Printer Friendly

Emerging and re-emerging arboviral diseases in southeast Asia.

INTRODUCTION

Contagions or rapidly spreading highly infectious diseases, with an estimated high fatality rate of 17 million deaths per year worldwide are major issue of public health concern (1-3). The most overpopulated and economically backward countries in Southeast Asia are particularly vulnerable. Among the emerging infectious diseases, the arboviral diseases group has particularly warrant attention in global health landscape with its potential for epidemics and its unprecedented spread (4,5).

The arboviral diseases (arthropod-borne viral) are caused by a wide variety of RNA viruses with a life cycle that requires both a host (birds or mammals) and a vector (6). The transmission is preceded by a biological replication in an arthropod vector (e.g. mosquitoes, sandflies, ticks, or midges) and these viruses typically circulate among wild animals. More than 130 arboviruses are known to cause human disease, and are responsible for some of the most explosive epidemics of emerging infectious diseases over the past decade. Most arboviruses of public health importance belong to one of three virus genera: Flavivirus, Alphavirus and Bunyavirus. Arboviral diseases include: WNV disease, Yellow fever (YF), DEN, Murray Valley fever (MV), JE, Equine encephalitis, CHIK fever, Rift Valley fever (RFV) and among the tick-borne diseases, tick-borne encephalitis, hemorrhagic fevers except KFDV, CCHF are less common infections.

The evolution and diversification in the tropics of the many arboviruses resulted in more invasive and virulent strains (6,7). Although enzootic amplification is one characteristic of the viruses, some like dengue and chikungunya have lost this requirement and exclusively utilize humans as reservoir and amplification hosts, thus able to cause extensive epidemics. A review of the factors that may lead to emergence and re-emergence of arboviral diseases is presented here, with focus on Southeast Asia region.

Current status of arboviral diseases in Southeast Asia

The true magnitude of arboviral diseases and its associated human, economic and social costs are difficult to quantify, thus largely unknown (8). In one study, the burden of Disability Adjusted Life-Years (DALYs) lost attributable to YFV, JEV, CHIKV, and RFV was estimated to fall between 300,000 and 5,000,000 (9). DEN, considered as the most important human arbovirus, have increased in incidence by 30-fold in the last decade with an estimated 50-100 million annual cases (10,11). From the Southeast Asia region around 1.3 billion people are atrisk of dengue, which is the leading cause of hospitalization and death among children (12). JE is the leading cause of encephalitis epidemic worldwide, mainly in Korea, China, India, and Indonesia. The virus has large geographical range and it puts more than 3 billion people residing in Asia at-risk, and approximately 30,000-50,000 cases are reported annually (13). CHIKV, which often mimics the clinical manifestation of dengue disease, started causing epidemics in India and Southeast Asia since 1950s and has become endemic in many countries (14,15).

The diseases caused by arbovirus are increasingly becoming common causes of severe febrile disease that can progress to long-term physical or cognitive impairment or result in early death. Large number of people is at risk and the limitation in the health system in the endemic areas inevitably results in underestimation of the true burden of arboviral diseases.

Although most arboviral infections are asymptomatic, clinical manifestations range from mild febrile illness to severe encephalitis and are even occasionally fatal. Case definition and adequate surveillance, therefore, are major challenges. Treatment for arboviral diseases is mainly supportive (11,16).

Occurrence of emerging and re-emerging diseases in the last decade

In the past decade there have been sporadic outbreaks of a number of emerging and remerging zoonotic viral diseases in the Southeast Asia. In 2001-02 an outbreak of Nipah virus (NiV) disease in Malaysia among the pigs and pig farmers has claimed many lives. The Pteropus bats (fruit bats) are mainly thought as the reservoir for this virus. The NiV has been responsible for similar outbreaks in the neighbouring countries of Bangladesh and India (Siliguri, West Bengal in 2010-11).

Another highly infectious arboviral disease, the CCHF virus has claimed many lives in the Gujarat state of India in 2010-12 period. The CCHF virus is mainly transmitted via infected tick bites or contact with an infected person or through nosocomial transmission in the hospital setting.

Similarly, in enzootic state, KFD virus circulates through small mammals such as rodents, shrews, ground birds and an array of tick species, however, the species Haemaphysalis spinigera is considered as the main vector and maintained an enzootic in small mammal and monkeys in the forest. A recent outbreak of KFDV was reported during 2011-12, affected 80 villages across the Shimoga district of Karnataka.

