Vigilancia del vector del dengue en el límite de su distribución. Una experiencia colaborativa entre los ámbitos científico, municipal y ciudadano / Surveillance of the dengue vector at its distribution limit. A collaborative ex perience between the scientific, municipal and citizen ambits

Resumen Introducción: En Argentina, durante la última década se ha observado una expansión hacia el sur del mosquito Aedes aegypti, acompañada por la expansión en la transmisión del dengue. El objetivo de este estudio fue evaluar el establecimiento de Ae. aegypti en una localidad cercana al límite de su distribución mediante un trabajo colaborativo entre los ámbitos científico, municipal, y ciudadano. Métodos: Se implementó un sistema de vigilancia del vector mediante ovitrampas, el cual se complementó con fotografías y ejemplares aportados por los ciudadanos, y con búsqueda activa de criaderos del mosquito en distintos espacios urbanos de la ciudad de Tandil, Argentina. Resultados: Se demostró el establecimiento de una población de Ae. aegypti en el municipio, tanto por medio de las ovitrampas como por los aportes del conocimiento y participación de la comunidad: la ciencia ciudadana. La información obtenida permitió comenzar a visibilizar la problemática entre los funcionarios municipales y la ciudadanía. Discusión: El dengue es una enfermedad aún invisible en localidades donde se ha estado expandiendo el mosquito vector durante la última década. La participación pública y la información producida con la vigilancia entomológica es la base necesaria para abordar la comunicación social a fin de producir cambios de conducta en las autoridades responsables y en las familias.

Abstract Introduction: In Argentina, during the last decade a southward expansion of the mosquito Aedes aegypti has been observed, accompanied by an expansion in the dengue transmission. The objective of this study was to assess the establishment of the dengue mosquito vector in a locality next to its distribution limits by a collabora tive work among scientific, municipal and citizen ambits. Methods: A vector surveillance system through ovit raps was implemented, and it was complemented by pictures and mosquitoes captured by citizens, and by the active search of breeding sites in different urban spaces of Tandil City, Argentina. Results: The establishment of Aedes aegypti population in the city was demonstrated, both by ovitraps and citizen science contributions. This information made it possible to begin to make the problem visible among municipal authorities and citizens. Discussion: Dengue is an invisible disease in localities in which the mosquito vector has been spreading during the last decade. The information produced by the entomological surveillance is the necessary basis to address social communication to produce behavioral changes in the responsible authorities as well as in the families.

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.

A survey of mosquito species in public schools of Metro Manila, Philippines using Ovitraps as surveillance tool

@#<p style="text-align: justify;"><strong>OBJECTIVE:</strong> This study assessed the species composition of mosquitoes collected from ovitraps in selected public schools of Metro Manila, Philippines.</p><p style="text-align: justify;"><strong>MATERIALS AND METHODS:</strong> Ovitraps were installed from November 2013 to February 2014, in purposively selected public elementary and high schools of Metro Manila. Ovitraps were installed inside classrooms and collected weekly and examined for mosquito eggs and larvae. Speciation was done once a month from November 2013 to February 2014. All positive paddles were immersed in water for larval emergence, reared to fourth instars and were identified using taxonomic keys.</p><p style="text-align: justify;"><strong>RESULTS:</strong> A total of 1,482 ovitraps were installed in the selected public schools, and 18,325 larvae were collected from elementary schools, while 16,670 larvae were collected from high schools. The mean ovitrap index or infestation rate was 49.69% during the period of data collection. Mosquito larvae were identified as Aedes aegypti (88.94%) and Aedes albopictus (11.06%). Aedes aegypti and Aedes albopictus coexisted in some of the examined paddles. No significant differences were observed between the type of school and the presence of Aedes larvae. Significant differences were observed between total number of mosquito larvae and months of collection.</p><p style="text-align: justify;"><strong>CONCLUSION:</strong> The presence of Aedes mosquitoes in schools evidently shows that continuous vector surveillance in schools is necessary as this information will help in the formulation of proactive vector control activities, thereby preventing the occurrence of mosquito-borne diseases.</p>

Temporal distribution of Aedes aegypti Linnaeus (Diptera, Culicidae), in a Hospital in Cuiabá, State of Mato Grosso, Brazil / Distribuição Temporal de Aedes aegypti Linnaeus (Diptera, Culicidae), em um Hospital de Cuiabá, Mato Grosso, Brasil

This study aimed at registering and monitoring the presence of Aedes aegypti in the University Hospital Júlio Muller, Cuiabá-MT, as well as investigating the influence of temperature and rainfall on its temporal distribution and egg densities in ovitraps. The study was performed from April/2007 to March/2008, utilizing ovitraps with 10 percent of hay infusion and a wood paddle as an oviposition substrate. For surveillance, one ovitrap was placed in each of the 12 points distributed throughout the hospital. Ovitraps were collected monthly at the end of a 5-day installation period. After egg counting, wood paddles were immersed in water to allow larval eclosion for species identification through optical microscopy. Egg Density Index (EDI), Positive Ovitraps Index (POI), and Mean Number of Eggs (MNE) were used for data analysis. The presence of A. aegypti in the hospital was registered throughout the study period, except in July. The MNE was proportionally higher in the internal area (n= 8.47 eggs/paddle) when compared to the external area (n= 5.46 eggs/paddle), and was higher in September/October 2007 and January/February 2008. A significant increase in EDI, POI and MNE was registered in periods where the average temperature was higher, and the increase in POI was also concomitant with an increase in rainfall. The continuous presence of A. aegypti in the hospital throughout the study period, points out the need of including this mosquito in the arthropod control list in this environment. This is particularly important, considering that A. aegypti is an important vector of several arboviroses.

