The spatiotemporal distribution of Japanese Encephalitis cases in Yunnan Province, China, from 2007 to 2017

BACKGROUND

Japanese encephalitis (JE) is a vector-borne disease with a high prevalence in Yunnan Province, China. However, there has been a lack of a JE epidemic systematic analysis, which is urgently needed to guide control and prevention efforts.

METHODS

This study explored and described the spatiotemporal distribution of JE cases observed among two different age groups in Yunnan Province from 2007 to 2017. The epidemiological features and spatial features were analyzed according to basic statistics, ArcGIS software (version 9.3; ESRI, Redlands, CA) and SPSS software (version 20; IBM Corp., Armonk, New York).

RESULTS

Overall, the whole province had a high incidence of JE. The annual incidence rates in 2007 and 2017 were 1.668/100,000 and 0.158/100,000, respectively. The annual mortality was under 0.095/100,000 for these years. Although the whole province was in danger of JE, the Diqing autonomous prefecture and the Lijiang autonomous prefecture had no JE cases recorded for over 10 years. The JE cases were reported by hospitals located in 60 counties of 14 municipalities. The top ten areas with the most JE cases were Kunming City, Zhaotong City, Jinghong City, Wenshan City, Mangshi City, Pu'er City, Baoshan City, Dali City, Chuxiong City, and Gejiu City. The incidence declined smoothly, with a peak occurring from June to September, which accounted for 96.1% of the total cases. Children whose age was equal or less than 10 years old (LEQ10) still maintained a high frequency of JEV infection, and a large number of cases were reported in August, despite the Expanded Program on Immunization (EPI), which was established in April 2008. There was no difference in the quantity of cases between the two groups (t = -0.411, P>0.05); additionally, the number of JE cases among patients LEQ10 were significantly greater than those among patients older than 10 years (GTR10). Further analysis using local indicators of spatial association (LISA) revealed that the distribution of JE exhibited a high-high cluster characteristic (Z = 2.06, P<0.05), which showed that Jinghong City, Guangnan County, Yanshan County, Funing County, and Mengzi City were hot spots for the JE epidemic.

CONCLUSIONS

Although the EPI was established in 2008 and the incidence of JE declined smoothly in Yunnan Province, there was no difference in the number of cases between the two age groups, which reveals that the EPI has been conducted with a low level success. In the context of limited vaccine supply capacity, we should strengthen the implementation of the children's immunization program before strengthening other immunization programs.

Effective inhibition of different Japanese encephalitis virus genotypes by RNA interference targeting two conserved viral gene sequences in vitro and in vivo

Japanese encephalitis is a zoonotic, mosquito-borne, infectious disease caused by Japanese encephalitis virus (JEV), which is prevalent in China. At present, there are no specific drugs or therapies for JEV infection, which can only be treated symptomatically. Lentivirus-mediated RNA interference (RNAi) is a highly efficient method to silence target genes. In this study, two lentiviral shRNA, LV-C and LV-NS5, targeting the conserved viral gene sequences were used to inhibit different JEV genotypes strains in BHK21 cells and mice. The results showed that LV-C significantly inhibited JEV genotype I and genotype III strains in cells and mice. Quantitative RT-PCR analysis showed that JEV mRNA were reduced by 83.2-90.9% in cells by LV-C and that flow cytometry analysis confirmed the inhibitory activity of LV-C. The viral titers were reduced by about 1000-fold in cells and the brains of suckling mice by LV-C, and the pretreatment of LV-C protected 60-80% of mice against JEV-induced lethality. The inhibitory activities of LV-NS5 in cells and mice were weaker than those of LV-C. These results indicate that RNAi targeting of the two conserved viral gene sequences had significantly suppressed the replication of different JEV genotypes strains in vitro and in vivo, highlighting the feasibility of RNAi targeting of conserved viral gene sequences for controlling JEV infection.

Spatio-temporal epidemiology of Japanese encephalitis in Nepal, 2007-2015

Japanese encephalitis (JE) is a major public health problem in Nepal. For the effective management and surveillance of JE, a clear understanding of its epidemiology is essential. Therefore, we conducted descriptive and spatial analyses to understand the spatio-temporal distribution of JE in human in Nepal. From 2007 to 2015, 1,823 JE cases were reported with a cumulative mean incidence of 0.735/100,000 population and a case fatality rate of 6.6%. The death rate in the up-to-24 years of age group was 74%. The JE cases were most commonly reported in the age group of 1-14 years. There is a strong seasonal pattern of JE occurrence in Nepal which peaked in August and declined by October each year, which corresponds to the monsoon season. The JE cases were reported in 63 of 75 districts (84%), expanding in the mountain and hill regions. There was a strong clustering of JE incidence in the south-western and south-eastern Terai region, which is endemic for JE. Therefore, the JE surveillance system should be improved to better understand the drivers of disease expansion in Nepal for instituting a control program.

The A66G back mutation in NS2A of JEV SA14-14-2 strain contributes to production of NS1' protein and the secreted NS1' can be used for diagnostic biomarker for virulent virus infection