Factors responsible for arboviral diseases emergence

Emergence and re-emergence of arboviral infections undoubtedly are increasing phenomena in the last decade. The changing epidemiology and the responsible factors for the dramatic resurgence of arboviral diseases are complex and represent the evolutionary conflicts between rapidly evolving and adapting viruses and their evolving hosts (6,17).

The progress of arboviral disease to epidemic level requires competent vector intersecting with vertebrate host population within an environment that is permissive for such interaction. A large proportion of the arboviral diseases of humans are zoonotic. Further the catalysis by focal and/global environmental, societal and demographic changes will lead to causing spillover infection to humans.

The inherent ability of the RNA viruses to recombine and reassort can lead to genetic mutations and change in host range. The population of reservoir hosts or intermediate insect vectors also undergoes changes that are mainly linked to human movement and urbanization (5,7,18).

Dengue is one example of arboviral disease for which the urbanization factor is strongly associated with its emergence. As the vectors (Aedes aegypti) prefer artificial water containers as its larval habitat thus human habitations became its choice. The four different serotype of DENV can co-circulate and causing hyperendemicity in many areas (19), consequently give them greater epidemic potential and more likely to be transmitted from human to human (20,21).

WNV has spread to north America in the western hemisphere and caused major concern (4,22,23). The globalization, land use and development of rapid transportation systems are thought to be the underlying factors for the WNV invasion (24). It is initially known to be endemic across tropical parts of Africa and Asia. With mosquitoes (Culex species) as the principal vectors along with a bird-mosquito natural cycle, in India the role of ardeid birds in the maintenance of WNV has been described (25). The spread of WNV has also been reported from endemic area JEV, where a substantial proportion of the acute encephalitis syndrome cases can actually be attributed to emerging WNV (26). Wider epidemiological spread of WNV can be attributed to quick adaption of the virus to infect local mosquito vectors (27). Although normally humans are dead-end hosts for WNV, the risk of infection is greatly increased by the zoonotic viral amplification and its persistence in the environment.

JEV is closely related to WNV and is maintained in an enzootic cycle involving aquatic birds and primarily Culex species mosquitoes. However, other animals such as pigs have been shown to play a role as amplification hosts and contribute to the increasing risk of the disease to human and equine alike (4,28). The widespread expansion of JEV cannot be separated from the growth in human populations, land use for irrigated rice agricultural activity and in pig farming (13,29). The existence of JEV in India, Pakistan and Nepal where swine farming is limited may indicate an expanding role for migratory birds in JEV amplification (6,30).

Another factor that contributes to remarkable arbovirus invasions is air transport, which is inevitable in the world with dramatic increase in commerce and traffic volume. This in conjunction with adaptation for replication at higher temperature in mosquito vectors is crucial in enhancing urban transmission where previously the virus was unknown.

The seasonality and inter-annual variation in incidence of diseases are more pronounced for arboviral diseases, as the vector reservoirs are so susceptible to seasonal changes. Climatic conditions and disease transmission dynamics are interlinked, and as more knowledge on meteorological parameters is built, the impact of climate change can and should be mitigated. During the past 50 years or so, patterns of emerging arboviral diseases have changed significantly (8,18). Climate is a major factor in determining the geographic and temporal distribution of arthropods, the characteristics of arthropod life cycles, the consequent dispersal patterns of associated arboviruses, the evolution of arboviruses and the efficiency with which they are transmitted from arthropods to vertebrate hosts (18,31).

Therefore, with gradually increasing surface temperatures, urbanization, irrigation practices and commerce, it seems that the arboviruses will continue to emerge in new regions. For example, the CCHF reported from India (32,33), unexpected but successful establishment of CHIK fever in northern Italy (34-36), the sudden appearance of WNV in North America (22,24,37), the increasing frequency of RVF epidemics in the Arabian Peninsula (38,39), and relatively recent emergence of bluetongue virus in northern Europe (40,41).

As arthropods are dependent on specific climate for their epidemicity and the effect of climate on alteration of the natural cycles are well-documented, there is little doubt that climate change indeed play a role in the transmission dynamics of arboviral diseases. Table 1 summarizes the emerging arboviral diseases in SEA region, and Table 2 shows the categorization of re-emerging/newly emerging arboviral diseases, important viruses that may emerge and less important viruses, but may emerge in the Region.

