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Mwakutwaa AS, Ngugi HN, Ndenga BA, Krystosik A, Ngari M, Abubakar LU, Yonge S, Kitron U, LaBeaud AD, Mutuku FM. Pupal productivity of larval habitats of Aedes aegypti in Msambweni, Kwale County, Kenya. Parasitol Res 2023; 122:801-814. [PMID: 36683088 PMCID: PMC9988718 DOI: 10.1007/s00436-022-07777-0] [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: 10/04/2022] [Accepted: 12/30/2022] [Indexed: 01/24/2023]
Abstract
Aedes aegypti is an important vector of several arboviruses including dengue and chikungunya viruses. Accurate identification of larval habitats of Ae. aegypti is considered an essential step in targeted control. This study determined Ae. aegypti productivity in selected larval habitats in Msambweni, Kwale County, Kenya. Three sequential larval habitat surveys were conducted. The first survey was habitat census (baseline) through which 83 representative larval habitats were identified and selected. The second and third surveys involved estimating daily productivity of the 83 selected larval habitats for 30 consecutive days during a wet and a dry season, respectively. Of 664 larval habitats examined at baseline, 144 larval habitats (21.7%) were found to be infested with Ae. aegypti larvae. At baseline, majority (71%) of the pupae were collected from two (2/6) larval habitat types, tires and pots. Multivariate analysis identified habitat type and the habitat being movable as the predictors for pupal abundance. During the 30-day daily pupal production surveys, only a few of the habitats harbored pupae persistently. Pupae were found in 28% and 12% of the larval habitats during the wet and dry seasons, respectively. In the wet season, drums, tires, and pots were identified as the key habitat types accounting for 85% of all pupae sampled. Three habitats (all drums) accounted for 80% of all the pupae collected in the dry season. Predictors for pupal productivity in the wet season were habitat type, place (whether the habitat is located at the back or front of the house), habitat purpose (use of the water in the habitat), and source of water. Although the multivariate model for habitat type did not converge, habitat type and habitat size were the only significant predictors during the dry season. Drums, pots, and tires were sources of more than 85% of Ae. aegypti pupae, reinforcing the "key container concept." Targeting these three types of habitats makes epidemiological sense, especially during the dry season.
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Affiliation(s)
- Alawih S. Mwakutwaa
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya
| | - Harun N. Ngugi
- Department of Biological Sciences, Chuka University, Chuka, Kenya
| | - Bryson A. Ndenga
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Amy Krystosik
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA USA
| | - Moses Ngari
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Laila U. Abubakar
- Department of Pure and Applied Sciences, Technical University of Mombasa, Mombasa, Kenya
| | - Shadrack Yonge
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, GA USA
| | - A. Desiree LaBeaud
- Department of Pediatrics, Division of Infectious Diseases, Stanford University School of Medicine, Stanford, CA USA
| | - Francis M. Mutuku
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya
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Parker DM, Medina C, Bohl J, Lon C, Chea S, Lay S, Kong D, Nhek S, Man S, Doehl JSP, Leang R, Kry H, Rekol H, Oliveira F, Minin VM, Manning JE. Determinants of exposure to Aedes mosquitoes: A comprehensive geospatial analysis in peri-urban Cambodia. Acta Trop 2023; 239:106829. [PMID: 36649803 DOI: 10.1016/j.actatropica.2023.106829] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 12/23/2022] [Accepted: 01/07/2023] [Indexed: 01/15/2023]
Abstract
Aedes mosquitoes are some of the most important and globally expansive vectors of disease. Public health efforts are largely focused on prevention of human-vector contact. A range of entomological indices are used to measure risk of disease, though with conflicting results (i.e. larval or adult abundance does not always predict risk of disease). There is a growing interest in the development and use of biomarkers for exposure to mosquito saliva, including for Aedes spp, as a proxy for disease risk. In this study, we conduct a comprehensive geostatistical analysis of exposure to Aedes mosquito bites among a pediatric cohort in a peri‑urban setting endemic to dengue, Zika, and chikungunya viruses. We use demographic, household, and environmental variables (the flooding index (NFI), land type, and proximity to a river) in a Bayesian geostatistical model to predict areas of exposure to Aedes aegypti bites. We found that hotspots of exposure to Ae. aegypti salivary gland extract (SGE) were relatively small (< 500 m and sometimes < 250 m) and stable across the two-year study period. Age was negatively associated with antibody responses to Ae. aegypti SGE. Those living in agricultural settings had lower antibody responses than those living in urban settings, whereas those living near recent surface water accumulation were more likely to have higher antibody responses. Finally, we incorporated measures of larval and adult density in our geostatistical models and found that they did not show associations with antibody responses to Ae. aegypti SGE after controlling for other covariates in the model. Our results indicate that targeted house- or neighborhood-focused interventions may be appropriate for vector control in this setting. Further, demographic and environmental factors more capably predicted exposure to Ae. aegypti mosquitoes than commonly used entomological indices.
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Affiliation(s)
- Daniel M Parker
- Program in Public Health, University of California, Irvine, CA, USA.
| | - Catalina Medina
- Program in Public Health, University of California, Irvine, CA, USA; Department of Statistics, University of California, Irvine, CA, USA
| | - Jennifer Bohl
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Chanthap Lon
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | - Sophana Chea
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | - Sreyngim Lay
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | - Dara Kong
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Sreynik Nhek
- International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | - Somnang Man
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | - Johannes S P Doehl
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Rithea Leang
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Hok Kry
- Kampong Speu Provincial Health District, Ministry of Health, Cambodia
| | - Huy Rekol
- National Center of Parasitology, Entomology and Malaria Control, Ministry of Health, Phnom Penh, Cambodia
| | - Fabiano Oliveira
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
| | | | - Jessica E Manning
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA; International Center of Excellence in Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Phnom Penh, Cambodia
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3
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Djiappi-Tchamen B, Nana-Ndjangwo MS, Nchoutpouen E, Makoudjou I, Ngangue-Siewe IN, Talipouo A, Mayi MPA, Awono-Ambene P, Wondji C, Tchuinkam T, Antonio-Nkondjio C. Aedes Mosquito Surveillance Using Ovitraps, Sweep Nets, and Biogent Traps in the City of Yaoundé, Cameroon. INSECTS 2022; 13:793. [PMID: 36135494 PMCID: PMC9500714 DOI: 10.3390/insects13090793] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/27/2022] [Accepted: 08/29/2022] [Indexed: 05/07/2023]
Abstract
Arbovirus diseases represent a significant public health problem in Cameroon and vector surveillance is a key component of prevention strategies. However, there is still not enough evidence of the efficacy of different sampling methods used to monitor Aedes mosquito population dynamic in different epidemiological settings. The present study provides data on the evaluation of ovitraps and different adult sampling methods in the city of Yaoundé and its close vicinity. Entomological surveys were carried out from February 2020 to March 2021 in two urban (Obili, Mvan), two peri-urban (Simbock, Ahala), and two rural (Lendom, Elig-essomballa) sites in the city of Yaoundé. The efficacy of three sampling methods, namely ovitraps, Biogent Sentinel trap, and sweep nets, was evaluated. Different ovitrap indices were used to assess the infestation levels across study sites; a general linear model was used to determine if there are statistical differences between positive ovitraps across ecological zones. A total of 16,264 Aedes mosquitoes were collected during entomological surveys. Ovitraps provided the highest mosquito abundance (15,323; 91.14%) and the highest species diversity. Of the five Aedes species collected, Aedes albopictus (59.74%) was the most commonly recorded in both urban and rural settings. Different Aedes species were collected in the same ovitrap. The ovitrap positivity index was high in all sites and varied from 58.3% in Obili in the urban area to 86.08% in Lendom in the rural area. The egg density index varied from 6.42 in Mvan (urban site) to 13.70 in Lendom (rural area). Adult sampling methods recorded mostly Aedes albopictus. The present study supports high infestation of Aedes species in the city of Yaoundé. Ovitraps were highly efficient in detecting Aedes distribution across study sites. The situation calls for regular surveillance and control of Aedes population to prevent sudden occurrence of outbreaks.
