Integrated Strategies for Aedes aegypti Control Applied to Individual Houses: An Approach to Mitigate Vectorial Arbovirus Transmission.

Aedes aegypti and Culex quinquefasciatus mosquitoes are vectors of different arboviruses that cause a large burden of disease in humans worldwide. A key step towards reducing the impact of arboviruses on humans can be achieved through integrated mosquito surveillance and control approaches. We carried out an integrated approach of mosquito surveillance and control actions to reduce populations of these insects along with a viral surveillance in a neighborhood of Recife (Northeastern Brazil) with high mosquito densities and arbovirus transmission. The actions were carried out in 40 different houses in the Nova Descoberta neighborhood. The area was divided into two groups, the control group using tools to monitor the mosquito density (1 OVT; 1 Double BR-ovt; monthly capture of alates) and the experimental group with control actions using surveillance tools in an intensified way (2 OVTs; 2 Double BR-ovts; fortnightly capture of alates; toxic baits). We evaluated the study's impact on the mosquito density via the Egg Density (ED) and Adult Density (AD) over a period of 12 cycles of 28 days each. The collected adult mosquitoes were processed via RT-qPCR for DENV, CHIKV and ZIKV and, subsequently, the Minimum Infection Rate (MIR) was calculated. After 12 cycles, we observed a 91% and 99% reduction in Aedes ED and AD in the monitored properties, as well as a 76% reduction in the AD of Cx. quinquefasciatus in the same properties. Moreover, we detected circulating arboviruses (DENV and ZIKV) in 19.52% of captured adult mosquitoes. We show that enhancing entomological surveillance tools can aid in the early detection of possible risk areas based on vector mosquito population numbers. Additionally, the detection of important arboviruses such as ZIKV and DENV raises awareness and allows for a better selection of risk areas and silent virus spread. It offers supplementary information for guiding emergency mosquito control measures in the target area. The goal is to minimize human-vector interactions and, subsequently, to lower the risk of transmitting circulating arboviruses.

Detection of Wuchereria bancrofti in the city of São Luís, state of Maranhão, Brazil: New incursion or persisting problem?

BACKGROUND: The elimination of lymphatic filariasis (LF) from Brazil by 2020 was not accomplished; however, this goal can be achieved in the upcoming years with the assistance of specific strategies. The surveillance of LF can be performed using molecular xenomonitoring (MX), a noninvasive method used to infer the presence of the parasite in the human population. Herein, São Luís (state of Maranhão) was the first city to be investigated to identify whether LF transmission in Brazil has been interrupted and if there were any new incursions. METHODOLOGY/PRINCIPAL FINDINGS: Mosquitoes were collected by aspiration at 901 points distributed among 11 neighborhoods in São Luís with records of patients with microfilaremia. Pools of engorged or gravid Culex quinquefasciatus females were evaluated by WbCx duplex PCR with endogenous control for mosquitoes and target for W. bancrofti for determining the vector infection rate. Among the 10,428 collected mosquitoes, the most abundant species were C. quinquefasciatus (85%) and Aedes aegypti (12%). Significantly larger numbers of mosquitoes were collected from the neighborhoods of Areinha and Coreia (p<0.05). MX performed using PCR validated 705 pools of engorged or gravid females, fifteen of which were positive for Wuchereria bancrofti in two neighborhoods. CONCLUSIONS: The high density of engorged C. quinquefasciatus females per home, inadequate sanitation, and detection of W. bancrofti-infected mosquitoes in the city of São Luís represent a warning of the possible upsurge of LF, a disease that is still neglected; this underscores the need for the ostensive monitoring of LF in Brazil.

Outbreak of autochthonous cases of malaria in coastal regions of Northeast Brazil: the diversity and spatial distribution of species of Anopheles.

