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Alcântara JA, de Araújo FSA, da Costa Paz A, Alencar RM, de Albuquerque Caldas BY, Godoy RSM, Lacerda MVG, de Melo GC, Monteiro WM, de Souza Sampaio V, Secundino NFC, Duarte APM, Santana RAG, Pimenta PFP. Effect of fluralaner on the biology, survival, and reproductive fitness of the neotropical malaria vector Anopheles aquasalis. Malar J 2023; 22:337. [PMID: 37936198 PMCID: PMC10631211 DOI: 10.1186/s12936-023-04767-0] [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: 02/27/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Reducing mosquito abundance or interfering with its ability to support the parasite cycle can help to interrupt malaria in areas of significant risk of malaria transmission. Fluralaner is a safe and effective drug for veterinary use indicated for the treatment against fleas and ticks which acts as an antagonist of chloride ion channels mediated by γ-aminobutyric acid (GABA), preventing the entry of these ions into the postsynaptic neuron, leading to hyperexcitability of the postsynaptic neuron of the central nervous system of arthropods. Fluralaner demonstrated insecticidal activity against different insect species. METHODS The study aimed to evaluate the effects of fluralaner on the biology, survival, and reproductive fitness of Anopheles aquasalis. The following lethal concentrations (LC) were determined for An. aquasalis: LC5 = 0.511 µM; LC25 = 1.625 µM; LC50 = 3.237 µM. RESULTS A significant decrease (P < 0.001) was evident in the number of eggs, larvae, and pupae in the group exposed to a sublethal dose of fluralaner when compared to a control group (without the drug). Using blood from dogs after administration of fluralaner, it was observed that the drug causes 100% mortality in An. aquasalis in less than 24 h after feeding; this effect remains even after 90 days in all samples. DISCUSSION Fluralaner showed the same result for up to 60 days, and after that, there was a slight reduction in its effect, evidenced by a decrease in the percentage of dead females; however, still significant when compared to the control group. CONCLUSION Fluralaner affects the biology and reduction of survival in An. aquasalis in a lasting and prolonged period, and its fecundity with lower dosages, is a strong candidate for controlling disease vectors.
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Affiliation(s)
- João Arthur Alcântara
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Francys Sayara Andrade de Araújo
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Andréia da Costa Paz
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Rodrigo Maciel Alencar
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | | | - Raquel Soares Maia Godoy
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Marcus Vinicius Guimarães Lacerda
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto Leônidas e Maria Deane - Fundação Oswaldo Cruz - (ILMD - Fiocruz Amazônia), Manaus, Brazil
- University of Texas Medical Branch (UTMB), Galveston, USA
| | - Gisely Cardoso de Melo
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Wuelton Marcelo Monteiro
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Vanderson de Souza Sampaio
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Nágila Francinete Costa Secundino
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Ana Paula Marques Duarte
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Rosa Amélia Gonçalves Santana
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto Leônidas e Maria Deane - Fundação Oswaldo Cruz - (ILMD - Fiocruz Amazônia), Manaus, Brazil
| | - Paulo Filemon Paolucci Pimenta
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil.
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil.
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil.
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Kendie FA, Wale M, Nibret E, Ameha Z. Insecticide susceptibility status of Anopheles gambiae (s.l.) in and surrounding areas of Lake Tana, northwest Ethiopia. Trop Med Health 2023; 51:3. [PMID: 36639818 PMCID: PMC9838068 DOI: 10.1186/s41182-023-00497-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 01/04/2023] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Vector control is the most effective malaria control and prevention measure. Among these, IRS and LLINs are the most important chemical insecticide interventions used in malaria prevention and control strategies in Ethiopia. However, the long-term effectiveness of these strategies is under threat due to the emergency and spread of insecticide resistance in the principal malaria vector. Therefore, this study was carried out, under standardized laboratory conditions to assess the killing effect of some insecticides against An. gambiae s.l. METHODS Mosquitoes in late instar larvae and pupae stages were collected from different breeding habitats of the study sites using a soup ladle (350 ml capacity). The immature was reared to adults at optimum temperature and humidity in a field insectary using the WHO protocol. Four insecticides representing three chemical classes were used against adult mosquitoes. These were permethrin, deltamethrin, pirimiphos-methyl and bendiocarb. Susceptibility tests were carried out from September to December 2021 using the WHO standard procedures. Mortality rate, variation, interaction effect and knockdown times (KDT50 and KDT95%) were computed using descriptive statistics, multivariate analysis of variance and log-probit regression model using SPSS version 20 software. RESULTS Totally, 1300 Anopheles gambiae s.l. were tested to determine the susceptibility status to the four insecticides. Among these, 90.7% of them were susceptible to insecticides, whereas the remaining 9.3% of specimens were resistant to the insecticides. The results of the analysis of variance showed that mortality significantly varied between insecticides (F = 26.06, DF = 3, P < .0001), but not between study locations (F = 1.56, DF = 3, P = 0.212). On the other hand, the mean comparison of dead mosquitoes showed some signs of interaction between bendiocarb and locations, but not other insecticides and locations. CONCLUSIONS This study revealed that the knockdown times and effectiveness of different insecticides varied in different study sites. Therefore, insecticide resistance information is very essential for concerned bodies to make informed and evidence-based decisions on vector control.
