scholarly journals Feeding Ecology and Host Preferences of Mosquitoes in two Zoological Gardens in the United Kingdom

2020 ◽  
Author(s):  
Arturo Hernandez-Colina ◽  
Merit Gonzalez-Olvera ◽  
Emily Lomax ◽  
Freya Townsend ◽  
Amber Maddox ◽  
...  
Keyword(s):  
Host Species ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Control Strategies ◽  
Pathogen Transmission ◽  
Prevention Measures ◽  
Host Preferences ◽  
Diverse Range ◽  
Generalized Linear Modelling ◽  
Zoo Animals

Abstract Background: Zoological gardens contain unique configurations of exotic and endemic animals and plants that create a diverse range of developing sites and potential sources of blood meals for local mosquitoes. This may imply unusual interspecific pathogen transmission risks involving zoo animals, like avian malaria to captive penguins. Understanding mosquito ecology and host preferences is necessary to improve mosquito control and disease prevention measures in these environments. Methods: Mosquito sampling took place in Chester Zoo for three years (2017 to 2019) and for one year in Flamingo Land (2017) using different trapping methods. Blood-fed mosquitoes were identified and their bloodmeal was amplified by PCR, sequenced, and blasted for host species identification.Results: In total, 640 blood-fed mosquitoes were collected (Culex pipiens (n = 497), Culiseta annulata (n = 81), Anopheles maculipennis s.l. (n = 7), An. claviger (n = 1) and unidentifiable (n = 55)). Successful identification of the host species was achieved from 159 of the 640 blood-fed mosquitoes. Mosquitoes fed on birds (n = 74), non-human mammals (n = 20) and humans (n = 71). There were mixed bloodmeals from two hosts (n = 6). The proportions of blood-fed mosquitoes varied across sampling seasons and sites within the zoos. The use of resting traps and aspiration of vegetation were more efficient techniques for capturing blood-fed mosquitoes than traps for host-seeking or gravid mosquitoes. By relating the locations of zoo animals to where fed mosquitoes were trapped, the minimum travelling distances were calculated (13.7 to 366.7 meters). Temperature, precipitation, relative humidity, proximity to zoo animal exhibits and vegetation level were found to be significantly associated with the proportion of captured blood-fed mosquitoes by generalized linear modelling.Conclusions: Mosquito feeding behaviour in zoos is influenced by environmental variables and host availability, which highlights the value of mosquito monitoring in complex settings to plan control strategies and potentially reduce inherent disease transmission risks for humans and threatened zoo animals.

scholarly journals Blood-feeding ecology of mosquitoes in two zoological gardens in the United Kingdom

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Arturo Hernandez-Colina ◽  
Merit Gonzalez-Olvera ◽  
Emily Lomax ◽  
Freya Townsend ◽  
Amber Maddox ◽  
...  
Keyword(s):  
Host Species ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Blood Feeding ◽  
Pathogen Transmission ◽  
Host Feeding ◽  
Prevention Measures ◽  
Diverse Range ◽  
Generalized Linear Modelling ◽  
Blood Meals

Abstract Background Zoological gardens contain unique configurations of exotic and endemic animals and plants that create a diverse range of developing sites and potential sources of blood meals for local mosquitoes. This may imply unusual interspecific pathogen transmission risks involving zoo vertebrates, like avian malaria to captive penguins. Understanding mosquito ecology and host feeding patterns is necessary to improve mosquito control and disease prevention measures in these environments. Methods Mosquito sampling took place in Chester Zoo for 3 years (2017, 2018, and 2019) and for 1 year in Flamingo Land (2017) using different trapping methods. Blood-fed mosquitoes were identified and their blood meal was amplified by PCR, sequenced, and blasted for host species identification. Results In total, 640 blood-fed mosquitoes were collected [Culex pipiens (n = 497), Culiseta annulata (n = 81), Anopheles maculipennis s.l. (n = 7), An. claviger (n = 1), and unidentifiable (n = 55)]. Successful identification of the host species was achieved from 159 blood-fed mosquitoes. Mosquitoes fed on birds (n = 74), non-human mammals (n = 20), and humans (n = 71). There were mixed blood meals from two hosts (n = 6). The proportions of blood-fed mosquitoes varied across sampling seasons and sites within the zoos. The use of resting traps and aspiration of vegetation were more efficient techniques for capturing blood-fed mosquitoes than traps for host-seeking or gravid mosquitoes. By relating the locations of zoo vertebrates to where fed mosquitoes were trapped, the minimum travelling distances were calculated (13.7 to 366.7 m). Temperature, precipitation, relative humidity, proximity to zoo vertebrate exhibits, and vegetation level were found to be significantly associated with the proportion of captured blood-fed mosquitoes by generalized linear modelling. Conclusions Mosquito feeding behaviour in zoos is mainly influenced by time, location (sampling area), temperature, and host availability, which highlights the value of mosquito monitoring in complex settings to plan control strategies and potentially reduce inherent disease transmission risks for humans and threatened zoo vertebrates. Graphic abstract

scholarly journals Ungulate use of locally infectious zones in a re-emerging anthrax risk area