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Affiliation(s)
- Borel Djiappi-Tchamen
- Vector Borne Diseases Laboratory of the Research Unit Biology and Applied Ecology (VBID-RUBAE), Department of Animal Biology, Faculty of Science, University of Dschang, Dschang P.O. Box 067, Cameroon
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
| | - Mariette Stella Nana-Ndjangwo
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
- Laboratory of Parasitology and Ecology, Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 337, Cameroon
| | - Elysée Nchoutpouen
- Centre for Research in Infectious Disease (CRID), Yaoundé P.O. Box 13591, Cameroon
| | - Idene Makoudjou
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
- Laboratory of Parasitology and Ecology, Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 337, Cameroon
| | - Idriss Nasser Ngangue-Siewe
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
- Laboratory of Biology and Physiology of Animal Organisms, Faculty of Sciences, University of Douala, Douala P.O. Box 24157, Cameroon
| | - Abdou Talipouo
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
- Laboratory of Parasitology and Ecology, Department of Animal Physiology and Biology, Faculty of Science, University of Yaoundé I, Yaoundé P.O. Box 337, Cameroon
| | - Marie Paul Audrey Mayi
- Vector Borne Diseases Laboratory of the Research Unit Biology and Applied Ecology (VBID-RUBAE), Department of Animal Biology, Faculty of Science, University of Dschang, Dschang P.O. Box 067, Cameroon
| | - Parfait Awono-Ambene
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
| | - Charles Wondji
- Centre for Research in Infectious Disease (CRID), Yaoundé P.O. Box 13591, Cameroon
- Vector Biology Liverpool School of Tropical Medicine Pembroke Place, Liverpool L3 5QA, UK
| | - Timoléon Tchuinkam
- Vector Borne Diseases Laboratory of the Research Unit Biology and Applied Ecology (VBID-RUBAE), Department of Animal Biology, Faculty of Science, University of Dschang, Dschang P.O. Box 067, Cameroon
| | - Christophe Antonio-Nkondjio
- Institut de Recherche de Yaoundé (IRY), Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Yaoundé P.O. Box 288, Cameroon
- Vector Biology Liverpool School of Tropical Medicine Pembroke Place, Liverpool L3 5QA, UK
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Murphy AK, Salazar FV, Bonsato R, Uy G, Ebol AP, Boholst RP, Davis C, Frentiu FD, Bambrick H, Devine GJ, Hu W. Climate variability and Aedes vector indices in the southern Philippines: An empirical analysis. PLoS Negl Trop Dis 2022; 16:e0010478. [PMID: 35700164 PMCID: PMC9197058 DOI: 10.1371/journal.pntd.0010478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 05/09/2022] [Indexed: 11/18/2022] Open
Abstract
Background
Vector surveillance is an essential public health tool to aid in the prediction and prevention of mosquito borne diseases. This study compared spatial and temporal trends of vector surveillance indices for Aedes vectors in the southern Philippines, and assessed potential links between vector indices and climate factors.
Methods
We analysed routinely collected larval and pupal surveillance data from residential areas of 14 cities and 51 municipalities during 2013–2018 (House, Container, Breteau and Pupal Indices), and used linear regression to explore potential relationships between vector indices and climate variables (minimum temperature, maximum temperature and precipitation).
Results
We found substantial spatial and temporal variation in monthly Aedes vector indices between cities during the study period, and no seasonal trend apparent. The House (HI), Container (CI) and Breteau (BI) Indices remained at comparable levels across most surveys (mean HI = 15, mean CI = 16, mean BI = 24), while the Pupal Productivity Index (PPI) was relatively lower in most months (usually below 5) except for two main peak periods (mean = 49 overall). A small proportion of locations recorded high values across all entomological indices in multiple surveys. Each of the vector indices were significantly correlated with one or more climate variables when matched to data from the same month or the previous 1 or 2 months, although the effect sizes were small. Significant associations were identified between minimum temperature and HI, CI and BI in the same month (R2 = 0.038, p = 0.007; R2 = 0.029, p = 0.018; and R2 = 0.034, p = 0.011, respectively), maximum temperature and PPI with a 2-month lag (R2 = 0.031, p = 0.032), and precipitation and HI in the same month (R2 = 0.023, p = 0.04).
Conclusions
Our findings indicated that larval and pupal surveillance indices were highly variable, were regularly above the threshold for triggering vector control responses, and that vector indices based on household surveys were weakly yet significantly correlated with city-level climate variables. We suggest that more detailed spatial and temporal analyses of entomological, climate, socio-environmental and Aedes-borne disease incidence data are necessary to ascertain the most effective use of entomological indices in guiding vector control responses, and reduction of human disease risk.
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Affiliation(s)
- Amanda K. Murphy
- School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Brisbane Australia
- Mosquito Control Laboratory, Department of Population Health, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Ferdinand V. Salazar
- Department of Medical Entomology, Research Institute for Tropical Medicine (RITM), Manila, The Philippines
| | - Ryan Bonsato
- Department of Medical Entomology, Research Institute for Tropical Medicine (RITM), Manila, The Philippines
| | - Gemma Uy
- Department of Health, Center for Health Development 10, Northern Mindanao, Cagaya de Oro, The Philippines
| | - Antonietta P. Ebol
- Department of Health, Center for Health Development 11, Davao City, Davao del Sur, The Philippines
| | - Royfrextopher P. Boholst
- Department of Health, Center for Health Development Soccskargen Region, Cotabato City, The Philippines
| | - Callan Davis
- School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Brisbane Australia
| | - Francesca D. Frentiu
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Australia
| | - Hilary Bambrick
- School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Brisbane Australia
| | - Gregor J. Devine
- Mosquito Control Laboratory, Department of Population Health, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Wenbiao Hu
- School of Public Health and Social Work, Faculty of Health, Queensland University of Technology, Brisbane Australia
- * E-mail:
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Sasmita HI, Neoh KB, Yusmalinar S, Anggraeni T, Chang NT, Bong LJ, Putra RE, Sebayang A, Silalahi CN, Ahmad I, Tu WC. Ovitrap surveillance of dengue vector mosquitoes in Bandung City, West Java Province, Indonesia. PLoS Negl Trop Dis 2021; 15:e0009896. [PMID: 34710083 PMCID: PMC8577782 DOI: 10.1371/journal.pntd.0009896] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 11/09/2021] [Accepted: 10/11/2021] [Indexed: 11/22/2022] Open
Abstract
Larval surveillance is the central approach for monitoring dengue vector populations in Indonesia. However, traditional larval indices are ineffective for measuring mosquito population dynamics and predicting the dengue transmission risk. We conducted a 14-month ovitrap surveillance. Eggs and immature mosquitoes were collected on a weekly basis from an urban village of Bandung, namely Sekejati. Ovitrap-related indices, namely positive house index (PHI), ovitrap index (OI), and ovitrap density index (ODI), were generated and correlated with environmental variables, housing type (terraced or high-density housing), ovitrap placement location (indoor or outdoor; household or public place), and local dengue cases. Our results demonstrated that Aedes aegypti was significantly predominant compared with Aedes albopictus at each housing type and ovitrap placement location. Ovitrap placement locations and rainfall were the major factors contributing to variations in PHI, OI, and ODI, whereas the influences of housing type and temperature were subtle. Indoor site values were significantly positively correlated to outdoor sites’ values for both OI and ODI. OI and ODI values from households were best predicted with those from public places at 1- and 0-week lags, respectively. Weekly rainfall values at 4- and 3-week lags were the best predictors of OI and ODI for households and public places, respectively. Monthly mean PHI, OI, and ODI were significantly associated with local dengue cases. In conclusion, ovitrap may be an effective tool for monitoring the population dynamics of Aedes mosquitoes, predicting dengue outbreaks, and serving as an early indicator to initiate environmental clean-up. Ovitrap surveillance is easy for surveyors if they are tasked with a certain number of ovitraps at a designated area, unlike the existing larval surveillance methodology, which entails identifying potential breeding sites largely at the surveyors’ discretion. Ovitrap surveillance may reduce the influence of individual effort in larval surveillance that likely causes inconsistency in results. The dengue virus, transmitted by Aedes vectors, has been continuously spreading in tropical and subtropical countries, causing illness and fatality. Given the lack of a cost-effective dengue vaccine, the vector control approach for reducing the Aedes population remains the key method for mitigating dengue transmission. For a successful vector control program, an effective vector surveillance system is crucial for precisely predicting the spatial and temporal risk of a dengue outbreak. The ovitrap system improves data collection efficiency, aiding long-term dengue vector monitoring activities. This study is one of the few long-term dengue vector surveillance programs in Indonesia and provides compelling evidence of the need to improve the existing conventional larval surveillance system. The results demonstrated that two dengue vector mosquitoes, A. aegypti and A. albopictus, were present in the study area, and A. aegypti was more prevalent than A. albopictus. We observed an interactive relationship between ovitrap placement and rainfall in the dynamics of ovitrap-related indices; understanding this relationship allows for timely initiation of vector control and intervention strategies. We conclude that the ovitrap surveillance system is a sensitive tool for monitoring the population dynamics of Aedes vectors, predicting dengue outbreaks, and potentially improving community-based conventional larval surveillance.