Japanese encephalitis virus (JEV) is the most common cause of the prevalent encephalitis in Asia-Pacific region and poses a serious risk to public health. Here, we developed a reliable reverse genetics system based on the JEV SA14-14-2 strain to further explore the mechanism for the synthesis of NS1' protein and to investigate the function of NS1' protein during virus infection. NS1' is an additional form of NS1 protein with 52 amino acid carboxy-terminal extension and is expressed by the members of the Japanese encephalitis (JE) serogroup due to the translation frameshift. A66G substitution in NS2A gene of JEV SA14-14-2 strain contributed to recover the GC-rich pseudoknot and resulted in the formation of the NS1'. The NS1' protein has no significant effect on the virus replication properties in BHK-21 cells. Animal experiments demonstrated that the NS1' protein had a rather minor effect on neurovirulence of JEV SA14-14-2 strain. But the NS1'-expressing virus (rA66G) could induce a higher humoral immune response than the NS1'-non-expressing virus (rSA14-14-2). NS1' protein can be detected in the serum of JEV rA66G infected animal and in the cultural media of that infected mammalian cells. Interesting, only the dimer of NS1' can be detected in the cultural media of the infected BHK-21 cells and the amount of the secreted NS1' was in agreement with that of the secreted virion. In comparison with the live-attenuated JE vaccine strain which is incapable of formation of NS1', most of the virulent JEV strains produce the NS1' protein. And the secreted NS1' may serve as an early surrogate biomarker for viremia to distinguish the field infection from the vaccine inoculation. In total, in the present study, we identified the nt 66 in the viral NS2A gene as one of the critical site for the -1 programmed ribosomal frameshift to produce the NS1' protein and demonstrated the secreted NS1' could be used for diagnostic biomarker during JEV infection.

Epidemiological characteristics of Japanese encephalitis in Guizhou Province, China, 1971-2009

OBJECTIVE

The aim of the study was to establish the contemporary epidemiological characteristics of Japanese encephalitis (JE) in Guizhou Province.

METHODS

A retrospective study of National Notifiable Disease Reporting System (NNDRS) data from 1971 through 2009, was conducted to ascertain the geographical, seasonal, and age distributions of JE incidence in Guizhou Province, China.

RESULTS

A total of 68 425 JE cases were reported in Guizhou from 1971-2009. The JE cases occurred sporadically in all 9 prefectures of Guizhou, mostly among residents of rural areas. Seasonal distribution of JE remained consistent over the period from 1971-2009 with the main transmission season starting from June to September and peaking in August. JE occurred mainly in children under the age of 15 years with peak incidence in the 0-6-year age group. Pearson's correlation analysis showed that JE vaccine distribution had a negative correlation with JE incidence rates during 1971-2009 (coefficient of correlation=-0.475, P<0.01).

CONCLUSION

Over the period of 1971-2009, the JE incidence rate had declined dramatically in terms of geographical and age distributions due to JE vaccination to children at risk.

Japanese encephalitis (JE) part II: 14 years' follow-up of survivors

Japanese encephalitis, the commonest Arbovirus encephalitis, has been endemic in many parts of Asia, the Pacific Islands, and India; also, there have been many epidemics. Most of the post JE cases have been associated with neurological and neuropsychiatric deficits but have not been properly classified and followed. Practically all the previous studies were in children or young adults. The aim of this study, involving only adult cases, the largest ever being reported, has been to follow the 688/1,199 survivors of JE patients out of 1,282 of acute cases admitted during four epidemics for a period of 14 years after properly classifying the sequelae. This prospective study was conducted in B.R.D. Medical College Gorakhpur (India), involving 665/688 post JE cases with neuropsychiatric deficits from four epidemics of 1978, 1980, 1988 and 1989 which were properly classified in nine groups. While the first epidemic of 1978 was being studied, more disastrous episodes flared up and the patients were subsequently added. Hence, the total duration of this prospective study was from November 1978 to December 2003. There were 14 defaulted initially from 688 followed (23/688 without sequelae and 665/688 with neuropsychiatric deficits), and later 130 were lost from time to time at various stages of follow up. Four out of 23/688 discharged without any deficit had to be readmitted for bizarre movements, assaultative behaviour and euphoria without fever and altered sensorium. All of them improved by symptomatic treatment. Progressive improvement occurred in all the parameters consisting of psychological disturbances, higher cerebral dysfunction, speech disorders (dysphonia, dysarthria, dysphasias, apraxia and agnosia), extra pyramidal, pyramidal features, and hypothalamic disturbances, cranial nerves including pupils and fundi and seizures. Maximum cases improved between 6 months (55%) to 1 year (78%). Only some features improved between 5 to 14 years. Four patients of hemiplegia remained bed ridden. Some non disabling features like dysarthria and corticospinal features without paralysis persisted in 5% (95% improved) and 74% (26% improved) respectively. One patient with bizarre movement and nine with marked tremors could not regain normalcy. A large number of patients of JE are left with several minor or gross residual neuropsychiatric and neurological features after the acute phase. In this series also the discharged patients with neurological deficits who were quite disabled initially and needed constant care by family members and also those who required some help intermittently improved with passage of time and eventually returned to normal life. Some of them were left with non-disabling residual neurological signs even after 14 years. Fourteen of 544 (3%) could not return to their livelihood.

[Studies on the biological and genetic characteristics of a highly neurovirulent Japanese encephalitis virus strain SA4]

The biological and genetic characteristics of a highly neurovirulent JE virus strain SA4 were studied. Mice were inoculated intracerebrally with strain SA4 and SA14, and observed for 14 days, respectively. On different days, mice brains were harvested for titrations of the virus content in the brains. Full-length genome of SA4 was sequenced and compared with SA14 as well as other JE virus strains in the world. The results indicated that the mice inoculated by SA4 induced sickness and death more rapidly (24 hours faster) than those induced by the SA14. The virus titers in the brains of mice infected with SA4 were 0.5-1.0 lg PFU/mL higher than that infected with SA14. The sequence comparison indicated that the nucleotide and amino acid homology between SA4 and the other 21 JE strains were 84.6%-99.0% and 95.2%-99.7% respectively. Comparison with strain SA14 revealed that there were 17 amino acid differences between the two strains, of which 5 were in the E protein region. The results demonstrate that strain SA4 is a highly neurovirulent strain. The substitutions of the 17 amino acids in the SA4 strain can be the molecular basis for the biological characteristics of high neurovirulence.

[Analysis on disease burdern of Japanese encephalitis (JE) in Gansu province]

OBJECTIVE

To evaluate the disease burden of Japanese Encephalitis (JE), and provide strategy for disease control and prevention.

