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Dawah HA, Abdullah MA, Ahmad SK, Turner J, Azari-Hamidian S. An overview of the mosquitoes of Saudi Arabia (Diptera: Culicidae), with updated keys to the adult females. Zootaxa 2023; 5394:1-76. [PMID: 38220993 DOI: 10.11646/zootaxa.5394.1.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Indexed: 01/16/2024]
Abstract
Despite the fact that mosquito-borne infections have considerable consequences for public health in Saudi Arabia, there is neither a thorough review of the species that occur in the country nor updated keys for the identification of the adult females. In this study, species accounts are given for 49 Saudi Arabian mosquito species, as well as Aedes albopictus (Skuse), which is not recorded in Saudi Arabia, but is medically important and is found in some countries of the Middle East and North Africa. Taxonomic notes provide additional information for certain taxa and/or aid their identification.
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Affiliation(s)
- Hassan A Dawah
- Centre for Environmental Research and Studies; Jazan University; P.O. Box 2095; Jazan; Kingdom of Saudi Arabia.
| | - Mohammed A Abdullah
- Department of Biology; College of Science; King Khalid University; PO Box 9004; Abha-61413; Kingdom of Saudi Arabia.
| | - Syed Kamran Ahmad
- Department of Plant Protection; Faculty of Agricultural Sciences; Aligarh Muslim University; Aligarh; India.
| | - James Turner
- National Museum of Wales; Department of Natural Sciences; Entomology Section; Cardiff; CF10 3NP; UK.
| | - Shahyad Azari-Hamidian
- Research Center of Health and Environment; School of Health; Guilan University of Medical Sciences; Rasht; Iran; Department of Medical Parasitology; Mycology and Entomology; School of Medicine; Guilan University of Medical Sciences; Rasht; Iran.
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Rajaiah P, Mayilsamy M, Kumar A. West Nile virus in India: An update on its genetic lineages. J Vector Borne Dis 2023; 60:225-237. [PMID: 37843232 DOI: 10.4103/0972-9062.374039] [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] [Indexed: 10/17/2023] Open
Abstract
West Nile virus (WNV) is a rapidly spreading mosquito-transmitted zoonotic flavivirus. Mosquitoes belonging to the genus Culex are incriminated as the principal vectors of the virus, which causes West Nile fever (WNF) in humans. Manifestations of WNF include a mild, self-limiting, flu-like illness, which in severe cases (rare) may progress to encephalitis, resulting in life-threatening consequences. WNV is geographically distributed worldwide, covering Africa, the Americas, Europe, and Asia (except Antarctica). The virus exists in a bird-mosquito transmission cycle in nature, with humans and horses as incidental/accidental hosts. The virus can infect a large variety of hosts worldwide, i.e., about 300 birds and around 70 different mosquito species belonging to several genera. For a long time, it was believed that WNV was not highly virulent and caused only mild infection globally. However, the recent frequent and increasing incidence of clinically severe WNV infections, such as encephalitis in humans and horses with significant mortality, has been reported in the Americas, Europe, and several East Asian countries. The emergence of lineage 2 strains endemic to Africa, with epidemic potential in humans and horses in Europe, is considered a serious global health concern. Although WNV is known to circulate in India since 1952, its re-emergence with severe neuro-invasive pathogenic potential in humans in Assam, Kerala, West Bengal and Tamil Nadu states signals urgent efforts to understand the dynamics of circulating strains with regard to its vector, hosts, and environment. This could be done by prioritizing "One Health" approach for developing effective preventive and control strategies. In view of the global interest, we present an overview of the circulating genetic lineages of WNV in India in comparison with the global scenario. In addition, we stress on holistic approaches of "One Health" strategy as the current need of the hour for designing effective preventive and control strategies in the country.