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Affiliation(s)
- Fasil A. Kendie
- grid.442845.b0000 0004 0439 5951Department of Biology, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia
| | - Melaku Wale
- grid.442845.b0000 0004 0439 5951Department of Biology, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia
| | - Endalkachew Nibret
- grid.442845.b0000 0004 0439 5951Biotechnology Research Institute, Bahir Dar University, Bahir Dar, Ethiopia
| | - Zena Ameha
- grid.512241.1Amhara Public Health Institute, Bahir Dar, Ethiopia
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Jiang S, You C, Zhang S, Chen F, Peng G, Liu J, Xie D, Li Y, Guo X. Using search trends to analyze web-based users' behavior profiles connected with COVID-19 in mainland China: infodemiology study based on hot words and Baidu Index. PeerJ 2022; 10:e14343. [PMID: 36389414 PMCID: PMC9653070 DOI: 10.7717/peerj.14343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/14/2022] [Indexed: 11/10/2022] Open
Abstract
Background Mainland China, the world's most populous region, experienced a large-scale coronavirus disease 2019 (COVID-19) outbreak in 2020 and 2021, respectively. Existing infodemiology studies have primarily concentrated on the prospective surveillance of confirmed cases or symptoms which met the criterion for investigators; nevertheless, the actual impact regarding COVID-19 on the public and subsequent attitudes of different groups towards the COVID-19 epidemic were neglected. Methods This study aimed to examine the public web-based search trends and behavior patterns related to COVID-19 outbreaks in mainland China by using hot words and Baidu Index (BI). The initial hot words (the high-frequency words on the Internet) and the epidemic data (2019/12/01-2021/11/30) were mined from infodemiology platforms. The final hot words table was established by two-rounds of hot words screening and double-level hot words classification. Temporal distribution and demographic portraits of COVID-19 were queried by search trends service supplied from BI to perform the correlation analysis. Further, we used the parameter estimation to quantitatively forecast the geographical distribution of COVID-19 in the future. Results The final English-Chinese bilingual table was established including six domains and 32 subordinate hot words. According to the temporal distribution of domains and subordinate hot words in 2020 and 2021, the peaks of searching subordinate hot words and COVID-19 outbreak periods had significant temporal correlation and the subordinate hot words in COVID-19 Related and Territory domains were reliable for COVID-19 surveillance. Gender distribution results showed that Territory domain (the male proportion: 67.69%; standard deviation (SD): 5.88%) and Symptoms/Symptom and Public Health (the female proportion: 57.95%, 56.61%; SD: 0, 9.06%) domains were searched more by male and female groups respectively. The results of age distribution of hot words showed that people aged 20-50 (middle-aged people) had a higher online search intensity, and the group of 20-29, 30-39 years old focused more on Media and Symptoms/Symptom (proportion: 45.43%, 51.66%; SD: 15.37%, 16.59%) domains respectively. Finally, based on frequency rankings of searching hot words and confirmed cases in Mainland China, the epidemic situation of provinces and Chinese administrative divisions were divided into 5 levels of early-warning regions. Central, East and South China regions would be impacted again by the COVID-19 in the future.
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Affiliation(s)
- Shuai Jiang
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Changqiao You
- NanHua Bio-medicine Co.,Ltd., Changsha, Hunan, China
| | - Sheng Zhang
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Fenglin Chen
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Guo Peng
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Jiajie Liu
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Daolong Xie
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Yongliang Li
- College of Biology, Hunan University, Changsha, Hunan Province, China
| | - Xinhong Guo
- College of Biology, Hunan University, Changsha, Hunan Province, China
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Omotayo AI, Ande AT, Oduola AO, Adelaja OJ, Adesalu O, Jimoh TR, Ghazali AI, Awolola ST. Multiple insecticide resistance mechanisms in urban population of Anopheles coluzzii (Diptera: culicidae) from Lagos, South-West Nigeria. Acta Trop 2022; 227:106291. [PMID: 34958768 DOI: 10.1016/j.actatropica.2021.106291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 11/01/2022]
Abstract
Malaria is a major public health challenge in Africa with Nigeria accounting for the highest burden of the disease in the world. Vector control has proved to be a highly effective component of malaria control, however, the development and spread of insecticide resistance in major vectors of malaria have been a major challenge. This study assessed resistance mechanisms in Anopheles coluzzii populations from Kosofe, Lagos mainland and Ojo Local Government Areas in Lagos, Nigeria where An. gambiae s.l is resistant to DDT and Permethrin. WHO susceptibility bioassay test was used in determining resistance status of An. coluzzii to discriminating doses of DDT and Permethrin while synergist assay was used to assess the involvement of monooxygenases in resistance development. Sub-species of An. gambiae s.l (An. gambiae and An. coluzzii) were identified using polymerase chain reaction (PCR) and Restriction Fragment Length Polymorphism (PCR-RFLP) while Allele-Specific Polymerase Chain Reaction (AS-PCR) assay was used to detect knockdown mutation (kdr-West; L1014F). Biochemical assays were used in determining the activities of metabolic enzymes. High DDT resistance was recorded in An. coluzzii populations from the three sites. Mortality rate of mosquitoes exposed confirmed Permethrin resistance in Kosofe (50%) and Lagos mainland (48%) but resistance was suspected in Ojo (96%). All specimens tested were confirmed as An. coluzzii with low kdr frequency; 11.6%, 16.4% and 6.7% in Kosofe, Lagos mainland and Ojo respectively. Pre-exposure to synergist (PBO) before exposure to Permethrin led to increased mortality in all populations. Esterase activity was insignificantly overexpressed in Kosofe (p = 0.849) and Lagos mainland (p = 0.229) populations. In contrast, GST activity was significantly lower in populations from Lagos mainland (63.650 ± 9.861; p = 0.007) and Ojo (91.765 ± 4.959; p = 0.042) than Kisumu susceptible strains (120.250 ± 13.972). Monooxygenase activity was higher in Lagos mainland (2.371 ± 0.261) and Ojo (1.361 ± 0.067) populations, albeit significantly in Lagos mainland (p = 0.007) only. Presence of target-site mutation in all populations, increased mortality with pre-exposure to PBO and elevated monooxygenase in Lagos mainland population were confirmed. Multiple resistance mechanisms in some urban populations of An. coluzzii from Lagos, Nigeria calls for appropriate resistance management strategies.
