Epidemiology of Japanese encephalitis in the Philippines prior to routine immunization

Lopez, Anna Lena; Raguindin, Peter Francis; Aldaba, Josephine G.; Avelino, F.; Sy, Ava Kristy; Heffelfinger, James D.; Silva, Maria Wilda T.

doi:10.1016/j.ijid.2020.10.061

Cited by 13 publications

(11 citation statements)

References 19 publications

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“…Children are at greater risk of JEV infection than older people in countries where the virus is endemic, as most adults are exposed to infection during childhood. 1,22,23 However, our findings and the preliminary results of the NSW serosurvey 19 activities), or the greater lifetime risk of exposure through travel. Older seropositive participants may also have been exposed to other flaviviruses, such as MVEV, including during the large 1974 outbreak (25 of 27 JEV IgG-seropositive participants were aged 50 years or more), and our test results may have been confounded by antigenic cross-reactivity.…”

Section: Discussionmentioning

confidence: 50%

“…We found that sex was not a statistically significant risk factor for infection, but in regions where JEV is endemic boys and men are more likely to be infected, experience clinical illness, and have poor outcomes than girls and women. 5,22 As 18 of 45 cases of Japanese encephalitis in Australia since 2021 were in men aged 60 years or older, 26 further investigations in immunologically naïve populations are needed.…”

Section: Discussionmentioning

confidence: 99%

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Serosurvey for Japanese encephalitis virus antibodies following an outbreak in an immunologically naïve population, Victoria, 2022: a cross‐sectional study

Marsland,

Thomson,

O'Brien

et al. 2024

Medical Journal of Australia

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ObjectivesTo investigate the distribution and prevalence of Japanese encephalitis virus (JEV) antibody (as evidence of past infection) in northern Victoria following the 2022 Japanese encephalitis outbreak, seeking to identify groups of people at particular risk of infection; to investigate the distribution and prevalence of antibodies to two related flaviviruses, Murray Valley encephalitis virus (MVEV) and West Nile virus Kunjin subtype (KUNV).Study designCross‐sectional serosurvey (part of a national JEV serosurveillance program).SettingThree northern Victorian local public health units (Ovens Murray, Goulburn Valley, Loddon Mallee), 8 August – 1 December 2022.ParticipantsPeople opportunistically recruited at pathology collection centres and by targeted recruitment through community outreach and advertisements. People vaccinated against or who had been diagnosed with Japanese encephalitis were ineligible for participation, as were those born in countries where JEV is endemic.Main outcome measuresSeroprevalence of JEV IgG antibody, overall and by selected factors of interest (occupations, water body exposure, recreational activities and locations, exposure to animals, protective measures).Results813 participants were recruited (median age, 59 years [interquartile range, 42–69 years]; 496 female [61%]); 27 were JEV IgG‐seropositive (3.3%; 95% confidence interval [CI], 2.2–4.8%) (median age, 73 years [interquartile range, 63–78 years]; 13 female [48%]); none were IgM‐seropositive. JEV IgG‐seropositive participants were identified at all recruitment locations, including those without identified cases of Japanese encephalitis. The only risk factors associated with JEV IgG‐seropositivity were age (per year: prevalence odds ratio [POR], 1.07; 95% CI, 1.03–1.10) and exposure to feral pigs (POR, 21; 95% CI, 1.7–190). The seroprevalence of antibody to MVEV was 3.0% (95% CI, 1.9–4.5%; 23 of 760 participants), and of KUNV antibody 3.3% (95% CI, 2.1–4.8%; 25 of 761).ConclusionsPeople living in northern Victoria are vulnerable to future JEV infection, but few risk factors are consistently associated with infection. Additional prevention strategies, including expanding vaccine eligibility, may be required to protect people in this region from Japanese encephalitis.

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Section: Discussionmentioning

confidence: 50%

Section: Discussionmentioning

confidence: 99%

Serosurvey for Japanese encephalitis virus antibodies following an outbreak in an immunologically naïve population, Victoria, 2022: a cross‐sectional study

Marsland,

Thomson,

O'Brien

et al. 2024

Medical Journal of Australia

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“…The estimated incidence of severe JE disease in the district (approximately 1 case per 100,000) is similar to other low endemic countries before introduction of the vaccine and lower than many highly endemic regions 26,27 . On average under 1% of the population gets infected annually, and around 1:1,000 of infections result in severe disease and 1:10.000 result in death.…”

Section: Discussionmentioning

confidence: 55%

Informing an investment case for Japanese encephalitis vaccine introduction in Bangladesh