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Affiliation(s)
- Paramasivan Rajaiah
- ICMR-Vector Control Research Centre, Field Station, Madurai, Tamil Nadu, India
| | - Muniaraj Mayilsamy
- ICMR-Vector Control Research Centre, Field Station, Madurai, Tamil Nadu, India
| | - Ashwani Kumar
- ICMR-Vector Control Research Centre, Field Station, Madurai, Tamil Nadu, India
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Koh C, Frangeul L, Blanc H, Ngoagouni C, Boyer S, Dussart P, Grau N, Girod R, Duchemin JB, Saleh MC. Ribosomal RNA (rRNA) sequences from 33 globally distributed mosquito species for improved metagenomics and species identification. eLife 2023; 12:82762. [PMID: 36688360 PMCID: PMC10014081 DOI: 10.7554/elife.82762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
Total RNA sequencing (RNA-seq) is an important tool in the study of mosquitoes and the RNA viruses they vector as it allows assessment of both host and viral RNA in specimens. However, there are two main constraints. First, as with many other species, abundant mosquito ribosomal RNA (rRNA) serves as the predominant template from which sequences are generated, meaning that the desired host and viral templates are sequenced far less. Second, mosquito specimens captured in the field must be correctly identified, in some cases to the sub-species level. Here, we generate mosquito rRNA datasets which will substantially mitigate both of these problems. We describe a strategy to assemble novel rRNA sequences from mosquito specimens and produce an unprecedented dataset of 234 full-length 28S and 18S rRNA sequences of 33 medically important species from countries with known histories of mosquito-borne virus circulation (Cambodia, the Central African Republic, Madagascar, and French Guiana). These sequences will allow both physical and computational removal of rRNA from specimens during RNA-seq protocols. We also assess the utility of rRNA sequences for molecular taxonomy and compare phylogenies constructed using rRNA sequences versus those created using the gold standard for molecular species identification of specimens-the mitochondrial cytochrome c oxidase I (COI) gene. We find that rRNA- and COI-derived phylogenetic trees are incongruent and that 28S and concatenated 28S+18S rRNA phylogenies reflect evolutionary relationships that are more aligned with contemporary mosquito systematics. This significant expansion to the current rRNA reference library for mosquitoes will improve mosquito RNA-seq metagenomics by permitting the optimization of species-specific rRNA depletion protocols for a broader range of species and streamlining species identification by rRNA sequence and phylogenetics.
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Affiliation(s)
- Cassandra Koh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Lionel Frangeul
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Hervé Blanc
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
| | - Carine Ngoagouni
- Institut Pasteur de Bangui, Medical Entomology LaboratoryBanguiCentral African Republic
| | - Sébastien Boyer
- Institut Pasteur du Cambodge, Medical and Veterinary Entomology UnitPhnom PenhCambodia
| | | | - Nina Grau
- Institut Pasteur de Madagascar, Medical Entomology UnitAntananarivoMadagascar
| | - Romain Girod
- Institut Pasteur de Madagascar, Medical Entomology UnitAntananarivoMadagascar
| | - Jean-Bernard Duchemin
- Institut Pasteur de la Guyane, Vectopôle Amazonien Emile AbonnencCayenneFrench Guiana
| | - Maria-Carla Saleh
- Institut Pasteur, Université Paris Cité, CNRS UMR3569, Viruses and RNA Interference Unit, F-75015ParisFrance
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Paulraj PS, Rajamannar V, Renu G, Kumar A. Changing Paradigm in the epidemiology of Japanese encephalitis in India. J Vector Borne Dis 2022; 59:312-319. [PMID: 36751762 DOI: 10.4103/0972-9062.345180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Japanese encephalitis (JE) is a very serious public health problem in India and the conducive environment permit its emergence in non-endemic areas in the country. There are constant changes taking place in the pattern of current agricultural practices and vector breeding habitats which had far-reaching consequences on the epidemiology of JE and the severity of epidemic outbreaks today. Due to the continuous ecological changes taking place, vectors changed in their breeding dynamics, feeding, and resting behavior and started invading previously non-endemic areas. JE has recently spread to new territories due to land-use changes, including forest fragmentation and concentrated livestock production. Changes in the livestock population decreased the cattle pig ratio which enhanced the Japanese encephalitis virus (JEV) infection. This review brings forth the present widespread changes encountered that grossly impact the risk of infection in many places for the emergence of Japanese encephalitis and to address the implications for its control.