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Occurrence of L1014F and L1014S mutations in insecticide resistant Culex quinquefasciatus from filariasis endemic districts of West Bengal, India. PLoS Negl Trop Dis 2022; 16:e0010000. [PMID: 35025867 PMCID: PMC9135371 DOI: 10.1371/journal.pntd.0010000] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 11/13/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Lymphatic filariasis causes long term morbidity and hampers the socio-economic status. Apart from the available treatments and medication, control of vector population Culex quinquefasciatus Say through the use of chemical insecticides is a widely applied strategy. However, the unrestrained application of these insecticides over many decades has led to resistance development in the vectors. METHODS In order to determine the insecticide susceptibility/resistance status of Cx. quinquefasciatus from two filariasis endemic districts of West Bengal, India, wild mosquito populations were collected and assayed against six different insecticides and presence of L1014F; L1014S kdr mutations in the voltage-gated sodium channel gene was also screened along with the use of synergists to evaluate the role of major detoxifying enzymes in resistance development. RESULTS The collected mosquito populations showed severe resistance to insecticides and the two synergists used-PBO (piperonyl butoxide) and TPP (triphenyl phosphate), were unable to restore the susceptibility status of the vector thereupon pointing towards a minor role of metabolic enzymes. kdr mutations were present in the studied populations in varying percent with higher L1014F frequency indicating its association with the observed resistance to pyrethroids and DDT. This study reports L1014S mutation in Cx. quinquefasciatus for the first time.
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Chapungu L, Nhamo G. Interfacing vector-borne disease dynamics with climate change: Implications for the attainment of SDGs in Masvingo city, Zimbabwe. JAMBA (POTCHEFSTROOM, SOUTH AFRICA) 2021; 13:1175. [PMID: 34691367 PMCID: PMC8517737 DOI: 10.4102/jamba.v13i1.1175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 07/21/2021] [Indexed: 06/13/2023]
Abstract
This study used a mixed-methods research design to examine the sensitivity of vector-borne disease (VBD) patterns to the changes in rainfall and temperature trends. The research focused on malaria in Masvingo Province, Zimbabwe. The study interfaced the climate action, health and sustainable cities and communities with sustainable development goals (SDGs). Historical climate and epidemiological data were used to compute the correlations and determine the possible modifications of disease patterns. Clustered random and chain-referral sampling approaches were used to select study sites and respondents. Primary data were gathered through a questionnaire survey (n = 191), interviews and focus group discussions, with Mann-Kendal trend tests performed using XLSTAT 2020. The results show a positive correlation between malaria prevalence rates and temperature-related variables. A decline in precipitation-related variables, specifically mean monthly precipitation (MMP), was associated with an increase in malaria prevalence. These observations were confirmed by the views of the respondents, which show that climate change has a bearing on malaria spatial and temporal dynamics in Masvingo Province. The study concludes that climate change plays a contributory role in VBD dynamics, thereby impeding the attainment of the 2030 Agenda for Sustainable Development, especially SDG 3, which deals with health. The study recommends further research into appropriate adaptation mechanisms to increase the resilience of rural and urban communities against the negative transmutations associated with weather and climatic pressures.
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Affiliation(s)
- Lazarus Chapungu
- College of Economics and Management Sciences, Institute of Corporate Citizenship, Exxaro Chair of Climate and Sustainability Transitions, University of South Africa, Pretoria, South Africa
| | - Godwell Nhamo
- College of Economics and Management Sciences, Institute of Corporate Citizenship, Exxaro Chair of Climate and Sustainability Transitions, University of South Africa, Pretoria, South Africa
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Nissan H, Ukawuba I, Thomson M. Climate-proofing a malaria eradication strategy. Malar J 2021; 20:190. [PMID: 33865383 PMCID: PMC8053291 DOI: 10.1186/s12936-021-03718-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 03/30/2021] [Indexed: 11/10/2022] Open
Abstract
Two recent initiatives, the World Health Organization (WHO) Strategic Advisory Group on Malaria Eradication and the Lancet Commission on Malaria Eradication, have assessed the feasibility of achieving global malaria eradication and proposed strategies to achieve it. Both reports rely on a climate-driven model of malaria transmission to conclude that long-term trends in climate will assist eradication efforts overall and, consequently, neither prioritize strategies to manage the effects of climate variability and change on malaria programming. This review discusses the pathways via which climate affects malaria and reviews the suitability of climate-driven models of malaria transmission to inform long-term strategies such as an eradication programme. Climate can influence malaria directly, through transmission dynamics, or indirectly, through myriad pathways including the many socioeconomic factors that underpin malaria risk. These indirect effects are largely unpredictable and so are not included in climate-driven disease models. Such models have been effective at predicting transmission from weeks to months ahead. However, due to several well-documented limitations, climate projections cannot accurately predict the medium- or long-term effects of climate change on malaria, especially on local scales. Long-term climate trends are shifting disease patterns, but climate shocks (extreme weather and climate events) and variability from sub-seasonal to decadal timeframes have a much greater influence than trends and are also more easily integrated into control programmes. In light of these conclusions, a pragmatic approach is proposed to assessing and managing the effects of climate variability and change on long-term malaria risk and on programmes to control, eliminate and ultimately eradicate the disease. A range of practical measures are proposed to climate-proof a malaria eradication strategy, which can be implemented today and will ensure that climate variability and change do not derail progress towards eradication.
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Affiliation(s)
- Hannah Nissan
- Grantham Research Institute for Climate Change and the Environment, London School of Economics and Political Science, London, UK.
