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Turner EA, Christofferson RC. Exploring the transmission modalities of Bunyamwera virus. Exp Biol Med (Maywood) 2024; 249:10114. [PMID: 38510492 PMCID: PMC10954195 DOI: 10.3389/ebm.2024.10114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 12/11/2023] [Indexed: 03/22/2024] Open
Abstract
Bunyamwera virus (BUNV) (Bunyamwera orthobunyavirus) has been found in Sub-Saharan Africa and demonstrated recently as cocirculating with Rift Valley Fever Virus (RVFV). Little is known regarding the breadth of transmission modalities of Bunyamwera. Given its co-occurence with RVFV, we hypothesized the transmission system of BUNV shared similarities to the RVFV system including transmission by Ae. aegypti mosquitoes and environmentally mediated transmission through fomites and environmental contamination. We exposed Ae. aegypti mosquitoes to BUNV and evaluated their ability to transmit both vertically and horizontally. Further, we investigated the potential for a novel transmission modality via environmental contamination. We found that the LSU colony of Ae. aegypti was not competent for the virus for either horizontal or vertical transmission; but, 20% of larva exposed to virus via contaminated aquatic habitat were positive. However, transstadial clearance of the virus was absolute. Finally, under simulated temperature conditions that matched peak transmission in Rwanda, we found that BUNV was stable in both whole blood and serum for up to 28 days at higher total volume in tubes at moderate quantities (103-5 genome copies/mL). In addition, infectiousness of these samples was demonstrated in 80% of the replicates. At lower volume samples (in plates), infectiousness was retained out to 6-8 days with a maximum infectious titer of 104 PFU/mL. Thus, the potential for contamination of the environment and/or transmission via contaminated fomites exists. Our findings have implications for biosafety and infection control, especially in the context of food animal production.
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Athni TS, Childs ML, Glidden CK, Mordecai EA. Temperature dependence of mosquitoes: comparing mechanistic and machine learning approaches. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.04.569955. [PMID: 38105988 PMCID: PMC10723351 DOI: 10.1101/2023.12.04.569955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mosquito vectors of pathogens (e.g., Aedes , Anopheles , and Culex spp. which transmit dengue, Zika, chikungunya, West Nile, malaria, and others) are of increasing concern for global public health. These vectors are geographically shifting under climate and other anthropogenic changes. As small-bodied ectotherms, mosquitoes are strongly affected by temperature, which causes unimodal responses in mosquito life history traits (e.g., biting rate, adult mortality rate, mosquito development rate, and probability of egg-to-adult survival) that exhibit upper and lower thermal limits and intermediate thermal optima in laboratory studies. However, it remains unknown how mosquito thermal responses measured in laboratory experiments relate to the realized thermal responses of mosquitoes in the field. To address this gap, we leverage thousands of global mosquito occurrences and geospatial satellite data at high spatial resolution to construct machine-learning based species distribution models, from which vector thermal responses are estimated. We apply methods to restrict models to the relevant mosquito activity season and to conduct ecologically-plausible spatial background sampling centered around ecoregions for comparison to mosquito occurrence records. We found that thermal minima estimated from laboratory studies were highly correlated with those from the species distributions (r = 0.90). The thermal optima were less strongly correlated (r = 0.69). For most species, we did not detect thermal maxima from their observed distributions so were unable to compare to laboratory-based estimates. The results suggest that laboratory studies have the potential to be highly transportable to predicting lower thermal limits and thermal optima of mosquitoes in the field. At the same time, lab-based models likely capture physiological limits on mosquito persistence at high temperatures that are not apparent from field-based observational studies but may critically determine mosquito responses to climate warming.
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Isibor PO, Onwaeze OO, Kayode-Edwards II, Agbontaen DO, Ifebem-Ezima IAM, Bilewu O, Onuselogu C, Akinniyi AP, Obafemi YD, Oniha MI. Investigating and combatting the key drivers of viral zoonoses in Africa: an analysis of eight epidemics. BRAZ J BIOL 2023; 84:e270857. [PMID: 37531478 DOI: 10.1590/1519-6984.270857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 03/02/2023] [Indexed: 08/04/2023] Open
Abstract
Investigating the interplay of factors that result in a viral zoonotic outbreak is difficult, though it is increasingly important. As anthropogenic influences shift the delicate balance of ecosystems, new zoonoses emerge in humans. Sub-Saharan Africa is a notable hotspot for zoonotic disease due to abundant competent mammalian reservoir hosts. Furthermore, poverty, corruption, and an overreliance on natural resources play considerable roles in depleting biological resources, exacerbating the population's susceptibility. Unsurprisingly, viral zoonoses have emerged in Africa, including HIV/AIDS, Ebola, Avian influenza, Lassa fever, Zika, and Monkeypox. These diseases are among the principal causes of death in endemic areas. Though typically distinct in their manifestations, viral zoonoses are connected by underlying, definitive factors. This review summarises vital findings on viral zoonoses in Africa using nine notable case studies as a benchmark for future studies. We discuss the importance of ecological recuperation and protection as a central strategy to control zoonotic diseases. Emphasis was made on moderating key drivers of zoonotic diseases to forestall future pandemics. This is in conjunction with attempts to redirect efforts from reactive to pre-emptive through a multidisciplinary "one health" approach.
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Affiliation(s)
- P O Isibor
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - O O Onwaeze
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - I I Kayode-Edwards
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - D O Agbontaen
- University of South Wales, Department of Public Health, Pontypridd, United Kingdom
| | - I-A M Ifebem-Ezima
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - O Bilewu
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - C Onuselogu
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - A P Akinniyi
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - Y D Obafemi
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
| | - M I Oniha
- Covenant University, Department of Biological Sciences, Ota, Ogun State, Nigeria
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Larvicidal activity of plant extracts from Colombian North Coast against Aedes aegypti L. mosquito larvae. ARAB J CHEM 2022. [DOI: 10.1016/j.arabjc.2022.104365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Eifan S, Hanif A, Nour I, Alqahtani S, Eisa ZM, Dafalla O, Kohl A. Distribution and Molecular Identification of Culex pipiens and Culex tritaeniorhynchus as Potential Vectors of Rift Valley Fever Virus in Jazan, Saudi Arabia. Pathogens 2021; 10:1334. [PMID: 34684282 PMCID: PMC8540973 DOI: 10.3390/pathogens10101334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022] Open
Abstract
Entomologic investigations were conducted in the Al-Darb, Al-Reath, Al-Aridah, Abuareesh, Al-Ahad, Samttah, Sabyah, Damad and Beash areas by CO2-baited CDC miniature light traps in the Jazan region. Vectors were identified morphologically, as well as COI gene segment amplification and sequencing. The relative abundance (RA%) and pattern of occurrence (C%) were recorded. The presence of the Rift Valley fever virus (RVFV) in pooled mosquito samples was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Culex pipiens (C. pipiens) and Culex tritaeniorhynchus (C. tritaeniorhynchus) were found with RA% values of 96% and 4%, respectively, in the region. Significant variations in vector population densities were observed in different districts. The C. pipiens was found highly abundant in all districts and RA% value (100%) was recorded in the Al-Darb, Al-Reath, Al-Aridah, Samttah and Damad areas, whereas RA% values (93.75%, 93.33%, 92.30% and 91.66%) were noted in Al-Ahad, Sabyah, Abuareesh and Beash districts, respectively. RA% values for C. tritaeniorhynchus were recorded as 8.33%, 7.70%, 6.66% and 6.25% in Beash, Abuareesh, Sabyah and Al-Ahad areas, respectively. The pattern of occurrence for C. pipiens and C. tritaeniorhynchus was recorded as 100% and 44.4% in the region. Phylogenetic analysis of C. pipiens and C. tritaeniorhynchus exhibited a close relationship with mosquitoes from Kenya and Turkey, respectively. All mosquito samples tested by RT-PCR were found negative for RVFV. In summary, the current study assessed the composition, abundance, distribution of different mosquito vectors and presence of RVFV in different areas of the Jazan region. Our data will help risk assessments of RVFV future re-emergence in the region.