Esse estudo objetivou registrar e monitorar a presença de Aedes aegypti no Hospital Universitário Júlio Muller, Cuiabá - MT, bem como investigar a influência da temperatura e pluviosidade sobre sua distribuição temporal e densidade de ovos em ovitrampas. O estudo foi realizado de abril/2007 a março/2008, usando ovitrampas com 10 por cento de infusão de gramínea e uma palheta de madeira como substrato para oviposição. Para o monitoramento, uma ovitrampa foi colocada em cada um dos doze pontos distribuídos nas dependências do hospital. Mensalmente, as armadilhas eram recolhidas ao final do quinto dia de instalação. Após a contagem dos ovos, as palhetas foram imersas em água para eclosão das larvas e identificação da espécie alvo em microscopia óptica. Índice de Densidade de Ovos (IDO), Índice de Positividade de Ovitrampas (IPO) e Número Médio de Ovos (NMO) foram usados para análise dos dados. A presença do mosquito no hospital foi registrada ao longo de todo experimento, exceto em julho. A densidade média de ovos foi proporcionalmente maior na área interna (n= 8,47 ovos/palheta) comparada à externa (n= 5,46 ovos/palheta). O NMO foi mais elevado nos meses de setembro e outubro de 2007, janeiro e fevereiro de 2008. Aumentos significativos do NMO, IPO e IDO, foram registrados com a elevação da temperatura, e no IPO com aumento da pluviosidade. A constante presença do mosquito A. aegypti no hospital, indica a necessidade de incluir esse mosquito na lista de controle de artrópodes nesse ambiente. Isso é particularmente importante, considerando que o A. aegypti é importante vetor de várias arboviroses.

An entomological surveillance system based on open spatial information for participative dengue control

Aedes aegypti is a very efficient disseminator of human pathogens. This condition is the result of evolutionary adaptations to frequent haematophagy, as well as to the colonization of countless types of habitats associated with environmental and cultural factors that favor the proliferation of this mosquito in urban ecosystems. Studies using sensitive methods of monitoring demonstrate that the methods of surveillance used in the Brazilian program do not show the high degrees of the infestation of cities by this vector. To increase the capacity of the health sector, new tools are needed to the practice of surveillance, which incorporate aspects of the vector, place and human population. We describe here the SMCP-Aedes - Monitoring System and Population Control of Aedes aegypti, aiming to provide an entomological surveillance framework as a basis for epidemiological surveillance of dengue. The SMCP-Aedes is uphold in the space technology information, supported by the intensive use of the web and free software to collect, store, analyze and disseminate information on the spatial-temporal distribution of the estimated density for the population of Aedes, based on data systematically collected with the use of ovitraps. Planned control interventions, intensified where and when indicated by the entomological surveillance, are agreed with the communities, relying on the permanent social mobilization.

Associadas a fatores bióticos, climáticos e culturais que favorecem a proliferação do Aedes aegypti em ecossistemas urbanos, adaptações evolutivas à hematofagia freqüente e quase exclusiva em humanos e à colonização de tipos infinitos de habitats, fazem deste mosquito um disseminador extremamente eficiente de patógenos ao homem. Estudos utilizando métodos sensíveis de monitoramento demonstram que os métodos de vigilância usados no programa brasileiro não revelam as elevadas intensidades da infestação das cidades por este vetor. Para ampliar a capacidade do setor de saúde novos instrumentos são necessários à prática da vigilância, incorporando aspectos do vetor, do lugar e das pessoas do lugar. Apresentamos aqui o SMCP-Aedes - Sistema de Monitoramento e Controle Populacional do Ae. aegypti, cuja meta é a instrumentalização da vigilância entomológica como base para a vigilância epidemiológica da dengue. Para isso ele se apóia em tecnologias da informação espacial baseadas no uso intensivo da web e de software livre para coletar, armazenar, analisar e disseminar informações relativas à distribuição espaço-temporal da densidade estimada para a população do Aedes, com base em amostras obtidas continuamente com ovitrampas. Intervenções de controle planejadas e intensificadas onde e quando indicado pela vigilância entomológica, são pactuadas com os habitantes, apoiando-se na mobilização social permanente.

Seasonal dynamics of Aedes aegypti (Diptera: Culicidae) in the northernmost state of Brazil: a likely port-of-entry for dengue virus 4

Roraima is the northernmost state of Brazil, bordering both Venezuela and Guyana. Appropriate climate and vector conditions for dengue transmission together with its proximity to countries where all four dengue serotypes circulate make this state, particularly the capital Boa Vista, strategically important for dengue surveillance in Brazil. Nonetheless, few studies have addressed the population dynamics of Aedes aegypti in Boa Vista. In this study, we report temporal and spatial variations in Ae. aegypti population density using ovitraps in two highly populated neighbourhoods; Centro and Tancredo Neves. In three out of six surveys, Ae. aegypti was present in more than 80 percent of the sites visited. High presence levels of this mosquito suggest ubiquitous human exposure to the vector, at least during part of the year. The highest infestation rates occurred during the peak of the rainy seasons, but a large presence was also observed during the early dry season (although with more variation among years). Spatial distribution of positive houses changed from a sparse and local pattern to a very dense pattern during the dry-wet season transition. These results suggest that the risk of dengue transmission and the potential for the new serotype invasions are high for most of the year.

Developing new approaches for detecting and preventing Aedes aegypti population outbreaks: basis for surveillance, alert and control system

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 percent (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.