Aedes aegypti and Aedes albopictus mosquitoes are the main vectors for dengue virus (DENV) and other arboviruses, including Zika virus (ZIKV).Understanding the factors that affect transmission of arboviruses from mosquitoes to humans is a priority, because it could inform public health and targeted interventions. Reasoning that interactions among viruses

Dengue virus type 3 genotype I was detected in Brazil during epidemics in 2002–2004. To confirm this finding, we identified this virus genotype in naturally infected field-caught Aedes aegypti mosquitoes and eggs. Results showed usefulness of virus investigations in vectors as a component of active epidemiologic surveillance.

BackgroundDengue is a vector-borne disease caused by the dengue virus (DENV). Despite the crucial role of Aedes mosquitoes in DENV transmission, pure vector indices poorly correlate with human infections. Therefore there is great need for a better understanding of the spatial and temporal scales of DENV transmission between mosquitoes and humans. Here, we have systematically monitored the circulation of DENV in individual Aedes spp. mosquitoes and human patients from Caratinga, a dengue endemic city in the state of Minas Gerais, in Southeast Brazil. From these data, we have developed a novel stochastic point process pattern algorithm to identify the spatial and temporal association between DENV infected mosquitoes and human patients.MethodsThe algorithm comprises of: (i) parameterization of the variogram for the incidence of each DENV serotype in mosquitoes; (ii) identification of the spatial and temporal ranges and variances of DENV incidence in mosquitoes in the proximity of humans infected with dengue; and (iii) analysis of the association between a set of environmental variables and DENV incidence in mosquitoes in the proximity of humans infected with dengue using a spatio-temporal additive, geostatistical linear model.ResultsDENV serotypes 1 and 3 were the most common virus serotypes detected in both mosquitoes and humans. Using the data on each virus serotype separately, our spatio-temporal analyses indicated that infected humans were located in areas with the highest DENV incidence in mosquitoes, when incidence is calculated within 2.5–3 km and 50 days (credible interval 30–70 days) before onset of symptoms in humans. These measurements are in agreement with expected distances covered by mosquitoes and humans and the time for virus incubation. Finally, DENV incidence in mosquitoes found in the vicinity of infected humans correlated well with the low wind speed, higher air temperature and northerly winds that were more likely to favor vector survival and dispersal in Caratinga.ConclusionsWe have proposed a new way of modeling bivariate point pattern on the transmission of arthropod-borne pathogens between vector and host when the location of infection in the latter is known. This strategy avoids some of the strong and unrealistic assumptions made by other point-process models. Regarding virus transmission in Caratinga, our model showed a strong and significant association between high DENV incidence in mosquitoes and the onset of symptoms in humans at specific spatial and temporal windows. Together, our results indicate that vector surveillance must be a priority for dengue control. Nevertheless, localized vector control at distances lower than 2.5 km around premises with infected vectors in densely populated areas are not likely to be effective.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-2662-6) contains supplementary material, which is available to authorized users.

Abstract. Dengue is currently regarded as a major public health problem worldwide. In a hyperendemic region during an outbreak, we detected the co-circulation of all Dengue virus (DENV) serotypes including two different genotypes of DENV-3 and DENV-4, and concurrent infections with up to three serotypes were identified in symptomatic patients. A total of 49 acute phase plasma samples from patients clinically suspected of dengue were collected during the 4 weeks of May 2013. DENV-1-4 was detected by reverse transcriptase semi-nested polymerase chain reaction in 33 samples (67.3%), of which 26 DNA fragments were sequenced. Twenty samples (76.9%) were identified with a single DENV serotype and six (23.1%) with more than one serotype. DENV-3 was the predominant serotype of the outbreak. On the basis of phylogenetic analyses, DENV-1 isolates belong to genotype V, DENV-2 to American-Asian genotype, DENV-3 to genotypes I and III, and DENV-4 to genotypes I and II.Dengue is currently regarded globally as the most important mosquito-borne viral disease as it is a major public health problem worldwide.1 The disease is caused by four antigenically and genetically distinct viruses designated dengue virus 1-4 (DENV-1-4), which are subdivided into distinct genotypes. 2,3DENVs are transmitted by mosquito vectors, primarily Aedes aegypti.4 DENV infection is often unapparent but can lead to a wide range of clinical manifestations from mild disease to severe dengue cases with bleeding, plasma leakage, and shock. 5In dengue-endemic countries, the co-circulation of multiple DENV serotypes in the same area has been described with concurrent infections. 1,6 The first reported case of concurrent infection with two serotypes (DENV-1 and DENV-4) occurred in Puerto Rico in 1982. 4 Since this time, dual infections have been reported in locals in New Caledonia, Taiwan, China, Singapore, and India. In 1999, an infection with three serotypes (DENV-1/DENV-3/DENV-4) was detected in two patients from Indonesia and one from Mexico. 4,6 In this study, we report, for the first time in Brazil, the cocirculation and coinfection of DENV-1-4 during a severe outbreak in an endemic area of southeast Brazil. Our data raise new questions about biological and public health aspects related to dengue occurrence in Brazil.The study was performed in Contagem, Minas Gerais, which borders the city of Belo Horizonte (state capital), and it has an area of 195,268 km 2 with approximately 603,442 inhabitants. In 2013, Contagem underwent a dengue epidemic with the highest number of notified cases that has been ever recorded (23,436) and three deaths. In May 2013, a total of 49 acute phase plasma samples were collected during 4 weeks from clinically suspected dengue patients admitted to Geraldo Pinto Vieira Hospital in Contagem. Until this month, 22,808 (97.3%) cases had been reported. This research was approved by the Ethical Committee of UFMG. The residential addresses of DENV-positive patients are plotted on the map of Contagem shown in Figure 1.Viral RNA was extrac...

Equine infectious anemia (EIA) has a worldwide distribution, and is widespread in Brazil. The Brazilian Pantanal presents with high prevalence comprising equine performance and indirectly the livestock industry, since the horses are used for cattle management. Although EIA is routinely diagnosed by the agar gel immunodiffusion test (AGID), this serological assay has some limitations, so PCR-based detection methods have the potential to overcome these limitations and act as complementary tests to those currently used. Considering the limited number of equine infectious anemia virus (EIAV) sequences which are available in public databases and the great genome variability, studies of EIAV detection and characterization molecular remain important. In this study we detected EIAV proviral DNA from 23 peripheral blood mononuclear cell (PBMCs) samples of naturally infected horses from Brazilian Pantanal using a semi-nested-PCR (sn-PCR). The serological profile of the animals was also evaluated by AGID and ELISA for gp90 and p26. Furthermore, the EIAV PCR amplified DNA was sequenced and phylogenetically analyzed. Here we describe the first EIAV sequences of the 5' LTR of the tat gene in naturally infected horses from Brazil, which presented with 91% similarity to EIAV reference sequences. The Brazilian EIAV sequences also presented variable nucleotide similarities among themselves, ranging from 93,5% to 100%. Phylogenetic analysis showed that Brazilian EIAV sequences grouped in a separate clade relative to other reference sequences. Thus this molecular detection and characterization may provide information about EIAV circulation in Brazilian territories and improve phylogenetic inferences.