Segunda opinião formativa: quais as consequências da infecção por dengue, chikungunya e zika vírus na gestação?

Se a dengue representa um perigo para a população, para as grávidas se torna mais agravante. Esta doença de etiologia viral e de disseminação urbana comum é transmitida pela picada da fêmea do mosquito Aedes aegypti, os riscos para mãe infectada estão principalmente relacionados ao aumento de sangramentos. Mães que adquirem Chikungunya no período intraparto podem transmitir o vírus a recém-nascidos por via transplacetária, outro fator alarmante das infecções por arboviroses foi relatada pelo Ministério da Saúde, que confirmou a relação entre o vírus Zika e o surto de microcefalia. As gestantes necessitam de vigilância, independente da gravidade, devendo a equipe de assistência estar atenta aos riscos para mãe e o concepto.

Geographical Distribution Of The Association Between El Niño South Oscillation And Dengue Fever In The Americas: A Continental Analysis Using Geographical Information System-based Techniques.

El Niño South Oscillation (ENSO) is one climatic phenomenon related to the inter-annual variability of global meteorological patterns influencing sea surface temperature and rainfall variability. It influences human health indirectly through extreme temperature and moisture conditions that may accelerate the spread of some vector-borne viral diseases, like dengue fever (DF). This work examines the spatial distribution of association between ENSO and DF in the countries of the Americas during 1995-2004, which includes the 1997-1998 El Niño, one of the most important climatic events of 20(th) century. Data regarding the South Oscillation index (SOI), indicating El Niño-La Niña activity, were obtained from Australian Bureau of Meteorology. The annual DF incidence (AIy) by country was computed using Pan-American Health Association data. SOI and AIy values were standardised as deviations from the mean and plotted in bars-line graphics. The regression coefficient values between SOI and AIy (rSOI,AI) were calculated and spatially interpolated by an inverse distance weighted algorithm. The results indicate that among the five years registering high number of cases (1998, 2002, 2001, 2003 and 1997), four had El Niño activity. In the southern hemisphere, the annual spatial weighted mean centre of epidemics moved southward, from 6° 31' S in 1995 to 21° 12' S in 1999 and the rSOI,AI values were negative in Cuba, Belize, Guyana and Costa Rica, indicating a synchrony between higher DF incidence rates and a higher El Niño activity. The rSOI,AI map allows visualisation of a graded surface with higher values of ENSO-DF associations for Mexico, Central America, northern Caribbean islands and the extreme north-northwest of South America.

Effect of CO2 and 1-octen-3-ol attractants for estimating species richness and the abundance of diurnal mosquitoes in the southeastern Atlantic forest, Brazil

Studies have shown that both carbon dioxide (CO2) and octenol (1-octen-3-ol) are effective attractants for mosquitoes. The objective of the present study was to evaluate the attractiveness of 1-octen-3-ol and CO2 for diurnal mosquitoes in the southeastern Atlantic forest. A Latin square experimental design was employed with four treatments: CDC-light trap (CDC-LT), CDC-LT and 1-octen-3-ol, CDC-LT and CO2 and CDC-LT with 1-octen-3-ol and CO2. Results demonstrated that both CDC-CO2 and CDC-CO2-1-octen-3-ol captured a greater number of mosquito species and specimens compared to CDC-1-octen-3-ol; CDC-LT was used as the control. Interestingly, Anopheles (Kerteszia) sp. was generally attracted to 1-octen-3-ol, whereas Aedes serratus was the most abundant species in all Latin square collections. This species was recently shown to be competent to transmit the yellow fever virus and may therefore play a role as a disease vector in rural areas of Brazil.

