Viral etiology of acute childhood encephalitis in Beijing diagnosed by analysis of single samples

Mice as an Animal Model for Japanese Encephalitis Virus Research: Mouse Susceptibility, Infection Route, and Viral Pathogenesis

Japanese encephalitis virus (JEV), a zoonotic flavivirus, is principally transmitted by hematophagous mosquitoes, continually between susceptible animals and incidentally from those animals to humans. For almost a century since its discovery, JEV was geographically confined to the Asia-Pacific region with recurrent sizable outbreaks involving wildlife, livestock, and people. However, over the past decade, it has been detected for the first time in Europe (Italy) and Africa (Angola) but has yet to cause any recognizable outbreaks in humans. JEV infection leads to a broad spectrum of clinical outcomes, ranging from asymptomatic conditions to self-limiting febrile illnesses to life-threatening neurological complications, particularly Japanese encephalitis (JE). No clinically proven antiviral drugs are available to treat the development and progression of JE. There are, however, several live and killed vaccines that have been commercialized to prevent the infection and transmission of JEV, yet this virus remains the main cause of acute encephalitis syndrome with high morbidity and mortality among children in the endemic regions. Therefore, significant research efforts have been directed toward understanding the neuropathogenesis of JE to facilitate the development of effective treatments for the disease. Thus far, multiple laboratory animal models have been established for the study of JEV infection. In this review, we focus on mice, the most extensively used animal model for JEV research, and summarize the major findings on mouse susceptibility, infection route, and viral pathogenesis reported in the past and present, and discuss some unanswered key questions for future studies.

Antibody persistence upto 5 years after primary immunization and booster with an inactivated chromatographically purified Vero cell-derived Japanese encephalitis vaccine in Thai children

Japanese encephalitis is the main cause of viral encephalitis in Asia. In a previous single-arm vaccine trial, an inactivated chromatographically purified Japanese encephalitis Vero cell vaccine (CVI-JE; JEVAC^TM) was safe and immunogenic in 152 Thai children aged 1–3 years receiving a 2-dose primary immunization and booster dose 1 year later. We conducted a 5-year follow-up assessment of the persistence of the immune response the 144 children remaining in this cohort after first booster dose. Immunity was assessed by 50% plaque reduction neutralization test annually for up to 5 years post-booster. Seroprotection rates (95%CI) decreased from 100% (97.1–100) at 1 year post-booster to 93% (85.0–98.3) at 5 years post-booster. No serious vaccine-related adverse events or Japanese encephalitis infections were reported. A 2-dose primary immunization and booster 1 year later with CVI-JE provided long-lasting immunity in the majority of children.

Epidemiology, Etiology and Clinical Aspects of Childhood Acute Encephalitis in a Tertiary Pediatric Hospital in Costa Rica

BACKGROUND

Limited data are available on childhood encephalitis in Latin America. Our study aimed to increase insight on clinical presentation, etiology and outcome of children with acute encephalitis in Costa Rica.

METHODS

We conducted a prospective, observational study during an 8-month period at the Hospital Nacional de Niños "Dr. Carlos Sáenz Herrera" in Costa Rica. Case definition was according to "International Encephalitis Consortium" in children <13 years. We analyzed demographic characteristics, clinical symptoms, neurologic imaging, etiology, treatment and mortality.

RESULTS

Forty patients were identified. Mean age was 5 years and 57.5% were male. Most frequently neurologic symptoms were altered mental status (100.0%), headache (57.5%) and seizures (52.5%). Etiology was determined in 52.5% of cases. Probable or confirmed viral etiology was identified in 6 cases (15.0%) and bacterial etiology in also 6 cases (15.0%). A possible etiology was identified in 7 cases (17.5%). Autoimmune encephalitis was diagnosed in 2 patients (5.0%). Enterovirus and Streptococcus pneumoniae were the most common confirmed agents. No cases of herpes simplex virus were found. Etiology of 19 cases (47.5%) remained unknown. Sequelae were reported in 45.0% of patients. Mortality rate was 15.0% (6 cases), 3 caused by virus (adenovirus, human herpesvirus 6, enterovirus), 2 by bacteria (S. pneumoniae, Haemophilus influenzae type b) and 1 of unknown etiology. Diffuse cerebral edema was the most important mortality predictor (P < 0.001).

CONCLUSIONS

Acute encephalitis in our study was associated with significant morbidity and mortality. Early and aggressive antiviral, antibiotic and anticerebral edema treatment is necessary when acute encephalitis is suspected.