BACKGROUND: Brazil has the fourth highest prevalence of malaria of all countries in the Americas, with an estimated 42 million people at risk of contracting this disease. Although most cases occur in the Amazon region, cases of an autochthonous nature have also been registered in the extra-Amazonian region where Anopheles aquasalis and An. albitarsis are the mosquito species of greatest epidemiological interest. In 2019, the municipality of Conde (state of Paraíba) experienced an epidemic of autochthonous cases of malaria. Here we present preliminary results of an entomological and case epidemiology investigation, in an attempt to correlate the diversity and spatial distribution of species of Anopheles with the autochthonous cases of this outbreak of malaria. METHODS: Case data were collected using case report forms made available by the Conde Municipal Health Department. The entomological survey was carried out from July to November 2019. The various methods of capture included the use of battery-powered aspirators, mouth aspirators, Shannon traps, BG-Sentinel traps (with and without dry ice) and CDC light traps. Captured mosquitoes were separated, packaged and sent to the laboratory for sexing and molecular identification of the various species of anophelines. The data were tabulated and analyzed using Microsoft Excel. Spatial analysis of the data was performed using ArcGis 10 software. RESULTS: In 2019, 20 autochthonous cases and one imported case of malaria caused by Plasmodium vivax were diagnosed, with three cases of relapses. A total of 3713 mosquitoes were collected, of which 3390 were culicines and 323 were anophelines. Nine species of genus Anopheles were identified, with the most abundant being An. aquasalis (38.9%), followed by An. minor (18.2%) and An. albitarsis (9.0%). Spatial analysis of the data showed that the area could be considered to be at risk of malaria cases and that there was a high prevalence of Anopheles. CONCLUSIONS: The results presented indicate that this extra-Amazonian region has an environment conducive to maintenance of the malaria transmission cycle owing to the wide diversity of Anopheles species. This environment in combination with the high influx of people from endemic areas to the study area provides a perfect setting for the occurrence and maintenance of malaria.

Double BR-OVT: a new trap model for collecting eggs and adult mosquitoes from Culex quinquefasciatus and Aedes spp.

The circulation of arboviruses throughout the world and the maintenance of lymphatic filariasis endemicity in tropical countries, combined with the lack of vaccines and specific treatments, highlight the importance of reducing the populations of mosquitoes involved in the transmission of these pathogens, Aedes aegypti and Culex quinquefasciatus. To contribute to the development of new strategies for monitoring and controlling these culicids, we evaluated the performance of the Double BR-OVT trap individually and in pairs, in the field. After 18 months, the Double BR-OVT traps captured a mean of 3.5 ± 7.4 and 1.8 ± 3.2 of Culex and Aedes /residence/cycle, respectively, in addition to 410 ± 588.3 Aedes eggs/residence/cycle. When installed in pairs, the Double BR-OVT traps collected three times more adult mosquitoes of C. quinquefasciatus (9.4 ± 8.3 Culex /residence/bimester) and two times more Aedes spp. (3 ± 3.2 Aedes /residence/bimester) in comparison with the traps installed individually (2.6 ± 7.1 and 1.5 ± 3.2 Culex and Aedes /residence/bimester, respectively) (p < 0.05). The Double BR-OVT trap has an exceptional advantage: it aggregates different functionalities into a single instrument, as this type of trap can concomitantly collect eggs and adult mosquitoes of C. quinquefasciatus and A. aegypti , a feature that makes it a potentially useful tool among the strategies for monitoring and controlling these mosquitoes.

Infestation of an endemic arbovirus area by sympatric populations of Aedes aegypti and Aedes albopictus in Brazil.

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.

Development of a molecular xenomonitoring protocol to assess filariasis transmission.

According to the World Health Organization, lymphatic filariasis (LF), a mosquito-borne neglected tropical disease (NTD), should be eliminated as a public health concern by the end of 2020. To this end, the goals of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) include interrupting transmission through mass drug administration (MDA). After two decades, several countries have implemented MDA and are now ready to confirm whether transmission has been interrupted. The method for detecting the parasites in mosquito vectors known as xenomonitoring is a non-invasive tool for assessing the current transmission status of the filarial nematode Wuchereria bancrofti (which is responsible for 90% of cases) by their vectors. There are several methods available for detection of the worm in mosquito samples, such as dissection or polymerase chain reaction (PCR). However, most of these techniques still produce a considerable number of false-negative results. The present study describes a new duplex PCR protocol, which is an improvement on the traditional PCR methodology, enhanced by introducing the actin gene as an endogenous control gene. After adjusting the mosquito pool size, DNA extraction, and WbCx PCR duplex design, we achieved a reliable and sensitive molecular xenomonitoring protocol. This assay was able to eliminate 5% of false negative samples and detected less than one Wb larvae. This high sensitivity is particularly valuable after MDA, when prevalence declines. This new method could reduce the number of false-negative samples, which will enable us to improve our ability to generate accurate results and aid the monitoring strategies used by LF elimination programmes.

Culicidae fauna (Diptera: Culicidae) survey in urban, ecotonal and forested areas, from the Moreno municipality - Pernambuco State, Brazil.

INTRODUCTION: Mosquitoes are vectors of several pathogens in tropical regions. However, information on Culicidae in the northeast region of Brazil is scarce despite many municipalities having environmental conditions favorable for these insects. METHODS: We collected mosquitoes monthly for one year from urban, ecotonal, and ecological reserve areas in Moreno, Brazil, by using CDC Miniature light traps, aspiration, ovitraps, and liquid suction. RESULTS: We collected 1,401 insects in the Culicidae family. Fifteen species of seven genera of Culicidae were identified and five specimens were identified only at the genus level. CONCLUSIONS: There is a wide diversity of mosquito species in the sampled areas, some of which are important for human health.