Estimação da infestação predial por Aedes aegypti (Díptera: Culicidae) por meio da armadilha Adultrap

Foi utilizada a armadilha Adultrap em uma amostra de domicílio preconizada pelo levantamento de índice rápido de infestação por Aedes aegypti (LIRAa) para mensuração do número de adulto de Aedes aegypti no domicílio. Foi vistoriada uma média de 555 imóveis mês: 15 unidades continham criadouros da espécie; e 53, a presença de fêmeas. O índice de infestação para larva/pupa (IPL) variou de zero ao máximo de 4,9 por cento, enquanto o índice de infestação para adulto (IPA), de 2,21 a 17,32 por cento. O teste de MacNemar mostrou diferenças significativas entre a positividade de IPL e IPA em todos os meses do ano. Além disso, detectaram-se fêmeas de Ae. Aegypti em período de baixa densidade populacional, sem o caráter invasivo e incômodo da pesquisa de recipientes para o IPL. A Adultrap mostrou-se útil para revelar situações propícias à transmissão da dengue, bem como de fácil operacionalidade

Registro de Aedes albopictus em áreas epizoóticas de febre amarela das Regiões Sudeste e Sul do Brasil (Díptera:Culicidae)

Durante estudo biológico e ecológico sobre mosquitos levado a cabo em área com registro de epidemia de febre amarela silvestre e epizootia em macacos, foram encontrados adultos de Aedes Albopictus. A tendência da espécie para invadir ambiente extradomiciliar potencializa a chance de infecção natural, ao tempo em que evolui para formar um elo entre focos naturais de vírus e o ambiente urbano. Esta Nota Técnica representa um alerta aos gestores dos três poderes públicos sobre perspectivas de mudanças no perfil epidemiológico atual da febre amarela no Brasil

System Identification and Prediction of Dengue Fever Incidence in Rio de Janeiro

Identification, prediction, and control of a system are engineering subjects, regardless of the nature of the system. Here, the temporal evolution of the number of individuals with dengue fever weekly recorded in the city of Rio de Janeiro, Brazil, during 2007, is used to identify SIS (susceptible-infective-susceptible) and SIR (susceptible-infective-removed) models formulated in terms of cellular automaton (CA). In the identification process, a genetic algorithm (GA) is utilized to find the probabilities of the state transition S -> I able of reproducing in the CA lattice the historical series of 2007. These probabilities depend on the number of infective neighbors. Time-varying and non-time-varying probabilities, three different sizes of lattices, and two kinds of coupling topology among the cells are taken into consideration. Then, these epidemiological models built by combining CA and GA are employed for predicting the cases of sick persons in 2008. Such models can be useful for forecasting and controlling the spreading of this infectious disease.

Threat of Dengue to Blood Safety in Dengue-Endemic Countries

Dengue, the most common arbovirus infection globally, is transmitted by mosquito vectors. Healthcare-related transmission, including transmission by blood products, has been documented, although the frequency of these occurrences is unknown. Dengue is endemic to Singapore, a city-state in Asia. Using mathematical modeling, we estimated the risk for dengue-infected blood transfusions in Singapore in 2005 to be 1.625-6/10,000 blood transfusions, assuming a ratio of asymptomatic to symptomatic infections of 2:1 to 10:1. However, the level of viremia required to cause clinical dengue cases is person-dependent and unknown. Further studies are needed to establish the magnitude of the threat that dengue poses to blood safety in countries where it is endemic. It will then be possible to assess whether screening is feasible and to identify approaches that are most cost-effective on the basis of characteristics of local populations and seasonality of dengue.

Vectorial Competence of Larvae and Adults of Alphitobius diaperinus in the Transmission of Salmonella Enteritidis in Poultry

Introduction: The ingestion of food products originating from poultry infected with Salmonella spp. is one of the major causes of food poisoning in humans. The control of poultry salmonellosis is particularly difficult since birds are asymptomatic and numerous factors may expedite the maintenance of bacteria in poultry production facilities. Objective: The aim of the study was to determine the vectorial capacity of adults and larvae of Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the experimental transmission of Salmonella Enteritidis phage type 4 to 1-day-old specific pathogen-free White Leghorn chicks. Methods: Adult insects and larvae were starved for 1 day, fed for 24 h or 7 days on sterile ration that had been treated with Salmonella Enteritidis phage type 4, and the levels of bacterial infection were determined. Infected adult insects and larvae were fed to groups of day-old chicks, after which bacteria were recovered from cecum, liver, and spleen samples over a 7-day period. Results: Infected larvae were more efficient than adult insects in transmitting Salmonella Enteritidis to chicks. Higher concentrations of bacteria could be reisolated from the cecum, liver, and spleen of chicks that had ingested infected larvae compared with those that had ingested infected adults. Conclusions: The control of A. diaperinus, and particularly of the larvae, represents a critical factor in the reduction of Salmonella spp. in poultry farms.

