Estimates of the global burden of Japanese Encephalitis and the impact of vaccination from 2000-2015

Abstract

<jats:p>Japanese encephalitis (JE) is a mosquito-borne disease, known for its high death and disability rate among symptomatic cases. Many effective vaccines are available for JE, and the use of a recently developed and inexpensive vaccine has been increasing over the recent years particularly with Gavi support. Estimates of the local burden and the past impact of vaccination are therefore increasingly needed, but difficult due to the limitations of JE surveillance. In this study, we implemented a mathematical modelling method combined with age-stratifed case data which can overcome some of these limitations. We estimate in 2015 JE infections caused 100,308 cases (95%CI: 61,720 - 157,522) and 25,125 deaths (95%CI: 14,550 - 46,031), and that between 2000 and 2015 307,774 JE cases (95%CI: 167,442- 509,583) were averted due to vaccination. Our results highlight areas that could have the greatest benefit from starting vaccination or from scaling up existing programs and will be of use to support local and international policymakers in making vaccine allocation decisions.</jats:p>

Changes in Rice and Livestock Production and the Potential Emergence of Japanese Encephalitis in Africa

“…Japanese encephalitis virus (JEV) caused >100,000 cases of Japanese encephalitis (JE) and c . 25,000 deaths in 2015 [ 1 ]. There are 24 JE endemic countries in Asia, with sporadic outbreaks in Australasia [ 1 , 2 ].…”

“…25,000 deaths in 2015 [ 1 ]. There are 24 JE endemic countries in Asia, with sporadic outbreaks in Australasia [ 1 , 2 ]. Existing evidence suggests that the geographic distribution of JE is limited to these two regions; however, isolations of JEV have recently been made in Africa and Europe [ 3 , 4 , 5 ].…”

“…Quan et al [ 1 ] noted that the estimated force of infection for JEV from animals to humans broadly correlated with pig density and Cx. tritaeniorhynchus probability of presence across Asia (as estimated by [ 19 , 20 ]).…”

“…al. [ 1 ]) and for African countries over time; and (iii) compare land mass dedicated to rice production for the JE endemic countries in 2015 with that for African countries over time. Collectively, these data inform hypotheses about why JE may not have emerged previously in Africa, but also highlight the potential for emergence in some countries due to increases in pig production relative to cattle, coincident with increases in rice production.…”

How can the public health impact of vaccination be estimated?

“…Herd effects will not arise for all vaccine preventable diseases, for example, Japanese Encephalitis is vector-borne (i.e. not transmitted person-to-person) and the majority of cases are due to spillover events14 . Hence in this case, FVPs will not provide protection to others.In this analysis, we focus on calculating impact estimates for HepB (dynamic model with long-term outcomes and herd effects), measles (dynamic model with short-term outcomes and herd effects) and YF (static model without herd effects)[15][16][17][18] .We use anonymised countries for each of the pathogens, denoted by Country A for HepB, Country B for measles and Country C for YF, with a focus on the years 2000-2017.…”