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Chabi J, Van’t Hof A, N’dri LK, Datsomor A, Okyere D, Njoroge H, Pipini D, Hadi MP, de Souza DK, Suzuki T, Dadzie SK, Jamet HP. Rapid high throughput SYBR green assay for identifying the malaria vectors Anopheles arabiensis, Anopheles coluzzii and Anopheles gambiae s.s. Giles. PLoS One 2019; 14:e0215669. [PMID: 31002694 PMCID: PMC6474623 DOI: 10.1371/journal.pone.0215669] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 04/05/2019] [Indexed: 12/04/2022] Open
Abstract
The Anopheles gambiae sensu lato species complex consists of a number of cryptic species with different habitats and behaviours. These morphologically indistinct species are identified by chromosome banding. Several molecular diagnostic techniques for distinguishing between An. coluzzii and An. gambiae are still under improvement. Although, the current SINE method for identification between An. coluzzii and An. gambiae works reliably, this study describes a refinement of the SINE method to increase sensitivity for identification of An. coluzzii, An. gambiae and An. arabiensis based on amplicon dissociation curve characteristics. Field-collected samples, laboratory-reared colonies and crossed specimens of the two species were used for the design of the protocol. An. gambiae, An. coluzzii, and hybrids of the two species were sampled from Ghana and An. arabiensis from Kenya. Samples were first characterised using conventional SINE PCR method, and further assayed using SYBR green, an intercalating fluorescent dye. The three species and hybrids were clearly differentiated using the melting temperature of the dissociation curves, with derivative peaks at 72°C for An. arabiensis, 75°C for An. gambiae and 86°C for An. coluzzii. The hybrids (An. gambiae / An. coluzzii) showed both peaks. This work is the first to describe a SYBR green real time PCR method for the characterization of An. arabiensis, An. gambiae and An. coluzzii and was purposely designed for basic melt-curve analysis (rather than high-resolution melt-curve) to allow it to be used on a wide range of real-time PCR machines.
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Affiliation(s)
- Joseph Chabi
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Arjen Van’t Hof
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Louis K. N’dri
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Alex Datsomor
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Dora Okyere
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Harun Njoroge
- Kemri-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Dimitra Pipini
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Melinda P. Hadi
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
- Vestergaard Frandsen East Africa, Nairobi, Kenya
| | - Dziedzom K. de Souza
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Takashi Suzuki
- Section Environmental Parasitology, Kobe-Tokiwa University, Nagata-Ku, Japan
| | - Samuel K. Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Helen P. Jamet
- Vestergaard regional office, Washington DC, United States of America
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Animut A, Negash Y. Dry season occurrence of Anopheles mosquitoes and implications in Jabi Tehnan District, West Gojjam Zone, Ethiopia. Malar J 2018; 17:445. [PMID: 30497495 PMCID: PMC6267885 DOI: 10.1186/s12936-018-2599-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/26/2018] [Indexed: 11/20/2022] Open
Abstract
Background Generating evidence on the dry season occurrence of the larval and adult stages of Anopheles mosquitoes helps to design effective malaria vector control strategy as the populations of the vectors is expected to be low. Methods Larval and adult stages of Anopheles were surveyed during dry seasons in Mender Meter, Jiga Yehlmidar and Wongie Berkegn villages, Jabi Tehnan District, West Gojjam Zone, Ethiopia. Larvae were surveyed (along the available surface water collections), sampled, identified into genus, counted and late instars of the genus Anopheles identified into species. Indoor-resting adult mosquitoes were collected using insecticide aerosol spray, processed and identified into species. Data was analysed using SPSS version 20.0 to determine frequencies, mean differences and associations. Results A total of 3127 Anopheles larvae were collected among which most (91.7%; 2869/3127) were from streams followed by ponds (4.3%; 136/3127) and swamps (3.9%; 122/3127). Anopheles gambiae