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Affiliation(s)
- Hadian Iman Sasmita
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
- Center for Isotopes and Radiation Application, National Nuclear Energy Agency, Jakarta, Indonesia
| | - Kok-Boon Neoh
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Sri Yusmalinar
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, Indonesia
| | - Tjandra Anggraeni
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, Indonesia
| | - Niann-Tai Chang
- Department of Plant Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Lee-Jin Bong
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | - Ramadhani Eka Putra
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, Indonesia
| | - Amelia Sebayang
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
| | | | - Intan Ahmad
- School of Life Sciences and Technology, Institut Teknologi Bandung, Bandung, West Java, Indonesia
- * E-mail: (IA); (W-CT)
| | - Wu-Chun Tu
- Department of Entomology, National Chung Hsing University, Taichung, Taiwan
- * E-mail: (IA); (W-CT)
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Tsheten T, Gray DJ, Clements ACA, Wangdi K. Epidemiology and challenges of dengue surveillance in the WHO South-East Asia Region. Trans R Soc Trop Med Hyg 2021; 115:583-599. [PMID: 33410916 DOI: 10.1093/trstmh/traa158] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/02/2020] [Accepted: 11/18/2020] [Indexed: 11/13/2022] Open
Abstract
Dengue poses a significant health and economic burden in the WHO South-East Asia Region. Approaches for control need to be aligned with current knowledge on the epidemiology of dengue in the region. Such knowledge will ensure improved targeting of interventions to reduce dengue incidence and its socioeconomic impact. This review was undertaken to describe the contemporary epidemiology of dengue and critically analyse the existing surveillance strategies in the region. Over recent decades, dengue incidence has continued to increase with geographical expansion. The region has now become hyper-endemic for multiple dengue virus serotypes/genotypes. Every epidemic cycle was associated with a change of predominant serotype/genotype and this was often associated with severe disease with intense transmission. Classical larval indices are widely used in vector surveillance and adult mosquito samplings are not implemented as a part of routine surveillance. Further, there is a lack of integration of entomological and disease surveillance systems, often leading to inaction or delays in dengue prevention and control. Disease surveillance does not capture all cases, resulting in under-reporting, and has thus failed to adequately represent the true burden of disease in the region. Possible solutions include incorporating adult mosquito sampling into routine vector surveillance, the establishment of laboratory-based sentinel surveillance, integrated vector and dengue disease surveillance and climate-based early warning systems using available technologies like mobile apps.
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Affiliation(s)
- Tsheten Tsheten
- Department of Globa l Health, Research School of Population Health, Australian National University, Canberra, Australia.,Royal Centre for Disease Control, Ministry of Health, Bhutan
| | - Darren J Gray
- Department of Globa l Health, Research School of Population Health, Australian National University, Canberra, Australia
| | - Archie C A Clements
- Faculty of Health Sciences, Curtin University, Perth, Australia.,Telethon Kids Institute, Nedlands, Australia
| | - Kinley Wangdi
- Department of Globa l Health, Research School of Population Health, Australian National University, Canberra, Australia
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7
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Garjito TA, Susanti L, Mujiyono M, Prihatin MT, Susilo D, Nugroho SS, Mujiyanto M, Wigati RA, Satoto TBT, Manguin S, Gavotte L, Frutos R. Assessment of Mosquito Collection Methods for Dengue Surveillance. Front Med (Lausanne) 2021; 8:685926. [PMID: 34169085 PMCID: PMC8219211 DOI: 10.3389/fmed.2021.685926] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 04/27/2021] [Indexed: 11/25/2022] Open
Abstract
Several methods exist to collect and assess the abundance of dengue vector mosquitoes, i.e., morning adult collection, pupal collection, ovitraps, human landing, and larval collection. Several of these methods are officially implemented to monitor mosquito density and make decisions on treatments for dengue control. This monitoring is also constrained by the need to conduct this assessment on a “one point/one day” process, meaning that once the threshold of 100 households is reached, the assessment is made, and the collectors teams move to another place, thus preventing the use of long-term sampling methods. This diversity of methods might be a source of variability and lack of statistical significance. There is also a lack of published data regarding the efficacy of these methods. Furthermore, the Stegomyia indices are shown to be not reliable for assessing the risk of dengue outbreaks. A mosquito survey was, thus, conducted in 39 locations corresponding to 15 dengue endemic provinces in Indonesia by using the different adult and larval collection methods recommended nationwide. A total of 44,675 mosquitoes were collected. The single larva method was the most efficient. Out of a total of 89 dengue-positive pools, the most frequently encountered virus was DENV2, which made up half of the positive samples, followed by DENV3 and DENV1, respectively. Factor analysis of mixed data showed that no correlation could be found between any methods and the presence of dengue virus in mosquitoes. Moreover, no correlation could be found between any methods and the incidence of dengue. There was no consistency in the efficacy of a given method from one site to another. There was no correlation between any of the parameters considered, i.e., method, incidence of dengue, location, and the presence of dengue virus in mosquitoes.
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Affiliation(s)
- Triwibowo Ambar Garjito
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Lulus Susanti
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Mujiyono Mujiyono
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Mega Tyas Prihatin
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Dwi Susilo
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Sidiq Setyo Nugroho
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Mujiyanto Mujiyanto
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Raden Ajeng Wigati
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research and Development, The Ministry of Health of Indonesia, Salatiga, Indonesia
| | - Tri Baskoro Tunggul Satoto
- Department of Parasitology, Faculty of Medicine, Public Health and Nursing, Gadjah Mada University, Yogyakarta, Indonesia
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Morales-Pérez A, Nava-Aguilera E, Hernández-Alvarez C, Alvarado-Castro VM, Arosteguí J, Legorreta-Soberanis J, Flores-Moreno M, Morales-Nava L, Harris E, Ledogar RJ, Andersson N, Cockcroft A. Utility of entomological indices for predicting transmission of dengue virus: secondary analysis of data from the Camino Verde trial in Mexico and Nicaragua. PLoS Negl Trop Dis 2020; 14:e0008768. [PMID: 33104693 PMCID: PMC7588090 DOI: 10.1371/journal.pntd.0008768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 08/31/2020] [Indexed: 12/22/2022] Open
Abstract
Dengue vector entomological indices are widely used to monitor vector density and disease control activities. But the value of these indices as predictors of dengue infection is not established. We used data from the impact assessment of a trial of community mobilization for dengue prevention (Camino Verde) to examine the associations between vector indices and evidence of dengue infection and their value for predicting dengue infection levels. In 150 clusters in Mexico and Nicaragua, two entomological surveys, three months apart, allowed calculation of the mean Container Index, Breteau index, Pupae per Household Index, and Pupae per Container Index across the two surveys. We measured recent dengue virus infection in children, indicated by a doubling of dengue antibodies in paired saliva samples over the three-month period. We examined the associations between each of the vector indices and evidence of dengue infection at household level and at cluster level, accounting for trial intervention status. To examine the predictive value for dengue infection, we constructed receiver operating characteristic (ROC) curves at household and cluster level, considering the four vector indices as continuous variables, and calculated the positive and negative likelihood ratios for different levels of the indices. None of the vector indices was associated with recent dengue infection at household level. The Breteau Index was associated with recent infection at cluster level (Odds ratio 1.36, 95% confidence interval 1.14–1.61). The ROC curve confirmed the weak predictive value for dengue infection of the Breteau Index at cluster level. Other indices showed no predictive value. Conventional vector indices were not useful in predicting dengue infection in Mexico and Nicaragua. The findings are compatible with the idea of sources of infection outside the household which were tackled by community action in the Camino Verde trial. Vector control is the basis of preventing dengue virus infection. Measurement of dengue vector indices is widely used to monitor dengue control activities, but their utility as predictors of dengue infection is not clear. We used data about vector indices and evidence of recent dengue virus infection from a trial of community mobilization for dengue prevention in Mexico and Nicaragua (Camino Verde), to examine how four standard vector indices could predict dengue infection. Only the Breteau index was associated with evidence of dengue infection, and that only at cluster level. Receiver operating characteristic (ROC) curves confirmed the Breteau Index was only a weak predictor of infection at cluster level; none of the other indices had predictive value. These findings indicate that the four entomological indices studied were not useful predictors of dengue infection. The results are compatible with the idea of sources of infection outside the household which were tackled by community action in the Camino Verde trial.
