Use of Kisser glycerol gelatin to prepare microscope slides of Phlebotomine sandflies (Diptera: Psychodidae)

Abstract INTRODUCTION: Appropriate preservation of specimens is important for taxonomic identification. In sandfly research, various methods have been used for slide preparation; however, high cost, low commercial availability, and associated hazards make their use impossible in some studies. Therefore, the efficacy of Kisser glycerol gelatin for sandfly slide preparation was tested. METHODS: Kisser glycerol gelatin, as a substitute for Canada balsam and Berlese's fluid, was used for mounting sandflies. RESULTS: Forty-two mounted specimens were created and maintained even after 14 months. CONCLUSIONS: Use of Kisser glycerol gelatin is simple and efficient for preparing microscope slides of sandflies.

Serological tests fail to discriminate dogs with visceral leishmaniasis that transmit Leishmania infantum to the vector Lutzomyia longipalpis

Abstract INTRODUCTION The control of reservoirs for Leishmania infantum -induced zoonotic visceral leishmaniasis requires the identification of dogs posing a population risk. Here, we assessed the performance of several assays to identify Lutzomyia longipalpis infectious dogs. METHODS We evaluated 99 dogs that were positive for visceral leishmaniasis based on parasite identification. Serological analyses were performed using an enzyme-linked immunosorbent assay, immunofluorescence antibody tests in 1:40 and 1:80 dilutions, rapid dual path platform tests, immunochromatographic assay with a recombinant rK39 antigen, fast agglutination screening tests, and direct agglutination tests. We also performed PCR to analyze peripheral blood and xenodiagnosis. RESULTS Forty-six dogs infected at least one L. longipalpis specimen. Although the serological test sensitivities were above 85% for detecting L. longipalpis infectious dogs, none showed a satisfactory performance, as both specificity (0.06 to 13%) and the area under the receiver operating characteristic curve (45 to 53%) were low. The PCR results were also weak, with a sensitivity of 30%, specificity of 72%, and an area under the receiver operating characteristic curve of 51%. The infected L. longipalpis proportion was higher among asymptomatic dogs than symptomatic dogs. Among the symptomatic dogs, those with ulceration-free skin diseases were more infectious, with an odds ratio of 9.3 (confidence interval of 1.10 - 428.5). The larger the number of insects fed, the greater the detected infectiousness. CONCLUSIONS Our study supports the imperative to develop novel technologies for identifying the infectious dogs that transmit L. infantum for the benefit of public health.

Análise molecular da infecção natural de Lutzomyia longipalpis em área endêmica de leishmaniose visceral no Brasil / Molecular analysis of natural infection of Lutzomyia longipalpis in an endemic area for visceral leishmaniasis in Brazil

The main purpose of this study was to investigate natural infection by Leishmania chagasi in female sand flies in a visceral leishmaniasis (VL) focus on São Luís Island, Maranhão State, Brazil. Molecular analysis by polymerase chain reaction (PCR) was applied to determine the rate of natural infection of Lutzomyia longipalpis by L. chagasi in areas of old and recent human settlement on São Luís Island. Based on a sample of 800 female specimens captured from March to August 2005, the natural infection rate was 1.25 percent in an area of old settlement and 0.25 percent in two recently settled areas. Infection of L. longipalpis was detected in both areas, regardless of the number of reported human VL cases, indicating that other factors modulating infection in the wild need to be investigated. The results confirm PCR as a specific technique and an important tool for epidemiological surveillance.

O objetivo deste estudo foi investigar a infecção natural por Leishmania chagasi em flebotomíneos capturados em focos de leishmanioses visceral (LV) na ilha de São Luís, Maranhão, Brasil. Análise molecular por reação em cadeia da polimerase (PCR) foi aplicada para determinar a taxa de infecção natural de Lutzomyia longipalpis por L. chagasi em áreas de ocupação humana antiga e recente, na ilha de São Luís. Valendo-se de uma amostra de 800 fêmeas coletadas no período de março a agosto de 2005, foi possível determinar taxas de infecção natural equivalentes a 1,25 por cento em uma localidade de colonização antiga e 0,25 por cento em duas localidades de colonização recente. A infecção foi detectada nas duas localidades independentemente do número de casos humanos de LV notificados, o que demonstra que outros elementos que modulam a infecção no meio natural precisam ser investigados. Os resultados obtidos confirmam a PCR como técnica específica e importante ferramenta para as ações em vigilância epidemiológica.