Culicidae fauna (Diptera: Culicidae) survey in urban, ecotonal and forested areas, from the Moreno municipality - Pernambuco State, Brazil

Abstract INTRODUCTION: Mosquitoes are vectors of several pathogens in tropical regions. However, information on Culicidae in the northeast region of Brazil is scarce despite many municipalities having environmental conditions favorable for these insects. METHODS: We collected mosquitoes monthly for one year from urban, ecotonal, and ecological reserve areas in Moreno, Brazil, by using CDC Miniature light traps, aspiration, ovitraps, and liquid suction. RESULTS: We collected 1,401 insects in the Culicidae family. Fifteen species of seven genera of Culicidae were identified and five specimens were identified only at the genus level. CONCLUSIONS: There is a wide diversity of mosquito species in the sampled areas, some of which are important for human health.

Field evaluation of sticky BR-OVT traps to collect culicids eggs and adult mosquitoes inside houses.

INTRODUCTION: Culex quinquefasciatus is a mosquito of importance to public health, as it represents a real and/or potential risk for the transmission of pathogens to humans, such as some arthropod-borne viruses and nematodes that cause filariasis. In Brazil, three municipalities in the Metropolitan Region of Recife (RMR) that are endemic for lymphatic filariasis conducted control actions targeting this vector. With the goal of contributing novel C. quinquefasciatus collection strategies, a sticky trap capable of collecting eggs and imprisoning mosquitoes was investigated. METHODS: To evaluate the performance of the sticky BR-OVT trap, tests were carried out in the neighborhoods of Caixa d'Água and Passarinho (Olinda-PE-Brasil) between August 2011 and June 2012. Sixty traps were installed in the indoor areas of residences in the two districts. RESULTS: During the 11-month study, 0.52 [standard deviation (SD) = 1.52] Culex egg rafts, 2.16 (SD = 4.78) C. quinquefasciatus/trap/month, and 0.55 (SD = 1.28) Aedes/trap/month were caught. Female specimens predominated the traps (59% of C. quinquefasciatus and 96% of Aedes spp.). CONCLUSIONS: The results demonstrated that the sticky BR-OVT trap is a useful tool for the collection of adult culicids of medical importance and offers an innovative way to collect C. quinquefasciatus eggs and adults in a single trap.

Field evaluation of sticky BR-OVT traps to collect culicids eggs and adult mosquitoes inside houses

Abstract INTRODUCTION: Culex quinquefasciatus is a mosquito of importance to public health, as it represents a real and/or potential risk for the transmission of pathogens to humans, such as some arthropod-borne viruses and nematodes that cause filariasis. In Brazil, three municipalities in the Metropolitan Region of Recife (RMR) that are endemic for lymphatic filariasis conducted control actions targeting this vector. With the goal of contributing novel C. quinquefasciatus collection strategies, a sticky trap capable of collecting eggs and imprisoning mosquitoes was investigated. METHODS: To evaluate the performance of the sticky BR-OVT trap, tests were carried out in the neighborhoods of Caixa d'Água and Passarinho (Olinda-PE-Brasil) between August 2011 and June 2012. Sixty traps were installed in the indoor areas of residences in the two districts. RESULTS: During the 11-month study, 0.52 [standard deviation (SD) = 1.52] Culex egg rafts, 2.16 (SD = 4.78) C. quinquefasciatus/trap/month, and 0.55 (SD = 1.28) Aedes/trap/month were caught. Female specimens predominated the traps (59% of C. quinquefasciatus and 96% of Aedes spp.). CONCLUSIONS The results demonstrated that the sticky BR-OVT trap is a useful tool for the collection of adult culicids of medical importance and offers an innovative way to collect C. quinquefasciatus eggs and adults in a single trap.

Residential characteristics aggravating infestation by Culex quinquefasciatus in a region of Northeastern Brazil / Características agravantes por infestação residencial de Culex quinquefasciatus, em Olinda, PE