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Affiliation(s)
- Arcadio Morales-Pérez
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
| | - Elizabeth Nava-Aguilera
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
- * E-mail:
| | | | - Víctor Manuel Alvarado-Castro
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
| | | | - José Legorreta-Soberanis
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
| | - Miguel Flores-Moreno
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
| | - Liliana Morales-Nava
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
| | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, United States of America
| | | | - Neil Andersson
- Centro de Investigación de Enfermedades Tropicales (CIET), Universidad Autónoma de Guerrero, Acapulco, Guerrero, México
- Department of Family Medicine, McGill University, Montreal, Canada
| | - Anne Cockcroft
- Department of Family Medicine, McGill University, Montreal, Canada
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Ngugi HN, Nyathi S, Krystosik A, Ndenga B, Mbakaya JO, Aswani P, Musunzaji PS, Irungu LW, Bisanzio D, Kitron U, Desiree LaBeaud A, Mutuku F. Risk factors for Aedes aegypti household pupal persistence in longitudinal entomological household surveys in urban and rural Kenya. Parasit Vectors 2020; 13:499. [PMID: 33004074 PMCID: PMC7528257 DOI: 10.1186/s13071-020-04378-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 09/23/2020] [Indexed: 12/31/2022] Open
Abstract
Background Aedes aegypti is an efficient vector of several arboviruses of public health importance, including Zika and dengue. Currently vector management is the only available avenue for disease control. Development of efficient vector control strategies requires a thorough understanding of vector ecology. In this study, we identified households that are consistently productive for Ae. aegypti pupae and determined the ecological and socio-demographic factors associated with the persistence and abundance of pupae in households in rural and urban Kenya. Methods We collected socio-demographic, environmental and entomological data monthly from July 2014 to June 2018 from 80 households across four sites in Kenya. Pupae count data were collected via entomological surveillance of households and paired with socio-demographic and environmental data. We calculated pupal persistence within a household as the number of months of pupal presence within a year. We used spatially explicit generalized additive mixed models (GAMMs) to identify the risk factors for pupal abundance, and a logistic regression to identify the risk factors for pupal persistence in households. Results The median number of months of pupal presence observed in households was 4 and ranged from 0 to 35 months. We identified pupal persistence in 85 house-years. The strongest risk factors for high pupal abundance were the presence of bushes or tall grass in the peri-domicile area (OR: 1.60, 95% CI: 1.13–2.28), open eaves (OR: 2.57, 95% CI: 1.33–4.95) and high habitat counts (OR: 1.42, 95% CI: 1.21–1.66). The main risk factors for pupal persistence were the presence of bushes or tall grass in the peri-domicile (OR: 4.20, 95% CI: 1.42–12.46) and high number of breeding sites (OR: 2.17, 95% CI: 1.03–4.58). Conclusions We observed Ae. aegypti pupal persistence at the household level in urban and rural and in coastal and inland Kenya. High counts of potential breeding containers, vegetation in the peri-domicile area and the presence of eaves were strongly associated with increased risk of pupal persistence and abundance. Targeting households that exhibit pupal persistence alongside the risk factors for pupal abundance in vector control interventions may result in more efficient use of limited resources.![]()
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Affiliation(s)
- Harun N Ngugi
- School of Biological Sciences, Department of Zoology, University of Nairobi, Nairobi, Kenya.,Department of Biological Sciences, Chuka University, Chuka, Kenya
| | - Sindiso Nyathi
- Department of Epidemiology and Population Health, School of Medicine, Stanford University, Stanford, CA, USA
| | - Amy Krystosik
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Stanford University, Stanford, CA, USA
| | - Bryson Ndenga
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Joel O Mbakaya
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Peter Aswani
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | | | - Lucy W Irungu
- School of Biological Sciences, Department of Zoology, University of Nairobi, Nairobi, Kenya
| | - Donal Bisanzio
- RTI International, Washington, DC, USA.,Epidemiology and Public Health Division, School of Medicine, University of Nottingham, Nottingham, UK
| | - Uriel Kitron
- Department of Environmental Sciences, Emory University, Atlanta, GA, USA
| | - A Desiree LaBeaud
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Stanford University, Stanford, CA, USA
| | - Francis Mutuku
- Department of Environment and Health Sciences, Technical University of Mombasa, Mombasa, Kenya.
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10
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Garjito TA, Hidajat MC, Kinansi RR, Setyaningsih R, Anggraeni YM, Mujiyanto, Trapsilowati W, Jastal, Ristiyanto, Satoto TBT, Gavotte L, Manguin S, Frutos R. Stegomyia Indices and Risk of Dengue Transmission: A Lack of Correlation. Front Public Health 2020; 8:328. [PMID: 32793541 PMCID: PMC7393615 DOI: 10.3389/fpubh.2020.00328] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 06/15/2020] [Indexed: 01/24/2023] Open
Abstract
Dengue is present in 128 countries worldwide and is still expanding. There is currently no treatment or universally approved vaccine available. Therefore, prevention and control of mosquito vectors remain the most efficient ways of managing the risk of dengue outbreaks. The Stegomyia indices have been developed as quantitative indicators of the risk of dengue outbreaks. However, conflictual data are circulating about their reliability. We report in this article the first extensive study on Stegomyia indices, covering 78 locations of differing environmental and socio-economic conditions, climate, and population density across Indonesia, from West Sumatra to Papua. A total of 65,876 mosquito larvae and pupae were collected for the study. A correlation was found between incidence and human population density. No correlation was found between the incidence of dengue and the Stegomyia indices.
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Affiliation(s)
- Triwibowo Ambar Garjito
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia.,Université de Montpellier, Montpellier, France.,HydroSciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD), CNRS, Université de Montpellier, Montpellier, France
| | - Muhammad Choirul Hidajat
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Revi Rosavika Kinansi
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Riyani Setyaningsih
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Yusnita Mirna Anggraeni
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Mujiyanto
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Wiwik Trapsilowati
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Jastal
- Health Research and Development Unit Banjarnegara, National Institute of Health Research Development (NIHRD), MoH, Banjarnegara, Indonesia
| | - Ristiyanto
- Institute for Vector and Reservoir Control Research and Development, National Institute of Health Research Development (NIHRD), MoH, Salatiga, Indonesia
| | - Tri Baskoro Tunggul Satoto
- Department of Parasitology, Faculty of Medicine, Public Health and Nursing, Gadjah Mada University, Yogyakarta, Indonesia
| | | | - Sylvie Manguin
- Université de Montpellier, Montpellier, France.,HydroSciences Montpellier (HSM), Institut de Recherche pour le Développement (IRD), CNRS, Université de Montpellier, Montpellier, France
| | - Roger Frutos
- Université de Montpellier, Montpellier, France.,CIRAD, Intertryp, Montpellier, France.,IES, Université de Montpellier-CNRS, Montpellier, France
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11
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Ninditya VI, Purwati E, Utami AT, Marwaningtyaz AS, Fairuz NK, Widayanti R, Hamid PH. Artemisia vulgaris efficacies against various stages of Aedes aegypti. Vet World 2020; 13:1423-1429. [PMID: 32848320 PMCID: PMC7429375 DOI: 10.14202/vetworld.2020.1423-1429] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 05/28/2020] [Indexed: 11/16/2022] Open
Abstract
Background and Aim: Aedes aegypti is the vector of dengue fever, dengue hemorrhagic fever, chikungunya, and, most recently, Zika. Dengue fever is one of Indonesia’s endemic diseases. The principal tool for preventing dengue is controlling Ae. aegypti by chemical insecticides since vaccine against dengue is still under research. However, Ae. aegypti developed resistance to various chemical insecticides worldwide. Therefore, research on alternate compounds as mosquito insecticides is urgently needed. This study demonstrated the efficacy of Artemisia vulgaris extract as larvicidal, ovicidal, adulticidal, repellency, and oviposition deterrent activity against Ae. aegypti. Materials and Methods: A. vulgaris was obtained from Temanggung, Indonesia, while the eggs of Ae. aegypti were collected from Yogyakarta, Indonesia, and were hatched in Laboratory of Parasitology, Faculty of Veterinary Medicine, Universitas Gadjah Mada. Larvicidal activity was evaluated according to the WHO protocol; adulticidal activity was performed using the Centers for Disease Control protocol. Oviposition activity was evaluated using ovitraps added with A. vulgaris extract, complete protection time in the repellent assay was defined as the number of minutes elapsed between compound application and the landing of the first mosquito. Results: A test of the larvicidal activity of A. vulgaris extract returned an LC50 of 65.8 ppm (r2=0.9014) in 1 h and 18.6 ppm (r2=0.575) in 24 h. A. vulgaris was effective as an adulticidal, demonstrating LC50 values of 11.35 mg (r2=0.875) in 90 min, 9.63 mg (r2=0.924) in 105 min, and 6.46 mg (r2=0.925) in 120 min. A. vulgaris at a concentration of 1000 ppm was able to reach 96% of oviposition deterrent effect. The ovicidal assay, a concentration of 1000 ppm resulted in 82.67% of eggs remaining unhatched. An extract concentration of 80 mg/ml achieved 63.3±3.5% biting repellency in adults. Conclusion: This study gives a clear indication that A. vulgaris extract acts on Ae. aegypti at various developmental stages and is a potential alternative bioinsecticide for controlling this disease vector.
