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Goray M, Taylor D, Bibbo E, Fantinato C, Fonneløp AE, Gill P, van Oorschot RAH. Emerging use of air eDNA and its application to forensic investigations - A review. Electrophoresis 2024; 45:916-932. [PMID: 38419135 DOI: 10.1002/elps.202300228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 12/17/2023] [Accepted: 02/19/2024] [Indexed: 03/02/2024]
Abstract
Biological material is routinely collected at crime scenes and from exhibits and is a key type of evidence during criminal investigations. Improvements in DNA technologies allow collection and profiling of trace samples, comprised of few cells, significantly expanding the types of exhibits targeted for DNA analysis to include touched surfaces. However, success rates from trace and touch DNA samples tend to be poorer compared to other biological materials such as blood. Simultaneously, there have been recent advances in the utility of environmental DNA collection (eDNA) in identification and tracking of different biological organisms and species from bacteria to naked mole rats in different environments, including, soil, ice, snow, air and aquatic. This paper examines the emerging methods and research into eDNA collection, with a special emphasis on the potential forensic applications of human DNA collection from air including challenges and further studies required to progress implementation.
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Affiliation(s)
- Mariya Goray
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Duncan Taylor
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
- Forensic Science SA, Adelaide, South Australia, Australia
| | - Emily Bibbo
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Chiara Fantinato
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Ane Elida Fonneløp
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway
| | - Peter Gill
- Forensic Genetics Research Group, Department of Forensic Sciences, Oslo University Hospital, Oslo, Norway
- Department of Forensic Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Roland A H van Oorschot
- Victoria Police Forensic Services Department, Office of Chief Forensic Scientist, Macleod, Victoria, Australia
- School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
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Mwanga EP, Mchola IS, Makala FE, Mshani IH, Siria DJ, Mwinyi SH, Abbasi S, Seleman G, Mgaya JN, Jiménez MG, Wynne K, Sikulu-Lord MT, Selvaraj P, Okumu FO, Baldini F, Babayan SA. Rapid assessment of the blood-feeding histories of wild-caught malaria mosquitoes using mid-infrared spectroscopy and machine learning. Malar J 2024; 23:86. [PMID: 38532415 PMCID: PMC10964711 DOI: 10.1186/s12936-024-04915-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/22/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND The degree to which Anopheles mosquitoes prefer biting humans over other vertebrate hosts, i.e. the human blood index (HBI), is a crucial parameter for assessing malaria transmission risk. However, existing techniques for identifying mosquito blood meals are demanding in terms of time and effort, involve costly reagents, and are prone to inaccuracies due to factors such as cross-reactivity with other antigens or partially digested blood meals in the mosquito gut. This study demonstrates the first field application of mid-infrared spectroscopy and machine learning (MIRS-ML), to rapidly assess the blood-feeding histories of malaria vectors, with direct comparison to PCR assays. METHODS AND RESULTS Female Anopheles funestus mosquitoes (N = 1854) were collected from rural Tanzania and desiccated then scanned with an attenuated total reflectance Fourier-transform Infrared (ATR-FTIR) spectrometer. Blood meals were confirmed by PCR, establishing the 'ground truth' for machine learning algorithms. Logistic regression and multi-layer perceptron classifiers were employed to identify blood meal sources, achieving accuracies of 88%-90%, respectively, as well as HBI estimates aligning well with the PCR-based standard HBI. CONCLUSIONS This research provides evidence of MIRS-ML effectiveness in classifying blood meals in wild Anopheles funestus, as a potential complementary surveillance tool in settings where conventional molecular techniques are impractical. The cost-effectiveness, simplicity, and scalability of MIRS-ML, along with its generalizability, outweigh minor gaps in HBI estimation. Since this approach has already been demonstrated for measuring other entomological and parasitological indicators of malaria, the validation in this study broadens its range of use cases, positioning it as an integrated system for estimating pathogen transmission risk and evaluating the impact of interventions.