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Affiliation(s)
- Saleh Eifan
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.H.); (I.N.); (S.A.)
| | - Atif Hanif
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.H.); (I.N.); (S.A.)
| | - Islam Nour
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.H.); (I.N.); (S.A.)
| | - Sultan Alqahtani
- Botany and Microbiology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia; (A.H.); (I.N.); (S.A.)
| | - Zaki M. Eisa
- Saudi Center for Disease Control and Prevention (SCDC), Jazan 82722-2476, Saudi Arabia; (Z.M.E.); (O.D.)
| | - Ommer Dafalla
- Saudi Center for Disease Control and Prevention (SCDC), Jazan 82722-2476, Saudi Arabia; (Z.M.E.); (O.D.)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK;
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Mendoza-Cano O, Rincón-Avalos P, Watson V, Khouakhi A, la Cruz JLD, Ruiz-Montero AP, Nava-Garibaldi CM, Lopez-Rojas M, Murillo-Zamora E. The Burden of Dengue in Children by Calculating Spatial Temperature: A Methodological Approach Using Remote Sensing Techniques. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:4230. [PMID: 33923602 PMCID: PMC8073896 DOI: 10.3390/ijerph18084230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/12/2021] [Accepted: 04/12/2021] [Indexed: 12/02/2022]
Abstract
BACKGROUND Dengue fever is one of the most important arboviral diseases. Surface temperature versus dengue burden in tropical environments can provide valuable information that can be adapted in future measurements to improve health policies. METHODS A methodological approach using Daymet-V3 provided estimates of daily weather parameters. A Python code developed by us extracted the median temperature from the urban regions of Colima State (207.3 km2) in Mexico. JointPoint regression models computed the mean temperature-adjusted average annual percentage of change (AAPC) in disability-adjusted life years (DALY) rates (per 100,000) due to dengue in Colima State among school-aged (5-14 years old) children. RESULTS Primary outcomes were average temperature in urban areas and cumulative dengue burden in DALYs in the school-aged population. A model from 1990 to 2017 medium surface temperature with DALY rates was performed. The increase in DALYs rate was 64% (95% CI, 44-87%), and it seemed to depend on the 2000-2009 estimates (AAPC = 185%, 95% CI 18-588). CONCLUSION From our knowledge, this is the first study to evaluate surface temperature and to model it through an extensive period with health economics calculations in a specific subset of the Latin-American endemic population for dengue epidemics.
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Affiliation(s)
- Oliver Mendoza-Cano
- Facultad de Ingeniería Civil, Universidad de Colima, km. 9 Carretera Colima-Coquimatlán, Col. Jardines del Llano, Coquimatlán 28400, Colima, Mexico; (P.R.-A.); (J.L.-d.l.C.); (A.P.R.-M.); (M.L.-R.)
| | - Pedro Rincón-Avalos
- Facultad de Ingeniería Civil, Universidad de Colima, km. 9 Carretera Colima-Coquimatlán, Col. Jardines del Llano, Coquimatlán 28400, Colima, Mexico; (P.R.-A.); (J.L.-d.l.C.); (A.P.R.-M.); (M.L.-R.)
| | - Verity Watson
- Health Economics Research Unit, University of Aberdeen, Aberdeen AB25 2ZD, UK;
| | - Abdou Khouakhi
- School of Water, Energy and Environment, Centre for Environmental and Agricultural Informatics, Cranfield University, Cranfield MK43 0AL, UK;
| | - Jesús López-de la Cruz
- Facultad de Ingeniería Civil, Universidad de Colima, km. 9 Carretera Colima-Coquimatlán, Col. Jardines del Llano, Coquimatlán 28400, Colima, Mexico; (P.R.-A.); (J.L.-d.l.C.); (A.P.R.-M.); (M.L.-R.)
| | - Angelica Patricia Ruiz-Montero
- Facultad de Ingeniería Civil, Universidad de Colima, km. 9 Carretera Colima-Coquimatlán, Col. Jardines del Llano, Coquimatlán 28400, Colima, Mexico; (P.R.-A.); (J.L.-d.l.C.); (A.P.R.-M.); (M.L.-R.)
| | - Cynthia Monique Nava-Garibaldi
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, 1415 Engineering Dr, Madison, WI 53706, USA;
| | - Mario Lopez-Rojas
- Facultad de Ingeniería Civil, Universidad de Colima, km. 9 Carretera Colima-Coquimatlán, Col. Jardines del Llano, Coquimatlán 28400, Colima, Mexico; (P.R.-A.); (J.L.-d.l.C.); (A.P.R.-M.); (M.L.-R.)
| | - Efrén Murillo-Zamora
- Departamento de Epidemiología, Unidad de Medicina Familiar No. 19, Instituto Mexicano del Seguro Social, Av. Javier Mina 301, Col. Centro, Colima 28000, Colima, Mexico
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Liu B, Gao X, Zheng K, Ma J, Jiao Z, Xiao J, Wang H. The potential distribution and dynamics of important vectors Culex pipiens pallens and Culex pipiens quinquefasciatus in China under climate change scenarios: an ecological niche modelling approach. PEST MANAGEMENT SCIENCE 2020; 76:3096-3107. [PMID: 32281209 DOI: 10.1002/ps.5861] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 03/30/2020] [Accepted: 04/12/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Intense studies have been carried out on the effects of climate change on vector-borne diseases and vectors. Culex pipiens pallens and Culex pipiens quinquefasciatus are two medically concerned mosquito species in temperate and tropical areas, which serve as important disease-transmitting pests of a variety of diseases. The ongoing geographical expansion of these mosquitoes has brought an increasing threat to public health. RESULTS Based on mosquito occurrence records and high-resolution environmental layers, an ecological niche model was established to model their current and future potential distribution in China. Our model showed that the current suitable area for Cx. p. pallens is distributed in the central, eastern and northern parts of China, while Cx. p. quinquefasciatus is distributed in vast areas in southern China. Under future climate change scenarios, both species are predicted to expand their range to varying degrees and RCP 8.5 provides the largest expansion. Northward core shifts will occur in ranges of both species. Environmental variables which have significant impact on the distribution of mosquitoes were also revealed by our model. CONCLUSION Severe habitat expansion of vectors is likely to occur in the future 21st century. Our models mapped the high-risk areas and risk factors which needs to be paid attention. The results of our study can be referenced in further ecological surveys and will guide the development of strategies for the prevention and control of vector-borne diseases. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Boyang Liu
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Xiang Gao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Keren Zheng
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Jun Ma
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Zhihui Jiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Jianhua Xiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
| | - Hongbin Wang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
- Key Laboratory of the Provincial Education Department of Heilongjiang for Common Animal Disease Prevention and Treatment, College of Veterinary Medicine, Northeast Agricultural University, Harbin, P. R. China
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Liu B, Ma J, Jiao Z, Gao X, Xiao J, Wang H. Risk assessment for the Rift Valley fever occurrence in China: Special concern in south-west border areas. Transbound Emerg Dis 2020; 68:445-457. [PMID: 32568445 DOI: 10.1111/tbed.13695] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 04/29/2020] [Accepted: 06/14/2020] [Indexed: 12/29/2022]
Abstract
Rift Valley fever (RVF) is a mosquito-borne zoonotic disease. Since its first outbreak in 1930, RVF epidemics have caused huge economic losses and public health impacts in Africa. In 2000, RVF became a disease of global concern as it spread to the Arabian Peninsula. In our study, a Geographic Information System-based risk assessment for the occurrence of Rift Valley fever in China was established by means of ecological niche modelling. Based on occurrence records (RVF records from FAO EMPRES-i, vector records from literatures and GBIF) and high-resolution environmental layers, the prediction maps of RVF occurrence probability and distribution of five potential RVF vectors in China were modelled using Maxent. An internal validation was adopted for model verification, and high AUC values were obtained (0.918 for RVF and 0.837-0.992 for vectors). By overlaying the RVF prediction map with the combined RVF vector prediction map using Fuzzy overlay tool ('AND' operator) of ArcMap 10.2, we got the first risk map of possible RVF vector transmission. This map was further overlaid with the latest livestock distribution map ('AND' operator) to generate the second risk map of possible RVF threat to domestic livestock. The south-west border provinces in China, Yunnan, Guangxi and Tibet were predicted to have a high possibility of RVF occurrence. Conditions conducive to the local amplification of RVF also exist in these areas. Temperature seasonality, mean temperature of dry season and precipitation of the driest month were considered as key environmental variables for RVF, and common environmental conditions were found conductive for vectors. It is suggested to establish proper surveillance systems in south-west border areas to minimize the possibility of RVF invasion. Our findings can serve as a valuable reference for prevention measures to be implemented.
