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1.
Mem Inst Oswaldo Cruz ; 115: e190431, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32935748

RESUMO

BACKGROUND: Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated. OBJECTIVE: To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia. METHODS: A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention. FINDINGS: Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period. CONCLUSIONS: Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.


Assuntos
Anopheles/efeitos dos fármacos , Insetos Vetores/efeitos dos fármacos , Mosquiteiros Tratados com Inseticida , Inseticidas/administração & dosagem , Leishmaniose Cutânea/prevenção & controle , Controle de Mosquitos/métodos , Animais , Colômbia , Resistência a Inseticidas , Leishmaniose Cutânea/parasitologia , Mosquitos Vetores , População Rural
2.
PLoS One ; 15(9): e0237322, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881929

RESUMO

A bite from a La Crosse virus (LACV) infected Aedes mosquito can cause La Crosse encephalitis (LACE), which is a neuro-invasive disease that disproportionately affects children under the age of 16 in Southern Appalachia. The three vectors for LACV are Aedes albopictus (Skuse), Ae. japonicus (Theobald), and Ae. triseriatus (Say). Localized maps of the geographic distribution of vectors are practical tools for mosquito management personnel to target areas with high mosquito abundance. This study hypothesized that LACV vectors have unique species-specific spatial and temporal clusters. To test this, 44 sites were identified in Knox County, Tennessee for their land use/type. At each site, host-seeking mosquitoes were collected approximately every other week from May-October 2018. Spatial clusters of host-seeking mosquito collections for each of the three mosquito species were investigated using Kulldorff's spatial scan statistic, specifying a retrospective space-time Bernoulli model. Most vector clusters were identified in south-central Knox County while the seasonality of clusters varied by mosquito species. Clusters of Ae. albopictus were observed throughout the entire study period while clusters of Ae. japonicus and Ae. triseriatus only occurred May-June. The findings indicate that the relative abundance of LACV vectors were more abundant in south-central Knox County compared to the rest of the county. Of interest, these clusters spatially overlapped with previous LACE diagnosed cases. These findings are useful in guiding decisions on targeted mosquito control in Knox County and may be applied to other counties within Southern Appalachia.


Assuntos
Aedes/virologia , Comportamento Animal , Doenças Endêmicas , Interações Hospedeiro-Parasita , Vírus La Crosse/fisiologia , Análise Espaço-Temporal , Animais , Geografia , Insetos Vetores/virologia , Tennessee
3.
PLoS Negl Trop Dis ; 14(8): e0008251, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32853251

RESUMO

Yersinia pestis, the bacterial causative agent of plague, remains an important threat to human health. Plague is a rodent-borne disease that has historically shown an outstanding ability to colonize and persist across different species, habitats, and environments while provoking sporadic cases, outbreaks, and deadly global epidemics among humans. Between September and November 2017, an outbreak of urban pneumonic plague was declared in Madagascar, which refocused the attention of the scientific community on this ancient human scourge. Given recent trends and plague's resilience to control in the wild, its high fatality rate in humans without early treatment, and its capacity to disrupt social and healthcare systems, human plague should be considered as a neglected threat. A workshop was held in Paris in July 2018 to review current knowledge about plague and to identify the scientific research priorities to eradicate plague as a human threat. It was concluded that an urgent commitment is needed to develop and fund a strong research agenda aiming to fill the current knowledge gaps structured around 4 main axes: (i) an improved understanding of the ecological interactions among the reservoir, vector, pathogen, and environment; (ii) human and societal responses; (iii) improved diagnostic tools and case management; and (iv) vaccine development. These axes should be cross-cutting, translational, and focused on delivering context-specific strategies. Results of this research should feed a global control and prevention strategy within a "One Health" approach.


Assuntos
Doenças Negligenciadas/prevenção & controle , Peste/prevenção & controle , Yersinia pestis , Animais , Surtos de Doenças/prevenção & controle , Reservatórios de Doenças/microbiologia , Humanos , Insetos Vetores , Madagáscar/epidemiologia , Doenças Negligenciadas/epidemiologia , Peste/epidemiologia , Peste/transmissão , Roedores , Sifonápteros
4.
PLoS Negl Trop Dis ; 14(8): e0008411, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776929