OBJECTIVE: Analyse how basic sanitation conditions, water supply and housing conditions affect the concentration of Culex quinquefasciatus METHODS: Populations of C. quinquefasciatus in 61 houses in the municipality of Olinda, PE, were monitored between October 2009 and October 2010. Observations were carried out in homes without the presence of preferred breeding sites in order to identify characteristics that may be aggravating factors for the development of the mosquito. Five aggravating factors were analysed: vegetation cover surrounding the home, number of residents/home, water storage, sewage drainage and water drainage. These characteristics were analysed in terms of presence or absence and as indicators of the degree of infestation, which was estimated through monitoring the concentration of eggs (oviposition traps - BR-OVT) and adults (CDC light traps). RESULTS: Sewage drainage to a rudimentary septic tank or to the open air was the most frequent aggravating factor in the homes (91.8%), although the presence of vegetation was the only characteristic that significantly influenced the increase in the number of egg rafts (p = 0.02). The BR-OVT achieved positive results in 95.1% of the evaluations, with the presence of at least one egg raft per month. A total of 2,366 adults were caught, with a mosquito/room/night ratio of 32.9. No significant difference was found in the number of mosquitoes caught in the homes. CONCLUSIONS: Although the sanitation and water supply influence the population density of C. quinquefasciatus, residence features that are not usually considered in control measures can be aggravating factors in sustaining the mosquito population.

OBJETIVO: Analisar como as condições de saneamento básico, abastecimento de água e habitações afetam a densidade de Culex quinquefasciatus. MÉTODOS: Monitorou-se a população de C. quinquefasciatus em 61 residências do município de Olinda, PE, de outubro de 2009 a outubro de 2010. As observações foram realizadas em residências sem a presença de criadouros preferenciais, para identificar características que contribuíssem como agravantes para o desenvolvimento do mosquito. Cinco características agravantes foram analisadas: cobertura vegetal no peridomicílio, número de moradores por residência, armazenamento de água, escoamento de esgoto, escoamento de água. Essas características foram avaliadas quanto à presença ou ausência e como indicadores de níveis de infestação, estimados por monitoramento da densidade de ovos (armadilhas de oviposição BR-OVT) e adultos (armadilhas luminosas do tipo CDC). RESULTADOS: O escoamento de esgoto para fossa séptica/rudimentar e a céu aberto foi o mais frequente nas residências (91,8%), embora apenas a presença de vegetação tenha influenciado significativamente no aumento de jangadas (p = 0,02). As BR-OVT apresentaram-se positivas em 95,1% das avaliações, com presença de pelo menos uma jangada/mês. Foram capturados 2.366 espécimes adultos, com relação mosquito/quarto/noite de 32,9, sem diferença significativa no número de mosquitos capturados nas residências. CONCLUSÕES: Embora as condições de saneamento e de abastecimento de água influenciem na densidade populacional de C. quinquefasciatus, características da residência que normalmente não são consideradas nas medidas de controle podem ser fatores agravantes na manutenção da população de mosquito.

Residential characteristics aggravating infestation by Culex quinquefasciatus in a region of Northeastern Brazil.

OBJECTIVE: Analyse how basic sanitation conditions, water supply and housing conditions affect the concentration of Culex quinquefasciatus METHODS: Populations of C. quinquefasciatus in 61 houses in the municipality of Olinda, PE, were monitored between October 2009 and October 2010. Observations were carried out in homes without the presence of preferred breeding sites in order to identify characteristics that may be aggravating factors for the development of the mosquito. Five aggravating factors were analysed: vegetation cover surrounding the home, number of residents/home, water storage, sewage drainage and water drainage. These characteristics were analysed in terms of presence or absence and as indicators of the degree of infestation, which was estimated through monitoring the concentration of eggs (oviposition traps - BR-OVT) and adults (CDC light traps). RESULTS: Sewage drainage to a rudimentary septic tank or to the open air was the most frequent aggravating factor in the homes (91.8%), although the presence of vegetation was the only characteristic that significantly influenced the increase in the number of egg rafts (p = 0.02). The BR-OVT achieved positive results in 95.1% of the evaluations, with the presence of at least one egg raft per month. A total of 2,366 adults were caught, with a mosquito/room/night ratio of 32.9. No significant difference was found in the number of mosquitoes caught in the homes. CONCLUSIONS: Although the sanitation and water supply influence the population density of C. quinquefasciatus, residence features that are not usually considered in control measures can be aggravating factors in sustaining the mosquito population.

Two Bacillus sphaericus binary toxins share the midgut receptor binding site: implications for resistance of Culex pipiens complex (Diptera: Culicidae) larvae.

This work demonstrates that Bin1 and Bin2 toxins, produced by Bacillus sphaericus strains IAB59 and 2362, respectively, share a binding site in midgut brush border membranes (BBMF) from Culex pipiens complex larvae. However, a colony selected with strain IAB59, displaying a resistance ratio of only 42-fold to IAB59, but a 162,000-fold resistance to strain 2362, was found to miss receptors for Bin2 in the BBMF. This correlates with results showing that Bin1, produced in strain IAB59, failed to bind specifically to BBMF from other colony highly resistant to strain 2362. Data indicate the loss of the BBMF bound receptor as a general mechanism of resistance to binary toxins in mosquito.