Eliane Aparecida Fávaro

Physiological state of Aedes (Stegomyia) aegypti mosquitoes captured with MosquiTRAPs™ in Mirassol, São Paulo, Brazil

ABSTRACT We examined the best location in a house to install MosquiTRAPs, sticky ovitraps that attract and capture Aedes aegypti females and investigated the physiological state of captured female mosquitoes. The study was performed in a twenty-block area in Mirassol, São Paulo State, Brazil, in which five blocks were randomly chosen for MosquiTRAP installation. In each block, four houses were selected for the installation of eight traps: four indoors (bedroom, living room, bathroom, and kitchen) and four outdoors in the shade (two at the front of the house and two in the backyard). These houses were visited over an eight-week period. The outdoor MosquiTRAPs captured five times more females than indoor traps and appeared to be the best places to install MosquiTRAPs. There were no significant differences among indoor sites or among outdoor sites with respect to the number of females captured. The capacity of the MosquiTRAP to capture a large number of gravid Ae. aegypti females reinforces its potential as an entomological surveillance tool in dengue control programs.

Identification of the best ovitrap installation sites for gravid Aedes (Stegomyia) aegypti in residences in Mirassol, state of São Paulo, Brazil

This study aimed at identifying the best ovitrap installation sites for gravid Aedes aegypti in Mirassol, state of São Paulo, Brazil. Ovitraps were installed in ten houses per block over ten blocks. Four ovitraps were placed per residence, one in the bedroom, one in the living room, and two outdoors with one in a sheltered area and one in an outside site. Each week for eleven weeks, visits were made to examine the ovitraps and to change the paddles used for egg-laying. Eggs were analyzed according to the trap location. The results showed that the outdoor sites received significantly more oviposition than indoor sites. Additionally, in respect to the outdoor sites, the outside site received significantly more oviposition than the sheltered site. A strong correlation was observed between positive traps and egg numbers. The results are discussed with respect to the best installation site of the traps and their implications in surveillance and control of dengue vectors.

Assessment of entomological indicators of Aedes aegypti (L.) from adult and egg collections in São Paulo, Brazil

ABSTRACT We compared the presence and mean number of eggs from oviposition traps with the mean number of Aedes aegypti females captured by manual aspirators and by MosquiTRAPs™ to determine the sensitivity of each method and to standardize each indicator. The collections of adults and eggs were performed over 23 weeks in six neighborhoods of Mirassol, state of São Paulo, Brazil. A better assessment of indicators required larger number of MosquiTRAPs, but to quantify the number of females per house, one trap was sufficient. The sensitivities of MosquiTRAPs and manual aspirations to detect the presence of A. aegypti females were similar, but were lower compared to oviposition traps. The correlation coefficients between the number of females captured by MosquiTRAPs and manual aspirations and the number of eggs from oviposition traps were low, which may be a consequence of each method showing different stages of the mosquito life cycle.

Atividades de controle do dengue na visão de seus agentes e da população atendida, São José do Rio Preto, São Paulo, Brasil

The aim of this article was to identify daily situations experienced by dengue control agents in their relationship to local residents. A cross-sectional study applied questionnaires among vector control agents, community health workers, and a sample of local women. The answers by the dengue control agents and community health workers were grouped in the categories of work, private life, and community. The women were asked about the relationship with the vector control and community health workers. The difficulties cited in the private and work areas by the vector control agents were different from those reported by community health workers. At the community level they coincided and showed that neither group is adequately prepared to deal with these issues. Of the local women interviewed, 87.0% reported that they were well-informed or very well-informed about dengue, 84.0% stated that the work by the vector control agents and community health workers was always helpful, and 54.0% identified inappropriate visiting hours by vector control agents and community health workers as a difficulty. The study identified the need for a new job profile that would recognize and respect the specificities of the areas where their activities are conducted, integrating the communitys socio-environmental issues.

Aedes aegypti entomological indices in an endemic area for dengue in Sao Paulo State, Brazil

OBJECTIVE To evaluate the most productive types of properties and containers for Aedes aegypti and the spatial distribution of entomological indices. METHODS Between December 2006 and February 2007, the vectors immature forms were collected to obtain entomological indices in 9,875 properties in the Jaguare neighborhood of Sao Jose do Rio Preto, SP, Southeastern Brazil. In March and April 2007, a questionnaire about the conditions and characteristics of properties was administered. Logistic regression was used to identify variables associated with the presence of pupae at the properties. Indices calculated per block were combined with a geo-referenced map, and thematic maps of these indices were obtained using statistical interpolation. RESULTS The properties inspected had the following Ae. aegypti indices: Breteau Index = 18.9, 3.7 larvae and 0.42 pupae per property, 5.2 containers harboring Ae. aegypti per hectare, 100.0 larvae and 11.6 pupae per hectare, and 1.3 larvae and 0.15 pupae per inhabitant. The presence of yards, gardens and animals was associated with the presence of pupae. CONCLUSIONS Specific types of properties and containers that simultaneously had low frequencies among those positive for the vector and high participation in the productivity of larvae and pupae were not identified. The use of indices including larval and pupal counts does not provide further information beyond that obtained from the traditional Stegomyia indices in locations with characteristics similar to those of São José do Rio Preto. The indices calculated per area were found to be more accurate for the spatial assessment of infestation. The Ae. aegypti infestation levels exhibited extensive spatial variation, indicating that the assessment of infestation in micro areas is needed.

