Dengue in the State of Rio Grande do Norte, Brazil, 2010-2012.

OBJECTIVE: To present results of virological surveillance and epidemiological aspects of dengue in the State of Rio Grande do Norte, Brazil. METHODS: A total of 1581 cases, reported from 2010 to 2012 at various health centres in the state, were analysed by viral isolation and/or RT-PCR for viral detection and typing. To identify whether different genotypes were circulating in the state during this period, sequencing of the complete E gene for DENV (1485 bp in length) was performed directly from patient serum samples. RESULTS: All four serotypes of dengue virus circulated in Rio Grande do Norte, with the introduction of DENV-4 in the state in 2011. In 2012, DENV-4 represented 100% of positive confirmed cases. 53.97% of cases occurred in Natal. Case numbers peaked in April (21%) and May (23%). Genetic characterisation of circulating strains confirmed the circulation of genotypes V, south-east Asian/American and II, respectively, for DENV-1, DENV-2 and DENV-4. CONCLUSIONS: This work furthers a better understanding of dengue viruses in the State of Rio Grande do Norte. Strengthening control efforts in the region is important considering the impact of dengue.

Infrared spectroscopy (NIRS and ATR-FTIR) together with multivariate classification for non-destructive differentiation between female mosquitoes of Aedes aegypti recently infected with dengue vs. uninfected females.

One of the most important steps in preventing arboviruses is entomological surveillance. The main entomological surveillance action is to detect vector foci in the shortest possible stages. In this work, near and medium infrared spectra collected from female Aedes aegypti mosquitoes recently infected and not infected with dengue were used in order to build chemometric models capable of differentiating the spectra of each class. For this, computational algorithms such as Successive Projection Algorithm (SPA) and Genetic Algorithm (GA) were used together with Linear Discriminant Analysis (LDA). The constructed models were evaluated with sensitivity and specificity calculations. It was observed that models based on near infrared (NIR) spectra have better classification results when compared to mid infrared (MIR) spectra, as well as models based on GA present better results when compared to those based on SPA. Thus, NIR-GA-LDA obtained the best results, reaching 100.00 % for sensitivity and specificity. NIR spectroscopy is 18 times faster and 116 times cheaper than RT-qPCR. The findings reported in this study may have important applications in the field of entomological surveillance, prevention and control of dengue vectors. In the future, mosquito traps equipped with portable NIR instruments capable of detecting infected mosquitoes may be used, in order to enable an action plan to prevent future outbreaks of the disease.

Molecular fluorescence spectroscopy with multi-way analysis techniques detects spectral variations distinguishing uninfected serum versus dengue or chikungunya viral infected samples.

Significant attempts are being made worldwide in an attempt to develop a tool that, with a simple analysis, is capable of distinguishing between different arboviruses. Herein, we employ molecular fluorescence spectroscopy as a sensitive and specific rapid tool, with simple methodology response, capable of identifying spectral variations between serum samples with or without the dengue or chikungunya viruses. Towards this, excitation emission matrices (EEM) of clinical samples from patients with dengue or chikungunya, in addition to uninfected controls, were separated into a training or test set and analysed using multi-way classification models such as n-PLSDA, PARAFAC-LDA and PARAFAC-QDA. Results were evaluated based on calculations of accuracy, sensitivity, specificity and F score; the most efficient model was identified to be PARAFAC-QDA, whereby 100% was obtained for all figures of merit. QDA was able to predict all samples in the test set based on the scores present in the factors selected by PARAFAC. The loadings obtained by PARAFAC can be used in future studies to prove the direct or indirect relationship of spectral changes caused by the presence of these viruses. This study demonstrates that molecular fluorescence spectroscopy has a greater capacity to detect spectral variations related to the presence of such viruses when compared to more conventional techniques.

Epidemiologic and clinical investigations during a chikungunya outbreak in Rio Grande do Norte State, Brazil.

The first autochthonous case of chikungunya virus (CHIKV) infection in Brazil was in September 2014 in the State of Amapá, and from there it rapidly spread across the country. The present study was conducted in 2016 in the state of Rio Grande do Norte, and the aims were to describe the epidemiological and the clinical aspects of the CHIKV outbreak. Biological samples from 284 chikungunya suspected cases were screened for CHIKV and Flavivirus (FV) RNA using qRT-PCR. Negative PCR samples were also screened for anti-CHIKV and anti-FVIgM by ELISA. CHIKV RNA were detected in 125 samples mostly occurring from January through March (46%), mainly affecting adults and older adults. We found a gradual decrease in viral RNA over the disease time. Anti-CHIKV IgM was found in 47.5% after negative CHIKV qRT-PCR. Interestingly, 45.0% simultaneously had positive results for CHIKV and FV IgM, suggesting the occurrence of virus co-circulation. The most frequent symptom was fever (91%). Women presented more chance to develop nausea and abdominal pain compared to men. Our data described and allows us to better understand the clinical and epidemiological aspects of the 2016 chikungunya outbreak in Rio Grande do Norte and can help in the early clinical diagnosis of the virus.

Dengue virus in Aedes aegypti and Aedes albopictus in urban areas in the state of Rio Grande do Norte, Brazil: Importance of virological and entomological surveillance.

BACKGROUND: Vector control remains the sole effective method to prevent dengue virus (DENV) transmission, although a vaccine for dengue has recently become available and testing of its efficacy and coverage is being performed in multiple places. Entomological surveillance is a key factor in alerting authorities to possible outbreaks, but until now natural DENV infection of mosquito populations has been scarcely used as an early warning system to monitor fluctuating prevalence of infected mosquitoes. The purpose of this study was to determine the burden of adult and larval/pupae of Aedes aegypti and Aedes albopictus with DENV in urban areas in the state of Rio Grande do Norte, Brazil. METHODOLOGY/PRINCIPAL FINDINGS: Immature insect forms (larvae and pupae) were collected from April 2011 to March 2012, whereas the collection of adults was conducted along 3 years: May 2011 to April 2014. Total RNAs of the samples were extracted and the nested reverse transcriptase PCR assay for detecting and typing DENV was performed. Of the 1333 immature insects collected during the study period, 1186 (89%) were A. aegypti and 147 (11%) A. albopictus. DENV-4 was identified in pools of A. aegypti larvae. The rate of DENV infection in immature A. aegypti was expressed as MIR = 3.37. DENV wasnot detected in immature A. albopictus. A total of 1360 adult female mosquitoes of the Aedes genus were captured from May 2011 to April 2014. Of this total, 1293 were A. aegypti (95%) and 67 were A. albopictus (5%). From the 130 pools studied, 27 (20.7%) were positive for DENV. DENV-1 was identified in 2/27 (7.4%) pools; 1of A. albopictus and 1 of A. aegypti. DENV-2 was identified in only 1/27 (3.7%) A. aegypti pools. DENV-4 was the most prevalent, identified in 24/27 (88.8%) of the positive pools, with 19 being of A. aegypti and 5 of A. albopictus pools. The minimum infection rate for adults of the Aedes genus was 19.8, considering both A. aegypti and A. albopictus. CONCLUSIONS/SIGNIFICANCE: This work represents the most complete study to date on the interaction between dengue viruses and Aedes mosquitoes in the State of Rio Grande do Norte, and raises important questions about a possible role of A. albopictus in the transmission of dengue virus in Brazil.