Epidemiological Features, Clinical Symptoms, and Environmental Risk Factors for Notifiable Japanese Encephalitis in Taiwan From 2008 to 2020: Retrospective Study

Overview

Journal JMIR Public Health Surveill

Publisher JMIR Publications

Date 2025 Jan 29

PMID 39881432

Authors

Fu-Huang Lin

Yu-Ching Chou

Chi-Jeng Hsieh

Chia-Peng Yu

Affiliations

Soon will be listed here.

Abstract

Background: Japanese encephalitis (JE) is a zoonotic parasitic disease caused by the Japanese encephalitis virus (JEV), and may cause fever, nausea, headache, or meningitis. It is currently unclear whether the epidemiological characteristics of the JEV have been affected by the extreme climatic conditions that have been observed in recent years.

Objective: This study aimed to examine the epidemiological characteristics, trends, and potential risk factors of JE in Taiwan from 2008 to 2020. Specifically, the study focused on gender, age, season, residential area, clinical manifestations, high-risk areas, and the impact of environmental and climate factors.

Methods: This study reviewed publicly available annual summary data on reported JE cases in the Taiwan Centers for Diseases Control between 2008 and 2020.

Results: This study collected 309 confirmed domestic patients and 4 patients with imported JE. There was an increasing trend in the incidence of JE, 0.69-1.57 cases per 1,000,000 people, peaking in 2018. Case fatality rate was 7.7% (24/313). Comparing sex, age, season, and place of residence, the incidence rate was highest in males, 40- to 59-year-old patients, summer, and the Eastern region, with 1.89, 3.27, 1.25, and 12.2 cases per million people, respectively. The average coverage rate of the JE vaccine for children in Taiwan is 94.9%. Additionally, the major clinical manifestations of the cases included fever, unconsciousness, headache, stiff necks, psychological symptoms, vomiting, and meningitis. The major occurrence places of JE included paddy fields, pig farms, pigeon farms, poultry farms, and ponds. For air pollution factors, linear regression analysis showed that SO2 (ppb) concentration was positively associated with JE cases (β=2.184, P=.02), but O3 (ppb) concentration was negatively associated with them (β=-0.157, P=.01). For climate factors, relative humidity (%) was positively associated with JE cases (β=.380, P=.02).

Conclusions: This study is the first to report confirmed cases of JE from the surveillance data of the Taiwan Centers for Diseases Control between 2008 and 2020. It identified residence, season, and age as risk factors for JE in Taiwan. Air pollution and climatic factors also influenced the rise in JE cases. This study confirmed that JE remains a prevalent infectious disease in Taiwan, with its epidemic gradually increasing in severity. These findings empower clinicians and health care providers to make informed decisions, guiding their care and resource allocation for patients with JE, a disease that significantly impacts the health and well-being of the Taiwanese population.

References

Williams C, Webb C, Higgs S, van den Hurk A . Japanese Encephalitis Virus Emergence in Australia: Public Health Importance and Implications for Future Surveillance. Vector Borne Zoonotic Dis. 2022; 22(11):529-534. DOI: 10.1089/vbz.2022.0037. View

Lopalco P, Biasio L . Japanese Encephalitis can be devastating. Ann Ig. 2024; 36(3):370-375. DOI: 10.7416/ai.2024.2616. View

Pham D, Howard-Jones A, Hueston L, Jeoffreys N, Doggett S, Rockett R . Emergence of Japanese encephalitis in Australia: a diagnostic perspective. Pathology. 2022; 54(6):669-677. DOI: 10.1016/j.pathol.2022.07.001. View

Mayilsamy M, Vijayakumar A, Veeramanoharan R, Rajaiah P, Balakrishnan V, Kumar A . Impact of COVID-19 lockdown during 2020 on the occurrence of vector-borne diseases in India. J Vector Borne Dis. 2023; 60(2):207-210. DOI: 10.4103/0972-9062.364762. View

Lim M, Loh Z, Yeo H, Yenamandra S, Kong M, Pang H . Isolation and Genetic Characterization of Japanese Encephalitis Virus Two Decades after Its Elimination in Singapore. Viruses. 2022; 14(12). PMC: 9786948. DOI: 10.3390/v14122662. View

