Detecção e tipagem de vírus dengue em Aedes aegypti (Diptera: Culicidae) na Cidade de Manaus, Estado do Amazonas

The aim of this study was to detect and type dengue viruses in the vector Aedes aegypti. Between December 2005 and December 2006, 8,984 mosquitoes were collected in 46 districts of the city of Manaus, covering all of the geographical zones of the city. Of these, 819 were Aedes aegypti (414 females and 405 males). The females of Aedes aegypti were grouped in pools of 1 to 10 mosquitoes, thus totaling 138 pools, of which 111 pools were positive for DENV 3 and a single pool was positive for two serotypes (DENV 1 and DENV 3). The prevalence of Aedes aegypti infected with DENV 3 in the city of Manaus was 53%. The zonal prevalence was 70% in the western central zone, 60% in the southern zone, 53% in the western zone, 47% in the southern central zone, 30% in the northern zone and 23% in the eastern zone. Monitoring of virus circulation among mosquitoes by means of the reverse transcription polymerase chain reaction technique enables prior knowledge of the levels of virus spread in given areas, thus contributing towards determining the localities where prevention and control measures should be applied

High anti-SARS-CoV-2 antibody seroconversion rates before the second wave in Manaus, Brazil, and the protective effect of social behaviour measures: results from the prospective DETECTCoV-19 cohort

Background: The city of Manaus, Brazil, has seen two collapses of the health system due to the COVID-19 pandemic. We report anti-SARS-CoV-2 nucleocapsid IgG antibody seroconversion rates and associated risk factors in Manaus residents before the second wave of the epidemic in Brazil. Methods: A convenience sample of adult (aged ≥18 years) residents of Manaus was recruited through online and university website advertising into the DETECTCoV-19 study cohort. The current analysis of seroconversion included a subgroup of DETECTCoV-19 participants who had at least two serum sample collections separated by at least 4 weeks between Aug 19 and Oct 2, 2020 (visit 1), and Oct 19 and Nov 27, 2020 (visit 2). Those who reported (or had no data on) having a COVID-19 diagnosis before visit 1, and who were positive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at visit 1 were excluded. Using an in-house ELISA, the reactivity index (RI; calculated as the optical density ratio of the sample to the negative control) for serum anti-SARS-CoV-2 nucleocapsid IgG antibodies was measured at both visits. We calculated the incidence of seroconversion (defined as RI values ≤1·5 at visit 1 and ≥1·5 at visit 2, and a ratio >2 between the visit 2 and visit 1 RI values) during the study period, as well as incidence rate ratios (IRRs) through cluster-corrected and adjusted Poisson regression models to analyse associations between seroconversion and variables related to sociodemographic characteristics, health access, comorbidities, COVID-19 exposure, protective behaviours, and symptoms. Findings: 2496 DETECTCoV-19 cohort participants returned for a follow-up visit between Oct 19 and Nov 27, 2020, of whom 204 reported having COVID-19 before the first visit and 24 had no data regarding previous disease status. 559 participants were seropositive for anti-SARS-CoV-2 nucleocapsid IgG antibodies at baseline. Of the remaining 1709 participants who were seronegative at baseline, 71 did not meet the criteria for seroconversion and were excluded from the analyses. Among the remaining 1638 participants who were seronegative at baseline, 214 showed seroconversion at visit 2. The seroconversion incidence was 13·06% (95% CI 11·52–14·79) overall and 6·78% (5·61–8·10) for symptomatic seroconversion, over a median follow-up period of 57 days (IQR 54–61). 48·1% of seroconversion events were estimated to be asymptomatic. The sample had higher proportions of affluent and higher-educated people than those reported for the Manaus city population. In the fully adjusted and corrected model, risk factors for seroconversion before visit 2 were having a COVID-19 case in the household (IRR 1·49 [95% CI 1·21–1·83]), not wearing a mask during contact with a person with COVID-19 (1·25 [1·09–1·45]), relaxation of physical distancing (1·31 [1·05–1·64]), and having flu-like symptoms (1·79 [1·23–2·59]) or a COVID-19 diagnosis (3·57 [2·27–5·63]) between the first and second visits, whereas working remotely was associated with lower incidence (0·74 [0·56–0·97]). Interpretation: An intense infection transmission period preceded the second wave of COVID-19 in Manaus. Several modifiable behaviours increased the risk of seroconversion, including non-compliance with non-pharmaceutical interventions measures such as not wearing a mask during contact, relaxation of protective measures, and non-remote working. Increased testing in high-transmission areas is needed to provide timely information about ongoing transmission and aid appropriate implementation of transmission mitigation measures. Funding: Ministry of Education, Brazil; Fundação de Amparo à Pesquisa do Estado do Amazonas; Pan American Health Organization (PAHO)/WHO.World Health OrganizationRevisión por pare

Cross-reactivity between Potamotrygon motoro antivenoms and dorsal and stinger extracts of others stingrays (Chondrichthyes: Potamotrygonidae) from the Amazon basin

In this study, two mouse hyperimmune sera were produced, one using extract from the stinger of the stingray Potamotrygon motoro and the other using extract from the dorsal region of the same species and their cross-reactivity with extracts from the following species of stingrays from the Amazon basin was investigated using Western blot and dot ELISA: Paratrygon aiereba, Plesiotrygon iwamae, Potamotrygon orbignyi and Potamotrygon schroederi. The results show that the dorsal extract was as immunogenic as the stinger extract and induced high levels of antibodies, which reacted with homologous and heterologous antigens, indicating that both types of extract may be suitable for use in the production of antivenom to treat victims of envenomation by stingrays. © 2017, © 2017 Informa UK Limited, trading as Taylor & Francis Group