METHODS

Firstly, analysis the incidence, mortality and fatality rate of JE in Gansu province in 2006. Then the investigation was carried out for calculating all expenditure items of the patients, including medical cost of the hospitalization, medicines, the transport costs, and other non-medical direct cost.

RESULTS

In 2006, among the 27 type A and B notifiable infectious diseases in Gansu Province, JE mortality rate was at the top 3, fatality rate was at first rank. The direct cost of JE disease was 6889 RMB per case. In 2006, the direct cost of JE cases was 1,116,000 RMB in Gansu Province.

CONCLUSION

JE had the high mortality, and fatality. The fatality in adult was higher than in children. JE patients had to pay high costs. JE disease burden should not be underestimated.

Sequential changes in serum cytokines and chemokines in a rat model of Japanese encephalitis

OBJECTIVES

The mechanisms underlying inflammation and immune responses in viral encephalitis are not fully understood. Therefore, in the present study we aimed to investigate the cytokine and chemokine levels in Japanese encephalitis virus (JEV)-infected rats.

METHODS

Twelve-day-old Wistar rats were infected with 3 x 10(6) plaque-forming units of JEV intracerebrally. Cytokine and chemokine levels were analyzed in serum 3, 6, 10 and 20 days post inoculation (dpi).

RESULTS

There were increased levels of proinflammatory and anti-inflammatory cytokines and a chemokine (monocyte chemoattractant protein-1) in the serum of rats after JEV infection compared to controls. The levels of cytokines and chemokine peaked at 10 dpi and had declined significantly by 20 dpi. The neurological deficit also increased in the acute stage of disease and partially recovered thereafter.

CONCLUSION

Serum cytokine and chemokine levels decline at 10 dpi and do not significantly correlate with neurological dysfunction.

Early death of Japanese encephalitis virus-infected mice administered a neutralizing cross-reactive monoclonal antibody against glycoprotein E

In the present study, the effect of two haemagglutination-inhibition (HAI)-negative auto-reactive (NHA-1 and NHA-2) monoclonal antibodies (MAbs) against glycoprotein E (gpE) of Japanese encephalitis virus (JEV) administered 1 day before or 2 days after intracerebral (i.c.) inoculation of JEV was studied in mice. Of the two MAbs that cross-reacted with West Nile virus (WNV) and histones, the first one (NHA-1) neutralized JEV, while the second one was non-neutralizing. NHA-1 MAb given intraperitoneally (i.p.) 1 day before virus infection induced early death by about 2 days in comparison to controls, whereas mice administered HAI-positive anti-gpE JEV specific MAbs (Hs-1 or Hs-4) were invariably protected. In contrast, MAb NHA-2 failed to produce any effect in mice. Since the similar virus titers were recorded in the brains of experimental and control infected mice, the present results indicated a modification of the biological activity of JEV by the pre-existing MAb NHA-1 that might be leading to an early death of mice.

KEYWORDS

Japanese encephalitis virus; neutralizing cross-reactive monoclonal antibody.

Accumulation of T-cells with selected T-cell receptors in the brains of Japanese encephalitis virus-infected mice

Japanese encephalitis is a severe central nervous system (CNS) disease with a high case fatality rate in humans. We characterized T-cells infiltrating the brain after infection with Japanese encephalitis virus (JEV) in a mouse model and determined the clonality of the infiltrating T-cells by analyzing the sequences of complementary determining region 3 (CDR3) of the T-cell receptor. C3H/He mice died after intraperitoneal infection with the JaTH160 strain of JEV, demonstrating CNS degeneration and prominent T-cell infiltration. The percentages of T-cells bearing the VA5-1, VA17-1, VA19-1, VB2-1, VB8-3 and VB13-1 subfamilies were significantly increased following infiltration of the brains in infected mice. Additionally, CDR3 size spectratyping revealed the oligoclonality in T-cells bearing VA11-1 and VA18-1. CDR3 amino acid sequences were then determined for the VA5-1, VA11-1, VA18-1, VB8-3 and VB13-1 subfamilies. There were high levels of identity and similarity in amino acid sequences of CDR3 in these T-cells. Quantitative real-time PCR analysis also revealed that CD8, interferon-gamma and tumor necrosis factor-alpha were highly expressed in the infected mouse brain. These results indicate that T-cells with high clonality and similarity infiltrate the JEV-infected mouse brain, and that these T-cells are mainly CD8-positive and have the Th1/Tc1 phenotype.

Survival of mice immunized with monoclonal antibodies against glycoprotein E of Japanese encephalitis virus before or after infection with Japanese encephalitis, West Nile, and Dengue viruses

In the present study, the effect of monoclonal antibodies (MAbs) against glycoprotein E (gE) of Japanese encephalitis virus (JEV) strain 733913 administered 1 day before or 2 days after intracerebral (i.c.) challenge with West Nile virus (WNV) strain 68856 or Dengue virus (DENV-2) strain P23085, was studied in mice. Furthermore, two JEV strains belonging to group II (strains 641686 and 691004) that have lost reactivity against virus-specific MAbs were also used in passive immunization experiments. MAbs as ascitic fluids were administered intraperitoneally (i.p.) in mice. Hemagglutination-inhibition- (HAI) positive JEV-specific (Hs-3) MAbs given 2 days after the virus infection showed reduced mortality along with increased survival of mice challenged with WNV or with DENV-2. Also the HAI-positive flavivirus cross-reactive (Hx) MAbs produced a marginal increase in the survival of mice challenged with both JEV strains 641686 and 691004 belonging to the group II. As the MAbs reacting with HAI-positive JEV-specific (Hs) and HAI-negative JEV-specific (NHs) epitopes were neutralizing and protective in mice against JEV strain 733913 challenge, the results indicated presence of the cross-protection phenomenon that might be occurring in some of the localities endemic for the three closely related flaviviruses.