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Affiliation(s)
| | - Endah Purwati
- Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Ajeng Tyas Utami
- Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | | | | | - Rini Widayanti
- Faculty of Veterinary Medicine, Universitas Gadjah Mada, Yogyakarta, Indonesia
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12
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Wang JN, Hou J, Zhong JY, Cao GP, Yu ZY, Wu YY, Li TQ, Liu QM, Gong ZY. Relationships between traditional larval indices and meteorological factors with the adult density of Aedes albopictus captured by BG-mosquito trap. PLoS One 2020; 15:e0234555. [PMID: 32525905 PMCID: PMC7289416 DOI: 10.1371/journal.pone.0234555] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 05/28/2020] [Indexed: 12/02/2022] Open
Abstract
Objectives Larval indices have been used for Ae. albopictus surveillance for many years, while there is limited use in assessing dengue transmission risk and adult mosquito emergence. This study is aimed to explore the relationships between larval indices and the Ae. albopictus density captured by BG-mosquito trap (BG-trap) method, with considering the meteorological factors. Methods Data on larval density, adult mosquito density and meteorology factors were collected in an entomological survey carried out in Quzhou City, Zhejiang Province of China in 2018. The Spearman’s rank correlation and Pearson correlation were used for the analysis on the correlation of density indices. Generalized additive models were established to analyze the influencing factors of mosquito density. Results Breteau index (BI), House index (HI) and Container index (CI) were highly correlated with each other (r>0.7, p<0.05). The Ae. albopictus density was significantly correlated with CI (rs = 0.260, p<0.05), CI pre one week (rs = 0.259, p<0.05), and CI pre three weeks (rs = 0.329, p<0.05). BI was correlated with female Ae. albopictus density pre 4 weeks (r = -0.299, p<0.05). Female Ae. albopictus density was correlated with CI pre 3 weeks (rs = 0.303, p<0.05). The influencing factors of BI were average wind speed pre 1 week, average temperature and female Ae. albopictus density pre 4 weeks. The influencing factors of CI were average humidity pre 3 weeks and average temperature. The influencing factors of HI were average temperature and precipitation pre 4 weeks. The influencing factor of Ae. albopictus density and female Ae. albopictus density was temperature. Conclusions The adult Ae. albopictus density had low correlation with certain larval indices. Some of the meteorology factors played significant roles in the density of adult Ae. albopictus and larva with or without a time lag.
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Affiliation(s)
- Jin-Na Wang
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Juan Hou
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Jian-Yue Zhong
- Quzhou Center for Disease Control and Prevention, Quzhou, China
| | - Guo-Ping Cao
- Quzhou Center for Disease Control and Prevention, Quzhou, China
| | - Zhang-You Yu
- Quzhou Center for Disease Control and Prevention, Quzhou, China
| | - Yu-Yan Wu
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Tian-Qi Li
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Qin-Mei Liu
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
| | - Zhen-Yu Gong
- Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou, China
- * E-mail:
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13
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Spatial and temporal variation of dengue incidence in the island of Bali, Indonesia: An ecological study. Travel Med Infect Dis 2019; 32:101437. [PMID: 31362115 DOI: 10.1016/j.tmaid.2019.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 05/27/2019] [Accepted: 06/19/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Dengue fever control in the tropical island of Bali in Indonesia carries important significance both nationally and globally, as it is one of the most endemic islands in Indonesia and a worldwide popular travel destination. Despite its importance, the spatial and temporal heterogeneity in dengue risk and factors associated with its variation in risk across the island has not been not well explored. This study was aimed to analyze for the first time the geographical and temporal patterns of the incidence of dengue and to quantify the role of environmental and social factors on the spatial heterogeneity of dengue incidence in Bali. METHODS We analyzed retrospective dengue notification data at the sub-district level (Kecamatan) from January 2012 to December 2017 which obtained from the Indonesian Ministry of Health. Seasonality in notified dengue incidence was assessed by seasonal trend decomposition analysis with Loess (STL) smoothing. Crude standardized morbidity rates (SMRs) of dengue were calculated. Moran's I and local indicators of spatial autocorrelation (LISA) analysis were employed to assess spatial clustering and high-risk areas over the period studied. Bayesian spatial and temporal conditional autoregressive (CAR) modeling was performed to quantify the effects of rainfall, temperature, elevation, and population density on the spatial distribution of risk of dengue in Bali. RESULTS Strong seasonality of dengue incidence was observed with most cases notified during January to May. Dengue incidence was spatially clustered during the period studied with high-risk kecamatans concentrated in the south of the island, but since 2014, the high-risk areas expanded toward the eastern part of the island. The best-fitted CAR model showed increased dengue risk in kecamatans with high total annual rainfall (relative risk (RR): 1.16 for each 1-mm increase in rainfall; 95% Credible interval (CrI): 1.03-1.31) and high population density (RR: 7.90 per 1000 people/sq.km increase; 95% CrI: 3.01-20.40). The RR of dengue was decreased in kecamatans with higher elevation (RR: 0.73 for each 1-m increase in elevation; 95% CrI: 0.55-0.98). No significant association was observed between dengue RR and year except in 2014, where the dengue RR was significantly lower (RR: 0.53; 95% CrI: 0.30-0.92) relative to 2012. CONCLUSIONS Dengue incidence was strongly seasonal and spatially clustered in Bali. High-risk areas were spread from kecamatans in Badung and Denpasar toward Karangasem and Klungkung. The spatial heterogeneity of dengue risk across Bali was influenced by rainfall, elevation, and population density. Surveillance and targeted intervention strategies should be prioritized in the high-risk kecamatans identified in this study to better control dengue transmission in this most touristic island in Indonesia. Local health authorities should recommend travelers to use personal protective measures, especially during the peak epidemic period, before visiting Bali.
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14
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Husnina Z, Clements ACA, Wangdi K. Forest cover and climate as potential drivers for dengue fever in Sumatra and Kalimantan 2006-2016: a spatiotemporal analysis. Trop Med Int Health 2019; 24:888-898. [PMID: 31081162 DOI: 10.1111/tmi.13248] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To describe and quantify spatiotemporal trends of dengue fever at district level in Sumatra and Kalimantan, Indonesia in relation to forest cover and climatic factors. METHODS A spatial ecological study design was used to analyse monthly surveillance data of notified dengue fever cases from January 2006 to December 2016 in the 154 districts of Sumatra and 56 districts of Kalimantan. A multivariate, zero-inflated Poisson regression model was developed with a conditional autoregressive prior structure with posterior parameters estimated using Bayesian Markov chain Monte Carlo simulation with Gibbs sampling. RESULTS There were 230 745 cases in Sumatra and 132 186 cases in Kalimantan during the study period. In Sumatra, the risk of dengue fever decreased by 9% (95% credible interval [CrI] 8.5-9.5%) for a 1% increase in forest cover and by 12.2% (95% CrI 11.9-12.6%) for a 1% increase in relative humidity. In Kalimantan, dengue fever risk fell by 17.6% (95% CrI 17.1-18.1%) for a 1% increase in relative humidity and rose by 7.6% (95% CrI 6.9-8.4%) for a 1 °C increase in minimum temperature. There was no significant residual spatial clustering in Sumatra after accounting for climate and demographic variables. In Kalimantan, high residual risk areas were primarily centred in North and East of the island. CONCLUSIONS Dengue fever in Sumatra and Kalimantan was highly seasonal and associated with climate factors and deforestation. Incorporation of climate indicators into risk-based surveillance might be warranted for dengue fever in Indonesia.
