BACKGROUND Aedes aegypti and Aedes albopictus are the most important arbovirus vectors in the world. OBJECTIVES This study aimed to investigate and compare the infestation pattern of these species in a neighbourhood of Recife, Brazil, endemic for arboviruses in 2005 (T1) and 2013 (T2). METHODS Infestation, distribution and relative abundance of these sympatric species were recorded by egg collection using a network of 59 sentinel ovitraps (s-ovt) at fixed sampling stations for 12 months in T1 and T2. FINDINGS A permanent occupation pattern was detected which was characterised by the presence of egg-laying females of one or both species with a high ovitrap positivity index (94.3 to 100%) throughout both years analysed. In terms of abundance, the total of eggs collected was lower (p < 0.005) in T2 (146,153) than in T1 (281,103), although ovitraps still displayed a high index of positivity. The spatial distribution showed the presence of both species in 65.1% of the 148 s-ovt assessed, while a smaller number of traps exclusively contained Ae. aegypti (22%) or Ae. albopictus (13.2%) eggs. MAIN CONCLUSIONS Our comparative analysis demonstrated the robustness of the spatial occupation and permanence of Ae. aegypti and Ae. albopictus populations in this endemic urban area.

BACKGROUND Fluctuations in climate have been associated with variations in mosquito abundance. OBJECTIVES To analyse the influence of precipitation, temperature, solar radiation, wind speed and humidity on the oviposition dynamics of Aedes aegypti in three distinct environmental areas (Brasília Teimosa, Morro da Conceição/Alto José do Pinho and Dois Irmãos/Pintos) of the city of Recife and the Fernando de Noronha Archipelago northeastern Brazil. METHODS Time series study using a database of studies previously carried out in the areas. The eggs were collected using spatially distributed geo-referenced sentinel ovitraps (S-OVTs). Meteorological satellite data were obtained from the IRI climate data library. The association between meteorological variables and egg abundance was analysed using autoregressive models. FINDINGS Precipitation was positively associated with egg abundance in three of the four study areas with a lag of one month. Higher humidity (β = 45.7; 95% CI: 26.3 - 65.0) and lower wind speed (β = −125.2; 95% CI: −198.8 - −51.6) were associated with the average number of eggs in the hill area. MAIN CONCLUSIONS The effect of climate variables on oviposition varied according to local environmental conditions. Precipitation was a main predictor of egg abundance in the study settings.

The use of attractants and larvicides in oviposition traps is of practical interest for the surveillance and control of urban mosquitoes. In addition to increasing the safety of the traps, this combination is essential for an attract-and-kill control strategy based on trapping mosquito eggs. The combination of Bacillus thuringiensis var. israelensis (Bti) and grass infusion (GI) vs. GI alone were tested for their ability to attract in paired BR-OVT traps in the backyards of 10 houses in Recife, Brazil, for a period of 45 days. Results show that females prefer to oviposit in traps containing Bti (363 compared with 251 egg rafts over 45 days). Results from a one-year trial on the efficacy of BR-OVT traps loaded with GI and Bti as a sampling tool to monitor temporal fluctuations in the population densities of Culex quinquefasciatus in an urban environment are also reported. From December 2006-January 2007, one trap per home was installed and maintained for 348 consecutive days in 134-151 houses located in three urban blocks. Throughout the one-year field trial a total of 43,151 Culex egg rafts were collected in the traps. The data show that BR-OVT loaded with GI and Bti is sensitive enough to demonstrate continuous reproductive activity of Cux. quinquefasciatus in the study area throughout the year and to monitor temporal fluctuations in population density.

A new approach to dengue vector surveillance based on permanent egg-collection using a modified ovitrap and Bacillus thuringiensis israelensis(Bti) was evaluated in different urban landscapes in Recife, Northeast Brazil. From April 2004 to April 2005, 13 egg-collection cycles of four weeks were carried out. Geo-referenced ovitraps containing grass infusion, Bti and three paddles were placed at fixed sampling stations distributed over five selected sites. Continuous egg-collections yielded more than four million eggs laid into 464 sentinel-ovitraps over one year. The overall positive ovitrap index was 98.5% (over 5,616 trap observations). The egg density index ranged from 100 to 2,500 eggs per trap-cycle, indicating a wide spread and high density of Aedes aegypti (Diptera: Culicidae) breeding populations in all sites. Fluctuations in population density over time were observed, particularly a marked increase from January on, or later, according to site. Massive egg-collection carried out at one of the sites prevented such a population outbreak. At intra-site level, egg counts made it possible to identify spots where the vector population is consistently concentrated over the time, pinpointing areas that should be considered high priority for control activities. The results indicate that these could be promising strategies for detecting and preventing Ae. aegypti population outbreaks.