Factors associated with outcome of acute encephalitis in children: a retrospective study of three referral hospitals

BACKGROUND Encephalitis is more frequent in children and has a poor outcome. There was no data on encephalitis in children in Indonesia, so this study was aimed to evaluate clinical presentation and diagnostic examination of children with acute encephalitis, and factors related to outcome. METHODS This was a retrospective study of medical records between 2014 and 2018 in three referral hospitals in Jakarta and Tangerang. Clinical presentation at admission, cerebrospinal fluid analysis, neuroimaging, and electroencephalography (EEG) were documented. Outcome was determined at hospital discharge and classified as poor for severe neurological abnormalities at discharge or died. Logistic regression was used to evaluate associated factors with the outcome. RESULTS A total of 190 children were included and most were age >1 year (71%). Most subjects presented with fever (90%) and seizures (87%). Of those who had seizures, 80% experienced generalized seizures. Focal neurological deficit was seen in 90 patients (47%). EEG was positive in 90% subjects (n = 27/30). Probable cases were found in 51% of all subjects. The mortality was 23%. Focal seizures (odds ratio [OR] = 3.305, 95% confidence interval [CI] = 1.122–9.742) and age >1 year (OR = 3.076, 95% CI = 1.388–6.803) were risk factors for a poor outcome. CONCLUSIONS Acute encephalitis occurred most often in children aged >1 year. Fever and seizures were the most common symptoms. EEG was better than other examinations for confirming diagnosis of encephalitis. Focal seizures and age >1 year were associated with a three-fold increased risk for a poor outcome.

'More than devastating'-patient experiences and neurological sequelae of Japanese encephalitis§

BACKGROUND

Japanese encephalitis (JE), caused by the mosquito-borne JE virus, is a vaccine-preventable disease endemic to much of Asia. Travellers from non-endemic areas are susceptible if they travel to a JE endemic area. Although the risk to travellers of JE is low, the consequences may be severe.

METHODS

Here, we describe three cases of JE in British travellers occurring in 2014-15. In addition, we report, through interviews with survivors and their families, personal experiences of life after JE.

RESULTS

Three cases of JE were diagnosed in British travellers in 2014/15. One was acquired in Thailand, one in China and one in either Thailand, Laos or Cambodia. All three patients suffered severe, life-threatening illnesses, all were admitted to intensive care units and required medical evacuation back to the UK. One patient suffered a cardiac arrest during the acute stage but made a good recovery. The other two patients remain significantly paralysed and ventilator dependent. All three cases had clear indications for vaccination, and all have been left with life-changing neurological sequelae.

CONCLUSIONS

Travel health providers should be aware of the severity of JE, as well as the risk, allowing travellers to make fully informed decisions on JE vaccination.

Japanese encephalitis - the prospects for new treatments

Japanese encephalitis is a mosquito-borne disease that occurs in Asia and is caused by Japanese encephalitis virus (JEV), a member of the genus Flavivirus. Although many flaviviruses can cause encephalitis, JEV causes particularly severe neurological manifestations. The virus causes loss of more disability-adjusted life years than any other arthropod-borne virus owing to the frequent neurological sequelae of the condition. Despite substantial advances in our understanding of Japanese encephalitis from in vitro studies and animal models, studies of pathogenesis and treatment in humans are lagging behind. Few mechanistic studies have been conducted in humans, and only four clinical trials of therapies for Japanese encephalitis have taken place in the past 10 years despite an estimated incidence of 69,000 cases per year. Previous trials for Japanese encephalitis might have been too small to detect important benefits of potential treatments. Many potential treatment targets exist for Japanese encephalitis, and pathogenesis and virological studies have uncovered mechanisms by which these drugs could work. In this Review, we summarize the epidemiology, clinical features, prevention and treatment of Japanese encephalitis and focus on potential new therapeutic strategies, based on repurposing existing compounds that are already suitable for human use and could be trialled without delay. We use our newly improved understanding of Japanese encephalitis pathogenesis to posit potential treatments and outline some of the many challenges that remain in tackling the disease in humans.

Epidemiological Profile of Acute Viral Encephalitis in a Sample of Egyptian Children

INTRODUCTION

Acute encephalitis syndrome (AES) is a considerable public health problem.

AIM

This study was designed to describe the aetiology, demographic features, clinical picture, short-term outcome and risk factors of mortality of children with viral encephalitis in Egyptian children.

METHODS

PCR detection of viruses in the CSF of pediatric patients admitted to the pediatric unit or ICU Cairo University Pediatric hospital presenting with encephalitis syndrome.