2020 ◽  
Vol 7 (10) ◽  
pp. 200246 ◽  
Author(s):  
Morgan A. Walker ◽  
Maria Uribasterra ◽  
Valpa Asher ◽  
José Miguel Ponciano ◽  
Wayne M. Getz ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Control Strategies ◽  
Pathogen Transmission ◽  
Camera Traps ◽  
Risk Area ◽  
Southwestern Montana ◽  
Increased Risk ◽  
Anthrax Spores ◽  
Causative Bacterium ◽  
And Control

Environmentally mediated indirect pathogen transmission is linked to host movement and foraging in areas where pathogens are maintained in the environment. In the case of anthrax, spores of the causative bacterium Bacillus anthracis are released into the environment following host death and create locally infectious zones (LIZs) around carcass sites; by grazing at LIZs, herbivores are potentially exposed to spores. Here, we used camera traps to assess how ungulate species use carcass sites in southwestern Montana and evaluated how these behaviours may promote indirect anthrax transmission, thus providing, to our knowledge, the first detailed documentation and study of the fine-scale mechanisms underlying foraging-based disease transmission in this ecosystem. We found that carcasses at LIZs significantly increased aboveground biomass of vegetation and concentrations of sodium and phosphorus, potentially making these sites more appealing to grazers. Host behavioural responses to LIZs varied depending on species, sex, season and carcass age; but, overall, our results demonstrated that carcasses or carcass sites serve as an attractant to herbivores in this system. Attraction to LIZs probably represents an increased risk of exposure to B. anthracis and, consequently, increased anthrax transmission rates. Accordingly, continued anthrax surveillance and control strategies are critical in this system.

scholarly journals Antiviral Effectors and Gene Drive Strategies for Mosquito Population Suppression or Replacement to Mitigate Arbovirus Transmission by Aedes aegypti

Insects ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 52 ◽  
Author(s):  
Adeline Williams ◽  
Alexander Franz ◽  
William Reid ◽  
Ken Olson
Keyword(s):  
Aedes Aegypti ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Control Strategies ◽  
Mosquito Vector ◽  
Close Monitoring ◽  
Gene Drive ◽  
Population Replacement ◽  
Effector Genes ◽  
Population Suppression

The mosquito vector Aedes aegypti transmits arthropod-borne viruses (arboviruses) of medical importance, including Zika, dengue, and yellow fever viruses. Controlling mosquito populations remains the method of choice to prevent disease transmission. Novel mosquito control strategies based on genetically manipulating mosquitoes are being developed as additional tools to combat arbovirus transmission. Genetic control of mosquitoes includes two basic strategies: population suppression and population replacement. The former aims to eliminate mosquito populations while the latter aims to replace wild populations with engineered, pathogen-resistant mosquitoes. In this review, we outline suppression strategies being applied in the field, as well as current antiviral effector genes that have been characterized and expressed in transgenic Ae. aegypti for population replacement. We discuss cutting-edge gene drive technologies that can be used to enhance the inheritance of effector genes, while highlighting the challenges and opportunities associated with gene drives. Finally, we present currently available models that can estimate mosquito release numbers and time to transgene fixation for several gene drive systems. Based on the recent advances in genetic engineering, we anticipate that antiviral transgenic Ae. aegypti exhibiting gene drive will soon emerge; however, close monitoring in simulated field conditions will be required to demonstrate the efficacy and utility of such transgenic mosquitoes.

scholarly journals Genetic Characterization of Chikungunya Virus in Field-Caught Aedes aegypti Mosquitoes Collected during the Recent Outbreaks in 2019, Thailand

Pathogens ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 121 ◽  
Author(s):  
Intayot ◽  
Phumee ◽  
Boonserm ◽  
Sor-suwan ◽  
Buathong ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
South African ◽  
Chikungunya Virus ◽  
Mosquito Control ◽  
Control Strategies ◽  
Pathogen Transmission ◽  
Sequencing Analysis ◽  
Chikv Infection ◽  
Infected Female ◽  
Health Authorities