Unravelling the neuropathogenesis of Japanese encephalitis

Japanese encephalitis is a devastating disease that causes a frequently fatal encephalitis and is a major health problem throughout much of Asia. Mortality rates can be as high as 30%, with one-third of survivors suffering severe neurological sequelae. Viral cytopathology is important, but the contribution of blood-brain barrier breakdown, the inflammatory response and bystander cell death are unknown. Studies that address the mechanisms producing neuronal dysfunction and damage are required, including the examination of autopsy tissues. A better understanding of these mechanisms may lead to therapeutic strategies to reduce brain injury and neurological sequelae.

Epidemiological situation of Japanese encephalitis in Nepal

A human Japanese encephalitis (JE) case is considered to have elevated temperature (over 380 C) along with altered consciousness or unconsciousness and is generally confirmed serologically by finding of specific anti-JE IgM in the cerebro spinal fluid. No specific treatment for JE is available. Only supportive treatment like meticulous nursing care, introduction of Ryle's tube if the patient is unconscious, dextrose solution if dehydration is present, manitol injection in case of raised cranial temperature and diazepam in case of convulsion. Intra venous fluids, indwelling catheter in conscious patient and corticosteroids unless indicated should be avoided. Pigs, wading birds and ducks have been incriminated as important vertebrate amplifying hosts for JE virus due to viremia in them. Man along with bovines, ovines and caprines is involved in transmission cycle as accidental hosts and plays no role in perpetuating the virus due to the lack of viremia in them. The species Cx tritaeniorhyncus is suspected to be the principal vector of JE in Nepal as the species is abundantly found in the rice-field ecosystem of the endemic areas during the transmission season and JE virus isolates have been obtained from a pool of Cx tritaeniorhyncus females. Mosquito vector become infective 14 days after acquiring the JR virus from the viremic host. The disease was first recorded in Nepal in 1978 as an epidemic in Rupandehi district of the Western Development Region (WDR) and Morang of the Eastern Region (EDR). At present the disease is endemic in 24 districts. Although JE as found endemic mainly in tropical climate areas, existence and proliferation of encephalitis causing viruses in temperate and cold climates of hills and valleys are possible. Total of 26,667 cases and 5,381 deaths have been reported with average case fatality rate of 20.2% in an aggregate since 1978. More than 50% of morbidity and 60% mortality occur in the age group below 15 years. Upsurge of cases take place after the rainy season (monsoon). Cases start to appear in the month of April - May and reach its peak during late August to early September and start to decline from October. There are four designated referral laboratories, namely National Public Health Laboratory (Teku), Vector Borne Diseases Research and Training Center (Hetauda), B.P. Koirala Institute of Medical Sciences (Dharan) and JE Laboratory (Nepalgunj), for confirmatory diagnosis of JE. For prevention of JE infection; chemical and biological control of vectors including environmental management at breeding sites are necessary. Segregate pigs from humans habitation. Wear long sleeved clothes and trousers and use repellent and bed net to avoid exposure to mosquitos. For the prevention of the disease in humans, safe and efficacious vaccines are available. Therefore immunize population at risk against JE. Immunize pigs at the surroundings against JE. 225,000 doses of live attenuated SA-14-14.2 JE vaccine were received in donation from Boran Pharmaceuticals, South Korea for the first time in Nepal. Altogether 224,000 children aged between 1 to 15 years were vaccinated in Banke, Bardiya and Kailali districts during 1999. From China also, 2,000,000 doses of inactivated vaccine were received in 2000 and a total of 481,421 children aged between 6m to 10 yrs were protected from JE during 2001/2002. Ministry of Agriculture, Department of Livestock Services has vaccinated around 200,000 pigs against JE in terai zone during February 2001.

A Comparison of Clinical and Radiological Findings in Adults and Children With Japanese Encephalitis

BACKGROUND

Japanese encephalitis (JE) is the most common human endemic encephalitis, prevalent mainly in Southeast Asia. It affects both adults and children in different areas, but there is no comparative study of their clinical features and outcomes.

OBJECTIVE

To evaluate clinical and radiological features in adults and children with JE.

METHODS

Patients with serologically or virologically confirmed JE who were treated during the past 10 years were included in this study. All patients underwent a detailed neurological examination, computed tomography, or magnetic resonance imaging. The presence of movement disorders, anterior horn cell involvement, and electroencephalographic changes was noted. After 6 months, each patient's outcome was defined as poor, partial, or complete recovery. The clinical and radiological findings for both adults and children were compared using chi2 tests.

RESULTS

The results are based on 30 children and 37 adults. Seizure was present in 23 adults (62.2%) and in 17 children (56.7%). Three children had associated neurocysticercosis, and all of them had partial seizures. The occurrence of focal neurological deficit, anterior horn cell involvement, and parkinsonian features was not significantly different between adults and children. Dystonia was more common in children, occurring in 20 (66.7%) compared with 7 adults (18.9%). Six adults died, but none of the children did; however, the 6-month outcome was better for surviving adults compared with the children. Computed tomography and magnetic resonance imaging findings were not significantly different between the 2 groups.

CONCLUSIONS

Children with JE are more likely to have dystonia and a poor outcome at 6 months compared with adults. The difference in clinical findings and outcome in children and adults with JE may be owing to immunological factors, maturation of the central nervous system, and neuronal plasticity.