RESULTS

Of the 96 patients included in the study, viral etiological agents were detected in 20 cases (20.8%), while 76 patients (79.2%) had no definite viral aetiology. The most abundant virus detected was Enterovirus (EV) in fourteen (14.5%), two (2.1%) were positive for human herpes simplex virus 6 (HSV-6), one (1.0%), human herpes simplex virus1 (HSV-1), one (1.0%) Epstein Barr virus (EBV), one (1.0%), cytomegalovirus (CMV) and one (1.0%) with varicella-zoster virus (VZV). On the short term outcome, 22 (22.9) patients died, and 74 (77.1%) survived. Severity outcome among survival was vegetative in three cases (4%) severe in 9 (12.16%), moderate in 14 (18.9%), mild in 29 (39.2%) and full recovery in 19 (25.6%). Mortality risk factors for younger age, the presence of apnea, the need for mechanical ventilation and the presence of abnormal CT findings were all significantly associated with fatal outcome (p < 0.05).

CONCLUSION

Enterovirus was the most common cause of encephalitis among Egyptian children. Mortality was correlated with younger age and disease severity at admission. Sequelae were high among infected children.

Risk assessment for Japanese encephalitis vaccination

Japanese encephalitis (JE) is the most commonly diagnosed viral encephalitis in Asia. JE is caused by a virus called JE virus (JEV), a member of the genus Flavivirus, family Flaviviridae, and is transmitted by Culex mosquitoes. Neutralising antibody to JEV protects against JE, and can be induced by vaccination. JE is a potential threat to travellers to endemic areas, which are most of South and Southeast Asia and some Pacific Islands. The risk of JE can be expected to increase with increasing mosquito exposure and time spent in regions and seasons of active transmission. JE is very rare in travellers, but mortality is high, around 1 in 3, and there is a high rate of lasting neurological damage. JE can therefore be a profoundly life changing event for a traveller. Travellers and their healthcare providers need to balance the low risk of disease against the very high severity of disease if it does occur. In order to make an informed decision, the severity of JE disease should be carefully explained to travellers to Asia.

Etiology and prognosis of acute viral encephalitis and meningitis in Chinese children: a multicentre prospective study

BACKGROUND

In China, there were few studies about the pathogens of acute viral encephalitis and meningitis in children in recent years. The aims of this study were to characterize the etiology and prognosis of acute viral encephalitis and meningitis in Chinese children.

METHODS

This was a multicentre prospective study. Two hundred and sixty one viral encephalitis patients and 285 viral meningitis patients were enrolled. The mean age of viral encephalitis and meningitis were 5.88 ± 3.60 years and 6.39 ± 3.57 years, respectively. Real-time reverse transcription PCR and multiplex PCR were used to detect human enteroviruses and herpes viruses in cerebrospinal fluid (CSF) of patients with encephalitis or meningitis. The enzyme-linked immune absorbent assay (ELISA) was used for detecting IgM antibody against Japanese encephalitis virus (JEV) in CSF and against mumps virus, tick-borne encephalitis virus (TBEV), dengue virus and rubella virus in acute serum. The clinical and outcome data were collected during patients' hospitalization.

RESULTS

The etiology of viral encephalitis was confirmed in 52.5% patients. The primary pathogen was human enteroviruses (27.7%) in viral encephalitis. The incidence of sequelae and the fatality rate of viral encephalitis with confirmed etiology were 7.5% and 0.8%, respectively. The etiology of viral meningitis was identified in 42.8% cases. The leading pathogen was also human enteroviruses (37.7%) in viral meningitis. The prognosis of viral meningitis was favorable with only 0.7% patients had neurological sequelae.

CONCLUSIONS

Human enteroviruses were the leading cause both in acute viral encephalitis and viral meningitis in children. The incidence of sequelae and fatality rate of viral encephalitis with confirmed etiology were 7.5% and 0.8%, respectively. The prognosis of viral meningitis was favorable compared to viral encephalitis.

Acute Childhood Encephalitis at 2 Tertiary Care Children's Hospitals in Israel: Etiology and Clinical Characteristics

OBJECTIVES

The clinical characteristics, pathogens, and outcome were analyzed to investigate the etiology of acute pediatric encephalitis in 2 tertiary pediatric medical centers in Israel.

METHODS

A retrospective study among children aged 1 month to 18 years hospitalized with the diagnosis of acute encephalitis between January 1999 and December 2009. Data on presenting symptoms, clinical findings, microbiological, virologic, electroencephalographic and neuroimaging studies, laboratory results, and hospital course were retrieved from the medical records and the computerized microbiology database.