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Affiliation(s)
- Boyang Liu
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China.,College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Jun Ma
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Zhihui Jiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China.,College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China
| | - Xiang Gao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Jianhua Xiao
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Hongbin Wang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
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Sintayehu DW, Tassie N, De Boer WF. Present and future climatic suitability for dengue fever in Africa. Infect Ecol Epidemiol 2020; 10:1782042. [PMID: 32939230 PMCID: PMC7480615 DOI: 10.1080/20008686.2020.1782042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The number of dengue fever incidence and its distribution has increased considerably in recent years in Africa. However, due to inadequate research at the continental level, there is a limited understanding regarding the current and future spatial distribution of the main vector, the mosquitoAedes aegypti, and the associated dengue risk due to climate change. To fill this gap we used reported dengue fever incidences, the presence of Ae. aegypti, and bioclimatic variables in a species distribution model to assess the current and future (2050 and 2070) climatically suitable areas. High temperatures and with high moisture levels are climatically suitable for the distribution of Ae. aegypti related to dengue fever. Under the current climate scenario indicated that 15.2% of the continent is highly suitable for dengue fever outbreaks. We predict that climatically suitable areas for Ae. aegypti related to dengue fever incidences in eastern, central and western part of Africa will increase in the future and will expand further towards higher elevations. Our projections provide evidence for the changing continental threat of vector-borne diseases and can guide public health policy decisions in Africa to better prepare for and respond to future changes in dengue fever risk.
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Affiliation(s)
- Dejene W Sintayehu
- College of Agriculture and Environmental Sciences, Haramaya University, Dire Dawa, Ethiopia
| | - Nega Tassie
- College of Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| | - Willem F De Boer
- Wildlife Ecology and Conservation Group, Wageningen University, Wageningen, The Netherlands
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Hamid PH, Ninditya VI, Ghiffari A, Taubert A, Hermosilla C. The V1016G mutation of the voltage-gated sodium channel (VGSC) gene contributes to the insecticide resistance of Aedes aegypti from Makassar, Indonesia. Parasitol Res 2020; 119:2075-2083. [PMID: 32458116 DOI: 10.1007/s00436-020-06720-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 05/13/2020] [Indexed: 11/25/2022]
Abstract
Aedes aegypti represents one of the main vectors of at least five relevant arthropod-borne viral infections in humans (i.e., Rift Valley fever, Dengue fever, Zika, chikungunya, and yellow fever) worldwide. Ae. aegypti control strategies are mostly based on using chemical insecticides (i.e., organophosphates, pyrethroids, carbamates, and organochlorines) and reducing larval sources. Furthermore, monitoring the growth activity and mapping the geographical distribution of insecticide resistance are mandatory, as recommended by the WHO. Accordingly, we conducted a study on the possible mechanism by which Ae. aegypti develops resistance to several frequently used chemical insecticides (i.e., λ-cyhalothrin, bendiocarb, cyfluthrin, deltamethrin, malathion, and permethrin) in the city of Makassar, Sulawesi, Indonesia. The results showed the progression of resistance toward the examined insecticides in Ae. aegypti populations in Makassar. The mortality rate of Ae. aegypti was less than 90%, with the highest resistance recorded against 0.75% permethrin. The molecular evaluation of the voltage-gated sodium channel gene (VGSC) showed a significant correlation of the V1016G gene mutation in the tested 0.75% permethrin-resistant Ae. aegypti phenotypes. Nevertheless, the F1534C point mutation in the VGSC gene of Ae. aegypti did not show a significant correlation with the phenotype exhibiting insecticide resistance to 0.75% permethrin. These results indicate that Ae. aegypti mosquitoes in Makassar City have developed resistance against the frequently used insecticide permethrin, which might spread to less-populated regions of Sulawesi. Therefore, we call for further entomological monitoring of insecticide resistance not only on Sulawesi but also on other closely located islands of the Indonesian archipelago to delay the spread of Ae. aegypti insecticide resistance.
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Affiliation(s)
- P H Hamid
- Veterinary Medicine, Universitas Gadjah Mada, Jl. Fauna No. 2, Karangmalang, Yogyakarta, Indonesia.
| | - V I Ninditya
- Veterinary Medicine, Universitas Gadjah Mada, Jl. Fauna No. 2, Karangmalang, Yogyakarta, Indonesia
| | - A Ghiffari
- Faculty of Medicine, Universitas Muhammadiyah Palembang, Palembang, Indonesia
| | - A Taubert
- Institute of Parasitology, Biomedical Research Centre Seltersberg (BFS), Justus Liebig University Giessen, Schubertstr. 81,, 35392, Giessen, Germany
| | - C Hermosilla
- Institute of Parasitology, Biomedical Research Centre Seltersberg (BFS), Justus Liebig University Giessen, Schubertstr. 81,, 35392, Giessen, Germany
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Verster AM, Liang JE, Rostal MK, Kemp A, Brand RF, Anyamba A, Cordel C, Schall R, Zwiegers H, Paweska JT, Karesh WB, van Huyssteen CW. Selected wetland soil properties correlate to Rift Valley fever livestock mortalities reported in 2009-10 in central South Africa. PLoS One 2020; 15:e0232481. [PMID: 32421747 PMCID: PMC7233588 DOI: 10.1371/journal.pone.0232481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 04/15/2020] [Indexed: 11/18/2022] Open
Abstract
Outbreaks of Rift Valley fever have devastating impacts on ruminants, humans, as well as on regional and national economies. Although numerous studies on the impact and outbreak of Rift Valley fever exist, relatively little is known about the role of environmental factors, especially soil, on the aestivation of the virus. This study thus selected 22 sites for study in central South Africa, known to be the recurrent epicenter of widespread Rift Valley fever outbreaks in Southern Africa. Soils were described, sampled and analyzed in detail at each site. Of all the soil variables analyzed for, only eight (cation exchange capacity, exchangeable Ca2+, exchangeable K+, exchangeable Mg2+, soluble Ca2+, medium sand, As, and Br) were statistically identified to be potential indicators of sites with reported Rift Valley fever mortalities, as reported for the 2009–2010 Rift Valley fever outbreak. Four soil characteristics (exchangeable K+, exchangeable Mg2+, medium sand, and Br) were subsequently included in a discriminant function that could potentially be used to predict sites that had reported Rift Valley fever-associated mortalities in livestock. This study therefore constitutes an initial attempt to predict sites prone to Rift Valley fever livestock mortality from soil properties and thus serves as a basis for broader research on the interaction between soil, mosquitoes and Rift Valley fever virus. Future research should include other environmental components such as vegetation, climate, and water properties as well as correlating soil properties with floodwater Aedes spp. abundance and Rift Valley fever virus prevalence.
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Affiliation(s)
- Anna M. Verster
- Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, Republic of South Africa
| | - Janice E. Liang
- EcoHealth Alliance, New York City, New York, United States of America
| | - Melinda K. Rostal
- EcoHealth Alliance, New York City, New York, United States of America
| | - Alan Kemp
- National Institute for Communicable Diseases, Johannesburg, Republic of South Africa
| | - Robert F. Brand
- Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, Republic of South Africa
| | - Assaf Anyamba
- NASA Goddard Space Flight Center, Greenbelt, Maryland, United States of America
- Universities Space Research Association, Columbia, Maryland, United States of America
| | - Claudia Cordel
- ExecuVet Veterinary Clinical and Scientific Consulting, Bloemfontein, Republic of South Africa
| | - Robert Schall
- Department of Mathematical Statistics and Actuarial Sciences, University of the Free State, Bloemfontein, Republic of South Africa
| | - Herman Zwiegers
- Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, Republic of South Africa
| | - Janusz T. Paweska
- National Institute for Communicable Diseases, Johannesburg, Republic of South Africa
| | - William B. Karesh
- EcoHealth Alliance, New York City, New York, United States of America
| | - Cornie W. van Huyssteen
- Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, Republic of South Africa
- * E-mail:
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Saran S, Singh P, Kumar V, Chauhan P. Review of Geospatial Technology for Infectious Disease Surveillance: Use Case on COVID-19. JOURNAL OF THE INDIAN SOCIETY OF REMOTE SENSING 2020; 48. [PMCID: PMC7433774 DOI: 10.1007/s12524-020-01140-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
This paper discusses on the increasing relevancy of geospatial technologies such as geographic information system (GIS) in the public health domain, particularly for the infectious disease surveillance and modelling strategies. Traditionally, the disease mapping tasks have faced many challenges—(1) authors rarely documented the evidence that were used to create map, (2) before evolution of GIS, many errors aroused in mapping tasks which were expanded extremely at global scales, and (3) there were no fidelity assessment of maps which resulted in inaccurate precision. This study on infectious diseases geo-surveillance is divided into four broad sections with emphasis on handling geographical and temporal issues to help in public health decision-making and planning policies: (1) geospatial mapping of diseases using its spatial and temporal information to understand their behaviour across geography; (2) the citizen’s involvement as volunteers in giving health and disease data to assess the critical situation for disease’s spread and prevention in neighbourhood effect; (3) scientific analysis of health-related behaviour using mathematical epidemiological and geo-statistical approaches with (4) capacity building program. To illustrate each theme, recent case studies are cited and case studies are performed on COVID-19 to demonstrate selected models.
