American Visceral Leishmaniasis: Evalutation of parameters related to the vectorial capacity of Lutzomyia longipalpis in the urban area of Panorama municipality, São Paulo state, Brasil.

Author(s)

Fredy Galvis Ovallos

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Saúde Pública (FSP/CIR)
• Defense date: 2016-02-26

Examining board members

Eunice Aparecida Bianchi Galati; Claudio Casanova; Mara Cristina Pinto; Maria Anice Mureb Sallum; José Eduardo Tolezano

• Advisor: Eunice Aparecida Bianchi Galati

Abstract

Introduction: Visceral leishmaniasis (VL) is an important public health problem in Brazil, where annually about 3000 cases are notified. In the later years VL has spread through some states, associated mainly to environmental, anthropic and migratory process. Visceral leishmaniasis is caused by the infection with Leishmania infantum chagasi transmitted by the sand fly species Lutzomyia longipalpis (Diptera: Psychodidae). This species have a broad distribution in the Americas, however, there are evidences suggesting that it constitutes a cryptic species complex. The VL transmission dynamic is modulated by focal ecological factors that influence the pathogen-vector-host interactions. Thus, the analyses of variables associated to this interaction could contributes to elucidate the epidemiological links and to the public health decision-making. Objective: To evaluate parameters related to the vectorial capacity of Lutzomyia longipalpis in the Panorama municipality, São Paulo state, Brazil. Methods: Monthly captures of sand flies were undertaken during 48 months to evaluate the spatial and temporal distribution of Lu. longipalpis and its natural infection with Le. i. chagasi. Experiments of capture-mark-release-recapture to estimate the population survival, the gonotrophic cycle duration and the attractiveness of the most frequent host to Lu. longipalpis were also performed. Additionally experiments to evaluate the blood feeding rate of Lu. longipalpis on dog, experimental infection and the vectorial competence were undertaken. Results: In the Panorama municipality, Lu. longipalpis presents the highest frequencies during the rainy season (October - March) with high densities in areas with vegetation near to the domiciles and with the animal husbandry. In this areas was also demonstrated the circulation of sand flies naturally infected with Le. i. chagasi. Besides, it was corroborated that Lu. longipalpis presents eclectic haematophagic habit, high survival rates and it is competent to transmit Le. i. chagasi. It was also observed the heterogeneity of the female infection rates after them take the blood meal on infected dogs and a short time to complete the extrinsic incubation period. Conclusions: the observations of this study corroborate the vectorial capacity of Lu. longipalpis and reinforce the epidemiological importance of this species in the transmission of Le. i. chagasi. Considering the high vectorial efficiency of Lu. longipalpis and the presence of conditions favoring the interaction of the VL ecological components (competent vectors, infected hosts and susceptible humans), environmental management as well as educational and health promotion measures are recommended to the municipality authorities to reduce the potential risk of human infections. (AU)

• FAPESP's process: 11/23541-1 - AMERICAN VISCERAL LEISHMANIASIS: EVALUATION OF THE VECTORIAL CAPACITY PARAMETERS OF Lutzomyia longipalpis IN URBAN AREA IN THE SAO PAULO STATE, BRAZIL
• Grantee: Fredy Galvis Ovallos
• Support Opportunities: Scholarships in Brazil - Doctorate