#Vector #Competence: What Has #Zika Virus Taught Us? (Viruses, abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Viruses. 2019 Sep 17;11(9). pii: E867. doi: 10.3390/v11090867.

Vector Competence: What Has Zika Virus Taught Us?

Azar SR1,2,3, Weaver SC4,5,6.

Author information: 1 Department of Microbiology and Immunology, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. srazar@utmb.edu. 2 Institute for Translational Sciences, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. srazar@utmb.edu. 3 Institute for Human Infections and Immunity, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. srazar@utmb.edu. 4 Department of Microbiology and Immunology, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. sweaver@utmb.edu. 5 Institute for Translational Sciences, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. sweaver@utmb.edu. 6 Institute for Human Infections and Immunity, University of Texas Medical Branch, 300 University Blvd, Galveston, TX 77555, USA. sweaver@utmb.edu.

 

Abstract

The unprecedented outbreak of Zika virus (ZIKV) infection in the Americas from 2015 to 2017 prompted the publication of a large body of vector competence data in a relatively short period of time. Although differences in vector competence as a result of disparities in mosquito populations and viral strains are to be expected, the limited competence of many populations of the urban mosquito vector, Aedes aegypti, from the Americas (when its susceptibility is viewed relative to other circulating/reemerging mosquito-borne viruses such as dengue (DENV), yellow fever (YFV), and chikungunya viruses (CHIKV)) has proven a paradox for the field. This has been further complicated by the lack of standardization in the methodologies utilized in laboratory vector competence experiments, precluding meta-analyses of this large data set. As the calls for the standardization of such studies continue to grow in number, it is critical to examine the elements of vector competence experimental design. Herein, we review the various techniques and considerations intrinsic to vector competence studies, with respect to contemporary findings for ZIKV, as well as historical findings for other arboviruses, and discuss potential avenues of standardization going forward.

KEYWORDS: Aedes aegypti; Flaviviruses; Zika virus; arbovirus; mosquitoes; vector competence

PMID: 31533267 DOI: 10.3390/v11090867

Keywords: Mosquitoes; Aedes aegypti; Flavivirus; Zika Virus.

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#Transgenic #Aedes aegypti #Mosquitoes Transfer #Genes into a Natural #Population (Sci Rep., abstract)

[Source: Scientific Reports, full page: (LINK). Abstract, edited.]

Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population

Benjamin R. Evans, Panayiota Kotsakiozi, Andre Luis Costa-da-Silva, Rafaella Sayuri Ioshino, Luiza Garziera, Michele C. Pedrosa, Aldo Malavasi, Jair F. Virginio, Margareth L. Capurro & Jeffrey R. Powell

Scientific Reports, volume 9, Article number: 13047 (2019)

 

Abstract

In an attempt to control the mosquito-borne diseases yellow fever, dengue, chikungunya, and Zika fevers, a strain of transgenically modified Aedes aegypti mosquitoes containing a dominant lethal gene has been developed by a commercial company, Oxitec Ltd. If lethality is complete, releasing this strain should only reduce population size and not affect the genetics of the target populations. Approximately 450 thousand males of this strain were released each week for 27 months in Jacobina, Bahia, Brazil. We genotyped the release strain and the target Jacobina population before releases began for >21,000 single nucleotide polymorphisms (SNPs). Genetic sampling from the target population six, 12, and 27–30 months after releases commenced provides clear evidence that portions of the transgenic strain genome have been incorporated into the target population. Evidently, rare viable hybrid offspring between the release strain and the Jacobina population are sufficiently robust to be able to reproduce in nature. The release strain was developed using a strain originally from Cuba, then outcrossed to a Mexican population. Thus, Jacobina Ae. aegypti are now a mix of three populations. It is unclear how this may affect disease transmission or affect other efforts to control these dangerous vectors. These results highlight the importance of having in place a genetic monitoring program during such releases to detect un-anticipated outcomes.

Keywords: Genetics; Aedes aegypti; Brazil; GMOs.

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#Sindbis virus #polyarthritis #outbreak signalled by virus prevalence in the #mosquito vectors (PLoS Negl Trop Dis., abstract)

[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Sindbis virus polyarthritis outbreak signalled by virus prevalence in the mosquito vectors

Jan O. Lundström , Jenny C. Hesson, Martina L. Schäfer, Örjan Östman, Torsten Semmler, Michaël Bekaert, Manfred Weidmann, Åke Lundkvist, Martin Pfeffer

Published: August 29, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0007702 / This is an uncorrected proof.