Priority actions for the perpetual challenges

Disease surveillance is corner stone of response to emerging disease threats. Risk assessment and outbreak preparedness are imperative. Surveillance indicates where a disease has appeared and gives vital clues about how the emerging infectious agent may spread in nature. After surveillance has brought attention to the problem, however, actual prevention and control measures ultimately require additional information provided by the scientific research.

Countries in Southeast Asian region have not been able to give emerging disease surveillance, the priority status it deserves. Much of the surveillance in the region is centered in a few well-established laboratories where there is adequate expertise, sufficient funding and warranted commitment. Mathematical modeling can be used to forecast the risk of arboviral diseases more precisely and to determine the impact of emerging epidemics. Vector control efforts cannot be undermined in this realm and understanding their biology and adaptability are mandatory.

Considerable progress has been made in recent years to develop vaccines for the arboviruses, such as JE42 and DEN11. Novel candidates of vaccines are now being trialed for WNV2. Advances in clinical case management have decreased case fatality rates for DEN, yet there remain many challenges in diagnosing and treating other less common arboviral infection (43).

However, it can be stated that surveillance and other activities that traditionally fall within the domain of public health are not sufficient to adequately address the problem of emerging diseases. Basic, translational and operational research efforts to develop more effective and advanced tools to combat the resurgence of the arboviruses are of critical importance. Understanding the changing pattern and epidemiology of different diseases is imperative (44).

Strengthening the health system as a whole can definitely be beneficial as well, because resurgence of disease often worsened due to the breakdown in public health measures and inadequate capacity of the system to respond. Policy to improve surveillance, prevention and control programmes for arboviral and other zoonotic disease frequently being established late after the outbreak or epidemics had occurred.

Research priorities

With the constant evolution ongoing for the viruses, vectors and host, there is scarcity in the evidence generated from research in the arboviral diseases. Among others, the research priorities in this field should encompass: understanding environmental factors which facilitate emergence, maintenance and transmission of these diseases; studying the evolution of pathogenic infectious agents resulting in changes in infectivity, virulence, transmissibility and adaptations, host factors influencing emergence of new infection and their transmission; development of tools for diagnosis, management, control and prophylaxis; training and infrastructure for responding to emerging diseases; and information sharing on emerging infections and development of research-based evidence to influence policy modifications with respect to the public health improvement.

CONCLUSION

The history of emergence of arboviruses involves several mechanisms, notably geographical expansion linked to human transportation and development, enhanced transmission in peridomestic area and spillover of zoonotic cycle. Global warming increases vector distribution and transmission dynamics. The inherent ability of some arboviruses with Aedes vector to adapt also poses greater risk for explosive epidemics and wider epidemiological spread. The factors associated with the emergence and re-emergence of arboviral diseases are complex and mutually influenced with each other. Collaboration among academia and public health communities is critical in efforts to contain the menace of arboviral diseases emergence/resurgence.

ACKNOWLEDGEMENTS

The first two authors (A.P. Dash and Rajesh Bhatia) are staff members of the World Health Organization. The authors alone are responsible for the views expressed in this publication and they do not necessarily represent the decisions, policies or views of the World Health Organization.

REFERENCES

(1.) WHO global burden disease 2004 update. Available from: http://www.who.int/healthinfo/global burden disease/2004 report update/en/index.html

(2.) Morens D, Folkers G, Fauci A. The challenge of emerging and re-emerging infectious diseases. Nature 2004; 430: 242-9.

(3.) Fauci AS, Touchette NA, Folkers GK. Emerging infectious diseases: A 10-year perspective from the National Institute of Allergy and Infectious Diseases. Emerg Infect Dis 2005; 11(4): 51925. [serial on the Internet]. (accessed on February 27, 2013). Available from: http://wwwnc.cdc.gov/eid/article/11/4/041167.htm

(4.) Gubler DJ. The global emergence/resurgence of arboviral diseases as public health problems. Arc Med Res 2002; 33: 330-42.

(5.) Weaver SC, Reisen WK. Present and future arboviral threats. Antiviral Res 2010; &5(2): 328-45.