The Function and Three-Dimensional Structure of a Thromboxane A(2)/Cysteinyl Leukotriene-Binding Protein from the Saliva of a Mosquito Vector of the Malaria Parasite

The highly expressed D7 protein family of mosquito saliva has previously been shown to act as an anti-inflammatory mediator by binding host biogenic amines and cysteinyl leukotrienes (CysLTs). In this study we demonstrate that AnSt-D7L1, a two-domain member of this group from Anopheles stephensi, retains the CysLT binding function seen in the homolog AeD7 from Aedes aegypti but has lost the ability to bind biogenic amines. Unlike any previously characterized members of the D7 family, AnSt-D7L1 has acquired the important function of binding thromboxane A(2) (TXA(2)) and its analogs with high affinity. When administered to tissue preparations, AnSt-D7L1 abrogated Leukotriene C(4) (LTC(4))-induced contraction of guinea pig ileum and contraction of rat aorta by the TXA(2) analog U46619. The protein also inhibited platelet aggregation induced by both collagen and U46619 when administered to stirred platelets. The crystal structure of AnSt-D7L1 contains two OBP-like domains and has a structure similar to AeD(7). In AnSt-D7L1, the binding pocket of the C-terminal domain has been rearranged relative to AeD7, making the protein unable to bind biogenic amines. Structures of the ligand complexes show that CysLTs and TXA(2) analogs both bind in the same hydrophobic pocket of the N-terminal domain. The TXA(2) analog U46619 is stabilized by hydrogen bonding interactions of the omega-5 hydroxyl group with the phenolic hydroxyl group of Tyr 52. LTC(4) and occupies a very similar position to LTE(4) in the previously determined structure of its complex with AeD7. As yet, it is not known what, if any, new function has been acquired by the rearranged C-terminal domain. This article presents, to our knowledge, the first structural characterization of a protein from mosquito saliva that inhibits collagen mediated platelet activation.

Characterization of electrical penetration graphs of Bucephalogonia xanthophis, a vector of Xylella fastidiosa in citrus

The sharpshooter Bucephalogonia xanthophis (Berg) (Homoptera: Cicadellidae) is a vector of the xylem-limited bacterium, Xylella fastidiosa (Wells, Raju, Hung, Weisburg, Mandelco-Paul, and Brenner), which causes citrus variegated chlorosis. Despite the importance of citrus variegated chlorosis, the probing behavior of vectors on citrus and its implications for transmission of X. fastidiosa have not been studied. Here we studied electrical penetration graph (EPG-DC system) waveforms produced by B. xanthophis on Citrus sinensis (L.) Osbeck (Rutaceae), and their relationships with stylet activities and xylem ingestion. Electrical penetration graph waveforms were described based on amplitude, frequency, voltage level, and electrical origin of the observed traces during stylet penetration on plant tissues. The main waveforms were correlated with histological observations of salivary sheaths in plant tissues and excretion analysis, in order to determine stylet activities and their precise position. Six waveforms and associated activities are described: (S) secretion of salivary sheath and intracellular stylet pathway, (R) resting during stylet pathway, (Xc) contact of stylets with xylem vessels, (Xi) active xylem ingestion, (N) interruption within the xylem phase (during Xc or Xi), and (W) withdrawal of stylet from the plant. The sharpshooter spent 91.8% of its probing time with its stylet in the xylem, where the main activity was ingestion (Xi: 97.5%). During a probe, the most likely sequence of events is secretion of salivary sheath and pathway (S) through epidermal and parenchyma cells (all individuals), followed by contact with xylem (Xc) (67.6% of all individuals) and ingestion (Xi) (88.3% of those that exhibit waveform Xc). The mean time to contact the xylem (Xc) and initiate ingestion (Xi) after onset of the first probe was 27.8 and 34.2 min, respectively. However, sustained xylem ingestion (Xi > 5 min) was established after 39.8 min, on average. This information is basic for future studies on the transmission mechanisms of X. fastidiosa and in order to establish control strategies aimed at interfering with this process.