An ovitrap (BR-OVT) based on physical and chemical stimuli for attracting gravid Culex quinquefasciatus (Diptera: Culicidae) females was developed and evaluated under laboratory and field conditions. Attractants were assayed using alternative chamber bioassays prior to being used in the BR-OVT oviposition trap. A significant preference of gravid females for sites containing conspecific egg rafts was observed, as a response to the natural oviposition pheromone, as well as for sites treated with the synthetic pheromone erythro-6-acetoxy-5-hexadecanolide. Five- to 20-day old grass infusion was strongly attractive to gravid females for laying eggs. On the other hand, entomopathogenic Bacillus sphaericus (Bs) did not influence the choice of an oviposition site when used in combination with grass infusion and can therefore be used as a larvicide in ovitraps. Results from field trials showed that the BR-OVT with grass infusion and with or without Bs works as a preferred oviposition site for Cx. quinquefasciatus. The BR-OVT was more effective for egg collection when placed indoors and comparison with the number of egg rafts laid in cesspits over 40 days indicates that this very simple ovitrap may be a useful tool for monitoring populations of the most important of the vectors of bancroftian filariasis.

A prevalência da filariose canina causada por Dirofilaria immitis e Dipetalonema reconditum, foi estimada após a realização de inquérito hemoscópico em 1.519 cães domiciliados. Foram examinados 1.097 cães nos sete distritos sanitários da cidade de Maceió, Alagoas, 204 na Ilha de Santa Rita e 218 na cidade de Paripueira. Em Maceió, foram detectados 15 (1,3%) cães com microfilárias (MF) de D. immitis e 15 (1,3%) com MF de D. reconditum. Todos os casos positivos foram considerados autóctones. As MF de D. immitis e de D. reconditum mediram 298,1µm e 249,2µm de comprimento e 7,3µm e 4,4µm de largura, respectivamente. Além do diagnóstico parasitológico pela técnica de gota espessa (100µL), foi utilizado o teste imunológico Witness, para detecção de antígeno filarial circulante, o qual confirmou os dados parasitológicos e permitiu a detecção de casos de infecção oculta. De um total de 6.579 fêmeas examinadas, pertencentes a seis espécies de mosquitos, oito (0,1%) fêmeas de Culex quinquefasciatus foram encontradas naturalmente infectadas com larvas de D. immitis. Estes resultados demonstram a presença simultânea de D. immitis e D. reconditum na mesma área geográfica.

A survey on the prevalence of Dirofilaria immitis and Dipetalonema reconditum was conducted in 1,519 dogs from Maceió and two coastal areas in the State of Alagoas, Northeast Brazil, from 1995 to 1999, by testing for microfilariae in blood. All blood samples were from exclusively domiciled dogs with a known history, showing that the infections were autochthonous, confirming transmission of canine filariasis in these areas. In Greater Metropolitan Maceió, 15 (1.3%) microfilaremic dogs were detected with D. immitis and 15 (1,3%) with D. reconditum. In the southern coastal area there was an estimated prevalence of 12.7% for D. immitis. D. immitis and D. reconditum microfilaria were 298.1µm and 249.2µm long and 7.3µm and 4.4µm wide, respectively. A Witness immunotest that detects D. immitis antigen was used to confirm parasitological results and reveal occult dirofilariasis cases. Of the total 6,579 females examined, 8 (0.1%) Culex quinquefasciatus were observed to be naturally infected with D. immitis larvae. These results proved dirofilariasis transmission in Maceió and demonstrated D. reconditum in the same geographic area.