sensu lato was the most prevalent (84.9%; 921/1085) followed by Anopheles cinereus (7.0%; 76/1085), Anopheles chrysti (3.7%; 40/1085), Anopheles demeilloni (2.8%; 30/1085) and Anopheles rhodesiensis (1.6%; 18/1085). The mean number (mean = 15.3) of An. gambiae from Jiga Yehlmidar was significantly (p = 0.024) higher than the corresponding number (mean = 3.2) from Mender Meter. The mean number (mean = 36.3) of An. gambiae larvae in April 2017 was significantly (p = 0.001) higher than the number (mean = 4.0) in December 2013 and the number (mean = 2.6) in March 2013. A total of 1324 adult Anopheles were collected of which the highest proportion (79.1%; 1048/1324) was An. gambiae, followed by An. chrysti (11.7%; 155/1324), An. demeilloni (6%; 80/1324), An. cinereus (2.6%; 35/1324) and Anopheles coustani (0.5%; 6/1324). The highest proportion (54.3%; 569/1048) of the An. gambiae was collected from Wongie Berkegn followed by Jiga Yehlmidar (23.6%; 247/1048) and Mender Meter (22.1%; 232/1048). The mean number (mean = 7.8) of adult An. gambiae caught in Wongie Berkegn was significantly (p = 0.018) higher compared to the number (mean = 3.0) in Mender Meter. No significant difference was observed in the mean number of adult An. gambiae between the seasons. Conclusion and implication Streams were prolific breeding habitats of Anopheles mosquitoes followed by ponds and swamps in the dry seasons. In addition, a high population of indoor resting An. gambiae was caught from indoors. This implies the need for a strengthened vector control during dry seasons using breeding habitat management and improved housing in addition to the existing insecticide (LLINs and IRS) based interventions in Jabi Tehnan District, West Gojjam Zone, Ethiopia.
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Affiliation(s)
- Abebe Animut
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia.
| | - Yohannes Negash
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, P. O. Box 1176, Addis Ababa, Ethiopia
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Stevenson JC, Norris DE. Implicating Cryptic and Novel Anophelines as Malaria Vectors in Africa. INSECTS 2016; 8:E1. [PMID: 28025486 PMCID: PMC5371929 DOI: 10.3390/insects8010001] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 12/09/2016] [Accepted: 12/12/2016] [Indexed: 11/24/2022]
Abstract
Entomological indices and bionomic descriptions of malaria vectors are essential to accurately describe and understand malaria transmission and for the design and evaluation of appropriate control interventions. In order to correctly assign spatio-temporal distributions, behaviors and responses to interventions to particular anopheline species, identification of mosquitoes must be accurately made. This paper reviews the current methods and their limitations in correctly identifying anopheline mosquitoes in sub-Saharan Africa, and highlights the importance of molecular methods to discriminate cryptic species and identify lesser known anophelines. The increasing number of reports of Plasmodium infections in assumed "minor", non-vector, and cryptic and novel species is reviewed. Their importance in terms of evading current control and elimination strategies and therefore maintaining malaria transmission is emphasized.
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Affiliation(s)
- Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
- Macha Research Trust, Choma P.O. Box 630166, Southern Province, Zambia.
| | - Douglas E Norris
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
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Bass C, Williamson MS, Wilding CS, Donnelly MJ, Field LM. Identification of the main malaria vectors in the Anopheles gambiae species complex using a TaqMan real-time PCR assay. Malar J 2007; 6:155. [PMID: 18034887 PMCID: PMC2213665 DOI: 10.1186/1475-2875-6-155] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Accepted: 11/22/2007] [Indexed: 12/02/2022] Open
Abstract