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Affiliation(s)
- Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Idrisa S Mchola
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Faraja E Makala
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Doreen J Siria
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Sophia H Mwinyi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Godian Seleman
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Jacqueline N Mgaya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | | | - Klaas Wynne
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Maggy T Sikulu-Lord
- Faculty of Science, School of the Environment, The University of Queensland, Brisbane, QLD, Australia
| | - Prashanth Selvaraj
- Institute for Disease Modelling, Bill and Melinda Gates Foundation, Seattle, USA
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- School of Life Science and Bioengineering, The Nelson Mandela African, Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
| | - Francesco Baldini
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Simon A Babayan
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
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Toni ASB, Serrão JE, Fialho VS. A beetle for prosecution: exogenous DNA detection from larval and adult gut of a Neotropical carrion beetle. Forensic Sci Med Pathol 2023; 19:184-191. [PMID: 37243839 DOI: 10.1007/s12024-023-00658-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/18/2023] [Indexed: 05/29/2023]
Abstract
The use of recovered DNA ingested by necrophagous or hematophagous insects has increased in forensic sciences, mainly with representatives of flies. However, some beetles are also important for medico-legal forensic entomology because they feed on carcasses until advanced decomposition. This study evaluated whether the Neotropical carrion beetle Oxelytrum discicolle (Silphidae) has the potential for the detection of exogenous DNA into the gut. The whole gut or the gut contents were extracted from O. discicolle larvae and adult previously fed on pig carcass. The pig DNA recovery rate was 33.3% in larvae and 25% in adults, indicating that the carrion beetle's gut may be useful for DNA identification of ingested food. Samples with the whole gut or only gut contents showed the same DNA recovery rate. Exogenous DNA from the whole gut was recovered from samples stored in ethanol at -20 ºC for 11 days, showing that samples of O. discicolle can be stored in the forensic laboratory without loss in DNA recovery rate.
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Affiliation(s)
- Alessandra Santana Batista Toni
- Graduate Program in Cell and Structural Biology, Cell Ultrastructure Laboratory, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - José Eduardo Serrão
- Departament of General Biology, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
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Teltscher F, Bouvaine S, Gibson G, Dyer P, Guest J, Young S, Hopkins RJ. Understanding mosquito host-choice behaviour: a new and low-cost method of identifying the sex of human hosts from mosquito blood meals. Parasit Vectors 2021; 14:75. [PMID: 33482889 PMCID: PMC7825230 DOI: 10.1186/s13071-021-04577-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 01/01/2021] [Indexed: 12/03/2022] Open
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. ![]()
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Affiliation(s)
- Fiona Teltscher
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK.
| | - Sophie Bouvaine
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Gabriella Gibson
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Paul Dyer
- Anglia Ruskin University, East Road, Cambridge, CB1 1PT, UK
| | - Jennifer Guest
- Home Office, Lunar House, 40 Wellesley Road, Croydon, CR9 2BY, UK
| | - Stephen Young
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
| | - Richard J Hopkins
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent, ME4 4TB, UK
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5
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Trájer AJ. Which mosquitoes (Diptera: Culicidae) are candidates for DNA extraction in forensic practice? J Forensic Leg Med 2018; 58:183-191. [PMID: 30005339 DOI: 10.1016/j.jflm.2018.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Revised: 07/02/2018] [Accepted: 07/05/2018] [Indexed: 12/14/2022]
Abstract
Mosquitoes can be of importance in forensic context as a source of the perpretator's DNA. The aim of this study was to find how can we optimize the selection of appropriate mosquito individuals. The study was based on the data of 177833 trapped female mosquitoes and 105236 individuals which were collected directly from human skin. The mean human-specific biting willingness value of Aedes species was the highest (mean: 0.8). Significant differences were found between the human-specific biting willingness value variances of Aedes and Culex (p=0.0117) and barely significant differences between Anopheles and Culiseta (p = 0.5412), as well as between Aedes and Culiseta genera (p = 0.0562). Culiseta species showed the lowest human-specific biting willingness values (mean = 0.16). The mean of the human-specific biting willingness values of univoltine and multivoltine mosquitoes were 0.43 and 0.37 which means no significant difference between the variances of the two groups (p = 0.625). The mean of the human-specific biting willingness values of the predominantly mammal biting and non-mammal biting mosquitoes were 0.45 and 0.03 with a very significant difference (p<0.0001). Only five mosquito species have a relative biting risk index equal or more than 0.03 in Hungary, namely of Aedes vexans (0.43), Ochlerotatus cantans: (0.25), Ochlerotatus sticticus: (0.11), Culex modestus: (0.07) and Aedes cinereus: (0.03). It can be concluded that the mean human-specific biting willingness of mosquitoes depends on the genera, the host preference and it is independent of the annual number of generations or the breeding habitat preference. The relative biting risk index reflects the actual and annual relative abundances and the usefulness and availability of a mosquito for legal purposes reducing the financial and time requirements of the investigations.