- International Research Institute for Climate and Society, Columbia University, Palisades, NY, USA.
| | - Israel Ukawuba
- Mailman School for Public Health, Columbia University, New York, NY, USA
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Hinne IA, Attah SK, Mensah BA, Forson AO, Afrane YA. Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana. Parasit Vectors 2021; 14:193. [PMID: 33827667 PMCID: PMC8025514 DOI: 10.1186/s13071-021-04701-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/23/2021] [Indexed: 11/16/2022] Open
Abstract
Background Understanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons. Methods The spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification. Results Out of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05). Conclusion The most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control. Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04701-w.
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Affiliation(s)
- Isaac A Hinne
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Simon K Attah
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana
| | - Benedicta A Mensah
- Department of Epidemiology, Noguchi Memorial Institute of Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Akua O Forson
- Department of Medical Laboratory Science, School of Biomedical and Allied Health Sciences, University of Ghana, Korle-Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Korle-Bu, Accra, Ghana.
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Deguenon JM, Azondekon R, Agossa FR, Padonou GG, Anagonou R, Ahoga J, N’dombidje B, Akinro B, Stewart DA, Wang B, Gittins D, Tihomirov L, Apperson CS, McCord MG, Akogbeto MC, Roe RM. Imergard TMWP: A Non-Chemical Alternative for an Indoor Residual Spray, Effective against Pyrethroid-Resistant Anopheles gambiae (s.l.) in Africa. INSECTS 2020; 11:E322. [PMID: 32456154 PMCID: PMC7290382 DOI: 10.3390/insects11050322] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/29/2020] [Accepted: 05/18/2020] [Indexed: 11/17/2022]
Abstract
Malaria is the deadliest mosquito-borne disease and kills predominantly people in sub-Saharan Africa (SSA). The now widespread mosquito resistance to pyrethroids, with rapidly growing resistance to other insecticide classes recommended by the World Health Organization (WHO), may overturn the successes gained in mosquito control in recent years. It is of utmost importance to search for new, inexpensive, and safe alternatives, with new modes of action, that might improve the efficacy of current insecticides. The efficacy of a novel mechanical insecticidal mineral derived from volcanic rock, ImergardTMWP, was investigated to determine its efficacy as a stand-alone residual wall spray and as a mixture with deltamethrin (K-Othrine® Polyzone) in experimental huts in Cove, Benin. The evaluation was conducted with susceptible (Kisumu) and wild-type Anopheles gambiae (s.l.). Deltamethrin applied alone demonstrated 40-45% mortality (at 72 h post-exposure) during the first four months, which declined to 25% at six months for wild An. gambiae from Cove. ImergardTMWP alone and mixed with deltamethrin, under the same assay conditions, produced 79-82% and 73-81% mortality, respectively, during the same six-month period. ImergardTMWP met the 80% WHO bio-efficacy threshold for residual activity for the first five months with 78% residual activity at six months. ImergardTMWP can be used as a mixture with chemical insecticides or as a stand-alone pesticide for mosquito control in Africa.
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Affiliation(s)
- Jean M. Deguenon
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
| | - Roseric Azondekon
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Fiacre R. Agossa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Gil G. Padonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Rodrigue Anagonou
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Juniace Ahoga
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Boris N’dombidje
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - David A. Stewart
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Bo Wang
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - David Gittins
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Larissa Tihomirov
- Imerys Filtration Minerals, Inc., Roswell, GA 30076, USA; (D.A.S.); (B.W.); (D.G.); (L.T.)
| | - Charles S. Apperson
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
| | - Marian G. McCord
- College of Natural Resources, Campus Box 8001, 2820 Faucette Drive, North Carolina State University, Raleigh, NC 27695, USA;
| | - Martin C. Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou 06BP2604, Benin; (R.A.); (F.R.A.); (G.G.P.); (R.A.); (J.A.); (B.N.); (B.A.); (M.C.A.)
| | - R. Michael Roe
- Department of Entomology and Plant Pathology, Campus Box 7647, 3230 Ligon Street, North Carolina State University, Raleigh, NC 27695, USA; (J.M.D.); (C.S.A.)
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Yang L, Norris EJ, Jiang S, Bernier UR, Linthicum KJ, Bloomquist JR. Reduced effectiveness of repellents in a pyrethroid-resistant strain of Aedes aegypti (Diptera: culicidae) and its correlation with olfactory sensitivity. PEST MANAGEMENT SCIENCE 2020; 76:118-124. [PMID: 31338960 DOI: 10.1002/ps.5562] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/03/2019] [Accepted: 07/21/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND The mosquito, Aedes aegypti (Diptera: Culicidae), is a vector of dengue fever, zika, chikungunya, and yellow fever viruses, and in many areas possesses significant levels of resistance to pyrethroids. Behavioral performance was assessed in 15, 30, and 60 min exposures in a high throughput vapor phase spatial repellency assay to three contact repellent standards: N,N-diethyl-3-methylbenzamide (DEET), ethyl 3-[acetyl(butyl)amino] propanoate (IR3535), and 2-undecanone, as well as pyrethrum extract, transfluthrin, and metofluthrin in susceptible (Orlando) and a pyrethroid-resistant Puerto Rico strain of Aedes aegypti. Additionally, electroantennographic studies were used to investigate the antennal sensitivities to these compounds in both strains. RESULTS Resistance was found to all tested insect repellents in the Puerto Rico strain of Ae. aegypti. Resistance ratios at the different time points were about 2 for DEET, 3 for 2-undecanone, and 12 for IR3535. Resistance was also observed to pyrethrum extract (∼9-fold), transfluthrin (∼5-fold), and metofluthrin (∼48-fold) in repellent behavioral response. Electrophysiological analysis found decreased antennal sensitivity to all repellents tested, consistent with their behavioral effects. CONCLUSION The reduced sensitivity to these repellents may represent a fitness cost arising from the kdr mutation present in Puerto Rico Aedes aegypti. This work highlights the need for understanding collateral effects from the evolution of pesticide resistance in mosquitoes, and the importance of finding alternative strategies to control resistance development. © 2019 Society of Chemical Industry.