(6.) Weaver SC, Barrett ADT. Transmission cycles, host range, evolution and emergence of arboviral disease. Nature Rev Microbiol 2004; 2: 789-801.

(7.) Mackenzie JS, Gubler DJ, Petersen LR. Emerging flaviviruses: The spread and resurgence of Japanese encephalitis, West Nile and dengue viruses. Nat Med 2004; 10: S98-109.

(8.) Arthropod-borne and rodent-borne viral diseases. WHO Tech Rep Ser No. 708. Geneva, Switzerland: World Health Organization 1985; p.1-187.

(9.) LaBeaud AD, Bashir F, King CA. Measuring the burden of arboviral diseases: The spectrum of morbidity and mortality from four prevalent infections. Population Health Metrics 2011; 9: 1. Available from: http://www.pophealthmetrics.com/content/9/1/1.

(10.) Global strategy for dengue prevention and control 2012-20. Geneva: World Health Organization 2012: p. 1-5.

(11.) Comprehensive guidelines for prevention and control of dengue and dengue haemorrhagic fever--revised and expanded edition. New Delhi: WHO Regional Office for South East Asia 2011; p. xiv+196.

(12.) Gubler DJ. Epidemic dengue/dengue hemorrhagic fever as a public health, social and economic problem in the 21st century. Trends Microbiol 2002; 10: 100-3.

(13.) Erlanger TE, Weiss S, Keiser J, Utsinger J, Wiedenmayer K. Past, present and future of Japanese encephalitis. Emerg Infect Dis 2009; 115: 1-7.

(14.) Rao TR. Immunological surveys of arbovirus infections in Southeast Asia, with special reference to dengue, chikungunya, and Kyasanur Forest disease. Bull World Health Organ 1971; 44:

585-91.

(15.) Krishnamoorthy K, Harichandrakumar KT, Krishna Kumari A, Das LK. Burden of chikungunya in India: Estimates of disability adjusted life years (DALY) lost in 2006 epidemic. J Vector Borne Dis 2009; 46: 26-35.

(16.) Domingues RB. Treatment of viral encephalitis. Cent Nerv Syst Agents Med Chem 2009; 9: 56-62.

(17.) Guha-Sapir D, Schimmer B. Dengue fever: New paradigms for a changing epidemiology. Emerg Themes Epidemiol 2005; 2: 1. doi:10.1186/1742-7622-2-1.

(18.) Gould EA, Higgs S. Impact of climate change and other factors on emerging arbovirus diseases. Trans R Soc Trop Med Hyg 2009; 103(2): 109-21.

(19.) Gupta E, Mohan S, Bajpai M, Choudhary A, Singh G. Circulation of Dengue virus-1 (DENV-1) serotype in Delhi, during 201011 after Dengue virus-3 (DENV-3) predominance: A single centre hospital-based study. J Vector Borne Dis 2012; 49(2): 82-5.

(20.) Wang J, Zhang H, Sun X, Fu S, Wang H, Feng Y, et al. Distribution of mosquitoes and mosquito-borne arboviruses in Yunnan Province near the China-Myanmar-Laos border. Am J Trop Med Hyg 2011; 84(5): 738-to.

(21.) Lee VJ, Chow A, Zheng X, Carrasco LR, Cook Ar, Lye DC, et al. Simple clinical and laboratory predictors of chikungunya versus dengue infections in adults. PLoS Negl Trop Dis 2012; 6(9): e1876. doi: 10.1371/journal.pntd.0001786.

(22.) Roehr B. US hit by massive West Nile virus outbreak centred around Texas. BMJ 2012; 345:e5633. doi: 10.1136/bmj.e5633.

(23.) Petersen LR, Roehrig JI. West Nile virus: A re-emerging global pathogen. Emerg Infect Dis 2001; 7(4): 611-k

(24.) Kilpatrick MA. Globalization, land use and the invasion of West Nile virus. Science 2011; 334(6054):323-7. doi:10.1126/sci ence.1201010.

(25.) Paramasivan R, Mishra AC, Mourya DT. West Nile virus: The Indian scenario. Indian J Med Res 2003; 188: 101-8.

(26.) Khan AS, Dutta P, Khan AM, Chowdhury P, Borah J, Doloi P, Mahanta J. West Nile virus infection, Assam, India. Emerg Infect Dis 2011; 17(5): 947-8.

