Japanese encephalitis virus(JEV)As one of the important causes of human viral encephalitis in Asia,About1%The infected person developed into Japanese encephalitis (JE），And encephalitis Bdeath of illnessRateHighup30%。Survivors have25%-30%May suffer from neurological sequelae, which can develop into lifelong disability or cognitive impairment, so Japanese encephalitis should not be underestimated. WHO (WHO）It is estimated that each year worldwide6.8tens of thousands of casesJECase[1]However, the actual disease burden may reachAnnually17.5tens of thousands of cases[2]。

Because people sufferJELow viral load in the blood after,Usually not enough to spreadJEV inJEVSpread in natural circulation mainly by animal hostsand mosquito vectors, including Culex mosquitoes, wild waders (such as wild ducks and egrets) and pigs. Birds areJEVnatural hosts, bird migration can causeJEVof long-distance transmission and cause the virus to persist in nature。Pigs are amplification hosts,JEVHigh viral load in the blood of pigs,Usually infected by Culex mosquito bitesJEVAfter the pigs.,Bite other animals or people againcaused an outbreak of the epidemic.

Pigs are closely related to people, and in the past pig farmers raised pigs in their own pens, so pigsIt has a lot to do with the human epidemic. In the past prevention and control of Japanese encephalitis,The isolation of pig farms from human settlements is often used,also achieved remarkable results。However, epidemics of encephalitis B also occur in the absence of pigs, suggesting that other hosts in addition to pigs also function as amplification hosts in some cases.

Singapore is in20Century90After the elimination of the pig industry in the s, the localJEVThe incidence of infections has dropped significantly. However，21Early 20th century studies showed the presence of wild boars, dogs, chickens and goats in and around Singapore's offshore islands.JEVSpecific antibodies, indicating that these animals have been infected before.JEV inSingapore is in2010Year2017Year launched the wildlife and poultryJEVMonitoring system for the study of animal host serological characteristics. It was found that the local resident bird sample3.23%,samples of migratory birds9.45%, wild boar samples15.16%all presentJEVantibody positive[3]。

2018A case of local infection found in Seoul, South KoreaJEVHowever, no one in Seoul is raising pigs.[4]。2013Isolated from mosquitoes, humans and pigs in Henan, China inJEVstrains, found in mosquitoes and peopleJEVThe virus is the same type, and the virus in the pig is different from them.[5]。In some countries where pig farming is not common, such as Malaysia, India and South Korea, reportedJEVGenotypes from GenesIIIType (GIII）to the geneIType（GI）The transformation. Therefore, it is necessary to improve the existingJEVsecondary storage hostto explain where there are no pigs or low-density pigsJEVThe spread.

In areas that believe in Islam, such as Bangladesh, India, and Xinjiang, China, the development of the pig industry is restricted. The number of local cattle is dozens or even hundreds of times that of pigs. However, Bangladesh and India haveJEendemic areas. Poultry in these areas, including chickens, ducks and pigeons, make up the majority of the family fauna.50%even up100%。Xinjiang was also detected in mosquitoes collected from different animal farms during arbovirus surveillance.JEV[6]

All of the above indicate that there are some other transmissibleJEVPotential amplification hostsIn the future, the situation of prevention and control of encephalitis B is still grim.。

References

[1]WHO. Japanese encephalitis 2019.https://www.who.int/news-room/factsheets/detail/japanese-encephalitis 。

[2]Quan TM, Thao TTN, Duy NM, Nhat TM, Clapham H. Estimates of the global burden of Japanese encephalitis and the impact of vaccination, 2000-2015. Life. 2020 May 26; 9:E51027. doi: 10.7554/eLife.51027.PMID:32450946;PMCID:PMC7282807.

[3]Yap G, Lim XF, Chan S, How CB, Humaidi M, Yeo G, Mailepessov D, Kong M, Lai YL, Okumura C, Ng LC. Serological evidence of continued spread of Japanese encephalitis virus in Singapore nearly three decades after the end of pig farming. Parasite vectors. 2019 May 17; 12(1):244.doi: 10.1186/s13071-019-3501-0.PMID:31101069;PMCID:PMC6525359.

[4]Bae W, Kim JH, Kim J, Lee J, Hwang ES. Changes in the epidemiological characteristics of Japanese encephalitis virus infection and birds as potential virus transmitters in Korea. J Korean Med Sci. 2018 Feb 26; 33(9):e70.doi: 10.3346/jkms.2018.33.e70.PMID:29441740;PMCID:PMC5811662.

[5]Teng Ming, Luo Jie, Fan Jianming, Chen Ling, Wang Xutao, Yao Wen, Wang Qingqing, Zhang Ping. Molecular characterization of Japanese encephalitis virus transmitted among pigs and mosquitoes from pig farms in Henan Province, China. Viral Genes. 2013 Feb; 46(1):170-4.doi: 10.1007/s11262-012-0813-y.Epub format 2012 Sep 4.PMID:22945473.

[6]Hameed M, Khan S, Xu J, Zhang J, Wang X, Di D, Chen Z, Naveed Anwar M, Wahaab A, Ma X, Nawaz M, Liu K, Li B, Shao D, Qiu Y, Wei J, Ma Z. Detection of Japanese encephalitis virus in mosquitoes in Xinjiang in next-generation sequencing arbovirus surveillance. Transbound Emerg Dis. 2021 Mar; 68(2):467-476.doi: 10.1111/tbed.13697.Epub format 2020 Aug 15.PMID:32614516.

Introduction to the author:

Tang Qing is a researcher and doctoral supervisor of the Institute of Viral Disease Prevention and Control of the Chinese Center for Disease Control and Prevention. Has been engaged in the field of medical virology research work, has undertaken the National Natural Science Foundation and“863”Project, Sino-Japanese and Sino-French scientific and technological cooperation projects, as a sub-project leader participated in agricultural public welfare industry research projects and“Eleventh Five-Year Plan”Major national scientific research projects such as major national science and technology projects have won a number of national, provincial and ministerial science and technology awards and special government subsidies from the State Council.