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Affiliation(s)
- Zida Husnina
- Research School of Population Health, Australian National University, Canberra, ACT, Australia.,Department of Environmental Health, Faculty of Public Health, Universitas Airlangga, Jawa Timur, Indonesia
| | - Archie C A Clements
- Research School of Population Health, Australian National University, Canberra, ACT, Australia.,Faculty of Health Sciences, Curtin University, Perth, WA, Australia.,Telethon Kids Institute, Nedlands, WA, Australia
| | - Kinley Wangdi
- Research School of Population Health, Australian National University, Canberra, ACT, Australia
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15
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Harapan H, Michie A, Yohan B, Shu P, Mudatsir M, Sasmono RT, Imrie A. Dengue viruses circulating in Indonesia: A systematic review and phylogenetic analysis of data from five decades. Rev Med Virol 2019; 29:e2037. [DOI: 10.1002/rmv.2037] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Harapan Harapan
- Medical Research Unit, School of MedicineUniversitas Syiah Kuala Banda Aceh Indonesia
- School of Biomedical SciencesUniversity of Western Australia Nedlands Western Australia Australia
| | - Alice Michie
- School of Biomedical SciencesUniversity of Western Australia Nedlands Western Australia Australia
| | | | - Pei‐Yun Shu
- Center for Diagnostics and Vaccine Development, Centers for Disease ControlMinistry of Health and Welfare Taiwan Republic of China
| | - Mudatsir Mudatsir
- Medical Research Unit, School of MedicineUniversitas Syiah Kuala Banda Aceh Indonesia
- Department of Microbiology, School of MedicineUniversitas Syiah Kuala Banda Aceh Indonesia
| | | | - Allison Imrie
- School of Biomedical SciencesUniversity of Western Australia Nedlands Western Australia Australia
- Pathwest Laboratory Medicine Nedlands Western Australia Australia
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16
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Role of container type, behavioural, and ecological factors in Aedes pupal production in Dhaka, Bangladesh: An application of zero-inflated negative binomial model. Acta Trop 2019; 193:50-59. [PMID: 30790554 DOI: 10.1016/j.actatropica.2019.02.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/16/2019] [Accepted: 02/17/2019] [Indexed: 01/28/2023]
Abstract
The container-inhabiting Aedes mosquitoes are the major vectors transmitting dengue and several other arboviral diseases such as chikungunya and zika across the tropical world. Surveillance for immature Aedes, particularly pupae, is an effective tool for measuring dengue outbreak risk. While in Bangladesh, the greatest burden of dengue fever and dengue hemorrhagic fever cases has periodically been occurring since the first major outbreak in 2000, very limited research has yet been pursued to understand the dynamics of Aedes pupal production in this country. In this backdrop, this study was carried out to i) identify containers at household premises contributing to dengue vector productivity; ii) measure the extent of pupae productivity of household containers; and, iii) determine the effects of household ecological factors upon productivity of pupae in the city of Dhaka, Bangladesh. During the monsoon months of 2013, a total of 1,033 containers (674 wet and 363 dry) in 727 household premises in 12 wards of the city of Dhaka were inspected to measure container productivity and collect household ecological, and human behavioural data. The results reveal that the majority of immature mosquitoes (73.52% larvae and 84.91% pupae) developed in containers located outdoor that are used mostly for household chores. Plastic containers (57.55% of all immature mosquito-positive containers) used for household chores produce most of the immature mosquitos. The results of the zero-inflated negative binomial (ZINB) model reveal that pupae production significantly varies by container type (p-value = 0.0136) for the count regression group. However, when considering container size along with container type, container size is found significant for pupae production (p-value = 0.0041), showing that container size is confounded with the container type and the pupae production. Containers greater than 50 litres (L) are likely to produce 4.9 times more pupae than containers with <1L. Two household ecological factors are found to be significant (shade: p-value = 0.005 in the count regression group and type of water: p-value = 0.001 in the excess zero group) for pupae production. We found that containers with partial shade produce 4.6 times more pupae than without any shade, whereas in the excess zero group the expected number of observed zero pupae count is 86.5% lower in containers filled with rain water than those with tap water, tube-well water, ring well water and water from other sources. The most commonly used plastic-made containers (i.e., refrigerator trays, drums, buckets) and flower tubs/trays are the most abundant immature mosquito-positive containers. These findings would help the concerned authorities to formulate programs for changing human behaviour targeting the most productive containers for Aedes habitat management and vector control in the city of Dhaka, Bangladesh.
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Tuladhar R, Singh A, Varma A, Choudhary DK. Climatic factors influencing dengue incidence in an epidemic area of Nepal. BMC Res Notes 2019; 12:131. [PMID: 30867027 PMCID: PMC6417253 DOI: 10.1186/s13104-019-4185-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 03/11/2019] [Indexed: 12/14/2022] Open
Abstract
Objective Geographic expansion of dengue incidence has drawn a global interest to identify the influential factors that instigate the spread of this disease. The objective of this study was to find the environmental factors linked to dengue incidence in a dengue epidemic area of Nepal by negative binomial models using climatic factors from 2010 to 2017. Results Minimum temperature at lag 2 months, maximum temperature and relative humidity without lag period significantly affected dengue incidence. Rainfall was not associated with dengue incidence in Chitwan district of Nepal. The incident rate ratio (IRR) of dengue case rise by more than 1% for every unit increase in minimum temperature at lag 2 months, maximum temperature and relative humidity, but decrease by .759% for maximum temperature at lag 3 months. Considering the effect of minimum temperature of previous months on dengue incidence, the vector control and dengue management program should be implemented at least 2 months ahead of dengue outbreak season. Electronic supplementary material The online version of this article (10.1186/s13104-019-4185-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Reshma Tuladhar
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal. .,Amity Institute of Microbial Technology, Amity University, Noida, UP, India.
| | - Anjana Singh
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, UP, India
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Tuladhar R, Singh A, Banjara MR, Gautam I, Dhimal M, Varma A, Choudhary DK. Effect of meteorological factors on the seasonal prevalence of dengue vectors in upland hilly and lowland Terai regions of Nepal. Parasit Vectors 2019; 12:42. [PMID: 30658693 PMCID: PMC6339416 DOI: 10.1186/s13071-019-3304-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 01/07/2019] [Indexed: 11/16/2022] Open
Abstract
Background The expansion of dengue vectors from lowland plains to the upland hilly regions of Nepal suggests the likelihood of increased risk of dengue. Our objective was to assess the effects of meteorological variables on vector indices and populations of dengue vectors in two different ecological regions of Nepal. An entomological survey was conducted in Kathmandu and Lalitpur (upland) and Chitwan (lowland) of Nepal in three different seasons from July 2015 to May 2016. The effect of meteorological variables on vector indices (house index, container index and Breteau index) and Aedes spp. population abundance was analyzed. A gamma regression was used to fit the models for vector indices and a negative binomial regression was used to model Aedes spp. population abundance. Results Monsoon season showed higher values for vector indices and vector populations compared to post-monsoon and pre-monsoon. Overall, the factor temperature-rainfall effect had a more significant influence on vector indices compared to relative humidity. The regression models showed that relative humidity has a greater impact in Chitwan than in Kathmandu. Variation was observed in the effect of predictor variables on Aedes aegypti and Ae. albopictus abundance. Conclusions Temperature and rainfall contribute to the vector indices in the upland hilly region while relative humidity contributes in the lowland plains. Since vector prevalence is not only linked to meteorological factors, other factors such as water storage practices, waste disposal, sanitary conditions and vector control strategy should also be considered. We recommend strengthening and scaling up dengue vector surveillance and control programmes for monsoon season in both upland and lowland regions in Nepal. Electronic supplementary material The online version of this article (10.1186/s13071-019-3304-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Reshma Tuladhar
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal. .,Amity Institute of Microbial Technology, Amity University, Noida, UP, India.