(27.) Kramer LD, Styer LM, Ebel GD. A global perspective on the epidemiology of West Nile virus. Annu Rev Entomol 2008; 53: 61-81.

(28.) Lindahl J, Chirico J, Boqvist S, Thu HT, Magnusson U. Occurrence of Japanese encephalitis virus mosquito vectors in relation to urban pig holdings. Am J Trop Med Hyg 2012; 87(6): 107682.

(29.) Van den Hurk AF, Ritchie SA, Mackenzie JS. Ecology and geographical expansion of Japanese encephalitis virus. Annu Rev Entomol 2009; 54: 17-35.

(30.) Soman RS, Rodrigues FM, Guttikar SN, Guru PY. Experimental viraemia and transmission of Japanese encephalitis virus by mosquitoes in ardeid birds. Indian J Med Res 1977; 66: 709-18.

(31.) Zell R. Global climate change and the emergence/re-emergence of infectious diseases. Int J Med Microbiol 2004; 293 (Suppl. 37): 16-26.

(32.) Lahariya C, Goel MK, Kumar A, Puri M, Sodhi A. Emergence of viral hemorrhagic fevers: Is recent outbreak of Crimean-Congo hemorrhagic fever in India an indication? J Postgrad Med 2012; 58: 39-46.

(33.) Mourya DT, Yadav PD, Shete AM, Gurav YK, Raut CG, Jadi RS, et al. Detection, isolation and confirmation of Crimean-Congo hemorrhagic fever virus in human, ticks and animals in Ahmadabad, India, 2010-2011. PLoS Negl Trop Dis 2012; 6(5):e1653. doi: 10.1371/journal.pntd.0001653.

(34.) Staples JE, Breimau RF, Powers AM. Chikungunya fever: An epidemiological review of a re-emerging infectious disease. Clin Infect Dis 2009; 49: 942-8.

(35.) Rezza G, Nicoletti L, Angelini R, Romi R, Finarelli AC, Panning M, et al. Infection with chikungunya virus in Italy: An outbreak in a temperate region. Lancet 2007; 370: 1840-6.

(36.) Thiboutot MM, Kannan S, Kawalekar OU, Shedlock DJ, Khan AS, Sarangau G, et al. Chikungunya: A potentially emerging epidemic? PLoS Negl Trop Dis 2010; 4(4): e623. doi:10.1371/ journal.pntd. 0000623.

(37.) Centers for Disease Control and Prevention (CDC). West Nile virus disease and other arboviral diseases - United States 2011. MMWR Morb Mortal Wkly Rep 2012; 61(27): 510-4

(38.) Anyamba A, Chretien JP, Formenty PBH, Small J, Tucker Cj, Malone JL, et al. Rift valley fever potential, Arabian peninsula. Emerg Infect Dis 2006; 12(3): 518-20.

(39.) Madani TA, Al-Mazrou YY, Al-Jeffri MH, Mishkhas AA, Al Rabeah AM, Turkistani AM, et al. Rift valley fever epidemic in Saudi Arabia: Epidemiological, clinical, and laboratory characteristics. Clin Infect Dis 2003; 37: 1084-94.

(40.) Carpenter S, Wilson A, Mellor PS. Culicoides and the emergence of bluetongue virus in northern Europe. Trends Microbiol 2009; 17(4): 172-8.

(41.) Purse BV, Mellor PS, Rogers DJ, Samuel AR, Mertens PP, Baylis M. Climate change and the recent emergence of bluetongue in Europe. Nat Rev Microbiol 2005; 3(2): 171-81.

(42.) Okada K, Iwasa T, Namazue J, Akechi M, Ueda S. Safety and immunogenicity of a freeze-dried, cell culture-derived Japanese encephalitis vaccine (Inactivated) in children. Vaccine 2012; 30(41): 5967-72.

(43.) Lee VJ, Chow A, Zheng X, Carresco LR, Cook AR, Lye DC, et al. Simple clinical and laboratory predictors of Chikungunya versus dengue infections in adults. PLoS Negl Trop Dis 2012; 6(9): e1786. doi: 10.1371/journal.pntd.0001786.

(44.) Chakravarti A, Matlani M, Kashyap B, Kumar A. Awareness of changing trends in epidemiology of dengue fever is essential for epidemiological surveillance. Indian J Med Res 2012; 30(2): 2226.