Chikungunya virus (CHIKV) is a mosquito-borne virus belonging to the genus Alphavirus. The virus is transmitted to humans by the bite of infected female Aedes mosquitoes, primarily Aedes aegypti. CHIKV infection is spreading worldwide, and it periodically sparks new outbreaks. There are no specific drugs or effective vaccines against CHIKV. The interruption of pathogen transmission by mosquito control provides the only effective approach to the control of CHIKV infection. Many studies have shown that CHIKV can be transmitted among the Ae. aegypti through vertical transmission. The previous chikungunya fever outbreaks in Thailand during 2008–2009 were caused by CHIKV, the East/Central/South African (ECSA) genotype. Recently, there have been 3794 chikungunya cases in 27 provinces reported by the Bureau of Epidemiology of Health Ministry, Thailand during 1 January–16 June 2019; however, the cause of the re-emergence of CHIKV outbreaks is uncertain. Therefore, the aims of this study were to detect and analyze the genetic diversity of CHIKV infection in field-caught mosquitoes. Both female and male Ae. aegypti were collected from endemic areas of Thailand, and CHIKV detection was done by using E1-nested RT-PCR and sequencing analysis. A total of 1646 Ae. aegypti samples (900 females and 746 males) were tested. CHIKV was detected in 54 (3.28%) and 14 samples (0.85%) in female and male mosquitoes, respectively. Seventeen samples of female Ae. aegypti collected from the Ubon Ratchathani, Chiang Rai, Chiang Mai, Nakhon Sawan, and Songkhla provinces found mutation at E1: A226V. Interestingly, E1: K211E mutation was observed in 50 samples collected from Nong Khai, Bangkok, Prachuap Khiri Khan, and Krabi. In addition, the phylogenetic tree indicated that CHIKV in Ae. aegypti samples were from the Indian Ocean Clade and East/South African Clade. Both clades belong to the ECSA genotype. The information obtained from this study could be used for prediction, epidemiological study, prevention, and effective vector control of CHIKV. For instance, a novel CHIKV strain found in new areas has the potential to lead to a new outbreak. Health authorities could plan and apply control strategies more effectively given the tools provided by this research.

scholarly journals Strategic Approach, Advances, and Challenges in the Development and Application of the SIT for Area-Wide Control of Aedes albopictus Mosquitoes in Reunion Island

Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 770
Author(s):  
Louis Clément Gouagna ◽  
David Damiens ◽  
Clélia F. Oliva ◽  
Sébastien Boyer ◽  
Gilbert Le Goff ◽  
...  
Keyword(s):  
Aedes Albopictus ◽  
Disease Transmission ◽  
Mosquito Control ◽  
Control Strategies ◽  
Specific Treatment ◽  
Public Understanding ◽  
Reunion Island ◽  
Additional Tool ◽  
Awareness Campaigns ◽  
Réunion Island

The global expansion of Aedes albopictus, together with the absence of specific treatment and vaccines for most of the arboviruses it transmits, has stimulated the development of more sustainable and ecologically acceptable methods for control of disease transmission through the suppression of natural vector populations. The sterile insect technique (SIT) is rapidly evolving as an additional tool for mosquito control, offering an efficient and more environment-friendly alternative to the use of insecticides. Following the devastating chikungunya outbreak, which affected 38% of the population on Reunion Island (a French overseas territory in the southwest of the Indian Ocean), there has been strong interest and political will to develop effective alternatives to the existing vector control strategies. Over the past 10 years, the French Research and Development Institute (IRD) has established an SIT feasibility program against Ae. albopictus on Reunion Island in collaboration with national and international partners. This program aimed to determine whether the SIT based on the release of radiation-sterilized males is scientifically and technically feasible, and socially acceptable as part of a control strategy targeting the local Ae. albopictus population. This paper provides a review of a multi-year and a particularly broad scoping process of establishing the scientific and technological feasibility of the SIT against Ae. albopictus on Reunion Island. It also draws attention to some prerequisites of the decision-making process, through awareness campaigns to enhance public understanding and support, social adoption, and regulatory validation of the SIT pilot tests.