Assessment of the relationship between entomologic indicators of Aedes aegypti and the epidemic occurrence of dengue virus 3 in a susceptible population, São José do Rio Preto, São Paulo, Brazil

The aims of this study were to describe the occurrence of dengue in space and time and to assess the relationships between dengue incidence and entomologic indicators. We selected the dengue autochthonous cases that occurred between September 2005 and August 2007 in São José do Rio Preto to calculate incidence rates by month, year and census tracts. The monthly incidence rates of the city were compared to the monthly Breteau indices (BI) of the São José do Rio Region. Between December 2006 and February 2007, an entomological survey was conducted to collect immature forms of Aedes aegypti in Jaguaré, a São José do Rio Preto neighborhood, and to obtain entomological indices. These indices were represented using statistical interpolation. To represent the occurrence of dengue in the Jaguaré neighborhood in 2006 and 2007, we used the Kernel ratio and to evaluate the relationship between dengue and the entomological indices, we used a generalized additive model in a spatial case-control design. Between September 2005 and August 2007, the occurrence of dengue in São José do Rio Preto was almost entirely caused by DENV3, and the monthly incidence rates presented high correlation coefficients with the monthly BI. In Jaguaré neighborhood, the entomological indices calculated by hectare were better predictors of the spatial distribution of dengue than the indices calculated by properties, but the pupae quantification did not show better prediction qualities than the indices based on the container positivity, in relation to the risk of dengue occurrence. The fact that the municipalitys population had a high susceptibility to the serotype DENV3 before the development of this research, along with the almost total predominance of the occurrence of this serotype between 2005 and 2007, facilitated the analysis of the epidemiological situation of the disease and allowed us to connect it to the entomological indicators.

First genome sequence of St. Louis encephalitis virus (SLEV) isolated from a human in Brazil

St. Louis encephalitis virus (SLEV), a member of the family Flaviviridae, genus Flavivirus, is a causative agent of encephalitis in the Americas. In Brazil, sporadic cases of SLEV infection have been reported since 1953, but the first outbreak of SLEV in Brazil was identified only in 2007, concomitant with an outbreak of dengue virus (DENV) serotype 3. This finding, along with other reports, indicates that SLEV circulation in Brazil is largely unknown, and there may be epidemiological implications of the co-circulation of SLEV, DENV and other flaviviruses in Brazil. Here, we describe the first complete genome sequence of an SLEV strain isolated from a human patient in Brazil, strain BeH 355964. Phylogenetic analysis was performed to determine the genotype of BeH 355964 using the full-length genome and envelope (E) gene sequences separately. Both analyses showed that BeH 355964 could be classified as genotype V. Although the number of single gene sequences available is greater (such as for the E gene), the phylogenetic tree based on the complete genome sequence was better supported and provided further information about the virus.

Evaluation of two sweeping methods for estimating the number of immature Aedes aegypti (Diptera: Culicidae) in large containers

INTRODUCTION Here, we evaluated sweeping methods used to estimate the number of immature Aedes aegypti in large containers. METHODS III/IV instars and pupae at a 9:1 ratio were placed in three types of containers with, each one with three different water levels. Two sweeping methods were tested: water-surface sweeping and fi ve-sweep netting. The data were analyzed using linear regression. RESULTS The fi ve-sweep netting technique was more suitable for drums and water-tanks, while the water-surface sweeping method provided the best results for swimming pools. CONCLUSIONS Both sweeping methods are useful tools in epidemiological surveillance programs for the control of Aedes aegypti.

Using adult Aedes aegypti females to predict areas at risk for dengue transmission: A spatial case-control study

INTRODUCTION Traditional indices for measuring dengue fever risk in a given area are based on the immature forms of the vector (larvae and pupae surveys). However, this is inefficient because only adult female mosquitoes actually transmit the virus. Based on these assumptions, our objective was to evaluate the association between an entomological index obtained from adult mosquito traps and the occurrence of dengue in a hyperendemic area. Additionally, we compared its cost to that of the Breteau Index (BI). MATERIAL AND METHODS We performed this study in São José do Rio Preto, SP, Brazil, between the epidemiological weeks of 36/2012 and 19/2013. BG-Sentinel and BG-Mosquitito traps were installed to capture adult mosquitoes. Positive and negative cases of dengue fever were computed and geocoded. We generated biweekly thematic maps of the entomological index, generated by calculating the number of adult Aedes aegypti females (NAF) per 100 households during a week by kriging, and based on the number of mosquitoes captured. The relation between the occurrence of dengue fever and the NAF was tested using a spatial case-control design and a generalized additive model and was controlled by the coordinates of the positive and negative cases of dengue fever. RESULTS Our analyses showed that increases in dengue fever cases occurred in parallel with increases in the number of Ae. aegypti females. The entomological index produced in our study correlates positively with the incidence of dengue, particularly during intervals when vector control measures were applied less intensively. The operational costs of our index were lower than those of the BI: NAF used 71.5% less human resources necessary to measure the BI. CONCLUSIONS Spatial analysis techniques and the number of adult Ae. aegypti females were used to produce an indicator of dengue risk. The index can be applied at various levels of spatial aggregation for an entire study area, as well as for sub-areas, such as city blocks. Even though the index is adequate to predict dengue risk, it should be tested and validated in various scenarios before routine use.