RESUMO

Approximately 150 triatomine species are suspected to be infected with the Chagas parasite, Trypanosoma cruzi, but they differ in the risk they pose to human populations. The largest risk comes from species that have a domestic life cycle and these species have been targeted by indoor residual spraying campaigns, which have been successful in many locations. It is now important to consider residual transmission that may be linked to persistent populations of dominant vectors, or to secondary or minor vectors. The aim of this project was to define the geographical distributions of the community of triatomine species across the Chagas endemic region. Presence-only data with over 12, 000 observations of triatomine vectors were extracted from a public database and target-group background data were generated to account for sampling bias in the presence data. Geostatistical regression was then applied to estimate species distributions and fine-scale distribution maps were generated for thirty triatomine vector species including those found within one or two countries and species that are more widely distributed from northern Argentina to Guatemala, Bolivia to southern Mexico, and Mexico to the southern United States of America. The results for Rhodnius pictipes, Panstrongylus geniculatus, Triatoma dimidiata, Triatoma gerstaeckeri, and Triatoma infestans are presented in detail, including model predictions and uncertainty in these predictions, and the model validation results for each of the 30 species are presented in full. The predictive maps for all species are made publicly available so that they can be used to assess the communities of vectors present within different regions of the endemic zone. The maps are presented alongside key indicators for the capacity of each species to transmit T. cruzi to humans. These indicators include infection prevalence, evidence for human blood meals, and colonisation or invasion of homes. A summary of the published evidence for these indicators shows that the majority of the 30 species mapped by this study have the potential to transmit T. cruzi to humans.


Assuntos
Insetos Vetores , Triatominae/parasitologia , Trypanosoma cruzi , Distribuição Animal , Animais , Doença de Chagas/epidemiologia , Doença de Chagas/transmissão , Habitação , Humanos , América Latina/epidemiologia , Modelos Teóricos
5.
Parasit Vectors ; 13(1): 409, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32778178

RESUMO

The coronavirus disease 19 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected millions of people worldwide. Recent evidence raised the question about the possibility that cats may be a domestic host for SARS-CoV-2 with unknown implications in disease dissemination. Based on the fact that the domestic cat flea, Ctenocephalides felis, are abundant ectoparasites infesting humans, companion animals and wildlife and that coronavirus-like agents have been identified in the ectoparasite tick vector, Ixodes uriae of seabirds, herein we considered the presence of coronaviruses in general and SARS-CoV-2 in particular in C. felis. We identified coronavirus-derived and cell receptor angiotensin-converting enzyme RNA/proteins in C. felis. Although current evidence suggests that pets are probably dead-end-hosts with small risk of transmission to humans, our results suggested that cat flea may act as biological and/or mechanical vectors of SARS-CoV. Although preliminary, these results indicate a possibility of ectoparasites acting as reservoirs and vectors of SARS-CoV and related beta-coronavirus although with little disease risk due to systemic transmission route, low viremia, virus attenuation or other unknown factors. These results support the need to further study the role of animal SARS-CoV-2 hosts and their ectoparasite vectors in COVID-19 disease spread.


Assuntos
Infecções por Coronavirus/veterinária , Coronavirus/isolamento & purificação , Ctenocephalides/virologia , Insetos Vetores/virologia , Pneumonia Viral/veterinária , Sequência de Aminoácidos , Animais , Betacoronavirus/genética , Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/virologia , Humanos , Pandemias , Peptidil Dipeptidase A/genética , Pneumonia Viral/transmissão , Pneumonia Viral/virologia
6.
Parasitol Res ; 119(9): 2775-2781, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32737590

RESUMO

Triatoma platensis is occasionally found coexisting with Triatoma infestans in chicken coops in Argentina. Some authors have reported the presence of hybrid specimens of both species in chicken coops and other peridomestic habitats. Given the coexistence of T. infestans with T. platensis and the possibility of generating fertile hybrids, it is important to evaluate the vectorial competence of these hybrids. The objective of this study was to record the dynamics of feeding-defecation behavior in fifth-stage nymphs and adults of hybrids between both species and to compare it with T. platensis and T. infestans. Three experimental groups were formed separated by stage and sex: Hybrid group, T. infestans group, and T. platensis group. During feeding, the following variables were recorded for each group: (i) blood meal size, (ii) feeding time, (iii) number of defecations during feeding, and (iv) number of defecations at 10 and 30 min after feeding. The results indicate that adults and fifth-instar nymphs of hybrids have a feeding and defecation behavior similar to T. infestans: they achieve feeding in a short time and first defecation occurs during or just after feeding. Nevertheless, hybrid's ingestion of blood occurs at higher velocity and they require higher blood intake to provoke early defecations. Considering the blood ingestion velocity, the amount of blood ingested, and the short time required for the production of the first defecation, the results of this study suggest that hybrid can be a competent Trypanosoma cruzi vector.