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Affiliation(s)
- Attila J Trájer
- Institute of Environmental Engineering, University of Pannonia, Egyetem utca 10, H-8200 Veszprém, Hungary; Department of Limnology, University of Pannonia, H-8200, Veszprém, Egyetem utca 10, Hungary.
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Carvalho GML, Rêgo FD, Tanure A, Silva ACP, Dias TA, Paz GF, Andrade Filho JD. Bloodmeal Identification in Field-Collected Sand Flies From Casa Branca, Brazil, Using the Cytochrome b PCR Method. JOURNAL OF MEDICAL ENTOMOLOGY 2017; 54:1049-1054. [PMID: 28399200 DOI: 10.1093/jme/tjx051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Indexed: 06/07/2023]
Abstract
PCR-based identification of vertebrate host bloodmeals has been performed on several vectors species with success. In the present study, we used a previously published PCR protocol followed by DNA sequencing based on primers designed from multiple alignments of the mitochondrial cytochrome b gene used to identify avian and mammalian hosts of various hematophagous vectors. The amplification of a fragment encoding a 359 bp sequence of the Cyt b gene yielded recognized amplification products in 192 female sand flies (53%), from a total of 362 females analyzed. In the study area of Casa Branca, Brazil, blood-engorged female sand flies such as Lutzomyia longipalpis (Lutz & Neiva, 1912), Migonemyia migonei (França, 1924), and Nyssomyia whitmani (Antunes & Coutinho, 1939) were analyzed for bloodmeal sources. The PCR-based method identified human, dog, chicken, and domestic rat blood sources.
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Affiliation(s)
- G M L Carvalho
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - F D Rêgo
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - A Tanure
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - A C P Silva
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - T A Dias
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - G F Paz
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
| | - J D Andrade Filho
- Grupo de Estudos em Leishmanioses, Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Avenida Augusto de Lima, 1715 Barro Preto, CEP 30190-002, Belo Horizonte, Minas Gerais, Brasil
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Curic G, Hercog R, Vrselja Z, Wagner J. Identification of person and quantification of human DNA recovered from mosquitoes (Culicidae). Forensic Sci Int Genet 2013; 8:109-12. [PMID: 24315597 DOI: 10.1016/j.fsigen.2013.07.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 07/20/2013] [Accepted: 07/23/2013] [Indexed: 10/26/2022]
Abstract
Mosquitoes (Culicidae) are widespread insects and can be important in forensic context as a source of human DNA. In order to establish the quantity of human DNA in mosquitoes' gut after different post-feeding interval and for how long after taking a bloodmeal the human donor could be identified, 174 blood-engorged mosquitoes (subfamily Anophelinae and Culicinae) were captured, kept alive and sacrificed at 8h intervals. Human DNA was amplified using forensic PCR kits (Identifiler, MiniFiler, and Quantifiler). A full DNA profiles were obtained from all Culicinae mosquitoes (74/74) up to 48 h and profiling was successful up to 88 h after a bloodmeal. Duration of post-feeding interval had a significant negative effect on the possibility of obtaining a full profile (p<0.001), and logistic regression found that the probability of obtaining the full profile is 15.5% less for every 8h increase in post-feeding interval. Culicinae mosquitoes are a suitable source of human DNA for forensic STR kits more than three days after a bloodmeal. Human DNA recovered from mosquito can be used for matching purposes and could be useful in revealing spatial and temporal relation of events that took place at the crime scene. Therefore, mosquitoes at the crime scene, dead or alive, could be a valuable piece of forensic evidence.