Strain origin drives virulence and persistence of Xylella fastidiosa in alfalfa

Generalist pathogens frequently exist as a complex of genetically differentiated strains, which can differ in virulence and transmissibility. A description of the extent to which strain variability mediates host species competence is needed to understand disease dynamics for systems with both host and pathogen strain diversity. This study tested the hypothesis that strain-specific variation of a generalist vector-borne plant pathogen, Xylella fastidiosa, affects disease severity in alfalfa (Medicago sativa) and competence of this crop as a reservoir host. Alfalfa seedlings were inoculated with one of 23 X. fastidiosa isolates collected from different hosts, eight identified as belonging to an almond strain, and the remainder from a grape strain. Pathogen population, symptom severity and infection incidence were compared over five successive harvests. Infected plant size, measured mainly by plant height, internode length and above ground biomass, was reduced up to 50% compared to buffer-inoculated controls, and more severe symptoms were observed at later harvests and for higher pathogen populations. Grape isolates had higher bacterial populations within alfalfa than almond isolates. In addition, infection with grape isolates resulted in more severe alfalfa stunting than that caused by almond isolates. Moreover, there was a strong positive relationship between isolate multiplication rate and both symptom severity and infection persistence (i.e. maintenance of chronic infection within host). Isolates with low initial populations had low incidence at the final harvest, with one isolate dying out altogether. The results showed that X. fastidiosa-genetic diversity contributed to variation in alfalfa disease severity. The results also suggest that pathogen strain may mediate host competence via differences in bacterial population density and persistence.

Determination of Wolbachia genome size by Pulsed-Field Gel Electrophoresis

Genome sizes of six different Wolbachia strains from insect and nematode hosts have been determined by pulsed-field gel electrophoresis of purified DNA both before and after digestion with rare-cutting restriction endonucleases. Enzymes SmaI, ApaI, AscI, and FseI cleaved the studied Wolbachia strains at a small number of sites and were used for the determination of the genome sizes of wMelPop, wMel, and wMelCS (each 1.36 Mb), wRi (1.66 Mb), wBma (1.1 Mb), and wDim (0.95 Mb). The Wolbachia genomes studied were all much smaller than the genomes of free-living bacteria such as Escherichia coli (4.7 Mb), as is typical for obligate intracellular bacteria. There was considerable genome size variability among Wolbachia strains, especially between the more parasitic A group Wolbachia infections of insects and the mutualistic C and D group infections of nematodes. The studies described here found no evidence for extrachromosomal plasmid DNA in any of the strains examined. They also indicated that the Wolbachia genome is circular.

Wolbachia infections of phlebotomine sand flies (Diptera: Psychodidae)

Old and New World phlebotomine sand fly species were screened for infection with Wolbachia, intracellular bacterial endosymbionts found in many arthropods and filarial nematodes. Of 53 samples representing 15 species, nine samples of four species were found positive for Wolbachia by polymerase chain reaction amplification using primers for the Wolbachia surface protein (wsp) gene. Five of the wsp gene fragments from four species were cloned, sequenced, and used for phylogenetic analysis. These wsp sequences were placed in three different clades within the arthropod associated Wolbachia (groups A and B), suggesting that Wolbachia has infected sand flies on more than one occasion. Two distantly related sand fly species, Lutzomyia (Psanthyromyia) shannoni (Dyar) and Lutzomyia (Nyssomyia) whitmani (Antunes & Coutinho), infected with an identical Wolbachia strain suggest a very recent horizontal transmission.

Wolbachia infection and expression of cytoplasmic incompatibility in Armigeres subalbatus (Diptera: Culicidae)

Polymerase chain reaction screening revealed that Armigeres subalbatus (Coquillett), a vector of filariasis, was infected with the intracellular bacteria Wolbachia. Laboratory crosses between infected males and uninfected females resulted in less than half the number of offspring than control crosses between uninfected individuals when young (2- to 3-d-old) males were used in the cross. However, incompatibility was lost when old (14- to 17-d-old) males were used. Field-collected females did not show detectable cytoplasmic incompatibility, and this may be because of the age at which males mate in the field. We used head pigment fluorescence levels to age field males collected from mating swarms, and found that 25-63% of swarming males were older than 13 d. Male age may be one factor influencing the observed low levels of cytoplasmic incompatibility detected in the field.