 

Abstract

Polyarthritis and rash caused by Sindbis virus (SINV), was first recognised in northern Europe about 50 years ago and is known as Ockelbo disease in Sweden and Pogosta disease in Finland. This mosquito-borne virus occurs mainly in tropical and sub-tropical countries, and in northern Europe it is suggested to cause regularly reoccurring outbreaks. Here a seven-year cycle of SINV outbreaks has been referred to in scientific papers, although the hypothesis is based solely on reported human cases. In the search for a more objective outbreak signal, we evaluated mosquito abundance and SINV prevalence in vector mosquitoes from an endemic area in central Sweden. Vector mosquitoes collected in the River Dalälven floodplains during the years before, during, and after the hypothesised 2002 outbreak year were assayed for virus on cell culture. Obtained isolates were partially sequenced, and the nucleotide sequences analysed using Bayesian maximum clade credibility and median joining network analysis. Only one SINV strain was recovered in 2001, and 4 strains in 2003, while 15 strains were recovered in 2002 with significantly increased infection rates in both the enzootic and the bridge-vectors. In 2002, the Maximum Likelihood Estimated infection rates were 10.0/1000 in the enzootic vectors Culex torrentium/pipiens, and 0.62/1000 in the bridge-vector Aedes cinereus, compared to 4.9/1000 and 0.0/1000 in 2001 and 0.0/1000 and 0.32/1000 in 2003 Sequence analysis showed that all isolates belonged to the SINV genotype I (SINV-I). The genetic analysis revealed local maintenance of four SINV-I clades in the River Dalälven floodplains over the years. Our findings suggest that increased SINV-I prevalence in vector mosquitoes constitutes the most valuable outbreak marker for further scrutinising the hypothesized seven-year cycle of SINV-I outbreaks and the mechanisms behind.

 

Author summary

The mosquito-borne Sindbis virus (SINV) causes polyarthritis and rash known as Ockelbo disease in Sweden and Pogosta disease in Finland. This mainly tropical and sub-tropical virus occurs in many countries, and in northern Europe it is suggested to cause reoccurring outbreaks every seventh year. The seven-year SIN outbreak cycle is commonly referred to in scientific papers, although the hypothesis is based solely on reported clinical cases. In the search for a more objective outbreak risk signal, we evaluated abundance and SINV prevalence in vector mosquitoes from Sweden. Vector mosquitoes collected in the River Dalälven floodplains the years before, during and after the hypothesized 2002 outbreak, were assayed for SINV. SINV prevalence was significantly increased in vector mosquitoes during the hypothesized 2002 outbreak, as compared to the 2001 pre-outbreak and the 2003 post-outbreak years. Genetic analysis showed a close relationship between the virus strains, indicating SINV has remained in local annual enzootic circulation since been introduced into the River Dalälven floodplains. We conclude that increased SINV prevalence in vector mosquitoes constitutes a marker most valuable for studying the seven-year outbreak cycle.

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Citation: Lundström JO, Hesson JC, Schäfer ML, Östman Ö, Semmler T, Bekaert M, et al. (2019) Sindbis virus polyarthritis outbreak signalled by virus prevalence in the mosquito vectors. PLoS Negl Trop Dis 13(8): e0007702. https://doi.org/10.1371/journal.pntd.0007702

Editor: Jason L. Rasgon, The Pennsylvania State University, UNITED STATES

Received: August 29, 2018; Accepted: August 13, 2019; Published: August 29, 2019

Copyright: © 2019 Lundström et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the paper and its Supporting Information files.

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Arbovirus; Sindbis virus; Polyarthritis; Sweden; Finland; Mosquitoes.

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First report on the #transmission of #Zika virus by #Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) during the 2018 Zika #outbreak in #India (Acta Trop., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Acta Trop. 2019 Aug 20:105114. doi: 10.1016/j.actatropica.2019.105114. [Epub ahead of print]

First report on the transmission of Zika virus by Aedes (Stegomyia) aegypti (L.) (Diptera: Culicidae) during the 2018 Zika outbreak in India.

Singh H1, Singh OP2, Akhtar N3, Sharma G4, Sindhania A5, Gupta N6, Valecha N7.