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Affiliation(s)
- Goran Curic
- Laboratory for DNA analysis, School of Medicine, J. J. Strossmayer University, Osijek, J. Huttlera 4, Croatia; Department of Pathology and Legal medicine, Clinical Hospital Centre, Osijek, J. Huttlera 4, Croatia.
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8
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Abstract
Mosquitoes use plant sugars and vertebrate blood as nutritional resources. When searching for blood hosts, some mosquitoes express preferential behavior for selected species. Here, we review the available knowledge on host preference, as this is expected to affect the life history and transmission of infectious pathogens. Host preference is affected by myriad extrinsic and intrinsic factors. Inherent factors are determined by genetic selection, which appears to be controlled by adaptive advantages that result from feeding on certain host species. Host preference of mosquitoes, although having a genetic basis, is characterized by high plasticity mediated by the density of host species, which by their abundance form a readily accessible source of blood. Host-selection behavior in mosquitoes is an exception rather than the rule. Those species that express strong and inherent host-selection behavior belong to the most important vectors of infectious diseases, which suggests that this behavioral trait may have evolved in parallel with parasite-host evolution.
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Affiliation(s)
- Willem Takken
- Laboratory of Entomology, Wageningen University and Research Center, 6700 EH Wageningen, The Netherlands.
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Kester KM, Toothman MH, Brown BL, Street WS, Cruz TD. Recovery of environmental human DNA by insects. J Forensic Sci 2011; 55:1543-51. [PMID: 20666923 DOI: 10.1111/j.1556-4029.2010.01500.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We tested the hypotheses that foraging insects can acquire human DNA from the environment and that insect-delivered human DNA is of sufficient quantity and quality to permit standard forensic analyses. Houseflies, German cockroaches, and camel crickets were exposed to dusty surfaces and then assayed for human mitochondrial and nuclear loci by conventional and qPCR, and multiplex STR amplification. Over two experiments, 100% of insect groups and 94% of dust controls tested positive for human DNA. Of 177 individuals, 33-67% tested positive and 13 yielded quantifiable human DNA (mean = 0.022 ± 0.006 ng; mean dust control = 2.448 ± 0.960 ng); four had at least one positive allele call for one or more locus; eight others showed multiple peaks at some loci. Results imply that application to routine forensic casework is limited given current detection methodology yet demonstrate the potential use of insects as environmental samplers for human DNA.
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Affiliation(s)
- Karen M Kester
- Department of Biology, Virginia Commonwealth University, 1000 W. Cary Street, Richmond, VA 23284-2012, USA.
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Torr SJ, Prior A, Wilson PJ, Schofield S. Is there safety in numbers? The effect of cattle herding on biting risk from tsetse flies. MEDICAL AND VETERINARY ENTOMOLOGY 2007; 21:301-311. [PMID: 18092968 DOI: 10.1111/j.1365-2915.2007.00705.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
In sub-Saharan Africa, tsetse (Glossina spp.) transmit species of Trypanosoma which threaten 45-50 million cattle with trypanosomiasis. These livestock are subject to various herding practices which may affect biting rates on individual cattle and hence the probability of infection. In Zimbabwe, studies were made of the effect of herd size and composition on individual biting rates by capturing tsetse as they approached and departed from groups of one to 12 cattle. Flies were captured using a ring of electrocuting nets and bloodmeals were analysed using DNA markers to identify which individual cattle were bitten. Increasing the size of a herd from one to 12 adults increased the mean number of tsetse visiting the herd four-fold and the mean feeding probability from 54% to 71%; the increased probability with larger herds was probably a result of fewer flies per host, which, in turn, reduced the hosts' defensive behaviour. For adults and juveniles in groups of four to eight cattle, > 89% of bloodmeals were from the adults, even when these comprised just 13% of the herd. For groups comprising two oxen, four cows/heifers and two calves, a grouping that reflects the typical composition of communal herds in Zimbabwe, approximately 80% of bloodmeals were from the oxen. Simple models of entomological inoculation rates suggest that cattle herding practices may reduce individual trypanosomiasis risk by up to 90%. These results have several epidemiological and practical implications. First, the gregarious nature of hosts needs to be considered in estimating entomological inoculation rates. Secondly, heterogeneities in biting rates on different cattle may help to explain why disease prevalence is frequently lower in younger/smaller cattle. Thirdly, the cost and effectiveness of tsetse control using insecticide-treated cattle may be improved by treating older/larger hosts within a herd. In general, the patterns observed with tsetse appear to apply to other genera of cattle-feeding Diptera (Stomoxys, Anopheles, Tabanidae) and thus may be important for the development of strategies for controlling other diseases affecting livestock.