Isolation of Japanese encephalitis and Getah viruses from mosquitoes (Diptera: Culicidae) collected near Camp Greaves, Gyonggi Province, Republic of Korea, 2000

As part of an evaluation of the ecology of arthropod-borne diseases in the Republic of Korea (ROK), we examined 8,765 mosquitoes captured in Paju County, Gyonggi Province, ROK, for the presence of viruses. Mosquitoes were captured in propane lantern/human-baited Shannon traps, Mosquito Magnet traps, or American Biophysics Corporation (East Greenwich, RI) miniature light traps with or without supplemental octenol bait and/or dry ice. Mosquitoes were identified to species, placed in pools of up to 40 mosquitoes each, and tested on Vero cells for the presence of virus. A total of 15 virus isolations were made from 293 pools of mosquitoes. Viruses were identified by reverse transcriptase-polymerase chain reaction and sequencing and consisted of 14 isolations of Japanese encephalitis (JE) virus and one isolation of Getah (GET) virus. All JE isolates were from Culex tritaeniorhynchus Giles, and the isolate of GET was from Aedes vexans (Meigen). The minimum field infection rate for JE in Cx. tritaeniorhynchus was 3.3 per 1,000, whereas the GET virus infection rate for Ae. vexans was 0.2 per 1,000. Isolation of JE and GET indicated that both viruses were actively circulating in northern Gyonggi Province, ROK. The lack of human cases of JE among the Korean population probably is because of an effective government-mandated vaccination program. The reason for no cases among >10,000 United States military and others that reside or train nearby is unknown, but may be related to personnel protection measures (permethrin-impregnated uniforms and use of deet repellent), adult mosquito control, mosquito selection of nonhuman hosts (unpublished data), and the low symptomatic to asymptomatic ratio of disease in adults.

Interferon alfa-2a in Japanese encephalitis: a randomised double-blind placebo-controlled trial

BACKGROUND

Japanese encephalitis virus (JEV), although confined to Asia, causes about 35000-50000 cases and 10000 deaths every year, and is the most important cause of encephalitis worldwide. There is no known antiviral treatment for any flavivirus. Results from in-vitro studies and work in animals have shown inteferon alfa has antiviral activity on Japanese encephalitis and other flaviviruses; therefore, we aimed to assess the efficacy of inteferon alfa-2a in Japanese encephalitis.

METHODS

We did a randomised double-blind placebo-controlled trial of interferon alfa-2a (10 million units/m2, daily for 7 days) in 112 Vietnamese children with suspected Japanese encephalitis, 87 of whom had serologically confirmed infections. Our primary endpoints were hospital death or severe sequelae at discharge. Analysis was by intention to treat.

FINDINGS

Overall, 21 children (19%) died, and 17 (15%) had severe sequelae. Outcome at discharge and 3 months did not differ between the two treatment groups; 20 children in the interferon group had a poor outcome (death or severe sequelae), compared with 18 in the placebo group (p=0.85, difference 0.1%, 95% CI -17.5 to 17.6%), there were no long-term side effects of interferon.

INTERPRETATION

The doses of interferon alfa-2a given in this regimen did not improve the outcome of patients with Japanese encephalitis.

Inhibition of Japanese encephalitis virus infection by diethyldithiocarbamate is independent of its antioxidant potential

Diethyldithiocarbamate (DDTC), a low molecular weight dithiol, has been described as an immunomodulator and modifier of diverse biological actions in human and animal models, and has also been shown to be effective in several disease conditions. Therefore, we studied the therapeutic aspect of DDTC in providing inhibition of Japanese encephalitis virus (JEV) infection. DDTC tested at various doses (10-100 micromol/kg) revealed that administration at low concentration (10 micromol/kg; i.p.) on alternate days prolonged the average survival time (AST) of mice infected with lethal dose of JEV (102 LD50, i.c.) and delayed progression of the disease. The low dose also provided > 80% survival in sub-clinical (10(5) LD50, i.c.) JEV infection. Administration of DDTC to JEV-infected mice enhanced the inducible nitric oxide synthase (iNOS) activity in brain and level of serum tumour necrosis factor-alpha (TNF-alpha). We have recently demonstrated the production of nitric oxide (NO) via induction of iNOS activity is meditated by circulating macrophage-derived factor (MDF), which may be responsible for the delayed progression of the disease. DDTC-mediated inhibition of JEV is believed to involve the augmentation of protective role of MDF as evidenced by the observation that pretreatment with anti-MDF antibody significantly decreased the AST of mice and together with the inhibition of iNOS activity. Interestingly, DDTC alone did not stimulate iNOS and TNF-alpha in mock-infected normal mice. These results show that DDTC may have a possible therapeutic role during JEV infection.

Japanese encephalitis in and around Pondicherry, South India: a clinical appraisal and prognostic indicators for the outcome

Japanese encephalitis (JE) is numerically one of the most important causes of viral encephalitis worldwide, with an estimated 50,000 cases and 15,000 deaths annually. About one-third of patients die and half of the survivors have severe neuropsychiatric sequelae. Three hundred patients clinically suspected of JE were tested in the present study. Laboratory confirmation of JE was on the basis of detection of antigen or presence of JE-specific IgM antibody and/or neutralizing antibody in a single CSF sample. The risk factors that were associated with fatal outcome were determined. Japanese encephalitis infection was confirmed in 70.7 per cent (212/300) of the patients. All patients were from rural areas and with low socioeconomic background. Prominent clinical findings were: fever in 100 per cent (212/212) patients, altered sensorium in 87.73 per cent (186/212), convulsion in 85.84 per cent (182/212), headache in 50 per cent (106/212), and vomiting in 47.64 per cent (101/212). The final clinical outcome was available for only 68.39 per cent (145/212) of patients, as children were taken home against medical advice. Of these, 35.86 per cent (52) died while 63.44 per cent (92) of patients survived. Correlations of investigative findings with the final outcome revealed that absence of virus-specific IgM and neutralizing antibodies in CSF were associated with fatal outcome. In patients diagnosed with Japanese encephalitis the presence of a virus-specific immune response is associated with a favourable outcome and an important parameter in recovery from illness.

