Environmental factors and spatiotemporal distribution of Japanese encephalitis after vaccination campaign in Guizhou Province, China (2004-2016)

Spatiotemporal distribution, environmental correlation and health risk analysis of Culex tritaeniorhynchus (Diptera: Culicidae) in Beijing, China

The Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) is major vector of Japanese encephalitis (JE) in China, and this study aimed to uncover the vector's spatiotemporal distribution and environmental correlation in Beijing. In study area, the Remote Sensing (RS), Global Position System (GPS), and Geographic Information System (GPS) were used to clarify the distribution characteristics of vector on spatial and temporal scales, and regressions analysis of cross-sectional study was performed to detect the environmental factors linked with the density and presence of Cx. tritaeniorhynchus. In study area, the scenic area was the major environmental area for breeding of the vector, August was the primary peak month, the new urban development area (NUDA) was major distribution subarea of Beijing, and the vector could be detected throughout the subarea of Beijing from June to September. In the scenic area, the total value of light index within buffer zones of 100 m (LT_100) and the total value of NDVI index within buffer zones of 800 m (NDVI_800) determined whether there was a positive or negative vector in the trapping sites, and the total value of NDVI index within buffer zones of 100 m (NDVI_100) and LT_100 was linked to the density of the vector. Our findings provide better insight into the spatio-temporal distribution pattern, associated environmental risk factors, and health risk of vector in Beijing. Based on the results here, we could predict the risk of JE and create and implement location-specific JE prevention and control measures to prevent future risks during the urbanization advancement of Beijing.

Trends in temporal and spatial changes of Japanese encephalitis in Chinese mainland, 2004-2019: A population-based surveillance study

BACKGROUND

Japanese encephalitis (JE) is a serious health concern in China, with approximately 80 % of global infections occurring in China. To develop effective prevention and control strategies, this study explored the epidemiological characteristics of JE in China based on spatiotemporal data, to understand the patterns and trends of JE incidence in different regions and time periods.

METHOD

The incidence and mortality rates of JE were extracted from the Public Health Data Center, the official website of the National Health Commission of the People's Republic of China, and the National Notifiable Infectious Disease Surveillance System from 2004 to 2019. Joinpoint regression was applied to examine the spatiotemporal patterns and annual percentage change in incidence and mortality of the JE.

RESULTS

From 2004 to 2019, a total of 43,569 cases of JE were diagnosed, including 2081 deaths. The annual incidence rate of JE decreased from 0.4171/100,000 in 2004 to 0.0298/100,000 in 2019, with an annual percentage change (APC) of -13.5 % (P < 0.001). The annual mortality rate of JE showed three stages of change, with inflection points in 2006 and 2014. The incidence and mortality rates of JE have declined in all provinces of China, and more cases were reported in 0-14 years of age, accounting for nearly 80 % of all patients.

CONCLUSIONS

The morbidity and mortality rates of JE in China are generally on a downward trend, and emphasis should be placed on strengthening disease surveillance in special areas and populations, popularizing vaccination, and increasing publicity.

Mass immunisation to eradicate Japanese encephalitis: Real-world evidence from Guizhou Province in 2005-2021

Objectives

To explore epidemiological changes of Japanese encephalitis (JE) in a long-time span and evaluate the impact of mass immunisation.

Method

Data on JE cases from hospitals and the county Centers for Disease Control and Prevention in Guizhou Province was collected between 2005 and 2021. Epidemiological changes were analyzed according to a series of policy implementations and the coronavirus disease 2019 (COVID-19) pandemic.

Results

A total of 5138 JE cases and 152 deaths were reported in Guizhou Province during 2005-2021. The average incidence and case fatality rates were 0.83/100,000 and 2.96%, respectively. The JE prevalence showed a declining trend over the years with the reduced incidence gap between age groups and narrowing of the high-epidemic regions. During the COVID-19 pandemic, the JE activity reached its nadir in 2020. The inclusion in the Expanded Program on Immunization of the JE vaccine and catch-up immunisations showed a significant impact on the JE declining incidence rate.

Conclusions

The implementation of JE immunisation programs has played a crucial role in controlling its spread. Continued efforts should be made to maintain high coverage of the JE vaccine and strengthen disease surveillance systems, ensuring JE effective control and eventual elimination.

Japanese encephlu emergence in Australia: the potential population at risk

Japanese encephalitis virus (JEV), an RNA virus transmitted by Culex mosquitoes, primarily cycles between aquatic birds and mosquitoes with pigs as amplifying hosts, posing a significant global encephalitis threat. The emergence and spread of the JEV in new epidemiological regions, such as recent cases in Australia and nonendemic areas like Pune, India, raise significant concerns. With an estimated 68 000 clinical cases and 13 600 to 20 400 deaths annually, JEV poses a substantial global health threat. The virus primarily affects children, with a case-fatality ratio of 20-30% and long-term neurological sequelae in survivors. The changing epidemiology, influenced by factors like bird migration, climate change, and increased urbanization, contributes to the geographic expansion of JEV. The recent outbreaks underscore the potential for the virus to establish itself in nonendemic regions, posing a threat to populations previously considered at low-risk. With limited treatment options and high rates of neurological complications, continued surveillance, traveler vaccination, and research into treatments are crucial to mitigate the impact of JEV on human health. The evolving scenario necessitates proactive measures to prevent and control the spread of the virus in both endemic and newly affected areas.