Assuntos
Defecação/fisiologia , Comportamento Alimentar/fisiologia , Insetos Vetores/fisiologia , Triatoma/fisiologia , Animais , Argentina , Doença de Chagas/transmissão , Galinhas/parasitologia , Ecossistema , Fezes/parasitologia , Feminino , Masculino , Ninfa/crescimento & desenvolvimento , Trypanosoma cruzi/crescimento & desenvolvimento
7.
PLoS Genet ; 16(8): e1008992, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32797092

RESUMO

Bacterial virulence factors facilitate host colonization and set the stage for the evolution of parasitic and mutualistic interactions. The Sodalis-allied clade of bacteria exhibit striking diversity in the range of both plant and animal feeding insects they inhabit, suggesting the appropriation of universal molecular mechanisms that facilitate establishment. Here, we report on the infection of the tsetse fly by free-living Sodalis praecaptivus, a close relative of many Sodalis-allied symbionts. Key genes involved in quorum sensing, including the homoserine lactone synthase (ypeI) and response regulators (yenR and ypeR) are integral for the benign colonization of S. praecaptivus. Mutants lacking ypeI, yenR and ypeR compromised tsetse survival as a consequence of their inability to repress virulence. Genes under quorum sensing, including homologs of the binary insecticidal toxin PirAB and a putative symbiosis-promoting factor CpmAJ, demonstrated negative and positive impacts, respectively, on tsetse survival. Taken together with results obtained from experiments involving weevils, this work shows that quorum sensing virulence suppression plays an integral role in facilitating the establishment of Sodalis-allied symbionts in diverse insect hosts. This knowledge contributes to the understanding of the early evolutionary steps involved in the formation of insect-bacterial symbiosis. Further, despite having no established history of interaction with tsetse, S. praecaptivus can infect reproductive tissues, enabling vertical transmission through adenotrophic viviparity within a single host generation. This creates an option for the use of S. praecaptivus in the biocontrol of insect disease vectors via paratransgenesis.


Assuntos
Percepção de Quorum/genética , Moscas Tsé-Tsé/genética , Fatores de Virulência/genética , 4-Butirolactona/análogos & derivados , 4-Butirolactona/biossíntese , 4-Butirolactona/genética , Animais , Enterobacteriaceae/genética , Enterobacteriaceae/patogenicidade , Humanos , Insetos Vetores/genética , Insetos Vetores/microbiologia , Insetos/genética , Simbiose/genética , Moscas Tsé-Tsé/microbiologia
8.
Med Hypotheses ; 143: 110121, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32759006

RESUMO

SARS-CoV-2 incidence and mortality in Europe have shown wide variation. Northern Italy in particular the Lombardy region, north-eastern French regions, Switzerland and Belgium were amongst the hardest hit, while the central and southern Italian regions, all the Balkan countries from Slovenia to Greece and the Islands of Malta and Cyprus had much fewer cases and deaths per capita, and deaths per number of cases. Differences in public health measures, and health care delivery, in the author's opinion, can only partly explain the difference. The geographical distribution of Phlebotomus sand-flies and the relative distribution of arthropod borne diseases Leishmaniasis and Phlebovirus infections especially the Sicilian Sandfly fever group corresponds to most areas of low prevalence of SARS-CoV-2. A hypothesis is proposed whereby repeated arthropod or sandfly vector infection of humans by novel viruses of zoonotic origins carrying bat or mammalian RNA/DNA, such as phleboviruses may have resulted in the development of an effective evolutionary immune response to most novel zoonotic viruses such as SARS-CoV-2 by means of survival of the fittest possibly over many generations. This process probably ran in parallel and concurrent with the progressive evolution of novel coronaviruses which spread from one mammalian species to another. Other possible, but less likely mechanisms for the role of sandfly meals within a much shorter time frame may have led to, (i) previous exposure and infection of humans with the SARS-Cov-2 virus itself, or a closely related corona virus in the previous decades, or (ii) exposure of human populations to parts coronavirus protein namely either S or more likely N protein carried mechanically by arthropods, but without clinical disease causing direct immunity or (iii) by causing infection with other arthropod borne viruses which could carry bat DNA/RNA and have similar functional proteins resulting in an immediate cross-reactive immune response rather than by natural selection. The Evidence possibly supporting or disputing this hypothesis is reviewed, however the major problem with the hypothesis is that to date no coronavirus has ever been isolated from arthropods. Such a hypothesis can only be supported by research investigating the possible biological relationship of arthropods and coronaviruses where paradoxically they may be promoting immunity rather than disease.