Book Review

2014 ◽  
Vol 11 (3) ◽  
pp. 387-390
Author(s):  
Antonina Levatino
Keyword(s):  
Control Strategies ◽  
Human Mobility ◽  
Diverse Range ◽  
Transnational Mobility ◽  
Migration Management ◽  
Nation States ◽  
Migration Control ◽  
Political Economic ◽  
Controversial Nature

Martin Geiger & Antoine Pécoud (eds.), Disciplining the Transnational Mobility of People, Palgrave Macmillan, 2013, 271 pp., (ISBN 978-1-137-26306-3).In the last decades a very diverse range of initiatives have been undertaken in order to intensify and diversify the ways human mobility is managed and restricted. This trend towards a ‘diversification’ of the migration control strategies stems from the increased awareness by the nation-states of the profoundly controversial nature of the migration management enterprise because of its political, economic, social and moral implications.

scholarly journals Estimating asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan: a mathematical modeling study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xi Huo ◽  
Jing Chen ◽  
Shigui Ruan
Keyword(s):  
Disease Transmission ◽  
Large Scale ◽  
Transmission Rate ◽  
Control Strategies ◽  
Herd Immunity ◽  
Antibody Prevalence ◽  
Screening Process ◽  
Vaccination Programs ◽  
Prevalence Level ◽  
The Impact

Abstract Background The COVID-19 outbreak in Wuhan started in December 2019 and was under control by the end of March 2020 with a total of 50,006 confirmed cases by the implementation of a series of nonpharmaceutical interventions (NPIs) including unprecedented lockdown of the city. This study analyzes the complete outbreak data from Wuhan, assesses the impact of these public health interventions, and estimates the asymptomatic, undetected and total cases for the COVID-19 outbreak in Wuhan. Methods By taking different stages of the outbreak into account, we developed a time-dependent compartmental model to describe the dynamics of disease transmission and case detection and reporting. Model coefficients were parameterized by using the reported cases and following key events and escalated control strategies. Then the model was used to calibrate the complete outbreak data by using the Monte Carlo Markov Chain (MCMC) method. Finally we used the model to estimate asymptomatic and undetected cases and approximate the overall antibody prevalence level. Results We found that the transmission rate between Jan 24 and Feb 1, 2020, was twice as large as that before the lockdown on Jan 23 and 67.6% (95% CI [0.584,0.759]) of detectable infections occurred during this period. Based on the reported estimates that around 20% of infections were asymptomatic and their transmission ability was about 70% of symptomatic ones, we estimated that there were about 14,448 asymptomatic and undetected cases (95% CI [12,364,23,254]), which yields an estimate of a total of 64,454 infected cases (95% CI [62,370,73,260]), and the overall antibody prevalence level in the population of Wuhan was 0.745% (95% CI [0.693%,0.814%]) by March 31, 2020. Conclusions We conclude that the control of the COVID-19 outbreak in Wuhan was achieved via the enforcement of a combination of multiple NPIs: the lockdown on Jan 23, the stay-at-home order on Feb 2, the massive isolation of all symptomatic individuals via newly constructed special shelter hospitals on Feb 6, and the large scale screening process on Feb 18. Our results indicate that the population in Wuhan is far away from establishing herd immunity and provide insights for other affected countries and regions in designing control strategies and planing vaccination programs.

scholarly journals Livestock movement informs the risk of disease spread in traditional production systems in East Africa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Divine Ekwem ◽  
Thomas A. Morrison ◽  
Richard Reeve ◽  
Jessica Enright ◽  
Joram Buza ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Production Systems ◽  
Control Strategies ◽  
Herd Size ◽  
Transmission Risk ◽  
Disease Spread ◽  
Transmission Potential ◽  
Spatial And Temporal Scales ◽  
Transmission Distance ◽  
Risk Of Disease

AbstractIn Africa, livestock are important to local and national economies, but their productivity is constrained by infectious diseases. Comprehensive information on livestock movements and contacts is required to devise appropriate disease control strategies; yet, understanding contact risk in systems where herds mix extensively, and where different pathogens can be transmitted at different spatial and temporal scales, remains a major challenge. We deployed Global Positioning System collars on cattle in 52 herds in a traditional agropastoral system in western Serengeti, Tanzania, to understand fine-scale movements and between-herd contacts, and to identify locations of greatest interaction between herds. We examined contact across spatiotemporal scales relevant to different disease transmission scenarios. Daily cattle movements increased with herd size and rainfall. Generally, contact between herds was greatest away from households, during periods with low rainfall and in locations close to dipping points. We demonstrate how movements and contacts affect the risk of disease spread. For example, transmission risk is relatively sensitive to the survival time of different pathogens in the environment, and less sensitive to transmission distance, at least over the range of the spatiotemporal definitions of contacts that we explored. We identify times and locations of greatest disease transmission potential and that could be targeted through tailored control strategies.