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Affiliation(s)
| | | | - Govindarajan Renu
- ICMR-Vector Control Research Centre, Field Station, Madurai, Tamil Nadu, India
| | - Ashwani Kumar
- ICMR Vector Control Research Centre, Puducherry, India
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Japanese Encephalitis Virus Interaction with Mosquitoes: A Review of Vector Competence, Vector Capacity and Mosquito Immunity. Pathogens 2022; 11:pathogens11030317. [PMID: 35335641 PMCID: PMC8953304 DOI: 10.3390/pathogens11030317] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 02/01/2023] Open
Abstract
Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus and a major cause of human viral encephalitis in Asia. We provide an overview of the knowledge on vector competence, vector capacity, and immunity of mosquitoes in relation to JEV. JEV has so far been detected in more than 30 mosquito species. This does not necessarily mean that these species contribute to JEV transmission under field conditions. Therefore, vector capacity, which considers vector competence, as well as environmental, behavioral, cellular, and biochemical variables, needs to be taken into account. Currently, 17 species can be considered as confirmed vectors for JEV and 10 other species as potential vectors. Culex tritaeniorhynchus and Culex annulirostris are considered primary JEV vectors in endemic regions. Culex pipiens and Aedes japonicus could be considered as potentially important vectors in the case of JEV introduction in new regions. Vector competence is determined by various factors, including vector immunity. The available knowledge on physical and physiological barriers, molecular pathways, antimicrobial peptides, and microbiome is discussed in detail. This review highlights that much remains to be studied about vector immunity against JEV in order to identify novel strategies to reduce JEV transmission by mosquitoes.
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Auerswald H, Maquart PO, Chevalier V, Boyer S. Mosquito Vector Competence for Japanese Encephalitis Virus. Viruses 2021; 13:v13061154. [PMID: 34208737 PMCID: PMC8234777 DOI: 10.3390/v13061154] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/02/2021] [Accepted: 06/02/2021] [Indexed: 12/30/2022] Open
Abstract
Japanese encephalitis virus (JEV) is a zoonotic pathogen mainly found in East and Southeast Asia and transmitted by mosquitoes. The objective of this review is to summarize the knowledge on the diversity of JEV mosquito vector species. Therefore, we systematically analyzed reports of JEV found in field-caught mosquitoes as well as experimental vector competence studies. Based on the investigated publications, we classified 14 species as confirmed vectors for JEV due to their documented experimental vector competence and evidence of JEV found in wild mosquitoes. Additionally, we identified 11 mosquito species, belonging to five genera, with an experimentally confirmed vector competence for JEV but lacking evidence on their JEV transmission capacity from field-caught mosquitoes. Our study highlights the diversity of confirmed and potential JEV vector species. We also emphasize the variety in the study design of vector competence investigations. To account for the diversity of the vector species and regional circumstances, JEV vector competence should be studied in the local context, using local mosquitoes with local virus strains under local climate conditions to achieve reliable data. In addition, harmonization of the design of vector competence experiments would lead to better comparable data, informing vector and disease control measures.
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Affiliation(s)
- Heidi Auerswald
- Virology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia
- Correspondence:
| | - Pierre-Olivier Maquart
- Medical and Veterinary Entomology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia; (P.-O.M.); (S.B.)
| | - Véronique Chevalier
- Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia;
- UMR ASTRE, CIRAD, INRA, Université de Montpellier, 34000 Montpellier, France
| | - Sebastien Boyer
- Medical and Veterinary Entomology Unit, Institut Pasteur du Cambodge, Institut Pasteur International Network, Phnom Penh 120210, Cambodia; (P.-O.M.); (S.B.)