Author information: 1 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: hspawar@rediffmail.com. 2 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: singh@nimr.org.in. 3 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: nasreen84akhtar@gmail.com. 4 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: gunjan.sharma@gmail.com. 5 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: ankita@mrcindia.org. 6 Indian Council of Medical Research, Ansari Nagar, New Delhi, 110029, India. Electronic address: ngupta@icmr.org.in. 7 National Institute of Malaria Research, Sector 8 Dwarka, New Delhi 110077, India. Electronic address: neenavalecha@gmail.com.

 

Abstract

In a recent outbreak of Zika virus (ZIKV) infection in Jaipur city (Rajasthan, India), a total of 159 cases were reported in September 2018. In order to identify vector responsible for Zika transmission, mosquitoes were collected from houses with reported Zika cases and nearby houses. A total of 108 pools containing 522 mosquitoes were tested for presence of ZIKV virus using RT-PCR and Real Time RT-PCR. We detected presence of ZIKV in three pools of Aedes (Stegomyia) aegypti (L.), out of a total of 79 pools with 383 Ae. aegypti through RT-PCR as well as real-time RT-PCR. The presence of ZIKV in Ae. aegypti was further confirmed by DNA sequencing of the partial envelope region of ZIKV. Homology search of DNA sequence revealed highest identity (100%) with a ZIKV isolate from human from the study area which support the role of Ae. aegypti acting as a ZIKV vector. All other mosquitoes (Aedes vittatus and Culex quinquefasciatus) were negative for ZIKV. None of the F1 generation mosquito pools (276 mosquitoes in 43 pools) were found positive. This is the first report of presence of ZIKV in Ae. aegypti from the Indian subcontinent.

Copyright © 2019. Published by Elsevier B.V.

KEYWORDS: Entomological surveillance; Outbreak; RT-PCR; Transmission risk

PMID: 31442386 DOI: 10.1016/j.actatropica.2019.105114

Keywords: Zika Virus; Aedes aegypti; India; Mosquitoes.

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Integrated #vector #management with additional pre-transmission season thermal #fogging is associated with a reduction in #dengue #incidence in #Makassar, #Indonesia: Results of an 8-year observational study (PLoS Negl Trop Dis., abstract)

[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Integrated vector management with additional pre-transmission season thermal fogging is associated with a reduction in dengue incidence in Makassar, Indonesia: Results of an 8-year observational study

Isra Wahid , Hasanuddin Ishak, Abdul Hafid, Muhammad Fajri, Sukmawati Sidjal, Armin Nurdin, Naisyah Tun Azikin, Rusdyah Sudirman, Hajar Hasan, Muhammad Yusuf, Imam Bachtiar, William A. Hawley, Ronald Rosenberg, Neil F. Lobo

Published: August 5, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0007606 / This is an uncorrected proof.

 

Abstract

Dengue virus transmission is endemic in Makassar, Indonesia, with the majority of cases reported soon after the start of the annual rainy season. Before 2006, larval source reduction, larvaciding, and reactive routine, outdoor, insecticide fogging campaigns did not result in a reduction in seasonal dengue incidence. Beginning in 2006, village volunteers conducted comprehensive surveys for immature Aedes during the dry season, when vector populations were at their lowest. Based on this pre-season vector data, a single additional pre-emptive outdoor fogging with Malathion was conducted once annually before the rains began in villages with a pre-defined proportion of sampled houses positive for Aedes immatures. This additional procedure was associated with reduced temporal larval indices as well as an 83% reduction in reported cases during the transmission season over the 8-year period of implementation. Two cities adjacent to Makassar experienced substantial but smaller reductions in dengue incidence; while other cities further from the intervention area did not. This represents the first time an integrated intervention strategy has been coupled with substantially reduced dengue transmission in Indonesia.

 

Author summary

Dengue is the most common mosquito-borne viral disease in the world, infecting as many as 400 million people per year. While comprehensive, rigorous vector control can reduce transmission, in practice inadequate coverage, improper application, insecticide resistance, high labor costs, and community indifference hinder its wide implementation and sustainability. Maximum impact in reducing vector populations may be achieved when control interventions are implemented with high coverage and are integrated with other control strategies. A single thermal fogging application will not result in long lasting protection and will have low probability of affecting populations of the Aedes vectors and hence disease. This study catalogues an 83% reduction in dengue incidence in the city of Makassar, Indonesia, over an 8-year period, associated with the additional single evidence-based and targeted pre-emptive chemical intervention in addition to good case surveillance and an integrated vector management system—attributable to governmental commitment and investment in control of vector-borne disease. A vital part of the observations presented is that they are based on the normal function, capability, and capacity of a Ministry of Health team implementing a community-wide intervention.