Protection of mice against experimental Japanese encephalitis virus infections by neutralizing anti-glycoprotein E monoclonal antibodies

Neutralizing monoclonal antibodies (MAbs) to glycoprotein E (gpE) of Japanese encephalitis (JE) virus given intraperitoneally (i.p.) (0.1 ml of immune ascitic fluid (AF) diluted 1:10 per mouse) to about 4-week-old Swiss mice 1 day prior or 2 days after the virus challenge (100 LD50 of JE virus administered intracerebrally (i.c.)) resulted in a decreased mortality along with an increased survival of the animals as demonstrated by the HAI-positive virus-specific (Hs) MAbs. The protective effect produced by four Hs MAbs was maximum when given 1 day prior the virus challenge, while other, namely HAI-positive flavivirus cross-reactive (Hx) and HAI-negative virus-specific (NHs) MAbs did not produce any effect. Interestingly, one of the two NHs MAbs, namely NHs-1 showed a reduced survival of mice given the MAb 2 days after the virus challenge. Administration of combinations of two or more Hs MAbs may be recommended due to their possible enhanced protection against JE virus infections in mice.

Clinical outcome and neurological sequelae in serologically confirmed cases of Japanese encephalitis patients in Assam, India

We report the clinical outcome and prognostic factors in 39 cases of childhood Japanese Encephalitis admitted to a tertiary hospital of Upper Assam and followed up for 421 days in the community. The mortality rate was 20.5% in our study. The mean GCS (9.97 +/- 0.91) was higher in surviving cases than the fatal cases (GCS 7.5 +/- 1.78) at admission. The fatal cases died within 4.75 +/- 3.19 days in the hospital. All the patients had low BMI (surviving cases 13.54 +/- 2.3; fatal cases 12.05 +/- 0.12) and were anemic. Cerebrospinal fluid (CSF) was clear in 91.4% cases but pressure and protein content were increased in all cases. About 10% cases had parkinsonian features at the time of discharge. Residual symptoms remained in about one third of cases even after 421 days.

Japanese encephalitis vaccine for travelers: exploring the limits of risk

The prevention of Japanese encephalitis in travelers presents the juxtaposition of 4 factors: a disease that is widespread throughout Asia, a disease with a low incidence in travelers, a vaccine about which there are safety concerns, and a clinical course that can result in death or permanent disability in two-thirds of symptomatic cases. Travel medicine practitioners often seem to be polarized into 2 groups: a group that gives more weight to the severity of the disease (and therefore often recommend vaccination) and another group that is more persuaded by the low occurrence of cases in travelers (and therefore rarely recommend vaccination). This review assesses the known risks of contracting Japanese encephalitis and the risks associated with the vaccine and tries to develop an appropriate way to recommend this vaccine to travelers who may be at significant risk.

An investigation into the JE epidemic of 2000 in Upper Assam--a perspective study

The viral encephalitis epidemic during 2000 involved all the seven districts of Upper Assam (with 96.4% cases). The epidemiological, serological, clinical and entomological observations of the epidemic confirmed it to be due to JE. These were analysed, presented and discussed in the light of past history/records of the disease in the state. The epidemic was confined to the peak monsoon months of July and August (96% of the cases in the past). Serologically, 75-90% cases were confirmed to be due to JE. Case fatality Rate was 42.11% (overall average of the state in the past). There was no difference in case incidence among children or adults. Male to female ratio was 1:0.6. Based on the abundance and host preferences during the transmission period as well as virus isolation studies (as per past studies in the area) the main vectors Culex vishnui and Mansonia annulifera were susceptible to 4% DDT.

A study on the status of Japanese encephalitis infection in Arunachal Pradesh

Suspected cases of Japanese Encephalitis (J.E.) were recorded in the hospitals of Arunachal Pradesh from 1986 to 1995. 162 cases were diagnosed as J.E. with predominance in male sex and lower age group. Maximum cases were recorded between June to October. 11.3% pig sera showed J.E. antibodies when tested by ELISA test.

Induction of nitric oxide synthase during Japanese encephalitis virus infection: evidence of protective role

The ability of Japanese encephalitis virus (JEV) and JEV-induced macrophage-derived factor (MDF) to modulate nitric oxide synthase (NOS) activity in brain and tumor necrosis factor-alpha (TNF-alpha) and the possible antiviral role of NOS during JEV infection were investigated. NOS activity and particularly that of the inducible form of NOS (iNOS) was significantly enhanced in JEV or JEV-induced MDF-treated mice. Following JEV infection, total NOS activity in brain was gradually increased from Day 3 and reached a peak on Day 6. MDF-induced NOS activity and iNOS activity were dose dependent and maximum activity was observed at 1 h after treatment. The response was sensitive to anti-MDF antibody treatment and N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NOS. Pretreatment of JEV-infected mice with L-NMMA increased the mortality as evident from reduced mean survival time (MST, 11.8 days) compared to placebo treated JEV-infected mice (MST, 17 days). The enhanced level of TNF-alpha observed in the early phase of JEV infection correlated well with the enhanced activity of iNOS. These observations thus provide evidence of the protective role of iNOS during JEV infection and indicate that iNOS may be a key mediator in host innate immune response to infection.

Analysis of Japanese encephalitis epidemic in Western Nepal in 1997

We conducted an epidemiological study of a Japanese encephalitis (JE) outbreak in the southwestern part of Nepal in 1997. A high density of JE infections was found and it was estimated that 27.9% the total population were infected with JE virus in the study area. The fatality rate was 13.2% and there was no difference in the fatality rate between males and females over 5 years old. However, the case fatality rate was 2.1 times higher in females than in males (14.6% vs. 6.9%) among children under 5 years of age. Fifty-three blood samples were collected from suspected JE cases during the epidemic period in 1998. Findings for JE specific IgM revealed that clinical diagnoses of JE were serologically confirmed in an average 78% (70-93%) of patients in three collaborating hospitals. These studies demonstrated that JE was highly prevalent in the area and clinical diagnoses were reliable. Effective preventive measures should be taken against this vaccine-preventable disease.

