Spatial distribution and effects of land use and cover on cutaneous leishmaniasis vectors in the municipality of Paracambi, Rio de Janeiro, Brazil

ABSTRACT The municipality of Paracambi (Rio de Janeiro, Brazil) reports sporadic cases of American cutaneous leishmaniasis (ACL). Previous studies detected Nyssomyia intermedia (Diptera: Psychodidae) as the main vector in the region, but its spatial distribution and the presence of other vector species have not been evaluated. This study aims at filling this knowledge gap, by studying the ecology of sand flies, their spatiotemporal distribution, and correlation with land use/cover. Two campaigns of monthly sand fly collections using light traps and manual captures were conducted in 1992-1994 and 2001-2003. Females were dissected to detect natural Leishmania infections. The spatial distribution of sand flies was assessed using kernel density maps. Correlations with land use/cover were evaluated by extracting satellite imagery data around the capture points. A total of 17,232 sand flies from 13 species were captured. Medically important species included Ny. intermedia, Migonemyia migonei, Pintomyia fischeri and Ny. whitmani. No Leishmania-infected females were detected. Highest densities were detected in the peri-urban areas Cascata and Sabugo, and in rural areas São José and Mutirão. Ny. intermedia had statistically significant correlations with pasture and agricultural areas. Present results strengthened that Ny. intermedia and Mg. migonei are the main local ACL vectors. Correlations with land use evidence the association between ACL and anthropic environmental change.

Identification of climatic and environmental factors associated with incidence of cutaneous leishmaniasis in Central Iran using satellite imagery

Objective: To determine the effect of climatic and environmental factors on the incidence of cutaneous leishmaniasis in Qom province in 2018. Methods: In this cross-sectional study, the data on cutaneous leishmaniasis incidence were collected from the Disease Control and Prevention Center in Qom province. Climatic and environmental data including Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), and soil moisture were extracted using satellite images. Data of altitude and sunny hours were provided based on shuttle radar topography mission digital elevation model and hemispherical viewshed algorithm, respectively. The associations of climatic and environmental variables with the incidence of the disease were analyzed by Pearson correlation method. The ArcGIS 10.3 software was used to determine the geographical distribution of these factors. Results: There were positive correlations between cutaneous leishmaniasis incidence and the two climatic factors: LST and sunny hours per day (P=0.041, P=0.016), and it had weak negative correlations with the digital elevation model (P=0.27), soil moisture (P=0.54), and NDVI (P=0.62). The time delay analysis showed that in one-, two-, and three month periods, the correlations increased with a 95% confidence interval. Accordingly, the correlation with the three-month time delay was positive and relatively strong between the cutaneous leishmaniasis incidence and LST and sunny hours (P=0.027, P=0.02); nevertheless, there were negative correlations between the cutaneous leishmaniasis incidence and the soil moisture (P=0.27) and NDVI (P=0.62). Conclusions: As Qom is located in one of the semi-arid climate zones, topography and solar energy are important factors affecting the incidence of cutaneous leishmaniasis in autumn. Therefore, appropriate disease control programs are recommended.

Identification of climatic and environmental factors associated with incidence of cutaneous leishmaniasis in Central Iran using satellite imagery

Objective: To determine the effect of climatic and environmental factors on the incidence of cutaneous leishmaniasis in Qom province in 2018. Methods: In this cross-sectional study, the data on cutaneous leishmaniasis incidence were collected from the Disease Control and Prevention Center in Qom province. Climatic and environmental data including Normalized Difference Vegetation Index (NDVI), Land Surface Temperature (LST), and soil moisture were extracted using satellite images. Data of altitude and sunny hours were provided based on shuttle radar topography mission digital elevation model and hemispherical viewshed algorithm, respectively. The associations of climatic and environmental variables with the incidence of the disease were analyzed by Pearson correlation method. The ArcGIS 10.3 software was used to determine the geographical distribution of these factors. Results: There were positive correlations between cutaneous leishmaniasis incidence and the two climatic factors: LST and sunny hours per day (P=0.041, P=0.016), and it had weak negative correlations with the digital elevation model (P=0.27), soil moisture (P=0.54), and NDVI (P=0.62). The time delay analysis showed that in one-, two-, and three month periods, the correlations increased with a 95％ confidence interval. Accordingly, the correlation with the three-month time delay was positive and relatively strong between the cutaneous leishmaniasis incidence and LST and sunny hours (P=0.027, P=0.02); nevertheless, there were negative correlations between the cutaneous leishmaniasis incidence and the soil moisture (P=0.27) and NDVI (P=0.62). Conclusions: As Qom is located in one of the semi-arid climate zones, topography and solar energy are important factors affecting the incidence of cutaneous leishmaniasis in autumn. Therefore, appropriate disease control programs are recommended.

Cambios en la cobertura de manglares en Bahía Culebra, Pacífico Norte de Costa Rica (1945-2010) / Changes in mangrove coverage in Culebra Bay, North Pacific of Costa Rica (1945-2010)