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Citation: Wahid I, Ishak H, Hafid A, Fajri M, Sidjal S, Nurdin A, et al. (2019) Integrated vector management with additional pre-transmission season thermal fogging is associated with a reduction in dengue incidence in Makassar, Indonesia: Results of an 8-year observational study. PLoS Negl Trop Dis 13(8): e0007606. https://doi.org/10.1371/journal.pntd.0007606

Editor: Audrey Lenhart, Centers for Disease Control and Prevention, UNITED STATES

Received: February 1, 2019; Accepted: July 5, 2019; Published: August 5, 2019

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Data Availability: Data belong to the Ministry of Health and cannot be shared publicly. Data are available from Isra Wahid, Faculty of Medicine, UNHAS (email: israwahid@med.unhas.ac.id) for researchers who meet the confidentiality criteria for access set by the Ministry.

Funding: This work was funded as part or routine Makassar’s government operations through the local MoH office. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Dengue fever; Mosquitoes; Indonesia.

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No #evidence of #Zika, #dengue, or #chikungunya virus #infection in field-caught #mosquitoes from the Recife Metropolitan Region, #Brazil, 2015 (Wellcome Open Res., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Wellcome Open Res. 2019 Jun 10;4:93. doi: 10.12688/wellcomeopenres.15295.1. eCollection 2019.

No evidence of Zika, dengue, or chikungunya virus infection in field-caught mosquitoes from the Recife Metropolitan Region, Brazil, 2015.

Ramesh A#1,2, Jeffries CL#3, Castanha P4,5, Oliveira PAS1, Alexander N2, Cameron M3, Braga C1, Walker T3.

Author information: 1 Department of Parasitology, Instituto Aggeu Magalhães(IAM/FIOCRUZ Pernambuco), Recife, Brazil. 2 Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK. 3 Department of Disease Control, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK. 4 Department of Virology, Instituto Aggeu Magalhães(IAM/FIOCRUZ Pernambuco), Recife, Brazil. 5 Universidade Estadual de Pernambuco (UPE), Recife, Brazil. #Contributed equally

 

Abstract

Background:

The Recife Metropolitan Region (RMR), north-eastern Brazil, was the epicentre of the 2015 Zika virus (ZIKV) epidemic, which was followed by a 2016 chikungunya virus (CHIKV) epidemic. It historically has amongst the highest incidence of dengue virus (DENV) infections and is the only remaining focus of lymphatic filariasis (LF) in Brazil. In early 2015, a molecular xenomonitoring surveillance project focused on Culex (Cx.) quinquefasciatus commenced to inform LF elimination activities. Aedes (Ae.) aegypti mosquitoes were also collected, concurrent with the first microcephaly cases detected in the RMR. In terms of the 2015 ZIKV epidemic, these are the earliest known field-collected mosquitoes, preserved for potential RNA virus detection, when ZIKV was known to be circulating locally.

Methods:

Adult mosquitoes were collected in two sites (0.4 km 2) of Sítio Novo, Olinda, RMR, from July 22 to August 21, 2015. Mosquitoes were morphologically identified, sorted by physiological status, and pooled (up to 10 mosquitoes per house per day or week). RNA was extracted, reverse transcribed and the cDNA tested by real-time PCR.

Results:

A total of 10,139 adult female Cx. quinquefasciatus and 939 adult female Ae. aegypti were captured. All female Ae. aegypti specimens were included within 156 pools and screened for ZIKV, DENV and CHIKV. In addition, a sub-set of 1,556 Cx. quinquefasciatus adult females in 182 pools were screened for ZIKV. No evidence of infection with any of the three arboviruses was found.

Conclusions:

The absence of arbovirus detection may have been expected given the extremely restricted geographic area and collection of mosquitoes during a very short time period of peak mosquito abundance (July-September), but low arbovirus circulation (November-March).  However, this study demonstrates the potential to retrospectively screen for additional unexpected pathogens in situations of rapid emergence, such as occurred during the outbreak of ZIKV in the RMR.