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Affiliation(s)
- S J Torr
- Natural Resources Institute, University of Greenwich, Greenwich, U.K.
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Oshaghi MA, Chavshin AR, Vatandoost H. Analysis of mosquito bloodmeals using RFLP markers. Exp Parasitol 2006; 114:259-64. [PMID: 16716302 DOI: 10.1016/j.exppara.2006.04.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2006] [Revised: 04/02/2006] [Accepted: 04/03/2006] [Indexed: 10/24/2022]
Abstract
An important variable in the amplification of arthropod vector-borne diseases is the degree of contact between human hosts and mosquito vectors. To analyze this interaction, a DNA based method was developed to differentiate human bloodmeals from other sources in the mosquito Anopheles stephensi (Diptera: Culicidae) Liston. A portion of the host mitochondrial DNA cytochrome B genes were PCR amplified and classified to the species level based on their restriction fragment length polymorphism (RFLP). The cytochrome B sequences showed sufficient interspecific polymorphism to distinguish between human, cow, sheep, chicken, and guinea pig hosts. XhoI could distinguish human from other vertebrates whereas TaqI alone could separate the others. The importance of these results in epidemiological studies of malaria and other vector borne diseases is discussed.
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Affiliation(s)
- Mohammad Ali Oshaghi
- Department of Medical Entomology, School of Public Health and Institute of Health Researches, Tehran University of Medical Sciences, P.O.Box 14155-6446, Tehran, Iran.
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12
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Oshaghi MA, Chavshin AR, Vatandoost H, Yaaghoobi F, Mohtarami F, Noorjah N. Effects of post-ingestion and physical conditions on PCR amplification of host blood meal DNA in mosquitoes. Exp Parasitol 2006; 112:232-6. [PMID: 16364301 DOI: 10.1016/j.exppara.2005.11.008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2005] [Revised: 11/09/2005] [Accepted: 11/10/2005] [Indexed: 11/16/2022]
Abstract
The effects of post-ingestion and physical conditions under which killed mosquitoes are stored on the success of detecting blood meal DNA of Anopheles stephensi and Culex quinquefasiatus were investigated by polymerase chain reaction (PCR) amplification at the human mitochondrial DNA cytochrome b (cytB) gene. Host DNA extracted from the blood meal up to 33 h post-ingestion in both species acts as an efficient template for PCR amplification. However, more DNA concentration is needed for meals digested for a longer time, and successful PCR amplification from meals digested for 36 h,dropped to a faint band. There were no differences between PCR success rate for samples stored at +4 or -20 degrees C, but less successful products were observed in samples kept at 4 degrees C for the periods longer than 30 h digestion. The results of this study are important for conducting malaria epidemiological studies that provide information about the degree of contact between human hosts and mosquito vectors, impact of vector controls such as bed nets and repellents, and the transmission dynamics of human malaria and other vector-borne diseases.
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Affiliation(s)
- Mohammad Ali Oshaghi
- Department of Medical Entomology, School of Public Health and Institute of Health Researches, Tehran University of Medical Sciences, Iran.