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Affiliation(s)
- Liu Yang
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Edmund J Norris
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Shiyao Jiang
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
| | - Ulrich R Bernier
- USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, USA
| | - Kenneth J Linthicum
- USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, USA
| | - Jeffrey R Bloomquist
- Emerging Pathogens Institute, Department of Entomology and Nematology, University of Florida, Gainesville, FL, USA
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Debalke S, Habtewold T, Duchateau L, Christophides GK. The effect of silencing immunity related genes on longevity in a naturally occurring Anopheles arabiensis mosquito population from southwest Ethiopia. Parasit Vectors 2019; 12:174. [PMID: 30992084 PMCID: PMC6469062 DOI: 10.1186/s13071-019-3414-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 03/27/2019] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Vector control remains the most important tool to prevent malaria transmission. However, it is now severely constrained by the appearance of physiological and behavioral insecticide resistance. Therefore, the development of new vector control tools is warranted. Such tools could include immunization of blood hosts of vector mosquitoes with mosquito proteins involved in midgut homeostasis (anti-mosquito vaccines) or genetic engineering of mosquitoes that can drive population-wide knockout of genes producing such proteins to reduce mosquito lifespan and malaria transmission probability. METHODS To achieve this, candidate genes related to midgut homeostasis regulation need to be assessed for their effect on mosquito survival. Here, different such candidate genes were silenced through dsRNA injection in the naturally occurring Anopheles arabiensis mosquitoes and the effect on mosquito survival was evaluated. RESULTS Significantly higher mortality rates were observed in the mosquitoes silenced for FN3D1 (AARA003032), FN3D3 (AARA007751) and GPRGr9 (AARA003963) genes as compared to the control group injected with dsRNA against a non-related bacterial gene (LacZ). This observed difference in mortality rate between the candidate genes and the control disappeared when gene-silenced mosquitoes were treated with antibiotic mixtures, suggesting that gut microbiota play a key role in the observed reduction of mosquito survival. CONCLUSIONS We demonstrated that interference with the expression of the FN3D1, FN3D3 or GPRGr9 genes causes a significant reduction of the longevity of An. arabiensis mosquito in the wild.
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Affiliation(s)
- Serkadis Debalke
- Department of Medical Laboratory Science & Pathology, Jimma University, Jimma, Ethiopia
- Biometrics Research Group, Ghent University, Ghent, Belgium
| | - Tibebu Habtewold
- Biometrics Research Group, Ghent University, Ghent, Belgium
- Department of Life Sciences, Imperial College London, London, UK
| | - Luc Duchateau
- Biometrics Research Group, Ghent University, Ghent, Belgium
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Fagbohun IK, Oyeniyi TA, Idowu TE, Otubanjo OA, Awolola ST. Cytochrome P450 Mono-Oxygenase and Resistance Phenotype in DDT and Deltamethrin-Resistant Anopheles gambiae (Diptera: Culicidae) and Culex quinquefasciatus in Kosofe, Lagos, Nigeria. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:817-821. [PMID: 30753574 PMCID: PMC6467639 DOI: 10.1093/jme/tjz006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Indexed: 06/09/2023]
Abstract
Pyrethroids and DDT are key insecticides in the control of malaria, yellow fever, and lymphatic filariasis vectors. Knockdown and metabolic resistance mechanisms have been proven to be important in determining the efficacy of insecticides. Here we investigated cytochrome P450 as a resistance mechanism in Anopheles gambiae Giles and Culex quinquefasciatus Say exposed to deltamethrin and DDT. Two- to three-days-old adult female mosquitoes were used for insecticide exposures and PBO synergistic assays using WHO standard guidelines, kits and test papers (DDT 4%, deltamethrin 0.05%, and PBO 4%). Polymerase chain reaction (PCR) assays were used for the identification of the species and for characterization of the kdr allele. Mortality at 24 h post-exposure was 18 and 17% in An. gambiae s.s. exposed to DDT and deltamethrin, respectively; 1 and 5% in Cx. quinquefasciatus exposed to DDT and deltamethrin respectively. Significant (P < 0.01) levels of susceptibility was recorded in mosquitoes pre-exposed to PBO, as KDT50 and 24 h of exposure ranged from 37.6 min to 663.4 min and 27 to 80%, respectively. Presence of a knockdown resistance allele was recorded in An. gambiae s.s., 22.5% for homozygote resistance and 7.5% for heterozygotes, while Cx. quinquefasciatus populations showed no kdr allele despite the high level of resistance to DDT and deltamethrin. Findings from this study indicated that cytochrome P450 mono-oxygenase expression is highly implicated in the resistance phenotype to DDT and pyrethroids in An. gambiae and Cx. quinquefasciatus in the study area.
