Limitations in the laboratory identification of

Neotropical Entomology 36(2): 294-302 (2007) Avaliação da MosquiTRAP Although the MosquiTRAPAedes mosquitoes during the study, it was more sensitive than the larval survey to detect the presence of Aedes mosquitoes.KEY WORDS: Monitoring, dengue, mosquito northeastern states of Brazil, whereas cases decreased in yet the potential for further epidemics exists due to the

ObjectiveSince the 1980s, dengue incidence has increased 30‐fold. However, in 2017, there was a noticeable reduction in reported dengue incidence cases within the Americas, including severe and fatal cases. Understanding the mechanism underlying dengue's incidence and decline in the Americas is vital for public health planning. We aimed to provide plausible explanations for the decline in 2017.MethodsAn expert panel of representatives from scientific and academic institutions, Ministry of Health officials from Latin America and PAHO/WHO staff met in October 2017 to propose hypotheses. The meeting employed six moderated plenary discussions in which participants reviewed epidemiological evidence, suggested explanatory hypotheses, offered their expert opinions on each and developed a consensus.ResultsThe expert group established that in 2017, there was a generalised decreased incidence, severity and number of deaths due to dengue in the Americas, accompanied by a reduction in reported cases of both Zika and chikungunya virus infections, with no change in distribution among age groups affected. This decline was determined to be unlikely due to changes in epidemiological surveillance systems, as similar designs of surveillance systems exist across the region. Although sudden surveillance disruption is possible at a country or regional level, it is unlikely to occur in all countries simultaneously. Retrospective modelling with epidemiological, immunological and entomological information is needed. Host or immunological factors may have influenced the decline in dengue cases at the population level through immunity; however, herd protection requires additional evidence. Uncertainty remains regarding the effect on the outcome of sequential infections of different dengue virus (DENV) types and Zika virus (ZIKV), and vice versa. Future studies were recommended that examine the epidemiological effect of prior DENV infection on Zika incidence and severity, the epidemiological effect of prior Zika virus infection on dengue incidence and severity, immune correlates based on new‐generation ELISA assays, and impact of prior DENV/other arbovirus infection on ZIKV immune response in relation to number of infections and the duration of antibodies in relation to interval of protection. Follow‐up studies should also investigate whether increased vector control intensification activities contributed to the decline in transmission of one or more of these arboviruses. Additionally, proposed studies should focus on the potential role of vector competence when simultaneously exposed to various arboviruses, and on entomological surveillance and its impact on circulating vector species, with a goal of applying specific measures that mitigate seasonal occurrence or outbreaks.ConclusionsMultifactorial events may have accounted for the decline in dengue seen in 2017. Differing elements might explain the reduction in dengue including elements of immunity, increased vector control, and even vector and\or viruses changes or adaptations. Mo...

Between October, 1997 and September, 1999 in Belo Horizonte, Minas Gerais a study of seasonal variation of Lutzomyia longipalpis was carried out in three distinct areas of the municipality. Sand flies were sampled at 15-day intervals in three residences, in each of which two CDC light traps were installed, one indoors and the other in the peridomicile. A total of 397 sand flies were captured in the three areas, with 65%, 30% and 1% of specimens collected in the eastern, northeast and Barreiro districts, respectively. The overall proportions of sand flies collected inside and around the houses were similar (57% vs 43%) and this pattern was seen for both Lutzomyia longipalpis and Lutzomyia whitmani. The highest population levels during the two years of the study were from October to March. From October onwards, numbers increased constantly until February. A gradual fall was seen from April onwards until the lowest levels were reached in the months of June, July and August. Key-words: Sand fly. Seasonal variation. Control. Leishmaniasis. RESUMOEntre outubro de 1997 e setembro de 1999, em Belo Horizonte, Minas Gerais foi conduzido um estudo de variação sazonal de Lutzomyia longipalpis em três áreas distintas do município. Os flebotomíneos foram coletados quinzenalmente em três residências, em cada área, nas quais foram instaladas duas armadilhas luminosas CDC, sendo uma no intradomicílio e a outra no peridomicílio. Um total de 397 flebotomíneos foi capturado nas três áreas, com 65%, 30% e 1% exemplares coletados nos distritos Leste, Nordeste e Barreiro, respectivamente. A proporção total de flebotomíneos coletados no intradomicílio e peridomicílio foi semelhante (57% vs 43%) e este padrão foi visto para Lutzomyia longipalpis e Lutzomyia whitmani. Durante os dois anos de estudo, o nível da população foi maior no período de outubro a março. A partir de outubro o número de flebotomíneos aumenta constantemente até fevereiro. Uma gradual redução foi observada a partir de abril até alcançar o nível mais baixo nos meses de junho, julho e agosto. Palavras-chaves: Flebotomíneos. Variação sazonal. Controle. Leishmanioses.