Assuntos
Arbovirus/imunologia , Betacoronavirus/imunologia , Infecções por Coronavirus/imunologia , Imunidade Coletiva , Insetos Vetores/virologia , Pandemias , Phlebotomus/virologia , Pneumonia Viral/imunologia , Animais , Anticorpos Antivirais/análise , Conflitos Armados , Artrópodes/virologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/transmissão , Infecções por Coronavirus/veterinária , Infecções por Coronavirus/virologia , Reações Cruzadas , Reservatórios de Doenças/virologia , Europa (Continente)/epidemiologia , Especificidade de Hospedeiro , Interações Hospedeiro-Patógeno , Humanos , Incidência , Itália , Mamíferos/virologia , Pneumonia Viral/epidemiologia , Vírus da Febre do Flebótomo Napolitano/imunologia , Seleção Genética , Especificidade da Espécie , Proteínas Virais/imunologia , Zoonoses
9.
PLoS Negl Trop Dis ; 14(8): e0008528, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32764763

RESUMO

House Index, Container Index, and Breteau Index are the most commonly used indices for dengue vector surveillance. However, these larval indices are a poor proxy for measuring the adult population-which is responsible for disease transmission. Information on the adult distribution and density are important for assessing transmission risk as well as for developing effective control strategies. This study introduces a new entomological index, Gravitrap aegypti index (GAI), which estimates the adult female Aedes aegypti population in the community and presents its association with dengue cases. Gravitraps were deployed across 34 treatment sites in Singapore from September 2013 to September 2016. The GAI, derived from the Gravitrap surveillance data, was analysed to investigate the spatio-temporal patterns of the Ae. aegypti population in Singapore. The index was further categorised into low, moderate, and high-risk groups and its association with dengue cases were examined. A Before-After Control Impact analysis was performed to evaluate the epidemiology impact of Gravitrap system on dengue transmission. The Ae. aegypti population exhibits a seasonal pattern, and spatial heterogeneity in Ae. aegypti abundance was observed among treatment sites. The Ae. aegypti population was also found to be unevenly distributed among floors of an apartment block, with low floors (floors 1-4) having a higher abundance of mosquitoes trapped than mid (floors 5-8) and high (floors ≥9) floors. Areas with high GAI were shown to have higher dengue case count. Gravitrap has also demonstrated to be a good dengue control tool. The contribution of cases by treatment sites to the national numbers was lower after Gravitraps deployment. The GAI, which is of better relevance to dengue transmission risk, could be recommended as an indicator for decision making in vector control efforts, and to monitor the spatio-temporal variability of the adult Aedes population in the country. In addition, findings from this study indicate that Gravitraps can be used as a dengue control tool to reduce dengue transmission.


Assuntos
Aedes/fisiologia , Surtos de Doenças/prevenção & controle , Controle de Mosquitos/instrumentação , Controle de Mosquitos/métodos , Aedes/virologia , Animais , Dengue/epidemiologia , Vírus da Dengue , Meio Ambiente , Feminino , Insetos Vetores , Densidade Demográfica , Singapura
10.
PLoS Pathog ; 16(8): e1008754, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776975

RESUMO

Arbovirus infection of Aedes aegypti salivary glands (SGs) determines transmission. However, there is a dearth of knowledge on SG immunity. Here, we characterized SG immune response to dengue, Zika and chikungunya viruses using high-throughput transcriptomics. We also describe a transcriptomic response associated to apoptosis, blood-feeding and lipid metabolism. The three viruses differentially regulate components of Toll, Immune deficiency (IMD) and c-Jun N- terminal Kinase (JNK) pathways. However, silencing of the Toll and IMD pathway components showed variable effects on SG infection by each virus. In contrast, regulation of the JNK pathway produced consistent responses in both SGs and midgut. Infection by the three viruses increased with depletion of the activator Kayak and decreased with depletion of the negative regulator Puckered. Virus-induced JNK pathway regulates the complement factor, Thioester containing protein-20 (TEP20), and the apoptosis activator, Dronc, in SGs. Individual and co-silencing of these genes demonstrate their antiviral effects and that both may function together. Co-silencing either TEP20 or Dronc with Puckered annihilates JNK pathway antiviral effect. Upon infection in SGs, TEP20 induces antimicrobial peptides (AMPs), while Dronc is required for apoptosis independently of TEP20. In conclusion, we revealed the broad antiviral function of JNK pathway in SGs and showed that it is mediated by a TEP20 complement and Dronc-induced apoptosis response. These results expand our understanding of the immune arsenal that blocks arbovirus transmission.