Background The Anopheles gambiae sensu lato species complex comprises seven sibling species of mosquitoes that are morphologically indistinguishable. Rapid identification of the two main species which vector malaria, Anopheles arabiensis and An. gambiae sensu stricto, from the non-vector species Anopheles quadriannulatus is often required as part of vector control programmes. Currently the most widely used method for species identification is a multiplex PCR protocol that targets species specific differences in ribosomal DNA sequences. While this assay has proved to be reasonably robust in many studies, additional steps are required post-PCR making it time consuming. Recently, a high-throughput assay based on TaqMan single nucleotide polymorphism genotyping that detects and discriminates An. gambiae s.s and An. arabiensis has been reported. Methods A new TaqMan assay was developed that distinguishes between the main malaria vectors (An. arabiensis and An. gambiae s.s.) and the non-vector An. quadriannulatus after it was found that the existing TaqMan assay incorrectly identified An. quadriannulatus, An. merus and An. melas as An. gambiae s.s. The performance of this new TaqMan assay was compared against the existing TaqMan assay and the standard PCR method in a blind species identification trial of over 450 samples using field collected specimens from a total of 13 countries in Sub-Saharan Africa. Results The standard PCR method was found to be specific with a low number of incorrect scores (<1%), however when compared to the TaqMan assays it showed a significantly higher number of failed reactions (15%). Both the new vector-specific TaqMan assay and the exisiting TaqMan showed a very low number of incorrectly identified samples (0 and 0.54%) and failed reactions (1.25% and 2.96%). In tests of analytical sensitivity the new TaqMan assay showed a very low detection threshold and can consequently be used on a single leg from a fresh or silica-dried mosquito without the need to first extract DNA. Conclusion This study describes a rapid and sensitive assay that very effectively identifies the two main malaria vectors of the An. gambiae species complex from the non-vector sibling species. The method is based on TaqMan SNP genotyping and can be used to screen single legs from dried specimens. In regions where An. merus/melas/bwambae, vectors with restricted distributions, are not present it can be used alone to discriminate vector from non-vector or in combination with the Walker TaqMan assay to distinguish An. arabiensis and An. gambiae s.s.
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Affiliation(s)
- Chris Bass
- Department of Biological Chemistry, Rothamsted Research, Harpenden, AL5 2JQ, UK.
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Moffett A, Shackelford N, Sarkar S. Malaria in Africa: vector species' niche models and relative risk maps. PLoS One 2007; 2:e824. [PMID: 17786196 PMCID: PMC1950570 DOI: 10.1371/journal.pone.0000824] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Accepted: 08/06/2007] [Indexed: 11/19/2022] Open
Abstract
A central theoretical goal of epidemiology is the construction of spatial models of disease prevalence and risk, including maps for the potential spread of infectious disease. We provide three continent-wide maps representing the relative risk of malaria in Africa based on ecological niche models of vector species and risk analysis at a spatial resolution of 1 arc-minute (9 185 275 cells of approximately 4 sq km). Using a maximum entropy method we construct niche models for 10 malaria vector species based on species occurrence records since 1980, 19 climatic variables, altitude, and land cover data (in 14 classes). For seven vectors (Anopheles coustani, A. funestus, A. melas, A. merus, A. moucheti, A. nili, and A. paludis) these are the first published niche models. We predict that Central Africa has poor habitat for both A. arabiensis and A. gambiae, and that A. quadriannulatus and A. arabiensis have restricted habitats in Southern Africa as claimed by field experts in criticism of previous models. The results of the niche models are incorporated into three relative risk models which assume different ecological interactions between vector species. The “additive” model assumes no interaction; the “minimax” model assumes maximum relative risk due to any vector in a cell; and the “competitive exclusion” model assumes the relative risk that arises from the most suitable vector for a cell. All models include variable anthrophilicity of vectors and spatial variation in human population density. Relative risk maps are produced from these models. All models predict that human population density is the critical factor determining malaria risk. Our method of constructing relative risk maps is equally general. We discuss the limits of the relative risk maps reported here, and the additional data that are required for their improvement. The protocol developed here can be used for any other vector-borne disease.
