Doctoral Thesis
Epidemiological and Economic Studies on Japanese Encephalitis in the Province of Bali, Indonesia
Doctor of Philosophy (PhD), Murdoch University
2023
Abstract
Japanese encephalitis (JE) is endemic in Indonesia, with the annual incidence in Bali province estimated to be 7.1 per 100,000 children. As JE is a zoonotic disease, management programmes need to consider the complex nature of the disease. Therefore, epidemiological, and economic studies on Japanese encephalitis virus (JEV) in Bali, Indonesia, were designed and performed. To investigate the frequency of JEV infection in pigs in Bali, serum was collected from 443 pigs and tested using a commercial IgG ELISA. The estimated seroprevalence was very high (96.6%, 95%CI: 96.6 – 99.3) indicating high JEV transmission in the area. To identify the typical age of infection, a cohort study was conducted on two pig farms in Denpasar and Badung, Bali. Seroconversion between 5 to 8 weeks of age occurred in one pig, aligning with the identification of JEV genotype III in the blood sample. In addition, Culex quinquefasciatus, a competent JEV vector, was the dominant mosquito species found in the mosquito traps on the two farms. As JEV seemed to intensively circulate around pig farms, knowledge of JE and management practices associated with risk of JE were explored. The farmers surveyed from Denpasar were 4 times (OR 3.95, 95% CI: 2.06 – 7.70, p<0.001) more likely to be knowledgeable about JE compared to the farmers from Badung regency. However, there was no evidence of a difference in risk practices associated with JEV exposure and transmission in pig farmers from Badung compared to those from Denpasar (OR 1.04, 95% CI: 0.58 – 1.86, p>0.99). To explore the economic value of reducing the impact of the disease, a control programme of insecticide-treated mosquito net intervention was proposed and it was potentially beneficial over a 10-year period with an estimated net present value of USD 163,765 (90% PI: 153,587 – 173,943) and a benefit-cost ratio of 1.41 (90% PI: 1.32 – 1.50). The cost-effectiveness was USD 261 (90% PI: 245 - 277) per zDALY-averted. Overall, these findings indicate that JEV is circulating intensively in Bali, with pigs and Culex mosquitoes having an important role in viral transmission. Public awareness campaigns targeting effective JE prevention practices, combined with the use of insecticidetreated mosquito nets to cover pigpens are recommended for the local pig farmers.
Details
- Title
- Epidemiological and Economic Studies on Japanese Encephalitis in the Province of Bali, Indonesia
- Authors/Creators
- I M Kardena
- Contributors
- Mieghan Bruce (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthShafi Sahibzada (Supervisor) - Murdoch University, Centre for Biosecurity and One HealthMark O'Dea (Supervisor)
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005617462907891
- Murdoch Affiliation
- Centre for Biosecurity and One Health; School of Veterinary Medicine
- Resource Type
- Doctoral Thesis
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