ResumenLos manglares tienen gran importancia ecológica, económica, riqueza natural y prestan servicios ambientales. No obstante, son amenazados por la sobreexplotación, la contaminación y el cambio de uso de suelo. Costa Rica tiene manglares en las costas pacífica y caribeña. Según algunos estudios, la cobertura de manglar ha ido disminuyendo desde la década de 1980. Debido a que estos datos no son actualizados y se basan en estimaciones poco precisas, es necesario hacer una valoración de la extensión actual y la variación de la cobertura en los últimos años, que permita determinar cambios. En esta investigación se estudió la cobertura de dos manglares ubicados en Bahía Culebra, Pacífico Norte: Iguanita y Playa Panamá. Se usaron fotografías e imágenes de satélite para un período de 65 años (1945-2010). Se encontraron cambios espaciotemporales en la cobertura de manglar, bosques adyacentes y áreas sin vegetación. Las menores coberturas de manglar se registraron en la década de 1970, pero aumentaron en años posteriores. Los cambios en la cobertura de bosque alrededor de los manglares de Iguanita y Playa Panamá concuerdan con otros análisis históricos sobre el uso del suelo alrededor de Bahía Culebra. Antes de 1980 se dio un aumento de las prácticas de ganadería extensiva e intensiva, lo que aumentó la tasa de deforestación. Después de 1980 se abandonaron estas prácticas y la cobertura de bosque secundario aumentó hasta el año 2000. Para asegurar una adecuada protección de los manglares, es necesario evaluar también las áreas aledañas y establecer zonas de amortiguamiento alrededor, para reducir los impactos futuros.

Abstract:Despite the economic and environmental services that mangroves provide, they continue to be threatened by overexploitation, pollution, and land use change. Costa Rica has mangrove areas on the Pacific and Caribbean coasts, and cover has been declining since the 1980s. However, data on mangrove coverage are not continually updated and are often based on inaccurate estimates. It is therefore necessary to assess the current extension and variation of the mangrove cover in recent years, to determine changes. The mangrove cover was analyzed in two mangrove forests located in Bahía Culebra, North Pacific: Iguanita and Playa Panamá. For this, aerial photographs and satellite imagery were used to study changes for a 65 year period (1945-2010). Spatio-temporal changes were found in mangrove coverage, adjacent forests and areas without vegetation. Lower mangrove cover occurred during the 1970s (28.4 ha in Iguanita and 4.8 ha in Playa Panamá); but increased in recent years (38.9 ha in Iguanita and 12.0 ha in Panamá). Changes in forest cover by the Iguanita and Playa Panama mangroves were related to the history of land use around Bahía Culebra. Before 1980, there was extensive and intensive cattle ranching, increasing the deforestation rate; after that year, these practices were abandoned and secondary forest coverage increased until 2000. To ensure the adequate protection of mangroves, it is not only important to protect mangrove forests, but it is also necessary to establish buffer zones on their surroundings, to mitigate and/or reduce possible impacts. Rev. Biol. Trop. 64 (3): 955-964. Epub 2016 September 01.

Classificação orientada a objeto de imagens de sensoriamento remoto em estudos epidemiológicos sobre leishmaniose visceral em área urbana / Object-oriented remote sensing image classification in epidemiological studies of visceral leishmaniasis in urban areas / Clasificación orientada a objetos procedentes de imágenes satélite en los estudios epidemiológicos sobre leishmaniasis visceral en zonas urbanas

Neste estudo, explorou-se o uso da classificação orientada a objeto de imagens de sensoriamento remoto em estudos epidemiológicos sobre leishmaniose visceral (LV) em áreas urbanas. A classificação orientada a objeto foi aplicada a cenas Landsat 5 TM da cidade de Teresina, Piauí, Brasil, para obtenção de informações ambientais e temperatura. Para o período de 1993-1996, a taxa de incidência de LV nos setores censitários da cidade foi positivamente correlacionada com a área do setor censitário coberta por vegetação densa, rasteira e solo exposto e negativamente com a área coberta por água e áreas densamente ocupadas. No período de 2001-2006, foram encontradas correlações positivas com vegetação densa, rasteira, solo exposto e áreas densamente ocupadas e negativas com áreas urbanas com alguma vegetação. A temperatura da superfície terrestre foi negativamente associada à incidência de LV nos dois períodos. A classificação orientada a objeto pode ser útil para caracterizar paisagens associadas à ocorrência da LV em áreas urbanas e delimitar áreas de risco para definição de prioridades na implementação de intervenções.

This study explored the use of object-oriented classification of remote sensing imagery in epidemiological studies of visceral leishmaniasis (VL) in urban areas. To obtain temperature and environmental information, an object-oriented classification approach was applied to Landsat 5 TM scenes from the city of Teresina, Piauí State, Brazil. For 1993-1996, VL incidence rates correlated positively with census tracts covered by dense vegetation, grass/pasture, and bare soil and negatively with areas covered by water and densely populated areas. In 2001-2006, positive correlations were found with dense vegetation, grass/pasture, bare soil, and densely populated areas and negative correlations with occupied urban areas with some vegetation. Land surface temperature correlated negatively with VL incidence in both periods. Object-oriented classification can be useful to characterize landscape features associated with VL in urban areas and to help identify risk areas in order to prioritize interventions.

Este estudio investigó el uso de la clasificación orientada a objetos de imágenes satélite en estudios epidemiológicos acerca de la leishmaniasis visceral (LV) en zonas urbanas. Se aplicó la clasificación orientada a objetos en escenas Landsat 5 TM de la ciudad de Teresina, Piauí, Brasil, para obtener información ambiental y temperatura. De 1993 a 1996, la tasa de incidencia de LV en los sectores censales de la ciudad se correlacionó positivamente con el área del sector censal cubierto por vegetación densa, pastos y suelo desnudo, y negativamente con el área cubierta por agua y zonas densamente pobladas. De 2001 a 2006 se han encontrado correlaciones positivas con vegetación densa, vegetación tipo maleza, suelo desnudo y zonas densamente pobladas; y negativas con áreas urbanas con poca vegetación. La temperatura se asoció negativamente con la incidencia de la LV en ambos períodos. La clasificación orientada a objetos puede ser útil para caracterizar los paisajes asociados a la ocurrencia de la LV en áreas urbanas y delimitar zonas de riesgo para establecer prioridades de intervención.