RESULTS

Forty-four children were included. An etiologic agent was identified in 11 (25%): Mycoplasma pneumoniae (n = 2), enterovirus (n = 3), herpes simplex virus (HSV) (n = 1), Epstein-Barr virus (n = 2), human herpes virus 6 (n = 1), influenza virus type A (n = 1), and varicella zoster virus (n = 1). Presenting features included fever (90% of patients), seizures (39%), focal neurological signs (18%), and decreased consciousness (67%). Diagnostic findings included pleocytosis in the cerebrospinal fluid (76% of patients), electroencephalographic abnormalities (78%), and neuroimaging abnormalities (34%). All patients were treated with acyclovir until negative result for HSV polymerase chain reaction was received from cerebrospinal fluid, the child with HSV encephalitis was treated with intravenous acyclovir for 3 weeks. The outcomes at the time of discharge were: normal (66%), motor difficulties (14%), global neurological deficits (7%), visual defects (2%), and hearing impairment (2%) and no deaths.

CONCLUSIONS

The etiology of acute encephalitis remains unknown in the majority of cases. There was no correlation between adverse outcome and a specific etiologic agent. The high morbidity rate may suggest that current therapeutic modalities may not be sufficient.

Profiling of viral proteins expressed from the genomic RNA of Japanese encephalitis virus using a panel of 15 region-specific polyclonal rabbit antisera: implications for viral gene expression

Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is closely related to West Nile (WN), yellow fever (YF), and dengue (DEN) viruses. Its plus-strand genomic RNA carries a single open reading frame encoding a polyprotein that is cleaved into three structural (C, prM/M, and E) and at least seven nonstructural (NS1/NS1', NS2A, NS2B, NS3, NS4A, NS4B, and NS5) proteins, based on previous work with WNV, YFV, and DENV. Here, we aimed to profile experimentally all the viral proteins found in JEV-infected cells. We generated a collection of 15 JEV-specific polyclonal antisera covering all parts of the viral protein-coding regions, by immunizing rabbits with 14 bacterially expressed glutathione-S-transferase fusion proteins (for all nine viral proteins except NS2B) or with a chemically synthesized oligopeptide (for NS2B). In total lysates of JEV-infected BHK-21 cells, immunoblotting with these antisera revealed: (i) three mature structural proteins (~12-kDa C, ~8-kDa M, and ~53-kDa E), a precursor of M (~24-kDa prM) and three other M-related proteins (~10-14 kDa); (ii) the predicted ~45-kDa NS1 and its frameshift product, ~58-kDa NS1', with no evidence of the predicted ~25-kDa NS2A; (iii) the predicted but hardly detectable ~14-kDa NS2B and an unexpected but predominant ~12-kDa NS2B-related protein; (iv) the predicted ~69-kDa NS3 plus two major cleavage products (~34-kDa NS3N-term and ~35-kDa NS3C-term), together with at least nine minor proteins of ~16-52 kDa; (v) the predicted ~14-kDa NS4A; (vi) two NS4B-related proteins (~27-kDa NS4B and ~25-kDa NS4B'); and (vii) the predicted ~103-kDa NS5 plus at least three other NS5-related proteins (~15 kDa, ~27 kDa, and ~90 kDa). Combining these data with confocal microscopic imaging of the proteins' intracellular localization, our study is the first to provide a solid foundation for the study of JEV gene expression, which is crucial for elucidating the regulatory mechanisms of JEV genome replication and pathobiology.

Acute encephalitis in children: Progress and priorities from an Australasian perspective

Encephalitis is a complex neurological syndrome caused by inflammation of the brain that occurs with highest incidence in children. It is challenging to diagnose and manage due to the variety of aetiologies and non-specific clinical presentations. We discuss the recent progress in clinical case definitions; review recent, large, prospective epidemiological studies; and describe aetiologies. We emphasise infectious causes relevant to children in Australasia but also consider emerging immune-mediated syndromes responsive to immune therapies. We identify priorities for future research in children, given the potential for climate change and international travel to influence the emergence of infectious agents in our region.

Outcome of children with acute encephalitis and refractory status epilepticus

Acute encephalitis in children is a life-threatening neurological emergency. However, little is reported about the outcome of this devastating illness in the United States. The authors retrospectively reviewed the charts of patients admitted to a regional pediatric intensive care unit with the diagnosis of acute encephalitis between 2006 and 2011. In 41 cases that met the inclusion criteria, the most common presenting symptoms were fever (65.9%), altered mental status (61%), and seizures (58.5%). Eight patients (19.5%) who presented with refractory status epilepticus had a longer median length of stay in the pediatric intensive care unit (46 vs. 4 days; P < .0001) and a significant worsening of Pediatric Cerebral Performance Category score on discharge by 2 or more points (odds ratio 20.38; 95% confidence interval, 2.89-143.52). All children survived to hospital discharge. In conclusion, children with acute encephalitis who present with refractory status epilepticus have a worse neurological outcome and a longer stay in the pediatric intensive care unit.