A prevalência da filariose canina causada por Dirofilaria immitis e Dipetalonema reconditum, foi estimada após a realização de inquérito hemoscópico em 1.519 cães domiciliados. Foram examinados 1.097 cães nos sete distritos sanitários da cidade de Maceió, Alagoas, 204 na Ilha de Santa Rita e 218 na cidade de Paripueira. Em Maceió, foram detectados 15 (1,3%) cães com microfilárias (MF) de D. immitis e 15 (1,3%) com MF de D. reconditum. Todos os casos positivos foram considerados autóctones. As MF de D. immitis e de D. reconditum mediram 298,1µm e 249,2µm de comprimento e 7,3µm e 4,4µm de largura, respectivamente. Além do diagnóstico parasitológico pela técnica de gota espessa (100µL), foi utilizado o teste imunológico Witness, para detecção de antígeno filarial circulante, o qual confirmou os dados parasitológicos e permitiu a detecção de casos de infecção oculta. De um total de 6.579 fêmeas examinadas, pertencentes a seis espécies de mosquitos, oito (0,1%) fêmeas de Culex quinquefasciatus foram encontradas naturalmente infectadas com larvas de D. immitis. Estes resultados demonstram a presença simultânea de D. immitis e D. reconditum na mesma área geográfica.

A survey on the prevalence of Dirofilaria immitis and Dipetalonema reconditum was conducted in 1,519 dogs from Maceió and two coastal areas in the State of Alagoas, Northeast Brazil, from 1995 to 1999, by testing for microfilariae in blood. All blood samples were from exclusively domiciled dogs with a known history, showing that the infections were autochthonous, confirming transmission of canine filariasis in these areas. In Greater Metropolitan Maceió, 15 (1.3%) microfilaremic dogs were detected with D. immitis and 15 (1,3%) with D. reconditum. In the southern coastal area there was an estimated prevalence of 12.7% for D. immitis. D. immitis and D. reconditum microfilaria were 298.1µm and 249.2µm long and 7.3µm and 4.4µm wide, respectively. A Witness immunotest that detects D. immitis antigen was used to confirm parasitological results and reveal occult dirofilariasis cases. Of the total 6,579 females examined, 8 (0.1%) Culex quinquefasciatus were observed to be naturally infected with D. immitis larvae. These results proved dirofilariasis transmission in Maceió and demonstrated D. reconditum in the same geographic area.

The effect of sunlight on the efficacy and persistence of an experimental tablet formulation based on Bacillus thuringiensis sorovar. israelensis (C4P1) was evaluated against Aedes aegypti larvae under simulated field conditions. The initial mortality ranged from 93 to 100%, and the residual activity ( > or = 70% mortality) recorded in containers exposed to sunlight or shade were, respectively, 13-35 days and 40-54 days. The results suggest that C4P1 can provide long-term larvicidal effect and operational advantages.

Bacillus spp. based larvides are increasingly replacing, with numerous advantages, chemical insecticides in programmes for controlling black fly and mosquito populations. Brazil was among the pioneers in adopting Bacillus thuringiensis israelensis (B.t.i) to control black flies. However, the major current mosquito control programme in Brazil, the Programme for Eradication of Aedes aegypti launched in 1997, only recently decided to replace temephos by B.t.i based larvicides, in the State of Rio de Janeiro. In the last decade, works developed by research groups in Brazilian institutions have generated a significant contribution to this subject through the isolation of B. sphaericus new strains, the development of new products and the implementation of field trials of Bacillus efficacy against mosquito species under different environmental conditions.

The relationship between ingestion of microfilariae (mf), production of infective larvae (L3) and mf density in human blood has been suggested as an important determinant in the transmission dynamics of lymphatic filariasis. Here we assess the role of these factors in determining the competence of a natural vector Culex quinquefasciatus and a non vector Aedes aegypti to transmit Wuchereria bancrofti. Mosquitoes were infected via a membrane feeding procedure. Both mosquito species ingested more than the expected number of microfilariae (concentrating factor was 1.28 and 1.81 for Cx. quinquefasciatus and Ae. aegypti, respectively) but Cx. quinquefasciatus ingested around twice as many mf as Ae. aegypti because its larger blood meal size. Ae. aegypti showed a faster mf migration capacity compared to Cx. quinquefasciatus but did not allow parasite maturation under our experimental conditions. Similar proportions of melanized parasites were observed in Ae. aegypti (2.4%) and Cx. quinquefasciatus (2.1%). However, no relationship between rate of infection and melanization was observed. We conclude that in these conditions physiological factors governing parasite development in the thorax may be more important in limiting vectorial competence than the density of mf ingested.