KEYWORDS: Aedes aegypti; Culex quinquefasciatus; Zika virus; arboviruses; chikungunya virus; dengue virus; disease surveillance; molecular xenomonitoring; neglected tropical diseases; urban areas

PMID: 31363498 PMCID: PMC6644828 DOI: 10.12688/wellcomeopenres.15295.1

Keywords: Arbovirus; Zika virus; Chikungunya fever; Dengue fever; Mosquitoes; Culex quinquefasciatus; Aedes aegypti; Brazil.

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Changing #patterns in the #distribution of the #Mayaro virus #vector #Haemagogus species in #Trinidad, West Indies (Acta Trop., abstract)

[Source: US National Library of Medicine, full page: (LINK). Abstract, edited.]

Acta Trop. 2019 Jul 25:105108. doi: 10.1016/j.actatropica.2019.105108. [Epub ahead of print]

Changing patterns in the distribution of the Mayaro virus vector Haemagogus species in Trinidad, West Indies.

Ali R1, Mohammed A1, Jayaraman J1, Nandram N2, Feng RS1, Lezcano RD2, Seeramsingh R2, Daniel B1, Lovin DD3, Severson DW4, Ramsubhag A5.

Author information: 1 Department of Life Sciences, Faculty of Science & Technology, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago. 2 Insect Vector Control Division, Ministry of Health, Government of Trinidad and Tobago, Trinidad and Tobago. 3 Department of Biological Sciences and Eck institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States. 4 Department of Life Sciences, Faculty of Science & Technology, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago; Department of Biological Sciences and Eck institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States. 5 Department of Life Sciences, Faculty of Science & Technology, The University of the West Indies, St. Augustine Campus, Trinidad and Tobago. Electronic address: Adesh.Ramsubhag@sta.uwi.edu.

 

Abstract

The Mayaro virus disease (MAYVD) is an emerging mosquito borne zoonosis that was first reported on the island of Trinidad in 1954. The viral agent for this disease is known to presently be endemic to Central and South America. The enzootic cycle of the Mayaro virus (MAYV) is not fully characterized, though primates are thought to be the main reservoir with Haemagogus species of mosquitoes as the primary vector. This virus has been responsible for several sporadic cases of infections and limited outbreaks, but it is postulated that the MAYVD will become a major epidemic in the future, following in the steps of the recent pandemics caused by Chikungunya and Zika viruses. Mitigating possible major outbreaks of MAYVD in the future would require effective strategies for vector control, for which knowledge on the ecology and distribution of the Haemagogus mosquitoes would be vitally important. In Trinidad, Haemagogus species have only been reported in the northwestern peninsula of the island based on studies up to 1995. However, no recent investigations have been completed to determine the status of this important vector on the island. The aim of this study was to investigate the current spatial distribution of Haemagogus species in the island of Trinidad, West Indies. Adult Haemagogus (Hag.) mosquitoes and larvae were surveyed during a twenty-month period using human bait trapping and ovitraps in major forested areas on the island. Mosquito species were identified using classical taxonomic keys. Haemagogus species were widespread and found in all forest types surveyed. Hag. janthinomys (85.7%) was the most widely distributed and dominant species on the island. Lower levels of Hag. leucocelaneus (7.3%), Hag. equinus (6.4%) and Hag. celeste (0.6%) were also collected. Overall, the proportion of mosquitoes collected in the wet season (June – December) was 3.5 times more than in the dry season (January – May). Mangroves, young secondary forests, semi-evergreen and evergreen forest types had relatively high mean abundance levels of Haemagogus species as compared to deciduous and montane forests. Proximity analysis suggests that population settlements within a 1 km buffer of the forest peripherals may be at risk for any emerging arboviral disease associated with these mosquito vectors. Haemagogus species showed a much wider distribution in Trinidad as compared to previous reports from up to 20 years ago and were prevalent in areas with no known presence of non-human primates. Since the MAYV has been previously implicated in causing infections in vertebrate hosts like rodents, birds and small mammals, the findings of this study suggest that there may be alternative hosts and reservoirs of this virus in the sylvatic cycle in Trinidad, other than primates. This has significant epidemiological implications for mosquito-borne viral infections in the region.

Copyright © 2019. Published by Elsevier B.V.

KEYWORDS: Distribution; Haemagogus; Mayaro Virus; Trinidad; Yellow Fever

PMID: 31351893 DOI: 10.1016/j.actatropica.2019.105108

Keywords: Mayaro virus; Mosquitoes; Trinidad.

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