmission and the increase in treatment failure with antimonial drugs have raised the suspicion of anthroponotic transmission of American cutaneous leishmaniasis. METHODS: The objective of the present study was to explore the potential of humans as a source of infection for sand flies. Biological (xenodiagnosis and culture) and molecular (polymerase chain reaction/Southern blot) detection methods were used to evaluate peripheral-blood monocytes and tissue fluids from sites accessible to sand flies from 59 adult patients with parasitologically confirmed American cutaneous leishmaniasis. RESULTS: Overall, 44.1% of patients (26/59) presented biological and/or molecular evidence of Leishmania parasites in normal skin, peripheral-blood monocytes, lesion scars, or lesion border (by xenodiagnosis) before (18/59 [30.5%]) or after (10/27 [37.0%]) treatment. Leishmania parasites were cultured from the unaffected skin of 2 (3.6%) of 55 patients, and xenodiagnosis gave positive results for 5 (8.8%) of 57 patients before treatment. CONCLUSIONS: The presence of Leishmania parasites in the unaffected skin and peripheral-blood monocytes of a high proportion of patients even after treatment and the acquisition of infection by sand flies support the plausibility of anthroponotic transmission of American cutaneous leishmaniasis.

Leishmania (Viannia) braziliensis infection in two Colombian dogs: a note on infectivity for sand flies and response to treatment.

INTRODUCTION: Although canine cutaneous leishmaniasis has been reported in several foci of South America, no published information from Colombia is available. OBJECTIVE: We report on two cases found in the Pacific coast region of this country, which presented as a single scrotal ulcer in one dog, and two ulcers on the external surface of the ear in a second dog. MATERIALS AND METHODS: Parasites were isolated by culture in Senekjie's culture medium and identified using monoclonal antibodies. The capacity of these dogs to transmit the parasites to sand fly vectors (Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia longipalpis, Lutzomyia youngi) was tested by allowing the flies to feed on the lesion borders. RESULTS: Both isolates were identified as Leishmania (Viannia) braziliensis. No infections were detected upon dissection of engorged flies. A single peri-and sub-lesional injection of 1-2 ml of pentavalent antimony in the dog with ear lesions resulted in clinical cure 6 weeks post-treatment. CONCLUSIONS: These observations suggest that although dogs are susceptible to L. braziliensis, their reservoir competence could be low. However, if further studies indicate that canines are capable reservoir hosts of L. Viannia spp., the local treatment of lesions could become a feasible approach to diminish the risk of human infection in the peridomestic setting, without sacrificing infected dogs.

Differential identification of Ascogregarina species (Apicomplexa: Lecudinidae) in Aedes aegypti and Aedes albopictus (Diptera: Culicidae) by polymerase chain reaction.

We report 2 polymerase chain reaction (PCR)-based methods for distinguishing morphologically similar gregarine species based on amplification of variable regions of the internal transcribed spacer region of ribosomal DNA. The gregarines we investigated were Ascogregarina barretti (Vavra), A. culicis (Ross), and A. taiwanensis (Lien and Levine), parasites of the mosquitoes Ochlerotatus triseriatus (Say), Aedes aegypti (Linnaeus), and Ae. albopictus (Skuse), respectively. These 3 important vector mosquitoes often utilize the same container habitats, where larval development and infection by the parasite occurs, leaving ample opportunity for cross-species gregarine infection. Because previous studies have shown that the parasites A. culicis and A. taiwanensis variably affect fitness in both normal and abnormal mosquito hosts, distinguishing parasite infection and species is important. The task is complicated by the fact that these 2 parasite species are virtually identical in morphology, whereas A. barretti is morphologically distinct. Of the 2 PCR-based assays reported here, the first provides a rapid, sensitive, and straight-forward means of general ascogregarine detection based on a single PCR amplification. The second method provides a means of differentiation between A. culicis and A. taiwanensis based on a species-specific PCR assay. Together, these assays allow whole mosquitoes to be tested for the presence of Ascogregarina species as well as identification of both A. culicis and A. taiwanensis singly or in dual infections.

Impact of habitat degradation on phlebotominae (Diptera: Psychodidae) of tropical dry forests in Northern Colombia.

We examined changes in the phlebotomine fauna resulting from human intervention in a tropical dry forest of Northern Colombia where visceral and cutaneous leishmaniases are endemic. A natural forest reserve (Colosó) and a highly degraded area (San Andrés de Sotavento [SAS]) were sampled monthly for 8 mo using Shannon traps, sticky traps, and resting-site collections. Overall abundances were higher in Colosó (15,988) than in SAS (2,324). and species richness of phlebotomines was greater in the forest reserve (11 species) than in the degraded habitat (seven species). Fisher alpha, a measure of diversity, reinforced this trend. Both sand fly communities were dominated by Lutzomyia evansi (Nuòez-Tovar), vector of Leishmania chagasi (Cunha & Chagas), representing 92 and 81% of all captures in Colosó and SAS, respectively. Lutzomyia longipalpis (Lutz & Neiva), the common vector of visceral leishmaniasis, accounted for 4-7% of the sand fly community. Lutzornyia panamensis (Shannon) and Lutzomya gomezi (Nitzulescu), putative vectors of Leishmania braziliensis (Vianna), had low abundances at both study sites. The zoophilic species Lutzomyia cayennensis (Floch & Abonneuc) and Lutzomyia trinidadensis (Newstead) were present in variable numbers according to trapping methods and site. Habitat degradation negatively affected sand fly communities, but medically important species were able to exploit modified environments, thereby contributing to Lishmania endemicity.

Association of Lutzomyia columbiana (Diptera: Psychodidae) with a leismaniasis focus in Colombia due to species to the Leishmania mexicana complex

In Colombia, Leishmania mexicana has a scattered geographical destribution and no sand fly vectors have been associated with its transmission. During the present study, the anthropophilic sand fly Lutzomyia columbiana was found to be the only species collected using diverse methods, in a samall focus of Le. mexicana in the municipality of samaniego, SW Colombia. Ecological data indicate that this sand fly species is present in both peri and intradomestic habitats, where it readitly bites man. Further evidence comes from experimental infections of wild-caught Lu. columbiana with Le. mexicana after feeding on infected hamsters. Based on these results, it is suggested that this sand fly is the most likely vector in the study area, suggesting the existence of a previouly unknown sand fly-parasite association.