(45.) Kasabi GS, Murhekar MV, Sandhya VK, Raghunandan R, Kiran SK, Channabasappa GH. Coverage and effectiveness of Kyasanur Forest disease (KFD) vaccine in Karnataka, south India 2005-10. PLoS Negl Trop Dis 7(1): e2025. doi:10.1371 journal.pntd.0002025.

(46.) Pattnaik P. Kyasanur Forest disease: An epidemiological view in India. Rev Med Virol 2006; 16: 151.

(47.) Sreenivasan MA, Bhat HR, Rajagopalan PK. The epizootics of Kyasanur Forest disease in wild monkeys during 1964 to 1973. Trans R Soc Trop Med Hyg 1986; 80: 810-4.

(48.) Kasabi GS, Murhekar MV, Yadav PD, Raghunandan R, Kiran SK, Sandhya VK, et al. Kyasanur Forest Disease, India, 20112012. Emerg Infect Dis 2013; 19(2): 278-82.

(49.) Rao BL, Basu A, Wairagkar NS, Gore MM, Arankalle VA, Thakare JP, et al. A large outbreak of acute encephalitis with high fatality rate in children in Andhra Pradesh, India, in 2003, associated with Chandipura virus. Lancet 2004; 364(9437): 869-74.

(50.) Menghani S, Chikhale R, Raval A, Wadibhasme P, Khedekar P. Chandipura virus: An emerging pathogen. Acta Trop 2012; 124(1): 1-14.

(51.) Tesh RB, Modi GB. Growth and transovarial transmission of Chandipura virus (Rhabdoviridae:Vesiculovirus) in Phlebotomus papatasi. Am J Trop Med Hyg 1993; 32: 621-3.

(52.) Bondre VP, Spakal GN, Yergolkar PN, Fulmali PV, Sankararaman V, Ayachit VM, et al. Genetic characterization of Bagaza virus (BAGV) isolated in India and evidence of antiBAGV antibodies in sera collected from encephalitis patients. J Genet Virol 2009; 90: 2644-9.

(53.) Bayes EH. Zika virus outside Africa. Emerg Infect Dis 2009; 15(9): 1347-50.

(54.) Olson JG, Ksiazek TG. Suhandiman, Triwibowo. Zika virus, a cause of fever in Central Java, Indonesia. Trans R Soc Trop Med Hyg 1981; 75: 389-93. doi: 10.1016/0035-9203(81)90100-0.

(55.) Jaafar FM, Attoui H, Mertens PPC, Micco P, de Lamballerie X. Structural organization of an encephalitic human isolate of Banna virus (genus Seadornavirus, family Reoviridae). J Genet Virol 2005; 86: 1147-57.

(56.) Calzolari M, Gaibani P, Bellini R, Defilippo F, Pierro A, Albieri A, et al. Mosquito, bird and human surveillance of West Nile and Usutu viruses in Emilia-Romagna region (Italy) in 2010. PLoS One 7(5): e38058. doi:10.1371/journal.pone. 0038058.

(57.) Mackenzie JS, Williams DT. The zoonotic flaviviruses of southern, south-eastern and eastern Asia, and Australasia: The potential for emergent viruses. Zoonosis Pub Health 2009; 56(6-7): 338-56. doi: 10.1111/j.1863-2378.2008.01208.x.

(58.) Top FH Jr, Kraivapan C, Grossman RA, Rozmiarek H, Edelman R, Gould DJ. Ingwavuma virus in Thailand, infection of domestic pigs. Am J Trop Med Hyg 1974; 23(2): 251-7.

(59.) Converse JD, Tan Ri, Rachman IT, Lee VH, Shope RE. Ingwavuma virus (Simbu group) from Culex and Mansonia mosquitoes (Diptera: Culicidae) in Indonesia. J Med Entomol 1985; 5: 24.

A.P. Dash [1], Rajesh Bhatia [1], Temmy Sunyoto [1] & D.T. Mourya [2]

[1] Department of Communicable Diseases, World Health Organization/South East Asia Regional Office (SEARO), New Delhi; 2] National Institute of Virology, Pune, India

Correspondence to: Prof. A.P. Dash, Regional Advisor, Vector Borne and Neglected Tropical Disease Control, World Health Organization (SEARO), Mahatma Gandhi Marg, Indraprastha Estate, New Delhi-110 002, India.