Sapkal G, Wairagkar N, Ayachit V, Bondre V, Gore M . Detection and isolation of Japanese encephalitis virus from blood clots collected during the acute phase of infection. Am J Trop Med Hyg. 2008; 77(6):1139-45. View

Wu X, Lu Y, Zhou S, Chen L, Xu B . Impact of climate change on human infectious diseases: Empirical evidence and human adaptation. Environ Int. 2015; 86:14-23. DOI: 10.1016/j.envint.2015.09.007. View

Hong C, Zhang Q, Zhang Y, Davis S, Tong D, Zheng Y . Impacts of climate change on future air quality and human health in China. Proc Natl Acad Sci U S A. 2019; 116(35):17193-17200. PMC: 6717307. DOI: 10.1073/pnas.1812881116. View

Tandale B, Khude P, Deshmukh P, Narang R, Qazi M, Padmaja G . Effectiveness of Japanese encephalitis vaccination among children in central India. J Med Virol. 2022; 95(1):e28399. DOI: 10.1002/jmv.28399. View

10.

Chang Y, Chang H, Wu H, Chen K . Epidemiological Features of Japanese Encephalitis in Taiwan from 2000 to 2014. Am J Trop Med Hyg. 2016; 96(2):382-388. PMC: 5303041. DOI: 10.4269/ajtmh.16-0330. View

11.

Le Flohic G, Porphyre V, Barbazan P, Gonzalez J . Review of climate, landscape, and viral genetics as drivers of the Japanese encephalitis virus ecology. PLoS Negl Trop Dis. 2013; 7(9):e2208. PMC: 3772072. DOI: 10.1371/journal.pntd.0002208. View

12.

Zhang Y, Wang H, Du J, Wang Y, Zang C, Cheng P . Population genetic structure of Culex tritaeniorhynchus in different types of climatic zones in China. BMC Genomics. 2024; 25(1):673. PMC: 11225206. DOI: 10.1186/s12864-024-10589-4. View

13.

Wu Y, Chen J, Su C . Occurrence of old age Japanese Encephalitis: Current situation in Taiwan. J Formos Med Assoc. 2017; 116(12):915-916. DOI: 10.1016/j.jfma.2017.04.010. View

14.

Guo H, Sun L, Shen X, Hu W . A Retrospective Study of the Clinical Characteristics of Japanese Encephalitis in Adults. J Integr Neurosci. 2022; 21(5):125. DOI: 10.31083/j.jin2105125. View

15.

Su C, Yang C, Teng H, Lu L, Lin C, Tsai K . Molecular epidemiology of Japanese encephalitis virus in mosquitoes in Taiwan during 2005-2012. PLoS Negl Trop Dis. 2014; 8(10):e3122. PMC: 4183467. DOI: 10.1371/journal.pntd.0003122. View

16.

Ghosh D, Basu A . Japanese encephalitis-a pathological and clinical perspective. PLoS Negl Trop Dis. 2009; 3(9):e437. PMC: 2745699. DOI: 10.1371/journal.pntd.0000437. View

17.

Turtle L, Solomon T . Japanese encephalitis - the prospects for new treatments. Nat Rev Neurol. 2018; 14(5):298-313. DOI: 10.1038/nrneurol.2018.30. View

18.

Folly A, Dorey-Robinson D, Hernandez-Triana L, Ackroyd S, Vidana B, Lean F . Temperate conditions restrict Japanese encephalitis virus infection to the mid-gut and prevents systemic dissemination in Culex pipiens mosquitoes. Sci Rep. 2021; 11(1):6133. PMC: 7971067. DOI: 10.1038/s41598-021-85411-2. View

19.

Holland K, Jones C, Vivolo-Kantor A, Idaikkadar N, Zwald M, Hoots B . Trends in US Emergency Department Visits for Mental Health, Overdose, and Violence Outcomes Before and During the COVID-19 Pandemic. JAMA Psychiatry. 2021; 78(4):372-379. PMC: 7859873. DOI: 10.1001/jamapsychiatry.2020.4402. View

20.

Tewari P, Ma P, Gan G, Janhavi A, Choo E, Koo J . Non-linear associations between meteorological factors, ambient air pollutants and major mosquito-borne diseases in Thailand. PLoS Negl Trop Dis. 2023; 17(12):e0011763. PMC: 10752508. DOI: 10.1371/journal.pntd.0011763. View