Death waits for no man--does it wait for a virus? How enteroviruses induce and control cell death

Enteroviruses (EVs) are the most common human viral pathogens. They cause a variety of pathologies, including myocarditis and meningoencephalopathies, and have been linked to the onset of type I diabetes. These pathologies result from the death of cells in the myocardium, central nervous system, and pancreas, respectively. Understanding the role of EVs in inducing cell death is crucial to understanding the etiologies of these diverse pathologies. EVs both induce and delay host cell death, and their exquisite control of this balance is crucial for their success as human viral pathogens. Thus, EVs are tightly involved with cell death signaling pathways and interact with host cell signaling at multiple points. Here, we review the literature detailing the mechanisms of EV-induced cell death. We discuss the mechanisms by which EVs induce cell death, the signaling pathways involved in these pathways, and the strategies by which EVs antagonize cell death pathways. We also discuss the role of cell death in both the resulting pathology in the host and in the facilitation of viral spread.

Viral aetiology and clinico-epidemiological features of acute encephalitis syndrome in eastern India

This study reports clinico-epidemiological features and viral agents causing acute encephalitis syndrome (AES) in the eastern Indian region through hospital-based case enrolment during April 2011 to July 2012. Blood and CSF samples of 526 AES cases were investigated by serology and/or PCR. Viral aetiology was identified in 91 (17·2%) cases. Herpes simplex virus (HSV; types I or II) was most common (16·1%), followed by measles (2·6%), Japanese encephalitis virus (1·5%), dengue virus (0·57%), varicella zoster virus (0·38%) and enteroviruses (0·19%). Rash, paresis and cranial nerve palsies were significantly higher (P < 0·05) with viral AES. Case-fatality rates were 10·9% and 6·2% in AES cases with and without viral aetiology, respectively. Simultaneous infection of HSV I and measles was observed in seven cases. This report provides the first evidence on viral aetiology of AES viruses from eastern India showing dominance of HSV that will be useful in informing the public health system.

Japanese encephalitis: the virus and vaccines

Japanese encephalitis (JE) is an infectious disease of the central nervous system caused by Japanese encephalitis virus (JEV), a zoonotic mosquito-borne flavivirus. JEV is prevalent in much of Asia and the Western Pacific, with over 4 billion people living at risk of infection. In the absence of antiviral intervention, vaccination is the only strategy to develop long-term sustainable protection against JEV infection. Over the past half-century, a mouse brain-derived inactivated vaccine has been used internationally for active immunization. To date, however, JEV is still a clinically important, emerging, and re-emerging human pathogen of global significance. In recent years, production of the mouse brain-derived vaccine has been discontinued, but 3 new cell culture-derived vaccines are available in various parts of the world. Here we review current aspects of JEV biology, summarize the 4 types of JEV vaccine, and discuss the potential of an infectious JEV cDNA technology for future vaccine development.

Enter at your own risk: how enteroviruses navigate the dangerous world of pattern recognition receptor signaling

Enteroviruses are the most common human viral pathogens worldwide. This genus of small, non-enveloped, single stranded RNA viruses includes coxsackievirus, rhinovirus, echovirus, and poliovirus species. Infection with these viruses can induce mild symptoms that resemble the common cold, but can also be associated with more severe syndromes such as poliomyelitis, neurological diseases including aseptic meningitis and encephalitis, myocarditis, and the onset of type I diabetes. In humans, polarized epithelial cells lining the respiratory and/or digestive tracts represent the initial sites of infection by enteroviruses. Control of infection in the host is initiated through the engagement of a variety of pattern recognition receptors (PRRs). PRRs act as the sentinels of the innate immune system and serve to alert the host to the presence of a viral invader. This review assembles the available data annotating the role of PRRs in the response to enteroviral infection as well as the myriad ways by which enteroviruses both interrupt and manipulate PRR signaling to enhance their own replication, thereby inducing human disease.

The complete genome analysis of two enterovirus 96 strains isolated in China in 2005 and 2009

Enterovirus 96 (EV96) is a new member of species Human Enterovirus C (HEV-C). In this report, genomic characterization of two EV96 strains isolated from acute flaccid paralysis surveillance in Shandong province of China in 2005 and 2009 is described. The two strains, designated 05517 and 09228C1, had 82.7% genomic similarity with each other and 75.1-84.2% with other three strains available from GenBank in complete genome sequences. In VP1 coding region, they had 77.6-86.6% nucleotide similarity with other EV96 strains. Interestingly, deletions of 3 nucleotides in the VP3 coding region of strain 09228C1, and of 3 nucleotides in the 3A region of both Shandong strains were observed. Simplot and bootscanning analysis on HEV-C genome sequences were performed, and evidence of recombination in P3 region for Shandong EV96 strains was found. In conclusion, these strains had distant genetic relationship with each other and with other EV96 strains.