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Affiliation(s)
- Alexander Moffett
- Section of Integrative Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Nancy Shackelford
- Section of Integrative Biology, University of Texas at Austin, Austin, Texas, United States of America
| | - Sahotra Sarkar
- Section of Integrative Biology, University of Texas at Austin, Austin, Texas, United States of America
- * To whom correspondence should be addressed. E-mail:
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Hargreaves K, Hunt RH, Brooke BD, Mthembu J, Weeto MM, Awolola TS, Coetzee M. Anopheles arabiensis and An. quadriannulatus resistance to DDT in South Africa. MEDICAL AND VETERINARY ENTOMOLOGY 2003; 17:417-422. [PMID: 14651656 DOI: 10.1111/j.1365-2915.2003.00460.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The malaria control programme of KwaZulu-Natal Province, South Africa, includes Mamfene and Mlambo communities. Western-type houses there are currently sprayed with deltamethrin, whereas traditional houses are sprayed with DDT for malaria control. In 2002, mosquitoes of the Anopheles gambiae complex (Diptera: Culicidae) were collected from DDT-sprayed houses, by window exit traps, and from man-baited nets outdoors. Larval collections were also carried out at Mzinweni Pan near Mlambo. Species of the An. gambiae complex were identified by rDNA polymerase chain reaction assay. The majority of samples collected by window trap and baited nets were identified as the malaria vector An. arabiensis Patton, with a few An. merus Dönitz and An. quadriannulatus (Theobald). The larval collections were predominantly An. quadriannulatus with a small number of An. arabiensis. Standard WHO insecticide susceptibility tests using 4% DDT and 0.05% deltamethrin were performed on both wild-caught females and laboratory-reared progeny from wild-caught females. Wild-caught An. arabiensis samples from window traps gave 63% and 100% mortality 24-h post-exposure to DDT or deltamethrin, respectively. Wild-caught An. arabiensis samples from man-baited net traps gave 81% mortality 24-h post-exposure to DDT. The F1 progeny from 22 An. arabiensis females showed average mortality of 86.5% 24-h post-exposure to DDT. Less than 80% mortality was recorded from five of these families. Biochemical analyses of samples from each of the families revealed comparatively high levels of glutathione-S-transferases and non-specific esterases in some families, but without significant correlation to bioassay results. Wild-caught An. quadriannulatus larvae were reared through to adults and assayed on 4% DDT, giving 47% (n = 36) mortality 24-h post-exposure. Finding DDT resistance in the vector An. arabiensis, close to the area where we previously reported pyrethroid-resistance in the vector An. funestus Giles, indicates an urgent need to develop a strategy of insecticide resistance management for the malaria control programmes of southern Africa.
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Affiliation(s)
- K Hargreaves
- Malaria Control Programme, KwaZulu-Natal Department of Health, Jozini, South Africa
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Fettene M, Temu EA. Species-specific primer for identification of Anopheles quadriannulatus sp. B (Diptera: Culicidae) from Ethiopia using a multiplex polymerase chain reaction assay. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:112-115. [PMID: 12597664 DOI: 10.1603/0022-2585-40.1.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Anopheles quadriannulatus Theobald historically has been reported from southern Africa, Zanzibar islands, and Ethiopia. However, based on evidences of genetic incompatibility between crosses of South African and Ethiopian populations, the population from Ethiopia was recently reported as a distinct species designated as An. quadriannulatus sp. B. An. quadriannulatus sp. A, denoted the southern African population. To distinguish the two populations, the IGS (intergenic spacer) region of rDNA was sequenced to design a primer specific for An. quadriannulatus sp. B. A cocktail polymerase chain reaction (PCR) involving Anopheles gambiae Giles universal (UN) primer, the new primer and other primers specific for members of the An. gambiae complex produced the expected diagnostic products for the respective species. Using extracted DNA and crushed body parts as sources of template DNA, this assay was reliably used to identify samples of An. quadriannulatus sp. B.
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Affiliation(s)
- Messay Fettene
- Medical Entomology, Department of Clinical Microbiology and Infectious Diseases, School of Pathology of the National Health Laboratory Services and the University of Witwatersrand, PO Box 1038, Johannesburg 2000, South Africa.
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Fanello C, Santolamazza F, della Torre A. Simultaneous identification of species and molecular forms of the Anopheles gambiae complex by PCR-RFLP. MEDICAL AND VETERINARY ENTOMOLOGY 2002; 16:461-464. [PMID: 12510902 DOI: 10.1046/j.1365-2915.2002.00393.x] [Citation(s) in RCA: 365] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
For differential identification of sibling species in the Anopheles gambiae Giles complex (Diptera: Culicidae), including simultaneous separation of M and S molecular forms within An. gambiae Giles sensu stricto, we describe a PCR-RFLP method. This procedure is more efficient, faster and cheaper than those used before, so is recommended for large-scale processing of field-collected larval and adult specimens to be identified in malaria vector studies.
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Affiliation(s)
- C Fanello
- London School of Hygiene and Tropical Medicine, London, UK
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