Assuntos
Aedes/imunologia , Apoptose , Febre de Chikungunya/imunologia , Proteínas do Sistema Complemento/imunologia , Dengue/imunologia , Sistema de Sinalização das MAP Quinases , Glândulas Salivares/imunologia , Infecção por Zika virus/imunologia , Aedes/virologia , Animais , Febre de Chikungunya/metabolismo , Febre de Chikungunya/prevenção & controle , Febre de Chikungunya/virologia , Vírus Chikungunya/imunologia , Proteínas do Sistema Complemento/metabolismo , Dengue/metabolismo , Dengue/prevenção & controle , Dengue/virologia , Vírus da Dengue/imunologia , Feminino , Interações Hospedeiro-Patógeno , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Insetos Vetores/imunologia , Insetos Vetores/virologia , Glândulas Salivares/virologia , Transcriptoma , Replicação Viral , Zika virus/imunologia , Infecção por Zika virus/metabolismo , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/virologia
11.
PLoS Pathog ; 16(8): e1008710, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32817722

RESUMO

Rice stripe virus (RSV, genus Tenuivirus, family Phenuiviridae) is the causal agent of rice stripe disease transmitted by the small brown planthopper (SBPH, Laodelphax striatellus) in a persistent propagative manner. The midgut and salivary glands of SBPH are the first and last barriers to the viral circulation and transmission processes, respectively; however, the precise mechanisms used by RSV to cross these organs and transmit to rice plants have not been fully elucidated. We obtained the full-length cDNA sequence of L. striatellus α-tubulin 2 (LsTUB) and found that RSV infection increased the level of LsTUB in vivo. Furthermore, LsTUB was shown to co-localize with RSV nonstructural protein 3 (NS3) in vivo and bound NS3 at positions 74-76 and 80-82 in vitro. Transient gene silencing of LsTUB expression caused a significant reduction in detectable RSV loads and viral NS3 expression levels, but had no effect on NS3 silencing suppressor activity and viral replication in insect cells. However, suppression of LsTUB attenuated viral spread in the bodies of SBPHs and decreased RSV transmission rates to rice plants. Electrical penetration graphs (EPG) showed that LsTUB knockdown by RNAi did not impact SBPH feeding; therefore, the reduction in RSV transmission rates was likely caused by a decrease in viral loads inside the planthopper. These findings suggest that LsTUB mediates the passage of RSV through midgut and salivary glands and leads to successful horizontal transmission.


Assuntos
Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Insetos Vetores/metabolismo , Oryza/virologia , Doenças das Plantas/virologia , Tenuivirus/fisiologia , Tubulina (Proteína)/metabolismo , Animais , Sistema Digestório/metabolismo , Sistema Digestório/virologia , Hemípteros/genética , Hemípteros/virologia , Proteínas de Insetos/genética , Insetos Vetores/genética , Insetos Vetores/virologia , Glândulas Salivares/metabolismo , Glândulas Salivares/virologia , Tubulina (Proteína)/genética
12.
Artigo em Inglês | MEDLINE | ID: mdl-32844905

RESUMO

This study aimed to describe the spatial distribution and assess entomological indicators of synanthropic triatomines in Piaui State, Northeastern Brazil. We used surveillance data on the detection, identification and assessment of natural infection with trypanosomatids from triatomines in the State from 2014 to 2017. The State was divided into four macroregions. In relation to the dispersion rates of triatomines, they were much lower in the North, when compared to Southwest, Southeast and Central North macroregions. Infestation rates were higher in the Southwest and Southeast and intradomicile infestation rates varied during the study period, reaching high values in all regions. Insects belonging to the species Triatoma brasiliensis complex, Triatoma pseudomaculata, Triatoma sordida, and to the genus Panstrongylus spp. and Rhodnius spp. were collected during this period. T. brasiliensis was collected from all four regions of the State, but more frequently in those located in the Southeast. A similar pattern was observed for T. pseudomaculata. T. sordida was detected in the municipalities in the Southeast and Southwest regions, and less frequently in the Central North municipalities. Rhodnius spp. was detected in the Central North and North regions, and Panstrongylus spp. in the Central North and Southeast regions. The highest trypanosomatid-positivity rate of T. brasiliensis and Panstrongylus spp. was in the Southeast region. A significant proportion of the municipalities of Piaui State presents entomological parameters that indicate a risk of Chagas disease by vector transmission.