Viral etiology of encephalitis in children in southern Vietnam: results of a one-year prospective descriptive study

BACKGROUND

Acute encephalitis is an important and severe disease in children in Vietnam. However, little is known about the etiology while such knowledge is essential for optimal prevention and treatment. To identify viral causes of encephalitis, in 2004 we conducted a one-year descriptive study at Children's Hospital Number One, a referral hospital for children in southern Vietnam including Ho Chi Minh City.

METHODOLOGY/PRINCIPAL FINDINGS

Children less than 16 years of age presenting with acute encephalitis of presumed viral etiology were enrolled. Diagnostic efforts included viral culture, serology and real time (RT)-PCRs. A confirmed or probable viral causative agent was established in 41% of 194 enrolled patients. The most commonly diagnosed causative agent was Japanese encephalitis virus (n = 50, 26%), followed by enteroviruses (n = 18, 9.3%), dengue virus (n = 9, 4.6%), herpes simplex virus (n = 1), cytomegalovirus (n = 1) and influenza A virus (n = 1). Fifty-seven (29%) children died acutely. Fatal outcome was independently associated with patient age and Glasgow Coma Scale (GCS) on admission.

CONCLUSIONS/SIGNIFICANCE

Acute encephalitis in children in southern Vietnam is associated with high mortality. Although the etiology remains unknown in a majority of the patients, the result from the present study may be useful for future design of treatment and prevention strategies of the disease. The recognition of GCS and age as predictive factors may be helpful for clinicians in managing the patient.

An outbreak of aseptic meningitis caused by coxsackievirus A9 in Gansu, the People's Republic of China

BACKGROUND

An outbreak of aseptic meningitis occurred in Tianshui city of Gansu Province, the People's Republic of China, from March to June 2005. A total of 85 patients were clinical confirmed as aseptic meningitis in this outbreak.

RESULTS

CVA9 was mainly responsible for this outbreak supported by the clinical manifestations of the patients, epidemiological data of the outbreak, the results of RT-PCR and complete VP1 sequence determination, conventional neutralization assays, IgM serological assays, viral isolation and phylogenetics analysis. Through phylogenetic analysis and homogeneity analysis for partial VP1 gene, the nucleotide and amino acid homologies between Gansu isolates and former Chinese CVA9 strains were 88.2%-96.1% and 97.2%-99.2%, respectively. Multiple transmission chains of CVA9 occurred in different provinces or years in China. Moreover, in order to clarify the genotype of CVA9, Gansu CVA9 strains isolated in this outbreak were compared with other CVA9 isolates based on VP1/2A junction regions (genotyping region) and they might belong to a new genotype of CVA9, which could be assigned for genotype XIII, CONCLUSIONS: CVA9 was confirmed as the pathogen responsible for this outbreak. The phylogenetic analysis indicated that the CVA9 strains isolated in this outbreak might belong to a new genotype.

Etiological spectrum of clinically diagnosed Japanese encephalitis cases reported in Guizhou Province, China, in 2006

The proportion of laboratory-confirmed Japanese encephalitis (JE) virus (JEV) infections was compared to the number of JE cases reported on the basis of seasonality and the clinical symptoms of hospitalized patients in Guizhou Province, China, between April and November 2006. Of the 1,837 patients with reported JE, 1,382 patients in nine prefectures were investigated. JE was confirmed in 1,210 of 1,382 (87.6%) patients by a JEV-specific immunoglobulin M (IgM) antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA), heminested reverse transcriptase PCR, and virus isolation. Two strains of JEV belonging to genotype 1 were isolated. Other viral pathogens responsible for encephalitis, including echovirus, mumps virus, herpes simplex virus, and cytomegalovirus, were identified in 67 of 172 (38.9%) JE-negative cases. On the basis of the distribution of the laboratory-confirmed JE cases from different hospitals according to the Chinese administrative division, which included hospitals at the provincial, city, county, and township levels, county hospitals detected the highest number of JE cases (81.8%), whereas township hospitals detected the smallest number of JE cases (1.4%). Provincial and city hospitals had the highest and lowest rates of accuracy of providing a clinical diagnosis of JE, as confirmed by laboratory testing (91.8% and 76.7%, respectively). This study demonstrates that laboratory confirmation improves the accuracy of diagnosis of JE and that an enhanced laboratory capacity is critical for JE surveillance as well as the identification of other pathogens that cause encephalitic syndromes with clinical symptoms similar to those caused by JEV infection.