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Affiliation(s)
- Sameer Saran
- Indian Institute of Remote Sensing, Indian Space Research Organisation, #4, Kalidas Road, Dehradun, 248001 India
| | - Priyanka Singh
- Indian Institute of Remote Sensing, Indian Space Research Organisation, #4, Kalidas Road, Dehradun, 248001 India
| | - Vishal Kumar
- Indian Institute of Remote Sensing, Indian Space Research Organisation, #4, Kalidas Road, Dehradun, 248001 India
| | - Prakash Chauhan
- Indian Institute of Remote Sensing, Indian Space Research Organisation, #4, Kalidas Road, Dehradun, 248001 India
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Ciss M, Biteye B, Fall AG, Fall M, Gahn MCB, Leroux L, Apolloni A. Ecological niche modelling to estimate the distribution of Culicoides, potential vectors of bluetongue virus in Senegal. BMC Ecol 2019; 19:45. [PMID: 31676006 PMCID: PMC6825335 DOI: 10.1186/s12898-019-0261-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 10/14/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vector-borne diseases are among the leading causes of morbidity and mortality in humans and animals. In the Afrotropical region, some are transmitted by Culicoides, such as Akabane, bluetongue, epizootic haemorrhagic fever and African horse sickness viruses. Bluetongue virus infection has an enormous impact on ruminant production, due to its high morbidity and mortality rates. METHODS A nationwide Culicoides trapping campaign was organized at the end of the 2012 rainy season in Senegal. A Maximum Entropy approach (MaxEnt), Boosted Regression Tree (BRT) method and Ecological Niche Factor Analysis (ENFA) were used to develop a predictive spatial model for the distribution of Culicoides, using bio-climatic variables, livestock densities and altitude. RESULTS The altitude, maximum temperature of the warmest month, precipitation of the warmest quarter, mean temperature of the wettest quarter, temperature seasonality, precipitation of the wettest quarter and livestock density were among the most important factors to predict suitable habitats of Culicoides. Culicoides occurrences were, in most of the cases, positively correlated to precipitation variables and livestock densities; and negatively correlated to the altitude and temperature indices. The Niayes area and the Groundnut basin were the most suitable habitats predicted. CONCLUSION We present ecological niche models for different Culicoides species, namely C. imicola, C. oxystoma, C. enderleini and C. miombo, potential vectors of bluetongue virus, on a nationwide scale in Senegal. Through our modelling approach, we were able to determine the effect of bioclimatic variables on Culicoides habitats and were able to generate maps for the occurrence of Culicoides species. This information will be helpful in developing risk maps for disease outbreaks.
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Affiliation(s)
- Mamadou Ciss
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Biram Biteye
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Assane Gueye Fall
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Moussa Fall
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
| | - Marie Cicille Ba Gahn
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
- Laboratoire d’Ecologie Vectorielle et Parasitaire, Département de Biologie Animale, Faculté des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Senegal
| | - Louise Leroux
- CIRAD, UPR AIDA, Dakar, Senegal
- AIDA, Univ Montpellier, CIRAD, Montpellier, France
| | - Andrea Apolloni
- Institut Sénégalais de Recherches Agricoles/Laboratoire National de l’Elevage et de Recherches Vétérinaires, BP 2057, Dakar-Hann, Senegal
- AIDA, Univ Montpellier, CIRAD, Montpellier, France
- CIRAD, UMR ASTRE, 34398 Montpellier, France
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Tshilenge GM, Mulumba MLK, Misinzo G, Noad R, Dundon WG. Rift Valley fever virus in small ruminants in the Democratic Republic of the Congo. ACTA ACUST UNITED AC 2019; 86:e1-e5. [PMID: 31714136 PMCID: PMC6852419 DOI: 10.4102/ojvr.v86i1.1737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 05/02/2019] [Accepted: 05/07/2019] [Indexed: 11/01/2022]
Abstract
Rift Valley fever (RVF) is a zoonotic viral disease caused by the RVF phlebovirus (RVFV) that infects a variety of animal species including sheep and goats. Sera (n = 893) collected between 2013 and 2015 from randomly selected indigenous sheep and goats in seven provinces of the Democratic Republic of the Congo (DRC) were tested for the presence of specific immunoglobulin G (IgG) and M (IgM) against RVFV, using two commercially available enzyme-linked immunosorbent assays. The reverse transcription polymerase chain reaction (RT-PCR) was also used to detect RVFV nucleic acid. There was significant variation in true seroprevalence of RVFV for both sheep and goats between the seven provinces investigated. Values ranged from 0.0 (95% confidence interval [CI] 0.0-6.55) to 23.81 (95% CI 12.03-41.76) for goat and 0.0 (95% CI 0.0-7.56) to 37.11 (95% CI 15.48-65.94) for sheep, respectively. One serum (1.85%) out of 54 that tested positive for IgG was found to be IgM-positive. This same sample was also positive by RT-PCR indicating an active or recent infection. These findings report the presence of RVFV in small ruminants in the DRC for the first time and indicate variations in exposure to the virus in different parts of the country.
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Affiliation(s)
- Georges M Tshilenge
- Department of Preclinical Medicine, Faculty of Veterinary Medicine, University of Kinshasa, Kinshasa XI.
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Matowo NS, Abbasi S, Munhenga G, Tanner M, Mapua SA, Oullo D, Koekemoer LL, Kaindoa E, Ngowo HS, Coetzee M, Utzinger J, Okumu FO. Fine-scale spatial and temporal variations in insecticide resistance in Culex pipiens complex mosquitoes in rural south-eastern Tanzania. Parasit Vectors 2019; 12:413. [PMID: 31443737 PMCID: PMC6708135 DOI: 10.1186/s13071-019-3676-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/19/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Culex mosquitoes cause considerable biting nuisance and sporadic transmission of arboviral and filarial diseases. METHODS Using standard World Health Organization procedures, insecticide resistance profiles and underlying mechanisms were investigated during dry and wet seasons of 2015 and 2016 in Culex pipiens complex from three neighbouring administrative wards in Ulanga District, Tanzania. Synergist tests with piperonyl butoxide, diethyl maleate, and triphenyl phosphate, were employed to investigate mechanisms of the observed resistance phenotypes. Proportional biting densities of Culex species, relative to other taxa, were determined from indoor surveillance data collected in 2012, 2013, and 2015. RESULTS Insecticide resistance varied significantly between wards and seasons. For example, female mosquitoes in one ward were susceptible to bendiocarb and fenitrothion in the wet season, but resistant during the dry season, while in neighbouring ward, the mosquitoes were fully susceptible to these pesticides in both seasons. Similar variations occurred against bendiocarb, DDT, deltamethrin, and lambda-cyhalothrin. Surprisingly, with the exception of one ward in the wet season, the Culex populations were susceptible to permethrin, commonly used on bednets in the area. No insecticide resistance was observed against the organophosphates, pirimiphos-methyl and malathion, except for one incident of reduced susceptibility in the dry season. Synergist assays revealed possible involvement of monooxygenases, esterases, and glutathione S-transferase in pyrethroid and DDT resistance. Morphology-based identification and molecular assays of adult Culex revealed that 94% were Cx. pipiens complex, of which 81% were Cx. quinquefasciatus, 2% Cx. pipiens, and 3% hybrids. About 14% of the specimens were non-amplified during molecular identifications. Female adults collected indoors were 100% Cx. pipiens complex, and constituted 79% of the overall biting risk. CONCLUSIONS The Cx. pipiens complex constituted the greatest biting nuisance inside people's houses, and showed resistance to most public health insecticides possible. Resistance varied at a fine geographical scale, between adjacent wards, and seasons, which warrants some modifications to current insecticide resistance monitoring strategies. Resistance phenotypes are partly mediated by metabolic mechanisms, but require further evaluation through biochemical and molecular techniques. The high densities and resistance in Culex could negatively influence the acceptability of other interventions such as those used against malaria mosquitoes.