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Devos J, Geysen D. Epidemiological study of the prevalence of Babesia divergens in a veterinary practice in the mid-east of France. Vet Parasitol 2004; 125:237-49. [PMID: 15482881 DOI: 10.1016/j.vetpar.2004.08.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2003] [Revised: 01/12/2004] [Accepted: 08/02/2004] [Indexed: 11/26/2022]
Abstract
To assess the epidemiology of Babesia divergens in a veterinary practice based in the mid-east of France ("Monts du Lyonnais"), blood was collected from 254 cattle belonging to 24 herds. To assess the dynamics of the carrier state, six carriers were identified, treated with flumethrin and sampled once every 3 weeks during 6 months. Two different DNA extraction methods were compared. Each sample was tested for the presence of parasites using a PCR-RFLP test based on the 18S rRNA gene. The sensitivity of the test was equivalent to a parasitaemia as low as 10(-5)% (in "Filter Paper" samples) and 10(-6)% in 1 ml blood (extracted using "Matrix"). With the latter method, the rate of detection diminishes in the low parasitaemia range but could probably be improved. This test proved to be very useful in the detection of B. divergens carriers. Serology using IFAT showed 7% of the cattle seropositive, which is suggestive of a disease situation with a low clinical risk level. Analysis of the PCR results suggests a 20% prevalence rate of carriers in the cattle population. The use of the mean parasitaemia is proposed to serve as a babesiosis clinical risk indicator. This approach could also be used in other babesia infections provided the lowest detectable parasitaemia level (threshold level) could be resolved for each parasite species.
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Affiliation(s)
- J Devos
- chez Mathy, 42360 Panissières, France
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14
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Habtewold T, Prior A, Torr SJ, Gibson G. Could insecticide-treated cattle reduce Afrotropical malaria transmission? Effects of deltamethrin-treated Zebu on Anopheles arabiensis behaviour and survival in Ethiopia. MEDICAL AND VETERINARY ENTOMOLOGY 2004; 18:408-417. [PMID: 15642008 DOI: 10.1111/j.0269-283x.2004.00525.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Anopheles arabiensis Patton (Diptera: Culicidae) is the most widespread vector of malaria in the Afrotropical Region. Because An. arabiensis feeds readily on cattle as well as humans, the insecticide-treatment of cattle--as employed to control tsetse (Diptera: Glossinidae) and ticks (Acari: Ixodidae)--might simultaneously affect the malaria vectorial capacity of this mosquito. Therefore, we conducted field experiments in southern Ethiopia to establish whether Zebu cattle (Bos indicus L.) treated with a pour-on pyrethroid formulation of 1% deltamethrin, widely used to control ticks and tsetse, would be effective against An. arabiensis or cause the female mosquitoes to feed more frequently on humans, due to behavioural avoidance of insecticide-treated cattle. Contact bioassays (3 min exposure) showed that the insecticide remained effective for about 1 month (kill rate > 50%) against mosquitoes feeding on the flanks of treated cattle. A novel behavioural assay demonstrated that An. arabiensis readily fed on insecticide-treated cattle and were not deflected to human hosts in the presence of treated cattle. DNA-fingerprinting of bloodmeals revealed that An. arabiensis naturally feeds most frequently on older animals, consistent with the established practice of applying insecticide only to older cattle, while allowing younger untreated animals to gain immunity against infections transmitted by ticks. These encouraging results were tempered by finding that > 90% of An. arabiensis, An. pharoensis and An. tenebrosus females feed on the legs of cattle, farthest from the site of pour-on application along the animal's back and where the treatment may be least residual due to weathering. Observations of mosquitoes feeding naturally on insecticide-treated cattle showed that the majority of wild female anophelines alighted on the host animal for less than 1 min to feed, with significantly shorter mean duration of feeding bouts on insecticide-treated animals, and the effective life of the insecticide was only 1 week. Thus the monthly application of deltamethrin to cattle, typically used to control tsetse and ticks, is unlikely to be effective against An. arabiensis populations or their vectorial capacity. Even so, it seems likely that far greater impact on anopheline mosquitoes could be achieved by applying insecticide selectively to the legs of cattle.
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15
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Abstract
This review discusses how the use of molecular genetic techniques such as the polymerase chain reaction are helping in the management and prevention of malaria.
