-
Le Infezioni in Medicina 2022West Nile virus (WNV) is a member of the Japanese encephalitis serocomplex, which was first described in 1937 as neurotropic virus in Uganda in 1937. Subsequently, WNV... (Review)
Review
West Nile virus (WNV) is a member of the Japanese encephalitis serocomplex, which was first described in 1937 as neurotropic virus in Uganda in 1937. Subsequently, WNV was identified in the rest of the old-world and from 1999 in North America. Birds are the primary hosts, and WNV is maintained in a bird-mosquito-bird cycle, with pigs as amplifying hosts and humans and horses as incidental hosts. WNV transmission is warranted by mosquitoes, usually of the spp., with a tendency to spill over when mosquitoes' populations build up. Other types of transmissions have been described in endemic areas, as trough transplanted organs and transfused blood, placenta, maternal milk, and in some occupational settings. WNV infections in North America and Europe are generally reported during the summer and autumn. Extreme climate phenomena and soil degradation are important events which contribute to expansion of mosquito population and consequently to the increasing number of infections. Draught plays a pivotal role as it makes foul water standing in city drains and catch basins richer of organic material. The relationship between global warming and WNV in climate areas is depicted by investigations on 16,298 WNV cases observed in the United States during the period 2001-2005 that showed that a 5°C increase in mean maximum weekly temperature was associated with a 32-50% higher incidence of WNV infection. In Europe, during the 2022 season, an increase of WNV cases was observed in Mediterranean countries where 1,041 cases were reported based on ECDC data. This outbreak can be associated to the climate characteristics reported during this period and to the introduction of a new WNV-1 lineage. In conclusion, current climate change is causing an increase of mosquito circulation that supports the widest spread of some vector-borne virus including WNV diffusion in previously non-permissible areas. This warrant public health measures to control vectors circulation to reduce WNV and to screen blood and organ donations.
PubMed: 36908379
DOI: 10.53854/liim-3101-4 -
Journal of Infection and Public Health Sep 2022Japanese encephalitis (JE) is a viral zoonotic disease that has been found in several countries of Asia and is responsible for high mortality and morbidity of men and... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Japanese encephalitis (JE) is a viral zoonotic disease that has been found in several countries of Asia and is responsible for high mortality and morbidity of men and animals in rural and sub-urban endemic areas due to the virus re-circulation among diverse hosts and vectors. The present study estimates the prevalence of the JE virus in the vector and animal population of the Asian continent using a systematic review and meta-analysis.
METHODS
The Cochran collaborators' Preferred Reporting Items for Systematic Reviews and Meta-Analysis [PRISMA] guidelines were used for systematic review and meta-analysis. The heterogeneity was observed in meta-regression analysis due to several factors including region, species, and different diagnostic assays used in various studies. Thus we did sensitivity and subgroup analysis.
RESULTS
The prevalence of the JE virus was calculated using a total sample size of 47,391. Subgroup analysis revealed the JE virus prevalence of 39% in the Southeast Asia region, followed by East Asia with 35% and South Asia with 15% prevalence. Hence, the overall pooled prevalence of the JE virus was 26% in the Asian continent.
CONCLUSIONS
The highest proportion of infection was found in pigs amongst all animals, reinforcing the fact that they can be used as sentinels to predict outbreaks in humans. The findings of this study will enable researchers and policymakers in better understanding the disease's spatial and temporal distribution, as well as in creating and implementing location-specific JE prevention and control measures.
Topics: Animals; Culicidae; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Male; Mosquito Vectors; Prevalence; Swine
PubMed: 35914358
DOI: 10.1016/j.jiph.2022.07.010 -
ELife May 2020Japanese encephalitis (JE) is a mosquito-borne disease, known for its high mortality and disability rate among symptomatic cases. Many effective vaccines are available...
Japanese encephalitis (JE) is a mosquito-borne disease, known for its high mortality and disability rate among symptomatic cases. Many effective vaccines are available for JE, and the use of a recently developed and inexpensive vaccine, SA 14-14-2, 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 (catalytic model) combined with age-stratifed case data from our systematic review which can overcome some of these limitations. We estimate in 2015 JEV infections caused 100,308 JE cases (95% CI: 61,720-157,522) and 25,125 deaths (95% CI: 14,550-46,031) globally, and that between 2000 and 2015 307,774 JE cases (95% CI: 167,442-509,583) were averted due to vaccination globally. 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.