Assuntos
Doença de Chagas , Insetos Vetores/parasitologia , Triatoma/parasitologia , Triatominae/classificação , Trypanosoma cruzi/isolamento & purificação , Animais , Brasil , Doença de Chagas/diagnóstico , Doença de Chagas/transmissão , Triatominae/parasitologia
13.
Sci Rep ; 10(1): 11915, 2020 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-32681089

RESUMO

This research addresses public speculation that SARS-CoV-2 might be transmitted by mosquitoes. The World Health Organization has stated "To date there has been no information nor evidence to suggest that the new coronavirus could be transmitted by mosquitoes". Here we provide the first experimental data to investigate the capacity of SARS-CoV-2 to infect and be transmitted by mosquitoes. Three widely distributed species of mosquito; Aedes aegypti, Ae. albopictus and Culex quinquefasciatus, representing the two most significant genera of arbovirus vectors that infect people, were tested. We demonstrate that even under extreme conditions, SARS-CoV-2 virus is unable to replicate in these mosquitoes and therefore cannot be transmitted to people even in the unlikely event that a mosquito fed upon a viremic host.


Assuntos
Betacoronavirus/fisiologia , Culicidae/virologia , Aedes/virologia , Animais , Betacoronavirus/isolamento & purificação , Chlorocebus aethiops , Culex/virologia , Insetos Vetores/virologia , Células Vero
15.
Korean J Parasitol ; 58(3): 229-236, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32615736

RESUMO

Cutaneous leishmaniosis (CL) is the most common form of leishmaniasis.CL caused by L. major and L. tropica is endemic in 17 provinces of Iran. This study was carried out to elucidate situation of CL in Ardabil province and to predict distribution of Phlebotomus papatasi and Phlebotomus sergenti (Diptera: Psychodidae) as vectors of CL in the region. In this cross-sectional study, data on CL patients were collected from local health centers of Ardabil province, Iran during 2006-2018 to establish a geodatabase using ArcGIS10.3. A total of 20 CL cases were selected randomly and skin samples were collected and analyzed by PCR method. MaxEnt 3.3.3 model was used to determine ecologically suitable niches for the main vectors. A total, 309 CL human cases were reported and the highest incidence rate of disease was occurred in Bilasavar (37/100,000) and Germi (35/100,000). A total of 2,794 sand flies were collected during May to October 2018. The environmentally suitable habitats for P. papatasi and P. sergenti were predicted to be present in northern and central areas of Ardabil province. The most variable that contributed ratio in the modeling were Isothermality and slope factors. Ardabil province is possibly an endemic are for CL. The presence of P. papatasi and P. sergenti justifies local transmission while the vectors of CL are existing in the northern and central areas of the province.


Assuntos
Insetos Vetores , Leishmaniose Cutânea/epidemiologia , Phlebotomus , Animais , Estudos Transversais , Ecossistema , Feminino , Humanos , Incidência , Irã (Geográfico)/epidemiologia , Leishmaniose Cutânea/transmissão , Masculino , Fatores de Tempo
16.
PLoS Negl Trop Dis ; 14(7): e0007489, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32658913

RESUMO

Phlebotomus papatasi sand flies inject their hosts with a myriad of pharmacologically active salivary proteins to assist with blood feeding and to modulate host defenses. In addition, salivary proteins can influence cutaneous leishmaniasis disease outcome, highlighting the potential of the salivary components to be used as a vaccine. Variability of vaccine targets in natural populations influences antigen choice for vaccine development. Therefore, the objective of this study was to investigate the variability in the predicted protein sequences of nine of the most abundantly expressed salivary proteins from field populations, testing the hypothesis that salivary proteins appropriate to target for vaccination strategies will be possible. PpSP12, PpSP14, PpSP28, PpSP29, PpSP30, PpSP32, PpSP36, PpSP42, and PpSP44 mature cDNAs from field collected P. papatasi from three distinct ecotopes in the Middle East and North Africa were amplified, sequenced, and in silico translated to assess the predicted amino acid variability. Two of the predicted sequences, PpSP12 and PpSP14, demonstrated low genetic variability across the three geographic isolated sand fly populations, with conserved multiple predicted MHCII epitope binding sites suggestive of their potential application in vaccination approaches. The other seven predicted salivary proteins revealed greater allelic variation across the same sand fly populations, possibly precluding their use as vaccine targets.