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Affiliation(s)
| | - Tolulope A Oyeniyi
- Vector Research Laboratory, Nigeria Institute of Medical Research, Lagos, Nigeria
| | - Taiwo E Idowu
- Department of Zoology, University of Lagos, Lagos, Nigeria
| | | | - Samson T Awolola
- Vector Research Laboratory, Nigeria Institute of Medical Research, Lagos, Nigeria
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Ubulom PME, Ettebong EO, Udofia EJ, Inyang Etuk RS. In vivo antiplasmodial potential of aqueous seed extract of Ricinus communis. JOURNAL OF HERBMED PHARMACOLOGY 2019. [DOI: 10.15171/jhp.2019.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Introduction: Ricinus communis is used by the people of Niger-Delta region of Nigeria, for the treatment of various ailments, especially malaria. This study evaluated the antiplasmodial potentials of the aqueous seed extract of R. communis, using Plasmodium berghei berghei. Methods: Acute toxicity study was carried out to determine the median lethal dose (LD50) of the extract. Antiplasmodial effect of the extract was assessed in suppressive, repository/ prophylactic and curative models, using Swiss albino mice (15-29 g). Mice were infected intraperitoneally with 0.2 mL of parasitized blood. Extract doses administered were 54.77, 109.54 and 164.32 mg/kg/d of the seed extract and each dose had 6 replicates. Artesunate (5 mg/kg/d) and pyrimethamine (1.2 mg/kg/d) were used as standard drugs, while distilled water (10 mL/kg/d) served as control. Results: Acute toxicity study produced LD50 of 547.72 mg/kg. The extract demonstrated a dosedependent reduction in parasitaemia in all tests. At the end of 4-day test, suppressive effect of 20.80, 49.00, 75.00 and 88.40% were obtained for doses 54.77, 109.54 and 164.32 mg/kg/d of the seed extract and artesunate, respectively. In the repository test pyrimethamine was more potent (72.26%) than the seed extract (9.47%–51.42%). The extract also exhibited appreciable curative effect. The activity of the seed extract was significant when compared with the control (P < 0.05). Mice treated with the seed extract and drugs survived for longer duration than the control group. Conclusion: The aqueous seed extract of R. communis has antiplasmodial potential and its active principle should be elucidated and further investigated to help in the ongoing fight against malaria.
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Affiliation(s)
- Peace ME. Ubulom
- Department of Animal and Environmental Biology, Faculty of Science, University of Uyo, Uyo, Nigeria
| | - Ette O. Ettebong
- Department of Clinical Pharmacology and Therapeutics, Faculty of Clinical Sciences, University of Uyo, Uyo, Nigeria
| | - Edidiong J. Udofia
- Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria
| | - Rachel S Inyang Etuk
- Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria
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Chen J, Li TC, Pang R, Yue XZ, Hu J, Zhang WQ. Genome-Wide Screening and Functional Analysis Reveal That the Specific microRNA nlu-miR-173 Regulates Molting by Targeting Ftz-F1 in Nilaparvata lugens. Front Physiol 2018; 9:1854. [PMID: 30618850 PMCID: PMC6306441 DOI: 10.3389/fphys.2018.01854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/07/2018] [Indexed: 01/28/2023] Open
Abstract
Background: Molting is a crucial physiological behavior during arthropod growth. In the past few years, molting as well as chitin biosynthesis triggered by molting, is subject to regulation by miRNAs. However, how many miRNAs are involved in insect molting at the genome-wide level remains unknown. Results: We deeply sequenced four samples obtained from nymphs at the 2nd-3rd and 4th-5th instars, and then identified 61 miRNAs conserved in the Arthropoda and 326 putative novel miRNAs in the brown planthopper Nilaparvata lugens, a fearful pest of rice. A total of 36 mature miRNAs with significant different expression levels at the genome scale during molting, including 19 conserved and 17 putative novel miRNAs were identified. After comparing the expression profiles, we found that most of the targets of 36 miRNAs showing significantly differential expression were involved in energy and hormone pathways. One of the 17 putative novel miRNAs, nlu-miR-173 was chosen for functional study. nlu-miR-173 acts in 20-hydroxyecdysone signaling through its direct target, N. lugens Ftz-F1(NlFtz-F1), a transcription factor. Furthermore, we found that the transcription of nlu-miR-173 was promoted by Broad-Complex (BR-C), suggesting that its involvement in the 20-hydroxyecdysone pathway contributes to proper molting function. Conclusion: We provided a comprehensive resource of miRNAs associated with insect molting and identified a novel miRNA as a potential target for pest control.
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Affiliation(s)
- Jie Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Teng Chao Li
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Rui Pang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xiang Zhao Yue
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jian Hu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Wen Qing Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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de Alencar FEC, Malafronte RDS, Cerutti Junior C, Natal Fernandes L, Buery JC, Fux B, Rezende HR, Duarte AMRDC, Medeiros-Sousa AR, Miranda AE. Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil. Malar J 2018. [PMID: 29540186 PMCID: PMC5853114 DOI: 10.1186/s12936-018-2263-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario in which asymptomatic carriers play an important role. Objectives To determine the incidence of asymptomatic infection by detecting Plasmodium spp. DNA and its role in residual malaria transmission in a non-Amazonian region of Brazil. Methods Upon the report of the first malaria case in 2010 in the Atlantic Forest region of the state of Espírito Santo, inhabitants within a 2 km radius were invited to participate in a follow-up study. After providing signed informed consent forms, inhabitants filled out a questionnaire and gave blood samples for PCR, and thick and thin smears. Follow-up visits were performed every 3 months over a 21 month period, when new samples were collected and information was updated. Results Ninety-two individuals were initially included for follow-up. At the first collection, all of them were clearly asymptomatic. One individual was positive for Plasmodium vivax, one for Plasmodium malariae and one for both P. vivax and P. malariae, corresponding to a prevalence of 3.4% (2.3% for each species). During follow-up, four new PCR-positive cases (two for each species) were recorded, corresponding to an incidence of 2.5 infections per 100 person-years or 1.25 infections per 100 person-years for each species. A mathematical transmission model was applied, using a low frequency of human carriers and the vector density in the region, and calculated based on previous studies in the same locality whose results were subjected to a linear regression. This analysis suggests that the transmission chain is unlikely to be based solely on human carriers, regardless of whether they are symptomatic or not. Conclusion The low incidence of cases and the low frequency of asymptomatic malaria carriers investigated make it unlikely that the transmission chain in the region is based solely on human hosts, as cases are isolated one from another by hundreds of kilometers and frequently by long periods of time, reinforcing instead the hypothesis of zoonotic transmission. Electronic supplementary material The online version of this article (10.1186/s12936-018-2263-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Filomena E C de Alencar