Japanese Encephalitis epidemic in Anantapur district, Andhra Pradesh (October-November, 1999)

Epidemic of Japanese Encephalitis has occurred in Andhra Pradesh during October-November, 1999 affecting 15 out of 23 districts. In total, 873 cases with 178 deaths have been recorded up to the day 29.11.99. The epidemiological investigation has been done in Anantapur district in western Andhra Pradesh, where the outbreak has started in the third week of October. In the district 47 PHC have been affected. On an average 4.5 per cent of 3175 villages have been affected. Average number of cases per affected village have been 1.5. Rural population has been primarily affected. Age groups 1-14 years including infants have been affected but nearly 86.8% of cases have been among 1-9 year age group. The overall case fatality rate has been 18.4 per cent. Clinical features have been high fever, headache, altered sensorium, convulsions and coma. A marked seasonal onset of a few cases per village and 93.75 per cent of human serum samples collected from hospitalised cases showed the evidence of J.E. virus infection indicating that the present outbreak was due to JE virus. High density of Culex vishnui complex mosquitoes has been observed in the area. All the environmental and ecological conditions, temperature, rainfall and relative humidity have been in favour of JE transmission. Analysis of the data for the last 10 years showed that the human JE cases occurred in Anantapur in September-October months, which shifted to October-November, 99. Prolonged draught conditions were observed till October. Possibly the delayed monsoon and congenial atmospheric conditions after monsoon were favourable to the vector species for extra-human cycle of transmission in 1999. Low level transmission leading to small number of cases continued during the succeeding years every September-October till the present epidemic. In all 24 PHCs and urban towns were identified with 212 cases and 39 deaths till 29.11.99.

[Epidemiological analysis on inpatients with epidemic encephalitis B at No. 1 Hospital of Lian Yungang from 1988-1996]

To study the morbidity and mortality of inpatients with epidemic encephalitis B (EEB) admitted to No. 1 hospital of Lian Yungang city from 1988-1996, 107 inpatients with EEB in the pediatrics department the hospital were analyzed epidemiologically. Results showed that 107 children with EEB had a proportion of 0.65% to all children admitted in the pediatrics department during that 9 years including 98 cases from the countryside and 9 cases from cities. The ratio was 10.8/1.0 when comparing countryside to city. 87 inpatients (81.3%) of EEB children were below 4 year of age consisting. Most patients were infected in late July or early August in 1990 and 1992 with number of 55 out of 107 (51.4%) that consisted 1.56% and 1.53% of the inpatients in pediatrics those years. It was concluded that EEB had a strict seasonal feature. By comparing data from the first 4 years with the latter 5 years, we noticed that the incidence of the latter had a considerable decrease with more milder cases. The morbidity and mortality of the whole city also appeared a decreasing tendency.

Short report: an outbreak of Japanese encephalitis in Kathmandu, Nepal

We report the first proven outbreak of Japanese encephalitis (JE) occurring in the Kathmandu Valley of Nepal. During September and October 1995, we treated 15 patients with meningo-encephalitis. All of the patients were Nepalese, all but one lived in the Kathmandu Valley, and their overall mortality was 53%. Anti-JE virus (JEV) IgM in the cerebrospinal fluid was found in the two cases for whom it was tested. The two tested patients were similar to the other patients in clinical presentation and in home location. We recommend immunization against JEV for those traveling to Kathmandu during the months of August to October.

Japanese encephalitis in India

Japanese encephalitis (JE), caused by a mosquito-borne virus was first recognised in India in 1955 and since then many major out-breaks from different parts of the country have been reported, predominantly in rural areas. Children are mainly affected, with morbidity rate estimated at 0.30 to 1.5 per 100,000 population. Case fatality rate has ranged from 10% to 60%, and up to 50% of those who recover may be left with neurological deficits. Reported incidence has generally been higher in males than in females, but subclinical infections have occurred equally in both sexes. A large number of subclinical infections occur each year during the transmission season. Diagnosis at the primary health centre (PHC) level is based on clinical symptoms only. Therefore, there is a need to develop simple tests for use at the peripheral level both for diagnosis and for epidemiological surveys. JE is a vaccine preventable disease, but there are many logistic problems for effective implementation of vaccination.

Prognostic factors of early sequelae and fatal outcome of Japanese encephalitis

A clinical case control study to identify prognostic factors present at hospital admission associated with early sequelae and fatal outcome of acute Japanese encephalitis (JE) was carried out in Gusi county, Henan Province, central China from June to September 1991. A total of 70 patients with laboratory-confirmed acute JE were studied, of whom 3 cases died and 33 cases had neurological or psychiatric sequelae at the end of three months follow-up. The results showed that acute JE at younger age, with higher body temperature, high white cell count in CSF, and deep coma present at hospital admission were markers for unfavorable outcomes (sequelae or fatal). A history of the vaccination was not correlated with the early sequelae and fatal outcome of the disease. The paper suggests that early diagnosis and treatment and universal JE vaccination for all susceptible populations are keys for decreasing incidence of sequelae and fatal outcome of acute JE.

Detection of immune complexes in the CSF of Japanese encephalitis patients: correlation of findings with outcome

This paper reports the direct evidence for the presence of Japanese encephalitis virus (JEV)-specific immune complexes in the CSF of 31/185 confirmed patients for the first time. A monoclonal antibody-based capture ELISA was used for the detection of immune complexes. Amongst the 31 cases positive for immune complexes, 14 were positive for JEV IgM antibodies and/or neutralizing antibodies in the CSF, 6 were positive for viral antigen in the CSF and 11 for both antibody and antigen. Correlation of findings to final outcome revealed that the presence of immune complexes in CSF was significantly associated with death (p = 0.01).