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Affiliation(s)
- Nancy S. Matowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Givemore Munhenga
- Wits Research Institute for Malaria, Wits/SAMRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Salum A. Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - David Oullo
- US Army Medical Research Directorate-Africa, Kisumu, Kenya
| | - Lizette L. Koekemoer
- Wits Research Institute for Malaria, Wits/SAMRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Emanuel Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Halfan S. Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Maureen Coetzee
- Wits Research Institute for Malaria, Wits/SAMRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Fredros O. Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Jácome G, Vilela P, Yoo C. Present and future incidence of dengue fever in Ecuador nationwide and coast region scale using species distribution modeling for climate variability’s effect. Ecol Modell 2019. [DOI: 10.1016/j.ecolmodel.2019.03.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Leta S, Beyene TJ, De Clercq EM, Amenu K, Kraemer MUG, Revie CW. Global risk mapping for major diseases transmitted by Aedes aegypti and Aedes albopictus. Int J Infect Dis 2017; 67:25-35. [PMID: 29196275 DOI: 10.1016/j.ijid.2017.11.026] [Citation(s) in RCA: 242] [Impact Index Per Article: 34.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/21/2017] [Accepted: 11/23/2017] [Indexed: 11/29/2022] Open
Abstract
OBJECTIVES The objective of this study was to map the global risk of the major arboviral diseases transmitted by Aedes aegypti and Aedes albopictus by identifying areas where the diseases are reported, either through active transmission or travel-related outbreaks, as well as areas where the diseases are not currently reported but are nonetheless suitable for the vector. METHODS Data relating to five arboviral diseases (Zika, dengue fever, chikungunya, yellow fever, and Rift Valley fever (RVF)) were extracted from some of the largest contemporary databases and paired with data on the known distribution of their vectors, A. aegypti and A. albopictus. The disease occurrence data for the selected diseases were compiled from literature dating as far back as 1952 to as recent as 2017. The resulting datasets were aggregated at the country level, except in the case of the USA, where state-level data were used. Spatial analysis was used to process the data and to develop risk maps. RESULTS Out of the 250 countries/territories considered, 215 (86%) are potentially suitable for the survival and establishment of A. aegypti and/or A. albopictus. A. albopictus has suitability foci in 197 countries/territories, while there are 188 that are suitable for A. aegypti. There is considerable variation in the suitability range among countries/territories, but many of the tropical regions of the world provide high suitability over extensive areas. Globally, 146 (58.4%) countries/territories reported at least one arboviral disease, while 123 (49.2%) reported more than one of the above diseases. The overall numbers of countries/territories reporting autochthonous vector-borne occurrences of Zika, dengue, chikungunya, yellow fever, and RVF, were 85, 111, 106, 43, and 39, respectively. CONCLUSIONS With 215 countries/territories potentially suitable for the most important arboviral disease vectors and more than half of these reporting cases, arboviral diseases are indeed a global public health threat. The increasing proportion of reports that include multiple arboviral diseases highlights the expanding range of their common transmission vectors. The shared features of these arboviral diseases should motivate efforts to combine interventions against these diseases.
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Affiliation(s)
- Samson Leta
- Addis Ababa University, College of Veterinary Medicine, PO Box 34, Bishoftu, Ethiopia.
| | - Tariku Jibat Beyene
- Addis Ababa University, College of Veterinary Medicine, PO Box 34, Bishoftu, Ethiopia
| | - Eva M De Clercq
- Research Fellow FNRS, George Lemaître Institute for Earth and Climate Research, Université Catholique de Louvain, Place Louis Pasteur 3, 1348 Louvain-la-Neuve, Belgium
| | - Kebede Amenu
- Addis Ababa University, College of Veterinary Medicine, PO Box 34, Bishoftu, Ethiopia
| | - Moritz U G Kraemer
- Harvard Medical School, Boston, United States; Computational Epidemiology Lab, Boston Children's Hospital, Boston, United States; Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Crawford W Revie
- University of Prince Edward Island, Department of Health Management, Charlottetown, Canada
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Nyakarahuka L, Ayebare S, Mosomtai G, Kankya C, Lutwama J, Mwiine FN, Skjerve E. Ecological Niche Modeling for Filoviruses: A Risk Map for Ebola and Marburg Virus Disease Outbreaks in Uganda. PLOS CURRENTS 2017; 9:ecurrents.outbreaks.07992a87522e1f229c7cb023270a2af1. [PMID: 29034123 PMCID: PMC5614672 DOI: 10.1371/currents.outbreaks.07992a87522e1f229c7cb023270a2af1] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Uganda has reported eight outbreaks caused by filoviruses between 2000 to 2016, more than any other country in the world. We used species distribution modeling to predict where filovirus outbreaks are likely to occur in Uganda to help in epidemic preparedness and surveillance. METHODS The MaxEnt software, a machine learning modeling approach that uses presence-only data was used to establish filovirus - environmental relationships. Presence-only data for filovirus outbreaks were collected from the field and online sources. Environmental covariates from Africlim that have been downscaled to a nominal resolution of 1km x 1km were used. The final model gave the relative probability of the presence of filoviruses in the study area obtained from an average of 100 bootstrap runs. Model evaluation was carried out using Receiver Operating Characteristic (ROC) plots. Maps were created using ArcGIS 10.3 mapping software. RESULTS We showed that bats as potential reservoirs of filoviruses are distributed all over Uganda. Potential outbreak areas for Ebola and Marburg virus disease were predicted in West, Southwest and Central parts of Uganda, which corresponds to bat distribution and previous filovirus outbreaks areas. Additionally, the models predicted the Eastern Uganda region and other areas that have not reported outbreaks before to be potential outbreak hotspots. Rainfall variables were the most important in influencing model prediction compared to temperature variables. CONCLUSIONS Despite the limitations in the prediction model due to lack of adequate sample records for outbreaks, especially for the Marburg cases, the models provided risk maps to the Uganda surveillance system on filovirus outbreaks. The risk maps will aid in identifying areas to focus the filovirus surveillance for early detection and responses hence curtailing a pandemic. The results from this study also confirm previous findings that suggest that filoviruses are mainly limited by the amount of rainfall received in an area.
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Affiliation(s)
- Luke Nyakarahuka
- 1) Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway; 2) Department of Biosecurity, Ecosystems and Veterinary Public Health, Makerere University, Kampala Uganda; 3) Department of Arbovirology, Emerging and Re-Emerging disease, Uganda Virus Research Institute, Entebbe, Uganda
| | - Samuel Ayebare
- Climate Change and Biodiversity Unit, Wildlife Conservation Society, Bronx, New York, United States of America
| | - Gladys Mosomtai
- Earth Observation Unit, International Centre for Insect Physiology and Ecology, Nairobi, Kenya
| | - Clovice Kankya
- Department of Biosecurity, Ecosystems and Veterinary Public Health, Makerere University, Kampala, Uganda
| | - Julius Lutwama
- Department of Arbovirology, Emerging and Re-Emerging diseases, Uganda Virus Research Institute, Entebbe, Uganda
| | - Frank Norbert Mwiine
- Department of Biomolecular Resources and Biolab Sciences, Makerere University, Kampala, Uganda
| | - Eystein Skjerve
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
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Mweya CN, Mboera LEG, Kimera SI. Climate Influence on Emerging Risk Areas for Rift Valley Fever Epidemics in Tanzania. Am J Trop Med Hyg 2017; 97:109-114. [PMID: 28719317 DOI: 10.4269/ajtmh.16-0444] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Rift Valley Fever (RVF) is a climate-related arboviral infection of animals and humans. Climate is thought to represent a threat toward emerging risk areas for RVF epidemics globally. The objective of this study was to evaluate influence of climate on distribution of suitable breeding habitats for Culex pipiens complex, potential mosquito vector responsible for transmission and distribution of disease epidemics risk areas in Tanzania. We used ecological niche models to estimate potential distribution of disease risk areas based on vectors and disease co-occurrence data approach. Climatic variables for the current and future scenarios were used as model inputs. Changes in mosquito vectors' habitat suitability in relation to disease risk areas were estimated. We used partial receiver operating characteristic and the area under the curves approach to evaluate model predictive performance and significance. Habitat suitability for Cx. pipiens complex indicated broad-scale potential for change and shift in the distribution of the vectors and disease for both 2020 and 2050 climatic scenarios. Risk areas indicated more intensification in the areas surrounding Lake Victoria and northeastern part of the country through 2050 climate scenario. Models show higher probability of emerging risk areas spreading toward the western parts of Tanzania from northeastern areas and decrease in the southern part of the country. Results presented here identified sites for consideration to guide surveillance and control interventions to reduce risk of RVF disease epidemics in Tanzania. A collaborative approach is recommended to develop and adapt climate-related disease control and prevention strategies.