Assuntos
Proteínas de Insetos/genética , Insetos Vetores/genética , Phlebotomus/genética , Proteínas e Peptídeos Salivares/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Egito , Humanos , Proteínas de Insetos/imunologia , Insetos Vetores/imunologia , Jordânia , Phlebotomus/imunologia , Proteínas e Peptídeos Salivares/imunologia , Alinhamento de Sequência
17.
PLoS Negl Trop Dis ; 14(7): e0008404, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32687497

RESUMO

The northeastern semiarid region stands out in the Brazilian context regarding the eco-epidemiology of Chagas disease, in which Triatoma brasiliensis is the main vector of Trypanosoma cruzi. Persistent house invasion threatens the relative levels of progress achieved over previous decades. We conducted an intervention trial with a five-year follow-up to assess the impacts of residual spraying with pyrethroid insecticides on house infestation with T. brasiliensis in 18 rural villages (242 houses) located in the Tauá, Ceará. House infestations were assessed by systematic manual searches for triatomines in every domestic and peridomestic habitat on five occasions. Triatomines were collected in peridomestic (57.5%), sylvatic (35.8%), and intradomiciliary (6.7%) habitats. The most important ecotopes of T. brasiliensis were containing roofing tiles, bricks or rocks (23.4% ± 9.1). Residual insecticide spraying substantially reduced baseline house infestation rates from 27.9% to 5.9% by 6 months post first spraying (MPS). The decline was substantially greater in intradomiciles (11.2% to 0.8%) than in peridomiciles (16.7% to 5%). The mean relative density of triatomines recovered its preintervention values at 14 MPS in intradomiciles, and in the main peridomestic ecotopes. The house infestation levels recorded at 14 MPS persisted thereafter despite all reinfested houses were selectively sprayed on every occasion. Overall average bug infection rates with T. cruzi in the five occasions were in intradomiciles (11.1%), peridomiciles (4.7%) and wild habitats (3.3%). In peridomicile T. cruzi infection rates decreased significantly at all stages after chemical intervention. In intradomicile, the only significant difference occurred at 20 MPS (7.7% to 30.8%). The vectorial capacity of T. brasiliensis, combined with its invasive potential from sylvatic sources and the limited effectiveness of chemical control in the harsh caatinga landscape, pose serious obstacles to the definite elimination of domestic transmission risks. Systematic vector surveillance supported by community participation and locally adapted environmental management measures are needed to reduce the risks of establishment of domestic transmission with T. cruzi in this region.


Assuntos
Controle de Insetos/métodos , Insetos Vetores/efeitos dos fármacos , Inseticidas/farmacologia , Triatoma/efeitos dos fármacos , Distribuição Animal , Animais , Brasil , Habitação , Humanos , Insetos Vetores/fisiologia , Piretrinas/farmacologia , Saúde da População Rural , Triatoma/fisiologia
18.
Mem Inst Oswaldo Cruz ; 115: e200070, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667462

RESUMO

BACKGROUND Nyssorhynchus deaneorum is a potential malaria vector because it has been shown to be competent to transmit Plasmodium vivax and Plasmodium falciparum, and because it exhibits antropophilic and endophilic behaviors in some regions of the Amazon. This profile makes Ny. deaneorum a useful mosquito for experiments that model Plasmodium-vector interactions in the Amazon. OBJECTIVE Herein we describe how a free-mating colony of Ny. deaneorum has been established using an automated light stimulation system. METHODS Mosquitoes were captured in São Francisco do Guaporé, Rondônia. The F1 generation was reared until adult emergence at which point copulation was induced using an automatic copulation induction system (ACIS). FINDINGS After four generations, natural mating and oviposition began to occur without light stimulation. The number of pupae and adult mosquitoes increased from the F5 to F10 generations. The new Ny. deaneorum colony exhibited susceptibility to P. vivax. MAIN CONCLUSIONS Automated light stimulation is an effective method for establishing an Ny. deaneorum colony under laboratory conditions as it produces enough adults to create a stenogamic colony. The establishment of a stable, P. vivax-susceptible colony of Ny. deaneorum makes it possible to model parasite-vector interactions and to test novel drug therapies that target parasite development in mosquitoes.