E-mail: apdash@gmail.com

Received: 21 March 2013

Accepted in revised form: 1 May 2013
Table 1. Summary of emerging arboviruses in Southeast Asia

Arbovirus        Animal group(s)      Transmission
                 affected

Kyasanur         Mammals: Primarily   Vector: Ticks,
  forest           gray langurs         specifically
  disease          (Semnopithecus       nymphal stages
  virus            sp.) and the         of Haemaphysalis
  (KFDV)           red-faced            spinigera
                   bonnet monkey        (primarily).
                   (Macaca              Other
                   radiate), shrew      Haemaphysalis
                   (Suncus              sp. and Ixodid
                   murinus), rats,      sp. Direct
                   birds,               contact with an
                   squirrels,           infected animal
                   porcupine and        (rodent, monkey)
                   bats
Japanese         Primarily pigs       Vector:
  encephalitis     and the ardeid       Specifically
  virus (JEV)      birds.               Culex
                   Mortality in         tritaeniorhynchus.
                   equines may          Other Culicine sp.
                   occur                By the bite of
                                        infected mosquito

Dengue virus     Primarily man        Vector:
  (DENV)           and certain          Specifically Ae.
                   areas lower          aegypti. Other Ae.
                   primates             albopictus. By the
                                        bite of infected
                                        mosquito

West Nile        Primarily pigs       Vector: Specifically
  virus (WNV)      and the ardeid       Culex
                   birds. Equines       tritaeniorhynchus.
                   may succumb          Other Culicine sp.
                   to death             By the bite of
                                        infected mosquito

Chikungunya      Primarily man        Vector: Specifically
  virus                                 Ae. aegypti.
  (CHIKV)                               Other Ae.
                                        albopictus.
                                        By the bite of
                                        infected mosquito
Chandipura       Primarily human      Vector: Specifically
  virus (CDV)                           sandfly P.
                                        argentipes. By the
                                        bite of infected
                                        sandfly

Crimean-Congo    Primarily sheep,     Vector: Ticks,
  hemorrhagic      goat, cattle         specifically
  virus (CCHV)     and buffalo          nymphal stages
                                        of Hyalloma and
                                        Ixodid sp.
                                        Direct contact
                                        with an infected
                                        domestic animals
                                        and their
                                        tissues/blood

Arbovirus        Clinical signs      Severity

Kyasanur         Biphasic: Fever,    Mild to
  forest           tussis,             fatal
  disease          dehydration,
  virus            encephalitis,
  (KFDV)           epistaxis,
                   diarrhoea,
                   shock and
                   death

Japanese         Fever,              Mild to fatal.
  encephalitis     incoordination,     Recovered
  virus (JEV)      convulsions and     persons may
                   death               develop
                                       Permanent
                                       sequele like-
                                       Parkinson's
                                       disease
                                       abnormalities

Dengue virus     Fever, headache,    Mild to fatal
  (DENV)           bodyache,
                   petechial
                   hemorrhages
                   and low blood
                   pressure

West Nile        Fever,              Mild to fatal.
  virus (WNV)      convulsions         Recovered
                   and death           persons may
                                       develop loss
                                       of memory

Chikungunya      Fever, myalgia,     Mild to fatal
  virus            arthralgia and
  (CHIKV)          headache

Chandipura       Fever,              Mild to fatal
  virus (CDV)      convulsions,
                   headache and
                   death

Crimean-Congo    Fever, bodyache,    Fatal
  hemorrhagic      abdominal pain,
  virus (CCHV)     epistaxis,
                   hemoptysis and
                   melena

Arbovirus        Treatment            Prevention and
                                      control

Kyasanur         No specific          Vector control
  forest           treatment.           including insect
  disease          Supportive           repellents and
  virus            care especially      protective
  (KFDV)           for treatment        clothing; Proper
                   of dehydration       vaccination and
                   and hemorrhage       assessment