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Affiliation(s)
- Clement N Mweya
- Tukuyu Research Centre, National Institute for Medical Research, Tukuyu, Tanzania
| | - Leonard E G Mboera
- Headquarters, National Institute for Medical Research, Dar es salaam, Tanzania
| | - Sharadhuli I Kimera
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
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Ward T, Samuel M, Maoz D, Runge-Ranzinger S, Boyce R, Toledo J, Velayudhan R, Horstick O. Dengue data and surveillance in Tanzania: a systematic literature review. Trop Med Int Health 2017; 22:960-970. [PMID: 28556417 DOI: 10.1111/tmi.12903] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Although there is evidence that dengue virus is circulating in Tanzania, the country lacks a dengue surveillance system. Consequently, the true estimate of dengue seroprevalence, as well as the incidence in the population, the frequency and magnitude of outbreaks is unknown. This study therefore sought to systematically review available dengue data from Tanzania. METHODS The systematic review was conducted and reported using the PRISMA tool. Five databases (PubMed, Embase, Web of Science, WHOLIS and Google Scholar) were searched for articles using various keywords on the illness, data and geographical location. Identified articles were assessed for inclusion based on predefined eligibility criteria. Data were extracted from included articles, analysed and reported. RESULTS Based on the 10 seroprevalence studies in defined populations with estimates of acute confirmed infections that were included in the review, the estimated seroprevalence of past dengue infection in Tanzania ranged from 50.6% in a health facility-based study to 11% in a population-based study. Acute confirmed infections of dengue were estimated to be as high as 38.2% of suspected cases. Only one study reported on an outbreak. CONCLUSIONS It is evident that dengue needs to become part of regular disease surveillance in Tanzania. Control measures need to be instituted with a focus on building human resource capacity and integrating dengue control measures in ongoing health programmes, for both preventive and curative interventions. Systematic reviews are valuable in assessing health issues when surveillance data are not available.
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Affiliation(s)
- Tara Ward
- London School of Hygiene and Tropical Medicine, London, UK
| | - Moody Samuel
- Teaching Unit of the Institute of Public Health, University of Heidelberg, Heidelberg, Germany
| | - Dorit Maoz
- Department of Public Health, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland
| | - Silvia Runge-Ranzinger
- Teaching Unit of the Institute of Public Health, University of Heidelberg, Heidelberg, Germany.,Consultant in Public Health, Ludwigsburg, Germany
| | - Ross Boyce
- Division of Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Joao Toledo
- Public Health Specialist, Ministry of Health, Brasilia, Brazil
| | - Raman Velayudhan
- Department for the Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Olaf Horstick
- Teaching Unit of the Institute of Public Health, University of Heidelberg, Heidelberg, Germany
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Morales NS, Fernández IC, Baca-González V. MaxEnt's parameter configuration and small samples: are we paying attention to recommendations? A systematic review. PeerJ 2017; 5:e3093. [PMID: 28316894 PMCID: PMC5354112 DOI: 10.7717/peerj.3093] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 02/14/2017] [Indexed: 11/25/2022] Open
Abstract
Environmental niche modeling (ENM) is commonly used to develop probabilistic maps of species distribution. Among available ENM techniques, MaxEnt has become one of the most popular tools for modeling species distribution, with hundreds of peer-reviewed articles published each year. MaxEnt's popularity is mainly due to the use of a graphical interface and automatic parameter configuration capabilities. However, recent studies have shown that using the default automatic configuration may not be always appropriate because it can produce non-optimal models; particularly when dealing with a small number of species presence points. Thus, the recommendation is to evaluate the best potential combination of parameters (feature classes and regularization multiplier) to select the most appropriate model. In this work we reviewed 244 articles published between 2013 and 2015 to assess whether researchers are following recommendations to avoid using the default parameter configuration when dealing with small sample sizes, or if they are using MaxEnt as a "black box tool." Our results show that in only 16% of analyzed articles authors evaluated best feature classes, in 6.9% evaluated best regularization multipliers, and in a meager 3.7% evaluated simultaneously both parameters before producing the definitive distribution model. We analyzed 20 articles to quantify the potential differences in resulting outputs when using software default parameters instead of the alternative best model. Results from our analysis reveal important differences between the use of default parameters and the best model approach, especially in the total area identified as suitable for the assessed species and the specific areas that are identified as suitable by both modelling approaches. These results are worrying, because publications are potentially reporting over-complex or over-simplistic models that can undermine the applicability of their results. Of particular importance are studies used to inform policy making. Therefore, researchers, practitioners, reviewers and editors need to be very judicious when dealing with MaxEnt, particularly when the modelling process is based on small sample sizes.
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Affiliation(s)
- Narkis S. Morales
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, New South Wales, Australia
- Fundación Ecomabi, Santiago, Región Metropolitana, Chile
| | - Ignacio C. Fernández
- Fundación Ecomabi, Santiago, Región Metropolitana, Chile
- Landscape Ecology & Sustainability Laboratory, Arizona State University, Tempe, AZ, United States
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Ochieng AO, Nanyingi M, Kipruto E, Ondiba IM, Amimo FA, Oludhe C, Olago DO, Nyamongo IK, Estambale BBA. Ecological niche modelling of Rift Valley fever virus vectors in Baringo, Kenya. Infect Ecol Epidemiol 2016; 6:32322. [PMID: 27863533 PMCID: PMC5116061 DOI: 10.3402/iee.v6.32322] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 10/19/2016] [Accepted: 10/20/2016] [Indexed: 11/14/2022] Open
Abstract
Background Rift Valley fever (RVF) is a vector-borne zoonotic disease that has an impact on human health and animal productivity. Here, we explore the use of vector presence modelling to predict the distribution of RVF vector species under climate change scenario to demonstrate the potential for geographic spread of Rift Valley fever virus (RVFV). Objectives To evaluate the effect of climate change on RVF vector distribution in Baringo County, Kenya, with an aim of developing a risk map for spatial prediction of RVF outbreaks. Methodology The study used data on vector presence and ecological niche modelling (MaxEnt) algorithm to predict the effect of climatic change on habitat suitability and the spatial distribution of RVF vectors in Baringo County. Data on species occurrence were obtained from longitudinal sampling of adult mosquitoes and larvae in the study area. We used present (2000) and future (2050) Bioclim climate databases to model the vector distribution. Results Model results predicted potential suitable areas with high success rates for Culex quinquefasciatus, Culex univitattus, Mansonia africana, and Mansonia uniformis. Under the present climatic conditions, the lowlands were found to be highly suitable for all the species. Future climatic conditions indicate an increase in the spatial distribution of Cx. quinquefasciatus and M. africana. Model performance was statistically significant. Conclusion Soil types, precipitation in the driest quarter, precipitation seasonality, and isothermality showed the highest predictive potential for the four species.
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Affiliation(s)
- Alfred O Ochieng
- Department of Biological Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Mark Nanyingi
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.,Department of Public Health, Pharmacology and Toxicology, University of Nairobi, Nairobi, Kenya;
| | - Edwin Kipruto
- Division of Research Innovation and Outreach, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | - Isabella M Ondiba
- School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Fred A Amimo
- School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
| | | | - Daniel O Olago
- Department of Geology, University of Nairobi, Nairobi, Kenya
| | - Isaac K Nyamongo
- Institute of Anthropology, Gender and African Studies, University of Nairobi, Nairobi, Kenya
| | - Benson B A Estambale
- Division of Research Innovation and Outreach, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya
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Climate Change Influences Potential Distribution of Infected Aedes aegypti Co-Occurrence with Dengue Epidemics Risk Areas in Tanzania. PLoS One 2016; 11:e0162649. [PMID: 27681327 PMCID: PMC5040426 DOI: 10.1371/journal.pone.0162649] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 08/28/2016] [Indexed: 12/19/2022] Open
Abstract
Background Dengue is the second most important vector-borne disease of humans globally after malaria. Incidence of dengue infections has dramatically increased recently, potentially due to changing climate. Climate projections models predict increases in average annual temperature, precipitation and extreme events in the future. The objective of this study was to assess the effect of changing climate on distribution of dengue vectors in relation to epidemic risk areas in Tanzania. Methods/Findings We used ecological niche models that incorporated presence-only infected Aedes aegypti data co-occurrence with dengue virus to estimate potential distribution of epidemic risk areas. Model input data on infected Ae. aegypti was collected during the May to June 2014 epidemic in Dar es Salaam. Bioclimatic predictors for current and future projections were also used as model inputs. Model predictions indicated that habitat suitability for infected Ae. aegypti co-occurrence with dengue virus in current scenarios is highly localized in the coastal areas, including Dar es Salaam, Pwani, Morogoro, Tanga and Zanzibar. Models indicate that areas of Kigoma, Ruvuma, Lindi, and those around Lake Victoria are also at risk. Projecting to 2020, we show that risk emerges in Mara, Arusha, Kagera and Manyara regions, but disappears in parts of Morogoro, Ruvuma and near Lake Nyasa. In 2050 climate scenario, the predicted habitat suitability of infected Ae. aegypti co-occurrence with dengue shifted towards the central and north-eastern parts with intensification in areas around all major lakes. Generally, model findings indicated that the coastal regions would remain at high risk for dengue epidemic through 2050. Conclusion/Significance Models incorporating climate change scenarios to predict emerging risk areas for dengue epidemics in Tanzania show that the anticipated risk is immense and results help guiding public health policy decisions on surveillance and control of dengue epidemics. A collaborative approach is recommended to develop and adapt control and prevention strategies.
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Sindato C, Stevens KB, Karimuribo ED, Mboera LEG, Paweska JT, Pfeiffer DU. Spatial Heterogeneity of Habitat Suitability for Rift Valley Fever Occurrence in Tanzania: An Ecological Niche Modelling Approach. PLoS Negl Trop Dis 2016; 10:e0005002. [PMID: 27654268 PMCID: PMC5031441 DOI: 10.1371/journal.pntd.0005002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 08/24/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Despite the long history of Rift Valley fever (RVF) in Tanzania, extent of its suitable habitat in the country remains unclear. In this study we investigated potential effects of temperature, precipitation, elevation, soil type, livestock density, rainfall pattern, proximity to wild animals, protected areas and forest on the habitat suitability for RVF occurrence in Tanzania. MATERIALS AND METHODS Presence-only records of 193 RVF outbreak locations from 1930 to 2007 together with potential predictor variables were used to model and map the suitable habitats for RVF occurrence using ecological niche modelling. Ground-truthing of the model outputs was conducted by comparing the levels of RVF virus specific antibodies in cattle, sheep and goats sampled from locations in Tanzania that presented different predicted habitat suitability values. PRINCIPAL FINDINGS Habitat suitability values for RVF occurrence were higher in the northern and central-eastern regions of Tanzania than the rest of the regions in the country. Soil type and precipitation of the wettest quarter contributed equally to habitat suitability (32.4% each), followed by livestock density (25.9%) and rainfall pattern (9.3%). Ground-truthing of model outputs revealed that the odds of an animal being seropositive for RVFV when sampled from areas predicted to be most suitable for RVF occurrence were twice the odds of an animal sampled from areas least suitable for RVF occurrence (95% CI: 1.43, 2.76, p < 0.001). CONCLUSION/SIGNIFICANCE The regions in the northern and central-eastern Tanzania were more suitable for RVF occurrence than the rest of the regions in the country. The modelled suitable habitat is characterised by impermeable soils, moderate precipitation in the wettest quarter, high livestock density and a bimodal rainfall pattern. The findings of this study should provide guidance for the design of appropriate RVF surveillance, prevention and control strategies which target areas with these characteristics.
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Affiliation(s)
- Calvin Sindato
- National Institute for Medical Research, Tabora, Tanzania
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Southern African Centre for Infectious Disease Surveillance, Morogoro, Tanzania
- * E-mail:
| | - Kim B. Stevens
- Veterinary Epidemiology, Economics & Public Health Group, Department of Production & Population Health, Royal Veterinary College, London, United Kingdom
| | - Esron D. Karimuribo
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
- Southern African Centre for Infectious Disease Surveillance, Morogoro, Tanzania
| | | | - Janusz T. Paweska
- Center for Emerging and Zoonotic Diseases, National Institute for Communicable Diseases, of the National Health Laboratory Service, Sandringham, South Africa
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Dirk U. Pfeiffer
- Veterinary Epidemiology, Economics & Public Health Group, Department of Production & Population Health, Royal Veterinary College, London, United Kingdom
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DOOSTI S, YAGHOOBI-ERSHADI MR, SCHAFFNER F, MOOSA-KAZEMI SH, AKBARZADEH K, GOOYA MM, VATANDOOST H, SHIRZADI MR, MOSTA-FAVI E. Mosquito Surveillance and the First Record of the Invasive Mosquito Species Aedes ( Stegomyia) albopictus (Skuse) (Diptera: Culicidae) in Southern Iran. IRANIAN JOURNAL OF PUBLIC HEALTH 2016; 45:1064-1073. [PMID: 27928533 PMCID: PMC5139964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Epidemics of mosquito-borne viral infections such as dengue, chikungunya, West Nile and Rift Valley fevers in neighbouring countries and risk of introduction of exotic vectors into Iran have placed this country at a significant risk for these mosquito-borne diseases. METHODS After the first dengue case reported in Iran in 2008, active entomological surveillance of Aedes albopictus (Skuse) and Ae. aegypti (Linnaeus) were conducted in May/Jun, Sep, and Oct/Nov, 2008-2014. Based on occurrence of dengue cases and the presence of potential entry sides including ports and boarder gates, 121 sites in eight provinces were monitored for mosquito vectors. Larval collections were carried out using droppers or dippers and adult collections with CDC light traps, human landing catches, aspirator and Pyrethrum spray space catches. RESULTS A total of 8,186 larvae and 3,734 adult mosquitoes were collected belonging to 23 Culicinae species, including 13 of the genus Culex, 1 Culiseta, 1 Uranotaenia, and 8 of the genus Aedes. Five Aedes albopictus larvae were identified from the Sistan & Baluchestan province bordering Pakistan in 2009. In 2013, seven Ae. albopictus adult mosquitoes were also collected in a coastal locality near the city of Chabahar in the same province. CONCLUSION The detection of larvae and adults of this species in different parts of this province reveal its probable establishment in southeast Iran, which has implications for public health and requires active entomological surveillance as well as the implementation of vector control to prevent the further spread of this critical vector.
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Affiliation(s)
- Sara DOOSTI
- Dept. of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza YAGHOOBI-ERSHADI
- Dept. of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Corresponding Author:
| | - Francis SCHAFFNER
- National Center for Vector Entomology, Institute of Parasitology, University of Zurich, Zurich, Switzerland
| | - Seyed Hassan MOOSA-KAZEMI
- Dept. of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Kamran AKBARZADEH
- Dept. of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi GOOYA
- Communicable Disease Control Centre, Ministry of Health and Medical Education, Tehran, Iran
| | - Hassan VATANDOOST
- Dept. of Medical Entomology and Vector Control, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza SHIRZADI
- Communicable Disease Control Centre, Ministry of Health and Medical Education, Tehran, Iran
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Arsevska E, Hellal J, Mejri S, Hammami S, Marianneau P, Calavas D, Hénaux V. Identifying Areas Suitable for the Occurrence of Rift Valley Fever in North Africa: Implications for Surveillance. Transbound Emerg Dis 2015; 63:658-674. [PMID: 25655790 DOI: 10.1111/tbed.12331] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Indexed: 12/01/2022]
Abstract
Rift Valley fever (RVF) is a vector-borne zoonotic disease that has caused widespread outbreaks throughout Africa and the Arabian Peninsula, with serious consequences for livestock-based economies and public health. Although there have never been any reports of RVF in Morocco, Algeria, Tunisia and Libya, it is a priority disease in the Maghreb, due to the threat of introduction of the virus through transboundary livestock movements or infected mosquito vectors. However, the implementation of surveillance activities and early warning contingency plans requires better knowledge of the epidemiological situation. We conducted a multicriteria decision analysis, integrating host distribution with a combination of important ecological factors that drive mosquito abundance, to identify hotspots and suitable time periods for RVF enzootic circulation (i.e. stable transmission at a low to moderate level for an extended period of time) and an RVF epizootic event (i.e. a sudden occurrence of a large number of infected animals over a large geographic area) in the Maghreb. We also modelled vector species distribution using available information on vector presence and habitat preference. We found that the northern regions of the Maghreb were moderately suitable for RVF enzootics, but highly suitable for RVF epizootics. The vector species distribution model identified these regions as the most favourable mosquito habitats. Due to the low density of animal hosts and arid conditions, the desert region showed low RVF suitability, except in oases. However, the presence of competent vectors in putative unsuitable areas underlines the need for further assessments of mosquito habitat preference. This study produced monthly RVF suitability maps useful for animal health managers and veterinary services involved in designing risk-based surveillance programmes. The suitability maps can be further enhanced using existing country-specific sources of information and by incorporating knowledge - as it becomes available - on the epidemiology of the disease and distribution of vectors in the Maghreb.