Epidemiological profile of Japanese encephalitis in Gorakhpur district, Uttar Pradesh, 1982-1988

An in-depth study of Japanese Encephalitis (JE) situation in Gorakhpur district of Uttar Pradesh from 1982-1988 showed increasing trend in the incidence of JE. Total number of annual cases and case fatality rate (CFR) rose from 118 and 23.7 per cent in 1982 to 772 and 32.2 per cent in 1988 respectively. A definite increase was noticed in the number of cases per block following lull years in 1984 and 1987. Among the total affected 1201 villages, 1083 were affected only once. All age groups were affected and the disease showed marked seasonality during August to November. JE, which came in epidemic form in earlier years has established in the area in endemic form.

Epidemiology of Japanese encephalitis

Seven hundred and sixty-two cases of Japanese Encephalitis (JE) were studied during the last 5 years (1985-1989) in relation to age, sex, religion, nutritional status, living habits, exposure to domestic animals and mosquitos, clinical profile, seasonal variation and mortality pattern. The maximum occurrence was in 1987-1988 and it showed a preponderance in males (51-82%). The disease is progressively decreasing in Muslims (3-7%) and gradually increasing in tribes (25-60%). Children in the age-group of 6-7 years (19-25%) were maximally affected and the disease was rare in infancy. The common features were coma, convulsions, neck rigidity and fever (88-97%). Gastrointestinal manifestations were rare (3.6%) but were associated with the highest mortality. About 80-95% had exposure to domestic animals directly or indirectly and 95% of the patients were not using mosquito nets. The CSF protein and sugar content were normal, with or without slight leucocytosis while the lymphocyte count was variable. The CSF and blood picture had no significant relation with clinical presentation and prognosis.

Study of the outbreak of Japanese encephalitis in Lakhimpur district of Assam in 1989

An outbreak of Japanese encephalitis was reported from Lakhimpur district of Assam in July-August, 1989. The outbreak affected 90 villages of the district, covering a population of approximately 36,000. There were 140 cases and 70 deaths due to the epidemic, giving a case fatality rate of 50%. There were no cases from Gogamukh area of the district, where a pilot Japanese encephalitis vaccination project was conducted in the population between July-August 1987, with Kasauli Japanese encephalitis vaccine. Serological examination of acute and convalescent cases showed Japanese encephalitis specific IgM indicating strong evidence of recent Japanese encephalitis infection.

Effect of high-dose dexamethasone on the outcome of acute encephalitis due to Japanese encephalitis virus

Death due to Japanese encephalitis usually occurs in the first 5 days of hospitalization as a result of deepening coma with respiratory arrest. Death may result from edema-induced increases in intracranial pressure that might be reduced by the administration of steroids. Sixty-five patients presenting in Thailand to four hospitals with a diagnosis of acute Japanese encephalitis were randomized in a double-masked fashion and stratified by initial mental status into a placebo group (saline) or a treatment group (dexamethasone 0.6 mg/kg intravenously as a loading dose followed by 0.2 mg/kg every 6 h for 5 days). Fifty-five of the 65 had confirmed Japanese encephalitis as demonstrated by detection of virus or by Japanese encephalitis virus-specific IgM antibody. Important outcome measures included mortality (24%, treatment group; 27%, control group), days to alert mental status (3.9 vs. 6.2), and neurologic status 3 months after discharge (45% abnormal in each group). No statistically significant benefit of high-dose dexamethasone could be detected.

Japanese encephalitis in southeastern Nepal: clinical aspects in the 1986 epidemic

A multi disciplinary team furthered the collaborative study of acute encephalitis in southeastern Nepal during a major epidemic which occurred in the monsoon period of 1986. Viral studies of serum and cerebro-spinal fluid (CSF) confirmed Japanese Encephalitis Virus (JEV) as the causative agent. Analysis of epidemiologic data suggests recent introduction of the virus to the regional population. Children accounted for the majority of all hospital admissions and had a markedly lower fatality rate from the infection than adults. Unfavourable prognostic indicators identified include a reduced conscious level on admission to hospital and a low serum or CSF IgM response to JEV.

Japanese encephalitis in children in northern Thailand

Fifty-nine children with Japanese encephalitis admitted in Maharaj Nakhon Chiang Mai Hospital since 1984-1985 were studied. The male to female ratio was 1.18:1. The age range was between 1 to 14 years old with 74% in the age range of 6-14 years. The symptoms included change of consciousness (100%), fever (96%), headache (76%), convulsions (59%) and vomiting (52%). The neurologic signs, namely positive meningeal signs (61%), hyperreflexia (61%), positive Babinski's sign (49%) hemiplegia (42%), papilledema (22%), and other cranial nerve palsies (23%) were seen. Abnormal respiration were found in 23% and 8% of cases had hypertension. Most children (81%) had blood leukocytosis with predominant neutrophils. The average CSF white blood cell count was 200 cells per mm. with lymphocytosis in 76 percent of the patients. The average CSF protein was higher than normal. Almost all cases had normal CSF sugar levels. The JEV antibody response, mostly primary type, Occurred in about 62 percent of cases. All children received symptomatic and supportive treatment, such as antipyretics, anticonvulsants, anticerebral edema agents, adequate respiration and nutrition and physical and occupational therapies. Associated complications were treated according to the individual's need. The mortality rate and neurological sequelae were found in 17% and 57% of cases respectively. Eighteen percent of the patients suffered severe neurological sequelae. The neurological sequelae included memory deficit (46%), mental retardation (42%), hemiplegia (34%), emotional and behavioral disturbance (24%), epilepsy (20%), motor aphasia (16%), cranial nerve palsies (16%), involuntary limb movement (8%) and blindness (2%).

A review of Japanese encephalitis cases in the Philippines (1972-1985)

Few studies have shown that JE does occur in the Philippines with the majority of the cases affecting the 1-10 year age group in places where rice fields abound. The morbidity rate is 15-17%, with a mortality rate of about 7-30%.