Japanese         No specific          Vector control
  encephalitis     treatment.           including
  virus (JEV)      Symptomatic          insect
                   treatment as         repellents and
                   antipyretics,        bednets
                   anticonvulsants,
                   isotonic fluid
                   therapy. IV
                   mannitol to
                   reduce the
                   intracranial
                   pressure
Dengue virus     Symptomatic          Vector control
  (DENV)           treatment,           [source
                   fluid                reduction]
                   therapy              including
                                        insect
                                        repellents

West Nile        Symptomatic          Vector control
  virus (WNV)      treatment,           including insect
                   fluid                repellents and
                   therapy              bednets

Chikungunya      Symptomatic          Vector control
  virus            treatment,           (source
  (CHIKV)          fluid                reduction)
                   therapy              including insect
                                        repellents

Chandipura       Symptomatic          Vector control
  virus (CDV)      treatment            including
                   especially for       insect
                   fever, reducing      repellents and
                   the intracranial     bednets.
                   pressure and         Maintaining
                   isotonic fluid       cleanliness and
                   therapy              hygiene at
                                        animal sheds
                                        and houses
Crimean-Congo    Symptomatic          Vector control
  hemorrhagic      treament for         including insect
  virus (CCHV)     hemorrhagic          repellents and
                   abnormalities        protective
                                        clothing. Proper
                                        PPEs while
                                        handling animals
                                        and human
                                        patients.

Arbovirus        Zoonotic          Reference
                                   Nos.

Kyasanur         Yes.              45-18
  forest           Mortality
  disease          in humans
  virus            in enzootic
  (KFDV)           areas

Japanese         Yes.              5,13,
  encephalitis     Mortality         28,29
  virus (JEV)      in humans
                   in enzootic
                   areas

Dengue virus     Yes.              10.11
  (DENV)           Antibodies
                   have been
                   demonstrated
                   in monkeys.
                   No death in
                   domestic or
                   feral animals
                   have been
                   recorded
West Nile        Yes.              23-27
  virus (WNV)      Mortality in
                   equines and
                   crows may
                   be considered
                   as the
                   indicator
Chikungunya      Yes.              34-36
  virus            No domestic
  (CHIKV)          or feral
                   animal
                   mortality
                   reported.
Chandipura         Yes. No         49-51
  virus (CDV)      mortality
                   reported in
                   domestic or
                   feral animals

Crimean-Congo    Yes.              32.33
  hemorrhagic      Mortality
  virus (CCHV)     in humans
                   in enzootic
                   areas

Table 2. Re-emerging and newly emerging arboviruses

Arbovirus          Natural cycle     Vector                 Reference
                                                            Nos.

Dengue 1,2,3,4,    Mosquito,         Aedes                  10, 11,
  and                human,                                   23-27
  Chikungunya        monkey
Japanese           Mosquito, bird,   Cx. triaeniorhynchus   5, 13,
  encephalitis       pig, horse                               28, 29
Kyasanur Forest    Rodent + Lower    Tick; Haemaphysalis    45-48
  disease            primates          sp.
West Nile          Bird + Horse      Cx. vishnui gr.        23-27
Chandipura         Sandflies,        Sandflies; S.          49-51
  encephalitis       human             argentipes
Crimean-Congo      Domestic          Tick (Hyalomma)        32-33
  hemorrhagic        animals,
  fever              Hyalomma
                     ticks

Important and may emerge

Rift Valley        Mosquito,         Culicine sp.           1-5
  fever virus        human, large
                     animals
Yellow fever       Mosquito,         Aedes                  9
                     human,
                     monkey

Less important but may emerge

Bagaza virus       Pigs?             Culicine sp.           51
  flavivirus
Zika like DEN      Mosquito,         Aedes                  52.53
                     human
Banna Reo virus    Pigs?             Culicine sp.           54
  encephalitis
  --China
  like JE
Usutu virus        Pigs?             Culicine sp.           55.56
  mosquito-borne
  flavivirus
Ingwavuma          Pigs?             Culicine sp.           57-59
COPYRIGHT 2013 Indian Council of Medical Research
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2013 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Dash, A.P.; Bhatia, Rajesh; Sunyoto, Temmy; Mourya, D.T.
Publication:Journal of Vector Borne Diseases
Article Type:Report
Geographic Code:9INDI
Date:Jun 1, 2013
Words:4672
Previous Article:A case of vivax malaria with splenic infarction.
Next Article:Malaria vector population dynamics in highland and lowland regions of western Kenya.
Topics:

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters |