Júlio Cesar Voltolini

Associação entre incidência de dengue e variáveis climáticas

OBJECTIVE To describe the occurrence of autochthonous dengue cases according to sex, age, suspected infection site and its relation with climatic variables. METHODS Autochthonous dengue cases reported in São Sebastião, Southern Brazil, from 2001 to 2002 and confirmed in laboratory were studied. Larval density was verified by three indexes: building, recipients and Breteau. The relationship between rainfall, temperature and number of cases was analyzed through Spearmans correlation using time lag. RESULTS The annual incidence coefficients for 2001 and 2002 were 80.3 and 211.1 per 10,000 inhabitants, respectively. Most dengue cases (n=1,091; 65%) were reported in the districts central area. Females (n=969; 60%) and the age groups 20 to 29 and 30 to 39 years old of both sexes were mostly affected. Significant associations were not observed between climatic variables and the number of dengue cases in the first month; however, this association became evident in the second month throughout the fourth month. CONCLUSIONS The association between the number of dengue cases and abiotic factors identified the time lag in which rain and temperature favored the occurrence of new cases. These aspects, associated to tourist vulnerability in the coastal area, promoted conditions for dengue occurrence. The urbanization without sanitary infrastructure possibly affected mosquito density and dengue incidence. Such factors may have contributed to mosquito dispersion and dissemination of different dengue serotypes.

Dominância de Aedes aegypti sobre Aedes albopictus no litoral sudeste do Brasil

OBJECTIVE To assess infestation of Aedes aegypti and Aedes albopiticus and describe their association with weather conditions and container colonization in urban areas. METHODS The town of São Sebastião in the southeastern coast of Brazil was selected. It was used data from the Dengue and Yellow Fever Vector Control Program of the State of S o Paulo, Brazil, that encompasses entomological surveillance at strategic positions, traps and foci demarcation. Strategic positions sites are fixed sites with containers in adequate conditions for larvae growth. Statistical analysis was performed using Kruskal-Wallis test, Dwass-Steel-Chritchlow-Fligne test and Mann-Whitney test. RESULTS There was found an annual growth of positive traps and strategic positions of Ae. aegypti and a drop in Ae. albopictus population. An increase in immature Ae. aegypti and a drop of the other species were also seen. A gradual increase of positive dwellings for Ae. aegypti was noticed outgrowing Ae. albopictus population. There was a weak correlation of the Aedes species with abiotic factors. Higher numbers of immature mosquitoes of both species were found in artificial containers which could be eliminated. CONCLUSIONS The study showed Ae. aegypti was predominant in urban areas, indicating that its growth seems to have affected the coexistence with other species. Natural selection could be in place contributing to Aedes aegypti and albopictus species separation.

Variação sazonal de Aedes aegypti e Aedes albopictus no município de Potim, São Paulo

OBJETIVO: Verificar a variacao sazonal de Aedes aegypti e Aedes albopictus e testar a associacao da abundância das especies com fatores abioticos. METODOS: De novembro de 2002 a outubro de 2003 foram realizadas coletas mensais de imaturos de culicideos em pneus-armadilha expostos por 15 dias em area urbana de Potim, Vale do Paraiba, SP, Brasil. Os imaturos foram criados em laboratorio por 29 dias e identificados segundo especie. A associacao com temperatura, pluviosidade e umidade relativa do ar foram testadas utilizando-se correlacoes de Spearman (r s). As estatisticas descritivas foram apresentadas pela media e erro-padrao (EP) e nos testes foi utilizado alfa=0,05. RESULTADOS: Do total de 20.727 imaturos coletados, 95,3% eram Ae. aegypti e 4,7% Ae. albopictus. A especie Ae. aegypti esteve presente em todas as estacoes/meses do ano e Ae. albopictus somente de novembro a julho. As associacoes das especies coletadas com fatores abioticos foram significantes em relacao a temperatura maxima para Ae. aegypti (p=0,04) e Ae. albopictus (p=0,01), e pluviosidade (p=0,02) para esta ultima especie. CONCLUSOES: Ambas especies apresentaram variacao sazonal. Porem, Ae. aegypti esteve presente durante todo ano, com maiores quedas de densidade entre abril e maio e entre junho e julho. Ae. albopictus menos abundante, foi encontrado apenas de novembro a julho, com o pico em abril. A maior abundância de Ae. aegypti em relacao a Ae. albopictus em area urbana mostrou maior capacidade de Ae. aegypti em colonizar pneus. A existencia de tal criadouro no ambiente pode ser importante na manutencao e abundância de Ae. aegypti.

Evaluation of the cytotoxic and genotoxic potential of water from the River Paraíba do Sul, in Brazil, with the Allium cepa L. test

This work investigated the cytotoxic and genotoxic potential of water from the River Paraíba do Sul (Brazil) using Allium cepa roots. An anatomo-morphological parameter (root length), mitotic indices, and frequency of micronuclei were analysed. Eight bulbs were chosen at random for treatment for 24 to 120 hours with the River water collected in the years of 2005 and 2006 from sites in the cities of Tremembé and Aparecida (São Paulo state, Brazil). Daily measurements of the length of the roots grown from each bulb were carried out throughout the experiment. Mitotic index (MI) and frequency of micronuclei (MN) were determined for 2000 cells per root, using 3-5 root tips from other bulbs (7-10). Only in the roots treated with samples of the River water collected in 2005 in Tremembé city was there a decrease in the root length growth compared to the respective control. However, a reduction in MI values was verified for both sites analysed for that year. Considering the data involving root length growth and especially MI values, a cytotoxic potential is suggested for the water of the River Paraíba do Sul at Tremembé and Aparecida, in the year of 2005. On the other hand, since in this year the MN frequency was not affected with the river water treatments, genotoxicity is not assumed for the river water sampled at the aforementioned places.