Topics: Encephalitis, Japanese; Endemic Diseases; Global Burden of Disease; Humans; Japanese Encephalitis Vaccines; Vaccination
PubMed: 32450946
DOI: 10.7554/eLife.51027 -
Tropical Medicine and Infectious Disease Apr 2023Flaviviruses include virus species that are major public health threats worldwide. To determine the immunity landscape of these viruses, seroprevalence studies are often... (Review)
Review
Flaviviruses include virus species that are major public health threats worldwide. To determine the immunity landscape of these viruses, seroprevalence studies are often performed using IgG ELISA, which is a simple and rapid alternative to the virus neutralization test. In this review, we aim to describe the trends in flavivirus IgG ELISA-based serosurveys. A systematic literature review using six databases was performed to collate cohort and cross-sectional studies performed on the general population. A total of 204 studies were included in this review. The results show that most studies were performed on dengue virus (DENV), whereas Japanese Encephalitis Virus (JEV) was the least studied. For geographic distribution, serosurveys followed known disease prevalence. Temporally, the number of serosurveys increased after outbreaks and epidemics except for JEV, for which studies were performed to demonstrate the effectiveness of vaccination campaigns. Commercial kits were more commonly used than in-house assays for DENV, West Nile Virus (WNV), and Zika virus (ZIKV). Overall, most studies employed an indirect ELISA format, and the choice of antigens varied per virus. This review shows that flavivirus epidemiology is related to the regional and temporal distribution of serosurveys. It also highlights that endemicity, cross-reactivities, and kit availabilities affect assay choice in serosurveys.
PubMed: 37104349
DOI: 10.3390/tropicalmed8040224 -
Infection and Drug Resistance 2021Flaviviruses are a genus of enveloped single-stranded RNA viruses that include dengue virus (DENV), yellow fever virus, West Nile virus (WNV), Japanese encephalitis... (Review)
Review
INTRODUCTION
Flaviviruses are a genus of enveloped single-stranded RNA viruses that include dengue virus (DENV), yellow fever virus, West Nile virus (WNV), Japanese encephalitis virus, and Zika virus. Nowadays, diverse serological assays are available to diagnose flaviviruses. However, infection with flaviviruses induces cross-reactive antibodies, which are a challenge for serological diagnosis.
OBJECTIVE
This systematic review aimed to assess the magnitude of medically important mosquito-borne flavivirus-induced antibody cross-reactivity and its influence on serological test outcomes.
METHODS
This study was designed based on the PRISMA guidelines. It includes original research articles published between 1994 and 2019 that reported serological cross-reactions between medically important mosquito-borne flaviviruses. Articles were searched on PubMed using controlled vocabulary. Eligibility was assessed by title, abstract, and finally by reading the full paper. The articles included are compared, evaluated, and summarized narratively.
RESULTS
A total of 2,911 articles were identified, and finally 14 were included. About 15.4%-84% of antibodies produced against non-DENV flaviviruses were cross-reactive with DENV on different assays. Up to 30% IgM and up to 60% IgG antibodies produced against non-WNV flaviviruses were cross-reactive with WNV on EIA assays. The magnitude of antibodies produced against flaviviruses that are cross-reactive with chikungunya virus () was minimal (only about 7%). The highest antibody cross-reactivity of flaviviruses was reported in IgG-based assays compared to IgM-based assays and assays based on E-specific immunoglobulin compared to NS1-specific immunoglobulin. It was found that preexisting immunity due to vaccination or prior flavivirus exposure to antigenetically related species enhanced the cross-reactive antibody titer.
CONCLUSION
This review found the highest cross-reaction between DENV and non-DENV flaviviruses, especially yellow fever virus, and the least between chikungunya virus and DENV. Moreover, cross-reaction was higher on IgG assays than IgM ones and assays based on Eprotein compared to NS1protein. This implies that the reliability of serological test results in areas where more than one flavivirus exists is questionable. Therefore, interpretation of the existing serological assays should be undertaken with a great caution. Furthermore, research on novel diagnostic signatures for differential diagnosis of flaviviruses is needed.
PubMed: 34703255
DOI: 10.2147/IDR.S336351 -
Scientific Reports Jan 2023The increasing trend of mosquito-borne pathogens demands more accurate global estimations of infection and transmission risks between mosquitoes. Here, we systematically...
The increasing trend of mosquito-borne pathogens demands more accurate global estimations of infection and transmission risks between mosquitoes. Here, we systematically review field and laboratory studies to assess the natural field infection and experimental laboratory transmission risk in Culex mosquitoes. We studied four worldwide flaviviruses: West Nile, Usutu, Japanese encephalitis, and St. Louis encephalitis, belonging to the Japanese encephalitis Serocomplex (JES). The PRISMA statement was carried out for both approaches. The Transmission-Infection Risk of the diverse mosquito species for the different viruses was estimated through seven variables. We considered 130 and 95 articles for field and experimental approach, respectively. We identified 30 species naturally infected, and 23 species capable to transmit some of the four flaviviruses. For the JES, the highest Transmission-Infection Risk estimate was recorded in Culex quinquefasciatus (North America). The maximum Infection-Transmission Risk values for West Nile was Culex restuans, for Usutu it was Culex pipiens (Europe), for St. Louis encephalitis Culex quinquefasciatus (North America), and for Japanese encephalitis Culex gelidus (Oceania). We conclude that on a worldwide scale, a combination of field and experimental data offers a better way of understanding natural infection and transmission risks between mosquito populations.