| | - Anjana Singh
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Megha Raj Banjara
- Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Ishan Gautam
- Natural History Museum, Tribhuvan University, Kathmandu, Nepal
| | - Meghnath Dhimal
- Nepal Health Research Council, Ministry of Health and Population, Ramshah Path, Kathmandu, Nepal
| | - Ajit Varma
- Amity Institute of Microbial Technology, Amity University, Noida, UP, India
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Parra MCP, Fávaro EA, Dibo MR, Mondini A, Eiras ÁE, Kroon EG, Teixeira MM, Nogueira ML, Chiaravalloti-Neto F. Using adult Aedes aegypti females to predict areas at risk for dengue transmission: A spatial case-control study. Acta Trop 2018; 182:43-53. [PMID: 29462598 DOI: 10.1016/j.actatropica.2018.02.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/27/2018] [Accepted: 02/13/2018] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Traditional indices for measuring dengue fever risk in a given area are based on the immature forms of the vector (larvae and pupae surveys). However, this is inefficient because only adult female mosquitoes actually transmit the virus. Based on these assumptions, our objective was to evaluate the association between an entomological index obtained from adult mosquito traps and the occurrence of dengue in a hyperendemic area. Additionally, we compared its cost to that of the Breteau Index (BI). MATERIAL AND METHODS We performed this study in São José do Rio Preto, SP, Brazil, between the epidemiological weeks of 36/2012 and 19/2013. BG-Sentinel and BG-Mosquitito traps were installed to capture adult mosquitoes. Positive and negative cases of dengue fever were computed and geocoded. We generated biweekly thematic maps of the entomological index, generated by calculating the number of adult Aedes aegypti females (NAF) per 100 households during a week by kriging, and based on the number of mosquitoes captured. The relation between the occurrence of dengue fever and the NAF was tested using a spatial case-control design and a generalized additive model and was controlled by the coordinates of the positive and negative cases of dengue fever. RESULTS Our analyses showed that increases in dengue fever cases occurred in parallel with increases in the number of Ae. aegypti females. The entomological index produced in our study correlates positively with the incidence of dengue, particularly during intervals when vector control measures were applied less intensively. The operational costs of our index were lower than those of the BI: NAF used 71.5% less human resources necessary to measure the BI. CONCLUSIONS Spatial analysis techniques and the number of adult Ae. aegypti females were used to produce an indicator of dengue risk. The index can be applied at various levels of spatial aggregation for an entire study area, as well as for sub-areas, such as city blocks. Even though the index is adequate to predict dengue risk, it should be tested and validated in various scenarios before routine use.
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de Jong W, Rusli M, Bhoelan S, Rohde S, Rantam FA, Noeryoto PA, Hadi U, Gorp ECMV, Goeijenbier M. Endemic and emerging acute virus infections in Indonesia: an overview of the past decade and implications for the future. Crit Rev Microbiol 2018; 44:487-503. [PMID: 29451044 DOI: 10.1080/1040841x.2018.1438986] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Being the largest archipelago country in the world, with a tropical climate and a unique flora and fauna, Indonesia habitats one of the most diverse biome in the world. These characteristics make Indonesia a popular travel destination, with tourism numbers increasing yearly. These characteristics also facilitate the transmission of zoonosis and provide ideal living and breading circumstances for arthropods, known vectors for viral diseases. A review of the past 10 years of literature, reports of the Ministry of Health, Republic of Indonesia and ProMED-mail shows a significant increase in dengue infection incidence. Furthermore, chikungunya, Japanese encephalitis and rabies are proven to be endemic in Indonesia. The combination of cohort studies, governmental data and ProMED-mail reveals an integrated overview for those working in travel medicine and public health, focusing on both endemic and emerging acute virus infections. This review summarizes the epidemiology of acute virus infections in Indonesia, including outbreak reports, as well as public health response measurements and their potential or efficacy. Knowledge about human behaviour, animal reservoirs, climate factors, environment and their role in emerging virus infection are discussed. We aim to support public health authorities and health care policy makers in a One Health approach.
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Affiliation(s)
- Wesley de Jong
- a Department of Viroscience , Erasmus MC , Rotterdam , the Netherlands
| | - Musofa Rusli
- b Department of Internal Medicine, Division of Tropical & Infectious Disease, Faculty of Medicine , Airlangga University , Surabaya , Indonesia
| | - Soerajja Bhoelan
- c Department of Internal medicine , Havenziekenhuis Institute for Tropical Medicine , Rotterdam , the Netherlands
| | - Sofie Rohde
- a Department of Viroscience , Erasmus MC , Rotterdam , the Netherlands
| | - Fedik A Rantam
- d Institute of Tropical Disease, Airlangga University , Surabaya , Indonesia
| | - Purwati A Noeryoto
- b Department of Internal Medicine, Division of Tropical & Infectious Disease, Faculty of Medicine , Airlangga University , Surabaya , Indonesia
| | - Usman Hadi
- b Department of Internal Medicine, Division of Tropical & Infectious Disease, Faculty of Medicine , Airlangga University , Surabaya , Indonesia
| | - Eric C M van Gorp
- a Department of Viroscience , Erasmus MC , Rotterdam , the Netherlands
| | - Marco Goeijenbier
- a Department of Viroscience , Erasmus MC , Rotterdam , the Netherlands.,c Department of Internal medicine , Havenziekenhuis Institute for Tropical Medicine , Rotterdam , the Netherlands
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Kusmintarsih ES, Hayati RF, Turnip ON, Yohan B, Suryaningsih S, Pratiknyo H, Denis D, Sasmono RT. Molecular characterization of dengue viruses isolated from patients in Central Java, Indonesia. J Infect Public Health 2017; 11:617-625. [PMID: 29056517 DOI: 10.1016/j.jiph.2017.09.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 08/14/2017] [Accepted: 09/09/2017] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Dengue is hyper-endemic in Indonesia. Purwokerto city in Central Java province is routinely ravaged by the disease. Despite the endemicity of dengue in this city, there is still no data on the virological aspects of dengue in the city. We conducted a molecular surveillance study of the circulating dengue viruses (DENV) in Purwokerto city to gain information on the virus origin, serotype and genotype distribution, and phylogenetic characteristics of DENV. METHODS A cross-sectional dengue molecular surveillance study was conducted in Purwokerto. Sera were collected from dengue-suspected patients attending three hospitals in the city. Diagnosis was performed using dengue NS1 antigen and IgG/IgM antibodies detection. DENV serotyping was performed using Simplexa Dengue real-time RT-PCR. Sequencing was conducted to obtain full-length DENV Envelope (E) gene sequences, which were then used in phylogenetic and genotypic analyses. Patients' clinical and demographic data were collected and analyzed. RESULTS A total of 105 dengue-suspected patients' sera were collected, in which 80 (76.2%) were positive for IgM and/or IgG, and 57 (54.2%) were confirmed as dengue by NS1 antigen and/or DENV RNA detection using RT-PCR. Serotyping was successful for 47 isolates. All four serotypes circulated in the area with DENV-3 as the predominant serotype. Phylogenetic analyses grouped the isolates into Genotype I for DENV-1, Cosmopolitan genotype for DENV-2, and Genotype I and II for DENV-3 and -4, respectively. The analyses also revealed the close relatedness of Purwokerto isolates to other DENV strains from Indonesia and neighboring countries. CONCLUSION We reveal the molecular and virological characteristics of DENV in Purwokerto, Banyumas regency, Central Java. The genotype and phylogenetic analyses indicate the endemicity of the circulating DENV in the city. Our serotype and genotype data provide references for future dengue molecular epidemiology studies and disease management in the region.
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Affiliation(s)
- Endang S Kusmintarsih
- Fakultas Biologi, Universitas Jenderal Soedirman, Jl. dr. Soeparno No. 63, Purwokerto, 53122, Indonesia
| | - Rahma F Hayati
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta, 10430, Indonesia
| | - Oktaviani N Turnip
- Fakultas Biologi, Universitas Jenderal Soedirman, Jl. dr. Soeparno No. 63, Purwokerto, 53122, Indonesia; Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta, 10430, Indonesia
| | - Benediktus Yohan
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta, 10430, Indonesia
| | - Suhestri Suryaningsih
- Fakultas Biologi, Universitas Jenderal Soedirman, Jl. dr. Soeparno No. 63, Purwokerto, 53122, Indonesia
| | - Hery Pratiknyo
- Fakultas Biologi, Universitas Jenderal Soedirman, Jl. dr. Soeparno No. 63, Purwokerto, 53122, Indonesia
| | - Dionisius Denis
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta, 10430, Indonesia
| | - R Tedjo Sasmono
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta, 10430, Indonesia.