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Affiliation(s)
- Brian Greenwood
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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16
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Mukabana WR, Takken W, Knols BGJ. Analysis of arthropod bloodmeals using molecular genetic markers. Trends Parasitol 2002; 18:505-9. [PMID: 12473367 DOI: 10.1016/s1471-4922(02)02364-4] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Little is known about the transmission dynamics of human malaria and other vector-borne diseases, partly because of the limited availability and distribution of appropriate tools for quantifying human-mosquito contact rates. Recent developments in molecular biology have allowed a significant increase in the efficacy and reliability of bloodmeal identification, and DNA-based molecular markers are now being harnessed for typing arthropod bloodmeals. The extent to which these markers have been used for analysis of mosquito bloodmeals and the potential they might have for the future is discussed, and the contributions that the advent of PCR has made are examined here.
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17
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Prior A, Torr SJ. Host selection by Anopheles arabiensis and An. quadriannulatus feeding on cattle in Zimbabwe. MEDICAL AND VETERINARY ENTOMOLOGY 2002; 16:207-213. [PMID: 12109716 DOI: 10.1046/j.1365-2915.2002.00367.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In the Zambezi valley, mosquito females of the Anopheles gambiae Giles complex (Diptera: Culicidae) were collected from a hut containing pairs of cattle distinguishable by known DNA markers. DNA was extracted from the blood-fed mosquito abdomens and primer sets for ungulate and mosquito DNA loci were used to identify the mosquito sibling species and individual host source(s) of their bloodmeals. The 67 mosquitoes comprised a mixture of An. arabiensis Patton (31%) and An. quadriannulatus Theobald (69%). DNA from one or both of the cattle present in the hut was detected in 91% of samples. When the hut contained an adult and a calf, the percentage of bloodmeals from the adult, the calf and adult + calf were 58%, 27% and 15%, respectively; the trend towards meals from the adult host was consistent but not always significant. When the pair of cattle comprised two adults of roughly equal size and age, then mosquitoes generally showed no significant bias towards feeding from one individual. There was no significant difference in the pattern of host selection made by An. arabiensis and An. quadriannulatus but the former had a significantly higher percentage (20%) of mixed meals than An. quadriannulatus (9%). These two members of the An. gambiae complex appear to be less selective in their choice of cattle hosts compared to day-active Diptera such as tsetse and Stomoxys, possibly because the hosts are generally asleep when Anopheles are active and there is therefore less selective pressure to adapt to host defensive behaviour. The slight bias of Anopheles towards older and/or larger cattle may be related to the host's larger surface area.
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Affiliation(s)
- A Prior
- Natural Resources Institute, University of Greenwich, Chatham, UK.
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18
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Ansell J, Hamilton KA, Pinder M, Walraven GEL, Lindsay SW. Short-range attractiveness of pregnant women to Anopheles gambiae mosquitoes. Trans R Soc Trop Med Hyg 2002; 96:113-6. [PMID: 12055794 DOI: 10.1016/s0035-9203(02)90271-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Malaria is a major cause of illness and an indirect cause of mortality in pregnant women. It can also cause stillbirths and low-birthweight babies. We have shown previously that pregnant women attracted twice as many Anopheles gambiae mosquitoes, the principal African malaria vector, as their non-pregnant counterparts over distances of about 15 m. In the current study (in 1998/99) we compared the short-range attractiveness of both pregnant and non-pregnant women sleeping under untreated bednets in Gambian villages. First, we measured the rate of mosquito entry under bednets and, second, we calculated the proportion of mosquitoes biting mothers under each bednet compared to their children. The feeding preference of An. gambiae collected under nets was determined by DNA fingerprinting blood samples from human subjects sleeping under each bednet and comparing these to fingerprints obtained from mosquito bloodmeals. Pregnant women were more attractive to An. gambiae mosquitoes than non-pregnant women under an untreated bednet. The number of mosquitoes entering bednets each night was 1.7-4.5 times higher in the pregnant group (P = 0.02) and pregnant women also received a higher proportion of bites under the bednets than did non-pregnant women (70% vs 52%, P = 0.001). This study clearly demonstrates that pregnant women are more exposed to malaria parasites than other women, which contributes to the greater vulnerability of pregnant women to malaria.
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Affiliation(s)
- J Ansell
- School of Biological and Biomedical Sciences, University of Durham, South Road, Durham DH1 3LE, UK
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