Topics: Animals; Encephalitis Viruses, Japanese; Mosquito Vectors; West Nile virus; West Nile Fever; Encephalitis, St. Louis; Encephalitis, Japanese; Flavivirus; Culicidae; Culex
PubMed: 36609450
DOI: 10.1038/s41598-022-27236-1 -
International Journal of Infectious... Jan 2021Findings were published in 2015 that highlighted the endemicity of Japanese Encephalitis (JE) in the Philippines. The policymakers responded by conducting an...
BACKGROUND
Findings were published in 2015 that highlighted the endemicity of Japanese Encephalitis (JE) in the Philippines. The policymakers responded by conducting an immunization campaign and strengthening the surveillance system. Using data on the revitalized surveillance system, the epidemiology of JE in the country was updated.
METHODS
Electronic databases were searched, and conference proceedings related to JE in the Philippines were identified until 31 December 2018. Surveillance data from 01 January 2014 to 31 December 2017 were used. The 2015 population census was used to estimate the national and regional incidence for children aged <15 years.
RESULTS
Four studies reported the seroprevalence of JE in the Philippines, which showed increasing seroprevalence with increasing age. Seroprevalence rates were from 0% for infants (aged <1 year) to 65.7% in adolescents (12-18 years) before the immunization campaign. Among five studies on the clinical profile of JE, case fatality ranged from 0 to 21.1% and neurologic sequelae ranged from 5.2 to 81.8% of diagnosed cases. In the surveillance data, JE cases peaked annually from July to October, coinciding with the wet season. The national incidence was estimated at a minimum of 0.7 JE cases/100,000 among children aged <15 years, but higher rates were seen in the northern regions of the country.
CONCLUSION
Improved surveillance affirmed the burden of JE in the Philippines. A subnational immunization campaign in April 2019 was conducted in the northern regions of the country. This paper highlights the importance of including the JE vaccine in the immunization program and sustained high-quality surveillance to monitor its impact on JE control.
Topics: Databases, Factual; Encephalitis, Japanese; Humans; Immunization Programs; Incidence; Japanese Encephalitis Vaccines; Philippines; Seroepidemiologic Studies
PubMed: 33127505
DOI: 10.1016/j.ijid.2020.10.061 -
Vaccine Mar 2023Immunization is an essential component of national health plans. However, the growing number of new vaccine introductions, vaccination campaigns and increasing... (Review)
Review
Immunization is an essential component of national health plans. However, the growing number of new vaccine introductions, vaccination campaigns and increasing administrative costs create logistic and financial challenges, especially in resource-limited settings. Sub-national geographic targeting of vaccination programs is a potential strategy for governments to reduce the impact of infectious disease outbreaks while optimizing resource allocation and reducing costs, promoting sustainability of critically important national immunization plans. We conducted a systematic review of peer-reviewed literature to identify studies that investigated the cost-effectiveness of geographically targeted sub-national vaccination programs, either through routine immunization or supplementary immunization activities. A total of 16 studies were included in our review, covering nine diseases of interest: cholera, dengue, enterotoxigenic Escherichia coli (ETEC), hepatitis A, Japanese encephalitis, measles, rotavirus, Shigella and typhoid fever. All studies modelled cost-effectiveness of geographically targeted vaccination. Despite the variation in study design, disease focus and country context, studies generally found that in countries where a heterogenous burden of disease exists, sub-national geographic targeting of vaccination programs in areas of high disease burden was more cost-effective than a non-targeted strategy. Sensitivity analysis revealed that cost-effectiveness was most sensitive to variations in vaccine price, vaccine efficacy, mortality rate, administrative and operational costs, discount rate, and treatment costs. This systematic review identified several key characteristics related to geographic targeting of vaccination, including the vaccination strategy used, variations in modelling parameters and their impact on cost-effectiveness. Additional research and guidance is needed to support the appropriateness and feasibility of geographically targeted vaccination and to determine what country context would make this a viable complement to routine immunization programs.
Topics: Cost-Benefit Analysis; Vaccination; Immunization Programs; Immunization; Vaccines
PubMed: 36781333
DOI: 10.1016/j.vaccine.2023.02.006 -
Journal of Tropical Pediatrics May 2021Survivors of childhood encephalitis often suffer from physical and neurocognitive sequelae, particularly in tropical, resource-limited areas with a large burden of...