Duque,

Naser,

Paul

et al. 2024

Preprint

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Background Japanese encephalitis virus (JEV) is a major threat to human health. Bangladesh is considering introducing a JEV vaccine, however, the investment case is hampered by a poor understanding of key aspects of JEV ecology, including underlying patterns of infection, the infection fatality ratio, and which host and vectors maintain transmission. Methods We conducted a seroprevalence study in individuals of all ages in Chapai Nawabganj, Bangladesh. We tested blood samples for anti-JEV antibodies using a novel assay that limits cross-reactivity with dengue virus, trapped mosquitoes, and collected information about potential host species. We combined our results with data from a pig census, human case data and healthcare seeking patterns, all from the same region, and used mathematical models to recover risk factors for infection, and underlying probabilities of severe disease and death. Findings We found 14.3% (203/1455) of participants had antibodies against JEV. We estimated 0.5% of the susceptible population gets infected each year, however, infection risk was spatially heterogeneous, with the presence of pigs in the vicinity being the most important predictor of seropositivity. We identified 10 different known mosquito vectors for JEV. We estimated that 1 in 1,000 infections result in severe disease, 1 in 10,000 result in death, and 76% of severe cases are missed by surveillance systems. Interpretation JEV infection risk is highly spatially heterogeneous, with the underlying potential of vaccines linked to the distribution of pig-raising communities.

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“…5 articles also grouped patient outcome into severe/moderate/minor yet based on the degree of independent functioning and controllability of seizures or the author’s subjective assessment [ 17 , 83 – 86 ]. 4 articles adopted Modified Rankin Scale to measure the degree of disability or dependence in the daily activities [ 87 – 90 ]. 3 articles used Glasgow Coma Scale [ 91 – 93 ] and the remaining 2 articles used the Whitely’s method [ 94 , 95 ].…”

Section: Resultsmentioning

confidence: 99%

Estimates of Japanese Encephalitis mortality and morbidity: A systematic review and modeling analysis

et al. 2022

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Background Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Over the years, efforts in JE treatment and control might change the JE fatality risk. However, previous estimates were from 10 years ago, using data from cases in the 10 years before this. Estimating JE disease severity is challenging because data come from countries with different JE surveillance systems, diagnostic methods, and study designs. Without precise and timely JE disease severity estimates, there is continued uncertainty about the JE disease burden and the effect of JE vaccination. Methodology We performed a systematic review to collate age-stratified JE fatality and morbidity data. We used a stepwise model selection with BIC as the selection criteria to identify JE CFR drivers. We used stacked regression, to predict country-specific JE CFR from 1961 to 2030. JE morbidity estimates were grouped from similar study designs to estimate the proportion of JE survivors with long-term neurological sequelae. Principal findings We included 82 and 50 peer-reviewed journal articles published as of March 06 2021 for JE fatality and morbidity with 22 articles in both analyses. Results suggested overall JE CFR estimates of 26% (95% CI 22, 30) in 1961–1979, 20% (95% CI 17, 24) in 1980–1999, 14% (95% CI 11, 17) in 2000–2018, and 14% (95% CI 11, 17) in 2019–2030. Holding other variables constant, we found that JE fatality risk decreased over time (OR: 0.965; 95% CI: 0.947–0.983). Younger JE cases had a slightly higher JE fatality risk (OR: 1.012; 95% CI: 1.003–1.021). The odds of JE fatality in countries with JE vaccination is 0.802 (90% CI: 0.653–0.994; 95% CI: 0.62–1.033) times lower than the odds in countries without JE vaccination. Ten percentage increase in the percentage of rural population to the total population was associated with 15.35% (95% CI: 7.71, 22.57) decrease in JE fatality odds. Ten percentage increase in population growth rate is associated with 3.71% (90% CI: 0.23, 7.18; 95% CI: -0.4, 8.15) increase in JE fatality odds. Adjusting for the effect of year, rural population percent, age of JE cases, and population growth rate, we estimated that there was a higher odds of JE fatality in India compared to China. (OR: 5.46, 95% CI: 3.61–8.31). Using the prediction model we found that, in 2000–2018, Brunei, Pakistan, and Timor-Leste were predicted to have the highest JE CFR of 20%. Bangladesh, Guam, Pakistan, Philippines, and Vietnam had projected JE CFR over 20% for after 2018, whereas the projected JE CFRs were below 10% in China, Indonesia, Cambodia, Myanmar, Malaysia, and Thailand. For disability, we estimated that 36% (min-max 0–85) JE patients recovered fully at hospital discharge. One year after hospital discharge, 46% (min-max 0%-97%) JE survivors were estimated to live normally but 49% (min-max 3% - 86%)till had neurological sequelae. Conclusion JE CFR estimates were lower than 20% after 2000. Our study provides an updated estimation of CFR and proportion of JE cases with long-term neurological sequelae that could help to refine cost-benefit assessment for JE control and elimination programs.

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Epidemiology of Japanese encephalitis in the Philippines prior to routine immunization

Cited by 13 publications

References 19 publications

Serosurvey for Japanese encephalitis virus antibodies following an outbreak in an immunologically naïve population, Victoria, 2022: a cross‐sectional study

Serosurvey for Japanese encephalitis virus antibodies following an outbreak in an immunologically naïve population, Victoria, 2022: a cross‐sectional study

Informing an investment case for Japanese encephalitis vaccine introduction in Bangladesh

Estimates of Japanese Encephalitis mortality and morbidity: A systematic review and modeling analysis

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