scholarly journals Understanding mosquito host-choice behaviour: a new and low-cost method of identifying the sex of human hosts from mosquito blood meals

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Fiona Teltscher ◽  
Sophie Bouvaine ◽  
Gabriella Gibson ◽  
Paul Dyer ◽  
Jennifer Guest ◽  
...  
Keyword(s):  
Blood Meal ◽  
Host Species ◽  
Disease Transmission ◽  
Low Cost ◽  
Host Choice ◽  
Epidemiological Models ◽  
Choice Behaviour ◽  
Vector Borne ◽  
Transmission Models ◽  
Blood Meals

Abstract Background Mosquito-borne diseases are a global health problem, causing hundreds of thousands of deaths per year. Pathogens are transmitted by mosquitoes feeding on the blood of an infected host and then feeding on a new host. Monitoring mosquito host-choice behaviour can help in many aspects of vector-borne disease control. Currently, it is possible to determine the host species and an individual human host from the blood meal of a mosquito by using genotyping to match the blood profile of local inhabitants. Epidemiological models generally assume that mosquito biting behaviour is random; however, numerous studies have shown that certain characteristics, e.g. genetic makeup and skin microbiota, make some individuals more attractive to mosquitoes than others. Analysing blood meals and illuminating host-choice behaviour will help re-evaluate and optimise disease transmission models. Methods We describe a new blood meal assay that identifies the sex of the person that a mosquito has bitten. The amelogenin locus (AMEL), a sex marker located on both X and Y chromosomes, was amplified by polymerase chain reaction in DNA extracted from blood-fed Aedes aegypti and Anopheles coluzzii. Results AMEL could be successfully amplified up to 24 h after a blood meal in 100% of An. coluzzii and 96.6% of Ae. aegypti, revealing the sex of humans that were fed on by individual mosquitoes. Conclusions The method described here, developed using mosquitoes fed on volunteers, can be applied to field-caught mosquitoes to determine the host species and the biological sex of human hosts on which they have blood fed. Two important vector species were tested successfully in our laboratory experiments, demonstrating the potential of this technique to improve epidemiological models of vector-borne diseases. This viable and low-cost approach has the capacity to improve our understanding of vector-borne disease transmission, specifically gender differences in exposure and attractiveness to mosquitoes. The data gathered from field studies using our method can be used to shape new transmission models and aid in the implementation of more effective and targeted vector control strategies by enabling a better understanding of the drivers of vector-host interactions.

scholarly journals Quantity and Quality of Aquaculture Enrichments Influence Disease Epidemics and Provide Ecological Alternatives to Antibiotics

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 335
Author(s):  
Anssi Karvonen ◽  
Ville Räihä ◽  
Ines Klemme ◽  
Roghaieh Ashrafi ◽  
Pekka Hyvärinen ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Bacterial Infections ◽  
Environmental Heterogeneity ◽  
Pathogen Transmission ◽  
Central Component ◽  
Flavobacterium Columnare ◽  
Disease Epidemics ◽  
The Impact ◽  
Environmental Microbes

Environmental heterogeneity is a central component influencing the virulence and epidemiology of infectious diseases. The number and distribution of susceptible hosts determines disease transmission opportunities, shifting the epidemiological threshold between the spread and fadeout of a disease. Similarly, the presence and diversity of other hosts, pathogens and environmental microbes, may inhibit or accelerate an epidemic. This has important applied implications in farming environments, where high numbers of susceptible hosts are maintained in conditions of minimal environmental heterogeneity. We investigated how the quantity and quality of aquaculture enrichments (few vs. many stones; clean stones vs. stones conditioned in lake water) influenced the severity of infection of a pathogenic bacterium, Flavobacterium columnare, in salmonid fishes. We found that the conditioning of the stones significantly increased host survival in rearing tanks with few stones. A similar effect of increased host survival was also observed with a higher number of unconditioned stones. These results suggest that a simple increase in the heterogeneity of aquaculture environment can significantly reduce the impact of diseases, most likely operating through a reduction in pathogen transmission (stone quantity) and the formation of beneficial microbial communities (stone quality). This supports enriched rearing as an ecological and economic way to prevent bacterial infections with the minimal use of antimicrobials.

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