Um projeto piloto para o controle da filariose bancroftiana foi desenvolvido em duas áreas do Recife, com índices iniciais de prevalência de microfilaremia de 10%. Nas duas áreas, foi aplicado tratamento em massa com doses baixas de dietilcarbamazina. Em uma das áreas, esse tratamento foi associado ao controle do vetor, integrando medidas físicas, como o uso de camadas flutuantes de esferas de poliestireno, ao tratamento periódico dos criadouros com a bactéria entomopatógena Bacillus sphaericus. Como resultado, a densidade populacional do vetor, da ordem de sessenta a 120 Culex/quarto/noite antes das intervenções, foi drasticamente reduzida, mantendo-se, durante dois anos, em valores entre quatro e 16 Culex/quarto/noite. Neste contexto, as ações para envolver a comunidade escolar local no controle do vetor resultaram na realização de atividades curriculares e extraclasses, culminando com a participação efetiva de grupos de alunos ("Vigilantes de Vetores") na aplicação das medidas de controle e na divulgação de conhecimentos básicos sobre a biologia do Culex quinquefasciatus. O entusiástico envolvimento de professores e alunos mostrou ser a escola um espaço aberto à participação em programas desta natureza.

A pilot study for the control of Bancroftian filariasis transmission was developed in two areas of Recife, Brazil, where microfilaraemic prevalence was 10% in 1991. Mass treatment with diethylcarbamazine (DEC) using low and spaced doses was employed in both areas. In one such instance, DEC therapy was associated with vector control using physical measures and periodic treatment of Culex breeding sites with the entomopathogen Bacillus sphaericus. The vector population density, reaching 60 120 Culex/room /night before the intervention, was drastically reduced to 4 16 Culex/room/night, and maintained at this level for more than two years. Actions to engage the local school community in the vector control process were implemented, and as a consequence several classroom and extracurricular activities were put into practice, culminating with the effective participation of a team of students called the "Vector Vigilantes", in the application of control measures against the vector. The enthusiastic involvement of schoolteachers and students pointed to schools as a place amenable to programs such as this.

Um projeto piloto para o controle da filariose bancroftiana foi desenvolvido em duas áreas do Recife, com índices iniciais de prevalência de microfilaremia de 10%. Nas duas áreas, foi aplicado tratamento em massa com doses baixas de dietilcarbamazina. Em uma das áreas, esse tratamento foi associado ao controle do vetor, integrando medidas físicas, como o uso de camadas flutuantes de esferas de poliestireno, ao tratamento periódico dos criadouros com a bactéria entomopatógena Bacillus sphaericus. Como resultado, a densidade populacional do vetor, da ordem de sessenta a 120 Culex/quarto/noite antes das intervenções, foi drasticamente reduzida, mantendo-se, durante dois anos, em valores entre quatro e 16 Culex/quarto/noite. Neste contexto, as ações para envolver a comunidade escolar local no controle do vetor resultaram na realização de atividades curriculares e extraclasses, culminando com a participação efetiva de grupos de alunos ("Vigilantes de Vetores") na aplicação das medidas de controle e na divulgação de conhecimentos básicos sobre a biologia do Culex quinquefasciatus. O entusiástico envolvimento de professores e alunos mostrou ser a escola um espaço aberto à participação em programas desta natureza.

A pilot study for the control of Bancroftian filariasis transmission was developed in two areas of Recife, Brazil, where microfilaraemic prevalence was 10% in 1991. Mass treatment with diethylcarbamazine (DEC) using low and spaced doses was employed in both areas. In one such instance, DEC therapy was associated with vector control using physical measures and periodic treatment of Culex breeding sites with the entomopathogen Bacillus sphaericus. The vector population density, reaching 60 120 Culex/room /night before the intervention, was drastically reduced to 4 16 Culex/room/night, and maintained at this level for more than two years. Actions to engage the local school community in the vector control process were implemented, and as a consequence several classroom and extracurricular activities were put into practice, culminating with the effective participation of a team of students called the "Vector Vigilantes", in the application of control measures against the vector. The enthusiastic involvement of schoolteachers and students pointed to schools as a place amenable to programs such as this.

Integrated control measures against Culex quinquefasciastus have been implemented in a pilot urban area in Recife, Brazil. About 3,000 breeding sites found within the operational area were responsible for very high mosquito densities recorded during the pretrial period. Physical control measures have been applied to cess pits before starting a series of 37 treatments of the other sites with Bacillus sphaericus strain 2362, over 27 months. In spite of the difficulties due to environmental conditions, very significant reductions in preimaginal population of C. quinquefasciatus were achieved and, as a consequence, low adult mosquito densities were maintained for a relatively long period of time. Entomological and environmental data gathered in this pilot project can contribute to design an integrated mosquito control program in Recife city.