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
| | | | - Crispim Cerutti Junior
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Lícia Natal Fernandes
- Protozoology Laboratory, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Julyana Cerqueira Buery
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Blima Fux
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Helder Ricas Rezende
- Entomology and Malacology Unit, Espírito Santo State Department of Health (SESA), Vitória, Brazil
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Ramirez B. Support for research towards understanding the population health vulnerabilities to vector-borne diseases: increasing resilience under climate change conditions in Africa. Infect Dis Poverty 2017; 6:164. [PMID: 29228976 PMCID: PMC5725740 DOI: 10.1186/s40249-017-0378-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/23/2017] [Indexed: 11/10/2022] Open
Abstract
Background Diseases transmitted to humans by vectors account for 17% of all infectious diseases and remain significant public health problems. Through the years, great strides have been taken towards combatting vector-borne diseases (VBDs), most notably through large scale and coordinated control programmes, which have contributed to the decline of the global mortality attributed to VBDs. However, with environmental changes, including climate change, the impact on VBDs is anticipated to be significant, in terms of VBD-related hazards, vulnerabilities and exposure. While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change, there is still a paucity of research being undertaken in this area, and impeding the formulation of evidence-based health policy change. Main body One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area. The collaboration between the WHO Special Programme for Research and Training in Tropical Diseases (TDR) and the International Centre for Research and Development (IDRC) builds on more than 10 years of partnership in research capacity-building in the field of tropical diseases. From this partnership was born yet another research initiative on VBDs and the impact of climate change in the Sahel and sub-Saharan Africa. This paper lists the projects supported under this research initiative and provides a brief on some of the policy and good practice recommendations emerging from the ongoing implementation of the research projects. Conclusion Data generated from the research initiative are expected to be uptaken by stakeholders (including communities, policy makers, public health practitioners and other relevant partners) to contribute to a better understanding of the impacts of social, environmental and climate change on VBDs(i.e. the nature of the hazard, vulnerabilities, exposure), and improve the ability of African countries to adapt to and reduce the effects of these changes in ways that benefit their most vulnerable populations. Electronic supplementary material The online version of this article (10.1186/s40249-017-0378-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bernadette Ramirez
- Vectors, Environment and Society Unit, Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization (WHO), Geneva, Switzerland.
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17
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Gunda R, Chimbari MJ, Shamu S, Sartorius B, Mukaratirwa S. Malaria incidence trends and their association with climatic variables in rural Gwanda, Zimbabwe, 2005-2015. Malar J 2017; 16:393. [PMID: 28964255 PMCID: PMC5622423 DOI: 10.1186/s12936-017-2036-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 09/19/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is a public health problem in Zimbabwe. Although many studies have indicated that climate change may influence the distribution of malaria, there is paucity of information on its trends and association with climatic variables in Zimbabwe. To address this shortfall, the trends of malaria incidence and its interaction with climatic variables in rural Gwanda, Zimbabwe for the period January 2005 to April 2015 was assessed. METHODS Retrospective data analysis of reported cases of malaria in three selected Gwanda district rural wards (Buvuma, Ntalale and Selonga) was carried out. Data on malaria cases was collected from the district health information system and ward clinics while data on precipitation and temperature were obtained from the climate hazards group infrared precipitation with station data (CHIRPS) database and the moderate resolution imaging spectro-radiometer (MODIS) satellite data, respectively. Distributed lag non-linear models (DLNLM) were used to determine the temporal lagged association between monthly malaria incidence and monthly climatic variables. RESULTS There were 246 confirmed malaria cases in the three wards with a mean incidence of 0.16/1000 population/month. The majority of malaria cases (95%) occurred in the > 5 years age category. The results showed no correlation between trends of clinical malaria (unconfirmed) and confirmed malaria cases in all the three study wards. There was a significant association between malaria incidence and the climatic variables in Buvuma and Selonga wards at specific lag periods. In Ntalale ward, only precipitation (1- and 3-month lag) and mean temperature (1- and 2-month lag) were significantly associated with incidence at specific lag periods (p < 0.05). DLNM results suggest a key risk period in current month, based on key climatic conditions in the 1-4 month period prior. CONCLUSIONS As the period of high malaria risk is associated with precipitation and temperature at 1-4 month prior in a seasonal cycle, intensifying malaria control activities over this period will likely contribute to lowering the seasonal malaria incidence.
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Affiliation(s)
- Resign Gunda
- School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa.