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Agha SB, Tchouassi DP, Bastos ADS, Sang R. Assessment of risk of dengue and yellow fever virus transmission in three major Kenyan cities based on Stegomyia indices. PLoS Negl Trop Dis 2017; 11:e0005858. [PMID: 28817563 PMCID: PMC5574621 DOI: 10.1371/journal.pntd.0005858] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/29/2017] [Accepted: 08/07/2017] [Indexed: 11/18/2022] Open
Abstract
Dengue (DEN) and yellow fever (YF) are re-emerging in East Africa, with contributing drivers to this trend being unplanned urbanization and increasingly adaptable anthropophilic Aedes (Stegomyia) vectors. Entomological risk assessment of these diseases remains scarce for much of East Africa and Kenya even in the dengue fever-prone urban coastal areas. Focusing on major cities of Kenya, we compared DEN and YF risk in Kilifi County (DEN-outbreak-prone), and Kisumu and Nairobi Counties (no documented DEN outbreaks). We surveyed water-holding containers for mosquito immature (larvae/pupae) indoors and outdoors from selected houses during the long rains, short rains and dry seasons (100 houses/season) in each County from October 2014-June 2016. House index (HI), Breteau index (BI) and Container index (CI) estimates based on Aedes (Stegomyia) immature infestations were compared by city and season. Aedes aegypti and Aedes bromeliae were the main Stegomyia species with significantly more positive houses outdoors (212) than indoors (88) (n = 900) (χ2 = 60.52, P < 0.0001). Overall, Ae. aegypti estimates of HI (17.3 vs 11.3) and BI (81.6 vs 87.7) were higher in Kilifi and Kisumu, respectively, than in Nairobi (HI, 0.3; BI,13). However, CI was highest in Kisumu (33.1), followed by Kilifi (15.1) then Nairobi (5.1). Aedes bromeliae indices were highest in Kilifi, followed by Kisumu, then Nairobi with HI (4.3, 0.3, 0); BI (21.3, 7, 0.7) and CI (3.3, 3.3, 0.3), at the respective sites. HI and BI for both species were highest in the long rains, compared to the short rains and dry seasons. We found strong positive correlations between the BI and CI, and BI and HI for Ae. aegypti, with the most productive container types being jerricans, drums, used/discarded containers and tyres. On the basis of established vector index thresholds, our findings suggest low-to-medium risk levels for urban YF and high DEN risk for Kilifi and Kisumu, whereas for Nairobi YF risk was low while DEN risk levels were low-to-medium. The study provides a baseline for future vector studies needed to further characterise the observed differential risk patterns by vector potential evaluation. Identified productive containers should be made the focus of community-based targeted vector control programs. Despite the growing problem of dengue (DEN) and yellow fever (YF) evidenced from recent outbreaks in East Africa, risk assessment for their transmission and establishment through surveys of populations of the Aedes mosquito vectors, remain scarce. By estimating standard indices for the potential vectors, Aedes aegypti and Aedes bromeliae we partly could deduce the risk of transmission of these diseases in three major cities of Kenya, namely Kilifi (DEN-prone) and Kisumu and Nairobi (without any DEN outbreak reports). When compared to established threshold risk levels by WHO and PAHO, our findings suggest low-to-medium risk of urban YF, and high risk of DEN transmission for Kilifi and Kisumu but not Nairobi (low risk level for YF and low-to-medium risk for DEN). The observed seasonal risk patterns, higher Aedes infestation outdoors than indoors and productive container types (jerricans, drums, discarded containers and tyres), provide insights into the disease epidemiology and are valuable for targeted vector control, respectively.
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Affiliation(s)
- Sheila B. Agha
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- * E-mail: ,
| | | | - Armanda D. S. Bastos
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - Rosemary Sang
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
- Arbovirus/Viral Hemorrhagic Fever Laboratory, Centre for Virus Research, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
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Potential Sympatric Vectors and Mammalian Hosts of Venezuelan Equine Encephalitis Virus in Southern Mexico. J Wildl Dis 2017; 53:657-661. [PMID: 28384059 DOI: 10.7589/2016-11-249] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Arboviruses are important zoonotic agents with complex transmission cycles and are not well understood because they may involve many vectors and hosts. We studied sympatric wild mammals and hematophagous mosquitoes having the potential to act as hosts and vectors in two areas of southern Mexico. Mosquitoes, bats, and rodents were captured in Calakmul (Campeche) and Montes Azules (Chiapas), between November 2010 and August 2011. Spleen samples from 146 bats and 14 rodents were tested for molecular evidence of Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), western equine encephalitis virus (WEEV), and West Nile virus (WNV) using PCR protocols. Bat ( Artibeus lituratus , Carollia sowelli , Glossophaga soricina , and Sturnira parvidens) and rodent ( Sigmodon hispidus and Oryzomys alfaroi ) species were positive for VEEV. No individuals were positive for WNV, EEEV, or WEEV. A total of 1,298 mosquitoes were collected at the same sites, and five of the mosquito species collected were known VEEV vectors (Aedes fulvus, Mansonia indubitans, Psorophora ferox, Psorophora cilipes, and Psorophora confinnis). This survey simultaneously presents the first molecular evidence, to our knowledge, of VEEV in bats and rodents from southern Mexico and the identification of potential sympatric vectors. Studies investigating sympatric nonhuman hosts, vectors, and arboviruses must be expanded to determine arboviral dynamics in complex systems in which outbreaks of emerging and reemerging zoonoses are continuously occurring.
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Wijayanti SPM, Porphyre T, Chase-Topping M, Rainey SM, McFarlane M, Schnettler E, Biek R, Kohl A. The Importance of Socio-Economic Versus Environmental Risk Factors for Reported Dengue Cases in Java, Indonesia. PLoS Negl Trop Dis 2016; 10:e0004964. [PMID: 27603137 PMCID: PMC5014450 DOI: 10.1371/journal.pntd.0004964] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/09/2016] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Dengue is a major mosquito-borne viral disease and an important public health problem. Identifying which factors are important determinants in the risk of dengue infection is critical in supporting and guiding preventive measures. In South-East Asia, half of all reported fatal infections are recorded in Indonesia, yet little is known about the epidemiology of dengue in this country. METHODOLOGY/PRINCIPAL FINDINGS Hospital-reported dengue cases in Banyumas regency, Central Java were examined to build Bayesian spatial and spatio-temporal models assessing the influence of climatic, demographic and socio-economic factors on the risk of dengue infection. A socio-economic factor linking employment type and economic status was the most influential on the risk of dengue infection in the Regency. Other factors such as access to healthcare facilities and night-time temperature were also found to be associated with higher risk of reported dengue infection but had limited explanatory power. CONCLUSIONS/SIGNIFICANCE Our data suggest that dengue infections are triggered by indoor transmission events linked to socio-economic factors (employment type, economic status). Preventive measures in this area should therefore target also specific environments such as schools and work areas to attempt and reduce dengue burden in this community. Although our analysis did not account for factors such as variations in immunity which need further investigation, this study can advise preventive measures in areas with similar patterns of reported dengue cases and environment.
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Affiliation(s)
- Siwi P. M. Wijayanti
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- Public Health Department, Faculty of Health Sciences, University of Jenderal Soedirman, Purwokerto, Indonesia
- * E-mail: (SPMW); (TP); (AK)
| | - Thibaud Porphyre
- Centre for Immunity, Infection and Evolution (CIIE), Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail: (SPMW); (TP); (AK)
| | - Margo Chase-Topping
- Centre for Immunity, Infection and Evolution (CIIE), Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Stephanie M. Rainey
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Melanie McFarlane
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Esther Schnettler
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Roman Biek
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Alain Kohl
- MRC–University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (SPMW); (TP); (AK)
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Wijayanti SPM, Sunaryo S, Suprihatin S, McFarlane M, Rainey SM, Dietrich I, Schnettler E, Biek R, Kohl A. Correction: Dengue in Java, Indonesia: Relevance of Mosquito Indices as Risk Predictors. PLoS Negl Trop Dis 2016; 10:e0004683. [PMID: 27115990 PMCID: PMC4846080 DOI: 10.1371/journal.pntd.0004683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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