Etiology and clinico-epidemiological profile of acute viral encephalitis in children of western Uttar Pradesh, India

OBJECTIVES

To study the etiology of viral encephalitis (VE) in the children of western Uttar Pradesh, India and to assess the clinico-epidemiological profile of these children in relation to VE.

METHODS

Both cerebrospinal fluid and serum samples were collected from pediatric patients suffering from encephalitis hospitalized at Jawaharlal Nehru Medical College, Aligarh from July 2004 to November 2006. Viral isolation was done on RD cells, HEp-2 cells, and Vero cells from the cerebrospinal fluid samples of children with suspected VE. A microneutralization test was performed for enterovirus 71. An enzyme immunoassay for IgM antibodies was performed for measles virus, mumps virus, varicella zoster virus, herpes simplex virus 1, and Japanese encephalitis virus.

RESULTS

Eighty-seven patients were enrolled in the study. The most common etiology of VE was enterovirus 71 (42.1%), followed by measles (21.1%), varicella zoster virus (15.8%), herpes simplex virus (10.5%), and mumps (10.5%). Japanese encephalitis virus was not found in any case. Enterovirus 71 infection caused significant morbidity in children; mortality occurred in 50%. A preponderance of cases occurred in December. In our study generalized convulsions along with altered sensorium were the significant findings in patients with VE.

CONCLUSIONS

Enterovirus 71, the major etiology of VE in our study, was associated with significant mortality and morbidity. Such studies should be conducted frequently to assess the role of emerging VE in different regions.

Enterovirus-associated encephalitis in the California encephalitis project, 1998-2005

BACKGROUND

Encephalitis is a relatively rare presentation of enterovirus (EV) infections. Clinical and epidemiologic characteristics of EV encephalitis (EVE) have not been well characterized.

METHODS

Patients with encephalitis enrolled in the California Encephalitis Project from 1998 to 2005 were tested for a range of pathogens, including EV, using a standardized diagnostic algorithm. EVE was categorized as "confirmed" (EV detected in cerebrospinal fluid [CSF] or brain tissue) or "possible" (EV found in respiratory or fecal specimens or serum EV immunoglobulin [Ig] M detected). We compared clinical and epidemiologic characteristics of EVE with those of other infectious encephalitis cases.

RESULTS

EVE was diagnosed in 73 (4.6%) of 1571 patients (45 confirmed cases, 28 possible cases); 11.1% of cases had other infectious causes. Patients with confirmed EVE were younger, although 27% were adults, who presented with significantly less severe symptoms. Serotypes identified in EVE cases correlated with the predominant serotype for the given year reported to the National Enterovirus Surveillance System at the Centers for Disease Control and Prevention. Two of 4 fatal EVE cases were associated with EV71.

CONCLUSION

EVs are an important cause of encephalitis cases requiring hospitalization, in both children and adults. Our data suggest that EVE severity varies by serotype, confirm the importance of CSF/brain tissue polymerase chain reaction, and demonstrate that serum IgM findings are of little value in diagnosing EVE.

Childhood encephalitis in Sweden: etiology, clinical presentation and outcome

Acute encephalitis is a relatively uncommon but potentially harmful CNS inflammation usually caused by infection. The diagnosis is difficult to establish and the etiology often remains unclear. Furthermore, the long-term prognosis of acute encephalitis in children is poorly described. In this study, we characterize childhood encephalitis from a Swedish perspective in regard to etiology, clinical presentation and sequele. We retrospectively studied all children (n=93) who were admitted for acute encephalitis at Karolinska University Hospital in Stockholm during 2000-2004. A confirmed etiological agent was identified in eight cases and a probable one in 37; in 48 cases no etiological agent could be found. Tick-borne encephalitis virus, enterovirus, respiratory syncytial virus, varicella zoster virus and influenza virus predominated and represented 67% of all the confirmed or probable etiologies. Encephalopathy was present in 80% of the children, 81% had fever, 44% had focal neurological findings, and seizures occurred in 40%. EEG abnormalities were seen in 90% and abnormal neuroimaging was present in 30%. The cerebrospinal fluid showed pleocytosis in 55%. There was no mortality, but 60% of the children had persisting symptoms at the time of discharge, 41% of which were moderate to severe. We conclude that the etiology of encephalitis among Swedish children is at large the same as in other European countries with similar vaccination programs. Fever and encephalopathy were seen in a majority of children and the most sensitive tool for making the diagnosis was EEG examination. Furthermore, many children display persisting sequele at discharge for which the strongest predictive factor was focal neurological findings at presentation.