In Brazil, the entomological surveillance of Aedes (Stegomyia) aegypti is performed by government-mandated larval surveys. In this study, the sensitivities of an adult sticky trap and traditional surveillance methodologies were compared. The study was performed over a 12-week period in a residential neighbourhood of the municipality of Pedro Leopoldo, state of Minas Gerais, Brazil. An ovitrap and a MosquiTRAP were placed at opposite ends of each neighbourhood block (60 traps in total) and inspections were performed weekly. The study revealed significant correlations of moderate strength between the larval survey, ovitrap and MosquiTRAP measurements. A positive relationship was observed between temperature, adult capture measurements and egg collections, whereas precipitation and frequency of rainy days exhibited a negative relationship.

Because the potential urban yellow fever (YF) mosquito vectors Aedes aegypti and Ae. albopictus are at historical highs in Brazil, both in terms of density and geographical range, we assessed the risk of an urban YF epidemic in Brazil. We evaluated and confirmed in a laboratory setting the vector competence of Brazilian Ae. aegypti for a currently circulating strain of YF virus, and investigated the potential for Brazilian Ae. albopictus to transmit YF.

The mosquito Stegomyia albopicta is among the most important arbovirus vectors in the world, particularly for Dengue viruses. Their natural history suggests that biologically these viruses are highly adapted to their mosquito hosts and they were most likely mosquito viruses prior to becoming adapted to lower primates and humans. As well as being maintained by transmission among susceptible humans, Dengue viruses may also be maintained by vertical transmission in mosquitoes during inter-epidemic periods. The larvae and mosquitoes of Stegomyia albopicta were used to identify the vertical transmission of the dengue virus in nature and to confirm the vectorial capacity concerning the Dengue virus type 2 infection. The minimum infection rate concerning S. albopicta infection with the Dengue virus was 1:36.45. In Brazil this was the first time that high minimum infection rates of vertical transmission of S. albopicta were detected in this species.Keywords: Dengue virus, vertical transmission, Stegomyia albopicta, vectorial capacity. Transmissão vertical natural de Stegomyia albopicta como vetor de dengue no BrasilResumo O mosquito Stegomyia albopicta está dentre os mais importantes vetores de arbovírus do mundo, particularmente para o Dengue virus. A história natural sugere que biologicamente esses vírus são altamente adaptados aos seus mosquitos vetores e foram, provavelmente, os vírus que infectavam mosquitos antes de se tornarem adaptados a primatas não humanos e humanos. Além de serem mantidos entre os homens susceptíveis, os Dengue viruses podem também ser mantidos pela transmissão vertical em mosquitos durante os períodos interepidêmicos. As larvas e mosquitos da espécie Stegomyia albopicta foram utilizados para a identificação da transmissão vertical do vírus dengue na natureza e para confirmar a capacidade vetorial em relação à infecção pelo DENV-2 infection. A taxa mínima de infecção em relação à infecção do S. albopicta com o Dengue virus foi de 1:36,45. No Brasil, esta é a primeira vez que altas taxas de infecção mínima da transmissão vertical de S. albopicta foram detectadas nessa espécie.Palavras-chave: Dengue vírus, transmissão vertical, Stegomyia albopicta, capacidade vetorial.

-Anopheles darlingi Root is the principal malaria vector in Amazonia region. The objectives of this work were to study the periodicity of Anopheles darlingi Root, the host preference for peri or extra-domestic environments and the parous rate in four fi eld sites in Porto Velho (RO) by human-landing. All of the Anopheles specimens collected were identifi ed, but only A. darlingi was dissected for the parous study. The results showed that human-landing colleted a total of 985 anophelines, with A. darlingi (972) being the most abundant species. Female mosquitoes were more abundant at extra-domestic environments in two of the locations studied (São João e Candeias do Jamari) (P < 0.05). The parous rate was 96% and no periodicity was observed for captures of females of A. darlingi in the fi eld sites.