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Affiliation(s)
- E Arsevska
- Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France
| | - J Hellal
- Institut de Recherche Vétérinaire de Tunisie (IRVT), Tunis, Tunisie
| | - S Mejri
- Institut de Recherche Vétérinaire de Tunisie (IRVT), Tunis, Tunisie
| | - S Hammami
- Centre Nationale de Veille Zoosanitaire (CNVZ), Tunis, Tunisie
| | - P Marianneau
- Unité Virologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France
| | - D Calavas
- Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France
| | - V Hénaux
- Unité Epidémiologie, Laboratoire de Lyon, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Lyon, France.
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Mweya CN, Kimera SI, Mellau LSB, Mboera LEG. Inter-epidemic abundance and distribution of potential mosquito vectors for Rift Valley fever virus in Ngorongoro district, Tanzania. Glob Health Action 2015; 8:25929. [PMID: 25613346 PMCID: PMC4303619 DOI: 10.3402/gha.v8.25929] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 12/05/2014] [Accepted: 12/21/2014] [Indexed: 11/29/2022] Open
Abstract
Background Rift Valley fever (RVF) is a mosquito-borne viral zoonosis that primarily affects ruminants but also has the capacity to infect humans. Objective To determine the abundance and distribution of mosquito vectors in relation to their potential role in the virus transmission and maintenance in disease epidemic areas of Ngorongoro district in northern Tanzania. Methods A cross-sectional entomological investigation was carried out before the suspected RVF outbreak in October 2012. Mosquitoes were sampled both outdoors and indoors using the Centre for Disease Control (CDC) light traps and Mosquito Magnets baited with attractants. Outdoor traps were placed in proximity with breeding sites and under canopy in banana plantations close to the sleeping places of animals. Results A total of 1,823 mosquitoes were collected, of which 87% (N=1,588) were Culex pipiens complex, 12% (N=226) Aedes aegypti, and 0.5% (N=9) Anopheles species. About two-thirds (67%; N=1,095) of C. pipiens complex and nearly 100% (N=225) of A. aegypti were trapped outdoors using Mosquito Magnets. All Anopheles species were trapped indoors using CDC light traps. There were variations in abundance of C. pipiens complex and A. aegypti among different ecological and vegetation habitats. Over three quarters (78%) of C. pipiens complex and most (85%) of the A. aegypti were trapped in banana and maize farms. Both C. pipiens complex and A. aegypti were more abundant in proximity with cattle and in semi-arid thorn bushes and lower Afro-montane. The highest number of mosquitoes was recorded in villages that were most affected during the RVF epidemic of 2007. Of the tested 150 pools of C. pipiens complex and 45 pools of A. aegypti, none was infected with RVF virus. Conclusions These results provide insights into unique habitat characterisation relating to mosquito abundances and distribution in RVF epidemic-prone areas of Ngorongoro district in northern Tanzania.
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Affiliation(s)
- Clement N Mweya
- Tukuyu Research Centre, National Institute for Medical Research, Tukuyu, Tanzania; Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania;
| | - Sharadhuli I Kimera
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Lesakit S B Mellau
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
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Mweya CN, Holst N, Mboera LEG, Kimera SI. Simulation modelling of population dynamics of mosquito vectors for rift valley Fever virus in a disease epidemic setting. PLoS One 2014; 9:e108430. [PMID: 25259792 PMCID: PMC4178157 DOI: 10.1371/journal.pone.0108430] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 08/19/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Rift Valley Fever (RVF) is weather dependent arboviral infection of livestock and humans. Population dynamics of mosquito vectors is associated with disease epidemics. In our study, we use daily temperature and rainfall as model inputs to simulate dynamics of mosquito vectors population in relation to disease epidemics. METHODS/FINDINGS Time-varying distributed delays (TVDD) and multi-way functional response equations were implemented to simulate mosquito vectors and hosts developmental stages and to establish interactions between stages and phases of mosquito vectors in relation to vertebrate hosts for infection introduction in compartmental phases. An open-source modelling platforms, Universal Simulator and Qt integrated development environment were used to develop models in C++ programming language. Developed models include source codes for mosquito fecundity, host fecundity, water level, mosquito infection, host infection, interactions, and egg time. Extensible Markup Language (XML) files were used as recipes to integrate source codes in Qt creator with Universal Simulator plug-in. We observed that Floodwater Aedines and Culicine population continued to fluctuate with temperature and water level over simulation period while controlled by availability of host for blood feeding. Infection in the system was introduced by floodwater Aedines. Culicines pick infection from infected host once to amplify disease epidemic. Simulated mosquito population show sudden unusual increase between December 1997 and January 1998 a similar period when RVF outbreak occurred in Ngorongoro district. CONCLUSION/SIGNIFICANCE Findings presented here provide new opportunities for weather-driven RVF epidemic simulation modelling. This is an ideal approach for understanding disease transmission dynamics towards epidemics prediction, prevention and control. This approach can be used as an alternative source for generation of calibrated RVF epidemics data in different settings.
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Affiliation(s)
- Clement N. Mweya
- National Institute for Medical Research, Tukuyu, Tanzania
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Niels Holst
- Department of Agroecology, Aarhus University, Slagelse, Denmark
| | | | - Sharadhuli I. Kimera
- Department of Veterinary Medicine and Public Health, Sokoine University of Agriculture, Morogoro, Tanzania
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Conley AK, Fuller DO, Haddad N, Hassan AN, Gad AM, Beier JC. Modeling the distribution of the West Nile and Rift Valley Fever vector Culex pipiens in arid and semi-arid regions of the Middle East and North Africa. Parasit Vectors 2014; 7:289. [PMID: 24962735 PMCID: PMC4077837 DOI: 10.1186/1756-3305-7-289] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 06/14/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Middle East North Africa (MENA) region is under continuous threat of the re-emergence of West Nile virus (WNV) and Rift Valley Fever virus (RVF), two pathogens transmitted by the vector species Culex pipiens. Predicting areas at high risk for disease transmission requires an accurate model of vector distribution, however, most Cx. pipiens distribution modeling has been confined to temperate, forested habitats. Modeling species distributions across a heterogeneous landscape structure requires a flexible modeling method to capture variation in mosquito response to predictors as well as occurrence data points taken from a sufficient range of habitat types. METHODS We used presence-only data from Egypt and Lebanon to model the population distribution of Cx. pipiens across a portion of the MENA that also encompasses Jordan, Syria, and Israel. Models were created with a set of environmental predictors including bioclimatic data, human population density, hydrological data, and vegetation indices, and built using maximum entropy (Maxent) and boosted regression tree (BRT) methods. Models were created with and without the inclusion of human population density. RESULTS Predictions of Maxent and BRT models were strongly correlated in habitats with high probability of occurrence (Pearson's r=0.774, r=0.734), and more moderately correlated when predicting into regions that exceeded the range of the training data (r=0.666,r=0.558). All models agreed in predicting high probability of occupancy around major urban areas, along the banks of the Nile, the valleys of Israel, Lebanon, and Jordan, and southwestern Saudi Arabia. The most powerful predictors of Cx. pipiens habitat were human population density (60.6% Maxent models, 34.9% BRT models) and the seasonality of the enhanced vegetation index (EVI) (44.7% Maxent, 16.3% BRT). Maxent models tended to be dominated by a single predictor. Areas of high probability corresponded with sites of independent surveys or previous disease outbreaks. CONCLUSIONS Cx. pipiens occurrence was positively associated with areas of high human population density and consistent vegetation cover, but was not significantly driven by temperature and rainfall, suggesting human-induced habitat change such as irrigation and urban infrastructure has a greater influence on vector distribution in this region than in temperate zones.
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Affiliation(s)
- Amy K Conley
- Department of Geography, University of Miami, 1300 Campo Sano Avenue, Coral Gables, FL 33146, USA
| | - Douglas O Fuller
- College of Arts and Sciences, University of Miami, Miami, FL, USA
| | - Nabil Haddad
- Laboratory of Immunology, Faculty of Public Health, Lebanese University, Fanar, El-Metn, Lebanon
| | - Ali N Hassan
- Department of Basic Environmental Sciences, Institute of Environmental Studies & Research, Ain Shams University, Cairo, Egypt
| | - Adel M Gad
- Entomology Department, Ain Shams University, Cairo, Egypt
| | - John C Beier
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
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