BACKGROUND
Survivors of childhood encephalitis often suffer from physical and neurocognitive sequelae, particularly in tropical, resource-limited areas with a large burden of arboviral, neurotropic pathogens and limited resources with which to address chronic morbidities. Research into overall and pathogen-specific outcomes following childhood encephalitis may help identify risk factors for poor outcomes, quantify the burden of sequelae, assist with resource allocation and help focus rehabilitative efforts. However, such research is limited. To this end, we systematically reviewed the literature on this topic to identify gaps in knowledge worthy of future investigation.
METHODS
A search of PubMed, Web of Knowledge and the Cochrane databases was performed 10 January through 20 February 2020, using 17 search terms for sequelae and 14 for tropical, arboviral pathogens. Eligible reports demonstrated post-discharge follow-up of ≥3 months and assessment of clinical outcome in a child with an arboviral encephalitis ≤18 years of age at diagnosis.
RESULTS
Of 1513 articles, 35 were eligible, comprising 693 children. Japanese encephalitis accounted for 18 articles and 93.2% of all subjects (646 total). Sequelae were documented in ∼60% of subjects overall and in those with Japanese encephalitis. For non-Japanese encephalitis virus encephalitides (47 children), sequelae were found in 78.1%. No studies utilized comprehensive neurocognitive testing or assessed the efficacy of rehabilitative efforts. Only nine studies reported data from ≥1 follow-up visit.
CONCLUSION
Investigation into long-term outcomes following tropical childhood encephalitis is limited, particularly for neurocognitive sequelae, serial assessments over time and the effect of rehabilitative measures.
LAY SUMMARY
Encephalitis, an infection of the brain, is frequently caused by arboviruses (viruses spread via the bite of infected arthropods, such as mosquitoes) in tropical locales. Following infection, surviving children may be plagued with severe physical and cognitive deficits. Unfortunately, research into the type of deficits, their frequency and their responsiveness to rehabilitative efforts is lacking. We identified and reviewed 35 studies describing outcomes in children recovering from tropical, arboviral encephalitis at least 3 months following hospital discharge. Poor outcomes were common and found in up to 60% of children. Long-term and serial follow-up visits were rare, as was the use of comprehensive neurocognitive testing. No studies assessed the efficacy of rehabilitative measures. Further study into these areas is recommended.
Topics: Aftercare; Animals; Child; Cognition Disorders; Encephalitis, Arbovirus; Humans; Patient Discharge
PubMed: 34109400
DOI: 10.1093/tropej/fmab028 -
BMJ Global Health Oct 2023Microarray patches (MAPs) deliver vaccines to the epidermis and the upper dermis, where abundant immune cells reside. There are several potential benefits to using MAPs,... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Microarray patches (MAPs) deliver vaccines to the epidermis and the upper dermis, where abundant immune cells reside. There are several potential benefits to using MAPs, including reduced sharps risk, thermostability, no need for reconstitution, tolerability and self-administration. We aimed to explore and evaluate the immunogenicity, safety, usability and acceptability of MAPs for vaccination.
METHODS
We searched CINAHL, Cochrane Library, Ovid Embase, Ovid MEDLINE and Web of Science from inception to January 2023. Eligibility criteria included all research studies in any language, which examined microarrays or microneedles intended or used for vaccination and explored immunogenicity, safety, usability or acceptability in their findings. Two reviewers conducted title and abstract screening, full-text reviewing and data extraction.
RESULTS
Twenty-two studies were included (quantitative=15, qualitative=2 and mixed methods=5). The risk of bias was mostly low, with two studies at high risk of bias. Four clinical trials were included, three using influenza antigens and one with Japanese encephalitis delivered by MAP. A meta-analysis indicated similar or higher immunogenicity in influenza MAPs compared with needle and syringe (N&S) (standardised mean difference=10.80, 95% CI: 3.51 to 18.08, p<0.00001). There were no significant differences in immune cell function between MAPs and N&S. No serious adverse events were reported in MAPs. Erythema was more common after MAP application than N&S but was brief and well tolerated. Lower pain scores were usually reported after MAP application than N&S. Most studies found MAPs easy to use and highly acceptable among healthcare professionals, laypeople and parents.
CONCLUSION
MAPs for vaccination were safe and well tolerated and evoked similar or enhanced immunogenicity than N&S, but further research is needed. Vaccine uptake may be increased using MAPs due to less pain, enhanced thermostability, layperson and self-administration. MAPs could benefit at-risk groups and low and middle-income countries.
PROSPERO REGISTRATION NUMBER
CRD42022323026.
Topics: Humans; Influenza, Human; Vaccination; Vaccines; Pain
PubMed: 37827725
DOI: 10.1136/bmjgh-2023-012247