- Institut Pasteur, 75015 Paris, France
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Paulraj P, Thenmozhi V, Mishra S, Nagaraj J, Paramasivan R. Seasonal abundance and infection of Japanese encephalitis vectors from Gorakhpur district, Uttar Pradesh, India. J Vector Borne Dis 2021; 58:265-272. [DOI: 10.4103/0972-9062.321740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Lord JS, Al-Amin HM, Chakma S, Alam MS, Gurley ES, Pulliam JRC. Sampling Design Influences the Observed Dominance of Culex tritaeniorhynchus: Considerations for Future Studies of Japanese Encephalitis Virus Transmission. PLoS Negl Trop Dis 2016; 10:e0004249. [PMID: 26726881 PMCID: PMC4699645 DOI: 10.1371/journal.pntd.0004249] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 10/29/2015] [Indexed: 11/19/2022] Open
Abstract
Mosquito sampling during Japanese encephalitis virus (JEV)-associated studies, particularly in India, has usually been conducted via aspirators or light traps to catch mosquitoes around cattle, which are dead-end hosts for JEV. High numbers of Culex tritaeniorhynchus, relative to other species, have often been caught during these studies. Less frequently, studies have involved sampling outdoor resting mosquitoes. We aimed to compare the relative abundance of mosquito species between these two previously used mosquito sampling methods. From September to December 2013 entomological surveys were undertaken in eight villages in a Japanese encephalitis (JE) endemic area of Bangladesh. Light traps were used to collect active mosquitoes in households, and resting boxes and a Bina Pani Das hop cage were used near oviposition sites to collect resting mosquitoes. Numbers of humans and domestic animals present in households where light traps were set were recorded. In five villages Cx. tritaeniorhynchus was more likely to be selected from light trap samples near hosts than resting collection samples near oviposition sites, according to log odds ratio tests. The opposite was true for Cx. pseudovishnui and Armigeres subalbatus, which can also transmit JEV. Culex tritaeniorhynchus constituted 59% of the mosquitoes sampled from households with cattle, 28% from households without cattle and 17% in resting collections. In contrast Cx. pseudovishnui constituted 5.4% of the sample from households with cattle, 16% from households with no cattle and 27% from resting collections, while Ar. subalbatus constituted 0.15%, 0.38%, and 8.4% of these samples respectively. These observations may be due to differences in timing of biting activity, host preference and host-seeking strategy rather than differences in population density. We suggest that future studies aiming to implicate vector species in transmission of JEV should consider focusing catches around hosts able to transmit JEV. The relative numbers of individuals of each mosquito species in an area are important to estimate when identifying species that contribute the most to vector-borne pathogen transmission. However, methods to sample mosquitoes and enumerate the number of individuals collected often vary in their catch efficacy between species. For example, species that take a bloodmeal during daylight hours are less likely to be caught using a light trap than a species that feeds predominantly at night. Similarly, sampling near a mammalian host will more likely collect mosquitoes with a preference for mammals than those with a preference for birds. In this study we compare sampling methods for assessing the relative abundance of mosquito species that may be involved in Japanese encephalitis virus (JEV) transmission. Collections near cattle- a species unable to transmit JEV- have been influential in implicating Cx. tritaeniorhynchus as the primary vector of JEV in South Asia, due to the high number of individuals of this species caught relative to other species. Indeed, this mosquito constituted the majority of the mosquitoes collected by light traps in households with cattle in this study. However, other species were more common when sampling households without cattle or resting mosquitoes near oviposition sites. We propose that methods used to sample mosquitoes in studies aiming to implicate species in JEV transmission in South Asia be reconsidered given that there are other mosquito species that are able to transmit JEV, and these species may be underrepresented when sampling using light traps near cattle.