| | - Moses John Chimbari
- College of Health Sciences, University of KwaZulu-Natal, Howard Campus, Durban, South Africa
| | - Shepherd Shamu
- Department of Community Medicine, University of Zimbabwe, Harare, Zimbabwe
| | - Benn Sartorius
- Discipline of Public Health Medicine, School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa
| | - Samson Mukaratirwa
- School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa
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Sweileh WM, Sawalha AF, Al-Jabi SW, Zyoud SH, Shraim NY, Abu-Taha AS. A bibliometric analysis of literature on malaria vector resistance: (1996 - 2015). Global Health 2016; 12:76. [PMID: 27884199 PMCID: PMC5123357 DOI: 10.1186/s12992-016-0214-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Accepted: 11/08/2016] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Emergence of insecticide resistance in malaria vectors is a real threat to future goals of elimination and control of malaria. Therefore, the objective of this study was to assess research trend on insecticide resistance of Anopheles mosquito. In specific, number of publications, countries, institutions, and authors' research profile, citation analysis, international collaborations, and impact of journals publishing documents on insecticide resistance will be presented. It was conducted via Scopus search engine which was used to retrieve relevant data. Keywords used were based on literature available on this topic. The duration of study was set from 1996-2015. RESULTS A total of 616 documents, mainly as original research articles (n = 569; 92.37%) were retrieved. The average number of citations per article was 26.36. Poisson log-linear regression analysis indicated that there was a 6.00% increase in the number of publications for each extra article on pyrethroid resistance. A total of 82 different countries and 1922 authors participated in publishing retrieved articles. The United Kingdom (UK) ranked first in number of publications followed by the United States of America (USA) and France. The top ten productive countries included seven African countries. The UK had collaborations mostly with Benin (relative link strength = 46). A total of 1817 institution/ organizations participated in the publication of retrieved articles. The most active institution/ organization was Liverpool School of Tropical Medicine. Retrieved articles were published in 134 different scientific peer reviewed journals. The journal that published most on this topic was Malaria Journal (n = 101; 16.4%). Four of the top active authors were from South Africa and two were from the UK. Three of the top ten cited articles were published in Insect Molecular Biology journal. Six articles were about pyrethroid resistance and at least two were about DDT resistance. CONCLUSION Publications on insecticide resistance in malaria vector has gained momentum in the past decade. International collaborations enhanced the knowledge about the situation of vector resistance in countries with endemic malaria. Molecular biology of insecticide resistance is the key issue in understanding and overcoming this emerging problems.
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Affiliation(s)
- Waleed M. Sweileh
- Department of Physiology, Pharmacology, Toxicology, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
| | - Ansam F. Sawalha
- Department of Physiology, Pharmacology, Toxicology, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
| | - Samah W. Al-Jabi
- Department of Clinical and Community Pharmacy, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
| | - Sa’ed H. Zyoud
- Department of Clinical and Community Pharmacy, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
| | - Naser Y. Shraim
- Department of Pharmaceutical Chemistry and Technology, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
| | - Adham S. Abu-Taha
- Department of Physiology, Pharmacology, Toxicology, College of Medicine and Health Sciences, An-Najah National University, Nablus, 44839 Palestine
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Household perceptions and subjective valuations of indoor residual spraying programmes to control malaria in northern Uganda. Infect Dis Poverty 2016; 5:100. [PMID: 27716420 PMCID: PMC5053089 DOI: 10.1186/s40249-016-0190-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 08/29/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-based tools remain critical for controlling vector-borne diseases in Uganda. Securing public support from targeted populations for such tools is an important component in sustaining their long-run effectiveness. Yet little quantitative evidence is available on the perceived benefits and costs of vector control programmes among targeted households. METHODS A survey was administered to a clustered random sample of 612 households in Gulu and Oyam districts of northern Uganda during a period of very high malaria transmission and following a pilot indoor residual spray (IRS) programme. A discrete choice experiment was conducted within the survey, in which respondents indicated their preferences for different IRS programmes relative to money compensation in a series of experimentally controlled, hypothetical choice sets. The data were analysed using conditional logit regression models to estimate respondents' willingness to accept (WTA) some amount of money compensation in lieu of foregone malaria risk reductions. Latent class models were used to analyse whether respondent characteristics predicted WTA. RESULTS Average WTA is estimated at $8.94 annually for a 10 % reduction in malaria risk, and additional co-benefits of IRS were estimated to be worth on average $54-$56 (depending on insecticide type) per round of IRS. Significant heterogeneity is observed: Four in five household heads in northern Uganda have high valuations for IRS programmes, while the remaining 20 % experience costly side effects of IRS (valued at between $2 and $3 per round). Statistically significant predictors of belonging to the high-value group include respondent gender, mean age of household members, participation in previous IRS, basic knowledge of mosquito reproduction, and the number of mosquito nets owned. Proxies for household income and wealth are not found to be statistically significant predictors of WTA. CONCLUSIONS This study suggests that the majority of people in areas of high malaria transmission like northern Uganda place a high value on vector control programmes using IRS. However, there is significant heterogeneity in terms of the perceived side effects (positive and negative). This has implications for sustaining public support for these programmes in the long-term.
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Antibacterial and insecticidal activity of volatile compounds of three algae species of Oman Sea. INTERNATIONAL JOURNAL OF SECONDARY METABOLITE 2016. [DOI: 10.21448/http-ijate-net-index-php-ijsm.243308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Assessment of Burden of Malaria in Gwanda District, Zimbabwe, Using the Disability Adjusted Life Years. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:244. [PMID: 26907320 PMCID: PMC4772264 DOI: 10.3390/ijerph13020244] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/04/2016] [Accepted: 02/14/2016] [Indexed: 11/17/2022]
Abstract
Malaria is one of the highest contributors to morbidity and mortality in Zimbabwe. However, there is paucity of knowledge regarding disability adjusted life years (DALYs) as a measure of burden of malaria in affected communities. The DALYs metric was used to assess the burden of malaria in Gwanda District with the aim of contributing to a better understanding of the impact of disease on affected communities. Data was collected from health facility malaria registers and the District Health Information System (DHIS) to estimate DALYs at household and district levels respectively. The household DALYs included 130 malaria cases from 2013 to 2015 while the DALYs for the district included 719 confirmed malaria cases from 2011 to 2015. Households lost a total of 153.89 DALYs with the majority of the disease burden (65.55%) occurring in the most economically productive age group (15-45 years) with a mean loss of 1.18 DALYs per malaria case. At district level, 251.09 DALYs were lost due to malaria and the calculated average district DALY rate for 2011-2015 was 36.29 DALYs/100,000 persons per year. It is important to estimate malaria burden to assist policy makers in making informed decisions when channelling resources for control and prevention of the disease.
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