The identification and genetic characteristics of Quang Binh virus from field-captured Culex tritaeniorhynchus (Diptera: Culicidae) from Guizhou Province, China

BACKGROUND

Mosquitoes carry a variety of viruses that can cause disease in humans, animals and livestock. Surveys for viruses carried by wild mosquitoes can significantly contribute to surveillance efforts and early detection systems. In addition to mosquito-borne viruses, mosquitoes harbor many insect-specific viruses (ISVs). Quang Binh virus (QBV) is one such example, categorized as an ISV within the Flavivirus genus (family Flaviviridae). QBV has been specifically documented in Vietnam and China, with reports limited to several mosquito species.

METHODS

The homogenate obtained from female mosquitoes was cultured on C6/36 (Aedes albopictus) and BHK-21 (baby hamster kidney) cell lines. Positive cultures were identified by reverse transcription-polymerase chain reaction (RT‒PCR) with taxon- or species-specific primers. Next-generation sequencing was employed to sequence the complete genomes of the identified positive samples. Subsequently, phylogenetic, gene homology, molecular evolutionary and genetic variation analyses were conducted.

RESULT

In 2021, a total of 32,177 adult female mosquitoes were collected from 15 counties in Guizhou Province, China. The predominant mosquito species identified were Culex tritaeniorhynchus, Armigeres subalbatus and Anopheles sinensis. Among the collected mosquitoes, three positive cultures were obtained from Cx. tritaeniorhynchus pools, revealing the presence of Quang Binh virus (QBV) RNA sequences. Phylogenetic analysis indicated that the three Guizhou isolates, along with the prototype isolate from Vietnam, formed distinct branches. These branches were primarily closely related to other QBV isolates reported in China. Comparative analysis revealed a high degree of nucleotide and amino acid homology between the Guizhou isolates and both Vietnamese and other indigenous Chinese isolates. Additionally, nonsynonymous single-nucleotide variants (SNVs) were observed in these strains compared to the QBV prototype strain.

CONCLUSION

This study represents the first report of QBV presences in Cx. tritaeniorhynchus mosquitoes in Guizhou Province, China. Phylogenetic tree analysis showed that the three Guizhou isolates were most closely related to the QBV genes found in China. In addition, the study of the genetic characteristics and variation of this virus provided a deeper understanding of QBV and enriched the baseline data of these insect-specific flaviviruses (ISFVs).

The spatial-temporal pattern of Japanese encephalitis and its influencing factors in Guangxi, China

Japanese encephalitis (JE) is a major global public health threat. Using Japanese encephalitis incidence data from 2004 to 2010 in Guangxi Province, China, this study comprehensively explored the driving forces and the interactive effects between environmental and social factors of Japanese encephalitis using the Geo-detector method. The results indicated that the incidence of Japanese encephalitis showed a fluctuating downward trend from 2004 to 2010. The onset of JE was seasonal, mainly concentrated in June-July, and highly aggregated in northwestern Guangxi. Among the factors associated with Japanese encephalitis, days with temperatures >30 °C, accumulated temperatures >25 °C, slope, the normalized difference vegetation index, the gross domestic product of tertiary industries, the gross domestic product of primary industries and the number of pigs slaughtered showed higher contributions to Japanese encephalitis incidence. An enhanced interactive effect was found between environmental and social factors, and the interaction between days with humidity levels >80% and the gross domestic product of tertiary industries had the greatest combined effect on JE. These findings enhanced the understanding of the combined effect of social and environmental factors on the incidence of Japanese encephalitis and could help improve Japanese encephalitis transmission control and prevention strategies.

A comparison of clinical manifestations of Japanese encephalitis between children and adults in Gansu Province, Northwest China (2005-2020)

Japanese encephalitis (JE), a mosquito-borne zoonotic disease, has emerged as a major public health concern around the world. Previous research has shown that JE has serious sequelae, and the recent shift in the population from children to adults presents a significant challenge for JE treatment and prevention. Therefore, we examined the differences in clinical manifestations (clinical symptoms, clinical signs, complications, and clinical typing) of JE between children and adults over the 15 years in Gansu Province to provide a theoretical basis for better response to JE treatment. Clinical typing was found to be statistically significant in the child versus adult groups and the groups with or without vaccination. Only the dysfunction of consciousness differed statistically between children with and without vaccination, whereas neurological symptoms such as vomiting (jet vomiting), irritability, drowsiness, convulsions, and hyperspasmia differed statistically between children and adults, and the rest of the symptoms did not differ statistically. Only pupil size changes were statistically different in clinical signs between the children with and without vaccination, while blood pressure changes, change in pupil size, positive meningeal stimulation signs, and positive pathological reflexes (increased muscle tone and Babinski's sign) were statistically different between adults and children. Bronchopneumonia was the most common complication, especially in adults. Therefore, the authors believe that children and adults differ in some clinical manifestations and propose that efforts should be directed toward developing individualized treatment plans for different age groups and employing more effective supportive treatment for various populations. In addition, we suggest expanding the coverage of the JE vaccine and increasing overall vaccination rates and adopting multiple measures in conjunction with JE prevention and control.