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Affiliation(s)
- Jennifer S. Lord
- Vector Group, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | | | - Sumit Chakma
- Centre for Communicable Diseases, icddr,b, Mohakhali, Dhaka, Bangladesh
| | | | - Emily S. Gurley
- Centre for Communicable Diseases, icddr,b, Mohakhali, Dhaka, Bangladesh
| | - Juliet R. C. Pulliam
- Department of Biology, University of Florida, Gainesville, Florida, United States of America
- Emerging Pathogens Institute, University of Florida, Gainesville, Florida, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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Impoinvil DE, Baylis M, Solomon T. Japanese encephalitis: on the One Health agenda. Curr Top Microbiol Immunol 2013; 365:205-47. [PMID: 22886540 DOI: 10.1007/82_2012_243] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Japanese encephalitis (JE) is one of the most well studied arthropod zoonotic diseases with human and animal research and their integration spanning 6-7 decades. JE research and policy in some Asian countries has epitomized the 'One Health' strategy of attainment of optimal health for people, animals, and the environment. However, despite significant mitigation of JE in some Asian countries primarily due to vaccination programs and infrastructural development, JE continues to be a major disease burden in the Asian region. Arthropod-borne zoonotic infections such as JE present some of the greatest challenges to animal and human health globally. Their emergence involves a complex interplay of vectors, hosts, environment, climate, and anthropogenic factors. Therefore, the integrated management of infectious agents that affect both humans and animals is perhaps the most highly coveted strategy that public health policy makers aspire to attain in the twenty-first century. This is in response to the seemingly growing challenges of controlling the burden of emerging infectious diseases such as shrinking financial budgets and resources, increasing demand for public health deliverables, demographic shifts and mobility, global trade economies, and climate and landscape changes. Thus, while JE research and policy is an excellent example of the One Health strategy in action, further work is required to address the obstinate burden of transmission.
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Affiliation(s)
- Daniel E Impoinvil
- Department of Epidemiology and Population Health, Liverpool University Climate and Infectious Diseases of Animals (LUCINDA group), University of Liverpool-Institute of Infection and Global Health, Leahurst, Neston, Cheshire, CH64 7TE, UK
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Impoinvil DE, Baylis M, Solomon T. Japanese Encephalitis: On the One Health Agenda. Curr Top Microbiol Immunol 2012. [DOI: 10.1007/978-3-662-45792-4_243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gupta N, Chatterjee K, Karmakar S, Jain SK, Venkatesh S, Lal S. Bellary, India achieves negligible case fatality due to Japanese encephalitis despite no vaccination: an outbreak investigation in 2004. Indian J Pediatr 2008; 75:31-7. [PMID: 18245932 DOI: 10.1007/s12098-008-0003-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To confirm the existence of the outbreak of suspected Japanese encephalitis, identify the source, to understand the circumstances due to which the outbreak was taking place and to suggest measures for its control. METHODS The team visited Bellary from 4th to 10th Sept, 2004. The team interviewed the key persons and analyzed the records at District Surveillance Unit and Entomological Surveillance Unit and case records of suspected JE cases admitted in Encephalitis ward in Vijay Nagar Institute of Medical Sciences (VIMS). Eco-entomological survey was done in houses and surroundings of 3 randomly selected cases of Encephalitis in rural and urban areas of District Bellary. Their family members and neighbors were also asked for the awareness and presence of disease. Data was analyzed for epidemiological and clinical profiles. RESULTS The suspected JE cases were being reported from end of June 2004. The cases were sporadic and out of 34 cases reported to VIMS (till 10th of September), 32 were from Bellary district and 2 were from adjoining Andhra Pradesh. Among these 32, 22 were from Bellary Taluk, which in turn were mainly concentrated (10 were reported) in urban Bellary. The case fatality rate was zero as no death was reported. Entomological surveillance (done by District Surveillance Unit) revealed a high outdoor presence of Culex tritaeniorhynchus as well as an indoor rising density of this mosquito from 2 per man hour catch in January to 22 in the month of August in the affected villages. On the contrary, the investigations on 7th and 8th September revealed high densities of An.subpictus and An. peditaenatus and nil of Culex species in the urban areas. Amplifier host of pigs and water birds were occasionally sighted in the area. CONCLUSION A good community awareness of encephalitis, a prompt referral system and a good supportive treatment for the patients and a good surveillance system and response were observed. Very close proximity with amplifying hosts of pigs was avoided by the community, though piggeries were still not very far away (1-3 Km). These may explain the reduction in cases, deaths and disabilities due to this disease in this district over the years. Possibilities of mutant strain which is less virulent and/or a better immune status of at risk population may also need to be explored. The impact of the mass vaccination with SA 14-14-2, imported from China in Bellary during July, 2006 remains to be evaluated. This will further decrease the case load.