Assuntos
Anopheles/parasitologia , Copulação/fisiologia , Malária , Mosquitos Vetores/parasitologia , Oviposição , Animais , Anopheles/fisiologia , Brasil , Feminino , Insetos Vetores/crescimento & desenvolvimento , Insetos Vetores/fisiologia , Plasmodium falciparum , Plasmodium vivax
19.
Parasitol Res ; 119(10): 3305-3313, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32651636

RESUMO

The genetic structure of natural populations offers insight into the complexities of their dynamics, information that can be relevant to vector control strategies. Microsatellites are useful neutral markers to investigate the genetic structure and gene flow in Triatoma infestans, one of the main vectors of Chagas disease in South America. Recently, a heterogeneous pyrethroid-resistant hotspot was found in the Argentine Gran Chaco, characterized by the highest levels of deltamethrin resistance found at the present time. We applied population genetics analyses to microsatellite and village data and search for associations between the genetic variability and the heterogeneous toxicological pattern previously found. We genotyped 10 microsatellite loci in 67 T. infestans from 6 villages with no, low, and high pyrethroid resistance. The most genetically diverse populations were those susceptible or with low values of resistance. In contrast, high-resistance populations had lower herozygosity and some monomorphic loci. A negative association was found between variability and resistant ratios. Global and pairwise FSTs indicated significant differentiation between populations. The only susceptible population was discriminated in all the performed studies. Low-resistance populations were also differentiated by a discriminant analysis of principal components (DAPC) and were composed mostly by the same two genetic clusters according to STRUCTURE Bayesian algorithm. Individuals from the high-resistance populations were overlapped in the DAPC and shared significant proportions of a genetic cluster. These observations suggest that the resistant populations might have a common origin, although more genetic markers and samples are required to test this hypothesis more rigorously.


Assuntos
Insetos Vetores/genética , Resistência a Inseticidas/genética , Inseticidas/farmacologia , Nitrilos/farmacologia , Piretrinas/farmacologia , Triatoma/genética , Animais , Argentina/epidemiologia , Doença de Chagas/epidemiologia , Doença de Chagas/transmissão , Variação Genética , Repetições de Microssatélites/genética
20.
Mem Inst Oswaldo Cruz ; 115: e200218, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32696917

RESUMO

BACKGROUND: Southeast Brazil has recently experienced a Yellow Fever virus (YFV) outbreak where the mosquito Haemagogus leucocelaenus was a primary vector. Climatic factors influence the abundance of mosquito vectors and arbovirus transmission. OBJECTIVES: We aimed at describing the population dynamics of Hg. leucocelaenus in a county touched by the recent YFV outbreak. METHODS: Fortnightly egg collections with ovitraps were performed from November 2012 to February 2017 in a forest in Nova Iguaçu, Rio de Janeiro, Brazil. The effects of mean temperature and rainfall on the Hg. leucocelaenus population dynamics were explored. FINDINGS: Hg. leucocelaenus eggs were continuously collected throughout the study, with a peak in the warmer months (December-March). The climatic variables had a time-lagged effect and four weeks before sampling was the best predictor for the positivity of ovitraps and total number of eggs collected. The probability of finding > 50% positive ovitraps increased when the mean temperature was above 24ºC. The number of Hg. leucocelaenus eggs expressively increase when the mean temperature and accumulated precipitation surpassed 27ºC and 100 mm, respectively, although the effect of rainfall was less pronounced. MAIN CONCLUSIONS: Monitoring population dynamics of Hg. leucocelaenus and climatic factors in YFV risk areas, especially mean temperature, may assist in developing climate-based surveillance procedures to timely strengthening prophylaxis and control.


Assuntos
Culicidae/virologia , Florestas , Insetos Vetores/virologia , Dinâmica Populacional , Febre Amarela , Vírus da Febre Amarela/isolamento & purificação , Animais , Brasil , Culicidae/classificação , Insetos Vetores/classificação , Estações do Ano , Temperatura , Vírus da Febre Amarela/genética
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