Density of Aedes aegypti and Aedes albopictus and its association with number of residents and meteorological variables in the home environment of dengue endemic area, São Paulo, Brazil.

BackgroundMeasure the populations of Ae. aegypti and Ae. albopictus adults according to sex and location inside or outside the residence, estimate Ae. aegypti female density per house and per resident, and test the association with abiotic factors.MethodsAdult mosquitoes were collected monthly with a hand net and portable electric catcher in the peridomiciliary and intradomiciliary premises of residences in an urban area with ongoing dengue transmission in the municipality of São Sebastião, Brazil, from February 2011 to February 2012.ResultsOf the 1,320 specimens collected, 1,311 were Ae. aegypti, and nine were Ae. albopictus. A total of 653 male and 658 female of Ae. aegypti were recorded, of which 80% were intradomiciliary. The mean density of Ae. aegypti adult females was 1.60 females/house and 0.42 females/resident. There was an association between the number of females and the number of residents in both intradomiciliary and peridomiciliary premises (r2 = 0.92; p < 0.001 and r2 = 0.68; p < 0.001, respectively). There was an association between the number of females and the mean and total rainfall; the correlation was better in peridomiciliary premises (p = 0.00; r2 = 77%) than intradomiciliary premises in both cases (p = 0.01; r2 = 48%). Minimum temperature was associated in both environments, exhibiting the same coefficient of determination (p = 0.02; r2 = 40%). The low frequency of Ae. albopictus (seven females and two males) did not allow for detailed evaluation.ConclusionsAe. aegypti is well established within the urban area studied, and the frequency of isolation is higher inside the houses. Female density was directly proportional to the number of residents in the houses. Our data show that human population density positively affects the number of Ae. aegypti females within the residence. Meteorological variables also affected mosquito populations. These data indicate a high probability of human-vector contact, increasing the possible transmission and spread of the DEN virus. Entomological indicators of adult females revealed important information complimenting what was obtained with traditional Stegomyia indices. This information should be a part of an interconnected data set for evaluating and controlling the vector.

Study of the distribution and abundance of the eggs of Aedes aegypti and Aedes albopictus according to the habitat and meteorological variables, municipality of São Sebastião, São Paulo State, Brazil

BackgroundThis study focused on the distribution and abundance of the eggs of Aedes aegypti and Aedes albopictus.MethodsEighty ovitraps were exposed for four days of each month in peri- and intradomiciliary environments of 40 urban residences on 20 street blocks that were drawn monthly in Sebastião, SP, between February 2011 and February 2012. The monthly distribution of positive ovitrap indices (POI) and mean egg counts per trap (MET) of Ae. aegypti and Ae. albopictus were analyzed using the Kruskal-Wallis test, followed by the Dwass-Steel-Critchlow-Fligner (DSCF) test. Spearmans rank correlation coefficient and simple linear regression were used to determine the association between the meteorological variables of temperature and rainfall and the number of ovitraps with eggs and the egg count.ResultsThe POI and MET of Ae. aegypti were higher in peridomiciliary premises. A positive correlation was found between the temperature and the number of ovitraps with eggs and the egg count of this species in domestic environments. There was no difference in the POI and MET of Ae. albopictus between the environments. A positive correlation was found between temperature and positive ovitraps of Ae. albopictus in peridomiciliary premises. The POI and MET of Ae. aegypti were higher than those of Ae. albopictus.ConclusionsPeridomiciliary premises were the preferred environments for oviposition of Ae. aegypti. The use of ovitraps for surveillance and vector control is reiterated.

Método de varredura para exame de criadouros de vetores de dengue e febre amarela urbana

Com objetivo de estimar o numero minimo de varreduras para coletar uma amostra representativa das larvas presentes em um grande recipiente, foram adicionadas 200 larvas de quarto estadio em um tambor de 80 litros de agua. Com auxilio de peneira plastica, foram feitas dez varreduras em cada replica do experimento. Os resultados indicaram que oito varreduras foram suficientes para coletar ate 72% do total de 200 larvas de quarto estadio presentes no criadouro, ou seja, uma media de 143±1,97. A tecnica mostrou ser de facil e eficiente execucao quanto a inspecao de criadouros com grande volume de agua. Isto reforca sua utilizacao como instrumento com grande potencial para vigilância vetorial na rotina dos programas de controle de vetores do dengue e febre amarela.

Competição entre larvas de Aedes aegypti e Aedes albopictus em laboratório

This study had the aim of evaluating the effects of intra and interspecies larval competition between Aedes aegypti and Aedes albopictus, survival of larvae time taken to develop and wing length. The experiment was carried out with three densities and five proportions of the species. Aedes aegypti survival was greater than Aedes albopictus survival at intermediate density, while it was lower at high density. Only the time taken for Aedes albopictus to develop was affected. The differences found in comparing the species combinations demonstrated that the mean wing length of Aedes aegypti was generally greater than that of Aedes albopictus. For both species, competition had greater effect on wing length and survival than on the time taken to develop. Aedes aegypti seems to present better competitive capacity than does Aedes albopictus, at intermediate density.

Efeito da água de criação larval na oviposição de Aedes aegypti em laboratório

To evaluate the influence of larval rearing water on Aedes aegypti oviposition, four types of water were provided for gravid females. It was observed that more eggs were laid in the mixed larval rearing water (2,837) than in the Aedes albopictus water (690) or control water (938), but that this number was similar to what was seen in the Aedes aegypti water (2,361).