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Affiliation(s)
- Neeru Gupta
- Division of Reproductive Health & Nutrition, Indian Council of Medical Research, New Delhi, India.
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Singh Z, Agarwal VK. Japanese Encephalitis : Is Routine Immunization Required? Med J Armed Forces India 2005; 61:357-9. [PMID: 27407808 PMCID: PMC4922931 DOI: 10.1016/s0377-1237(05)80066-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Accepted: 10/14/2004] [Indexed: 11/24/2022] Open
Abstract
Japanese encephalitis is the leading cause of viral encephalitis in Asia. In endemic areas annual incidence ranges from 10-100 per 100000 population. Case fatality averages 30% and a high percentage of the survivors are left with permanent neuropshychiatric sequelae. There is no effective drug treatment for this disease. In recent decades, Japanese encephalitis virus has caused epidemics in previously unaffected countries like India, Myanmar, Nepal, Sri Lanka, Thailand and Viet Nam. No effective environmental control is known. Although socioeconomic improvement and changes in agricultural practices are likely to reduce viral transmission, large-scale vaccination of affected populations with an effective and affordable vaccine appears logical at least in the short term. The impact of large-scale Japanese Encephalitis vaccination is documented in some regions of China and systematic vaccination has contributed to significant decline in incidence in Japan, Republic of Korea and Thailand.
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Affiliation(s)
- Zile Singh
- ADH & Sr Adv (PSM), Military Hospital, Jalandhar
| | - V K Agarwal
- Reader, Department of PSM, Armed Forces Medical College, Pune-40
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Keiser J, Maltese MF, Erlanger TE, Bos R, Tanner M, Singer BH, Utzinger J. Effect of irrigated rice agriculture on Japanese encephalitis, including challenges and opportunities for integrated vector management. Acta Trop 2005; 95:40-57. [PMID: 15878762 DOI: 10.1016/j.actatropica.2005.04.012] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 03/31/2005] [Accepted: 04/05/2005] [Indexed: 10/25/2022]
Abstract
Japanese encephalitis (JE) is a disease caused by an arbovirus that is spread by marsh birds, amplified by pigs, and mainly transmitted by the bite of infected Culex tritaeniorhynchus mosquitoes. The estimated annual incidence and mortality rates are 30,000--50,000 and 10,000, respectively, and the estimated global burden of JE in 2002 was 709,000 disability-adjusted life years lost. Here, we discuss the contextual determinants of JE, and systematically examine studies assessing the relationship between irrigated rice agriculture and clinical parameters of JE. Estimates of the sizes of the rural population and population in irrigated areas are presented, and trends of the rural population, the rice-irrigated area, and the rice production are analyzed from 1963 to 2003. We find that approximately 1.9 billion people currently live in rural JE-prone areas of the world. Among them 220 million people live in proximity to rice-irrigation schemes. In 2003, the total rice harvested area of all JE-endemic countries (excluding the Russian Federation and Australia) was 1,345,000 km(2). This is an increase of 22% over the past 40 years. Meanwhile, the total rice production in these countries has risen from 226 millions of tonnes to 529 millions of tonnes (+134%). Finally, we evaluate the effect of different vector control interventions in rice fields, including environmental measures (i.e. alternate wet and dry irrigation (AWDI)), and biological control approaches (i.e. bacteria, nematodes, invertebrate predators, larvivorous fish, fungi and other natural products). We conclude that in JE-endemic rural settings, where vaccination rates are often low, an integrated vector management approach with AWDI and the use of larvivorous fish as its main components can reduce vector populations, and hence has the potential to reduce the transmission level and the burden of JE.
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Affiliation(s)
- Jennifer Keiser
- Swiss Tropical Institute, P.O. Box, CH-4002 Basel, Switzerland.
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