A study of acute febrile encephalopathy with special reference to viral etiology

OBJECTIVE

To study the etiological profile of patients with acute febrile encephalopathy syndrome focusing chiefly on the viral etiology, and to correlate clinical and radiological features of patients with viral encephalitis.

METHODS

A prospective hospital based study conducted on the consecutive patients admitted in a pediatric unit during the period of 1(st) February 2004 to 31st January 2005 based on the following inclusion criteria: (1) Age more than 1 month and less than 18 years and (2) A diagnoses of acute febrile encephalopathy, based on the following criteria: (i) fever (ii) acute depression of consciousness or mental deterioration for more than 12 hours with or without motor or sensory deficit and (iii) Total duration of illness at the time of admission 1 week or less.

RESULTS

The final study group comprised of 151 patients with mean age of 3.21 +/- 2.9 (range of mth-13 years) and male: female ratio of 1.71: 1. A diagnosis other than viral encephalitis was reached in 94 patients (62.3 %). Pyogenic meningitis was the most frequent diagnosis 51(33.8 %) followed by tubercular meningitis 12 (7.9 %), and cerebral malaria 8 (5.2 %) in the patient group of non-viral causes. Fifty-seven cases (37.3%) were suspected as viral encephalitis and mean age of the cases suspected as viral encephalitis was 2.8 +/- 2.9 (Range 1 mth-10 yrs) with male: female ratio of 1.28: 1. Etiological diagnosis was reached or considered probable in 41 (72%) cases out of the suspected patients. The most common etiological agent identified was enterovirus 71 in 20 patients (35.1 %). The other viruses identified were mumps in 6 (10.5%), Japanese encephalitis in 5 (8.7%), and measles in 4 (7%) cases. MRI brain was done in 39 patients and was abnormal in 14 patients. Out of 57 cases of suspected viral encephalitis 10 patients expired within 48 hours, 2 > 48 hours and 19 atients had significant neurological sequels at discharge.

CONCLUSION

The etiology of acute febrile encephalopathy varies from infectious etiologies to noninfectious metabolic disorders. There are no distinguishing clinical or radiological features to differentiate the various causes of viral encephalitis. The clinical and the radiological findings in encephalitis should be interpreted in the geographical and other epidemiological background.

Molecular typing and epidemiology of non-polio enteroviruses isolated from Yunnan Province, the People's Republic of China

This report presents an overview of human enteroviruses in Yunnan Province, the People's Republic of China. A total of 210 non-polioviruses isolated under acute flaccid paralysis (AFP) surveillance during a total study period of 5 years--1997 to 2000 and 2004--were examined. Of the 210 non-poliovirus isolates, 12 adenoviruses were serologically identified, and the remaining 198 isolates were used for molecular typing. The viral genomes of 195 non-polio enteroviruses (NPEVs) on VP1 partial region of virus capsid were translated to the corresponding amino acid sequences; these were compared with those of prototype strains. Based on molecular typing, 5 isolates were classified into 5 serotypes of the human enterovirus A species, 158 isolates, into 35 serotypes of the human enterovirus B species; and 32 isolates, into 6 serotypes of the human enterovirus C species. Viruses belonging to the human enterovirus D species were not isolated. Thus, under AFP surveillance, the human enterovirus B species accounted for 75.2% of the 210 isolates, and it was considered the predominant species. This was followed by human enterovirus C (12.2%), adenovirus (5.7%), and human enterovirus A (2.4%). Further, molecular analysis suggested that several serotypes of human enteroviruses B and C that exhibited genetic polymorphism were indigenous. Molecular typing methods may aid in understanding the epidemiology of NPEVs in Yunnan Province.

Study of Japanese encephalitis and other viral encephalitis in Nepali children

BACKGROUND

A hospital-based prospective cross-sectional study was conducted in children aged 1 month-14 years to identify the proportion of viral encephalitis due to Japanese encephalitis (JE) and compare the clinico-laboratory profile and outcome of JE with that of other viral encephalitis (non-JE).

METHODS

All probable cases of viral encephalitis on clinical and laboratory evaluation were confirmed as JE on anti-JE IgM in cerebrospinal fluid (CSF) and/or serum. Patients not having anti-JE IgM in CSF and/or serum were diagnosed as having non-JE.

RESULTS

Of 94 cases, 58 were JE and 36 non-JE. Although practice of rearing pigs at home was associated with JE (P = 0.0001), significantly higher serum creatinine, protein, aspartate aminotransferase and CSF protein levels were observed in non-JE. Longer duration of fever was associated with complete recovery in JE whereas shorter duration of fever was associated with recovery in non-JE. Risk of neurological sequelae (P = 0.01), especially hemiparesis (P = 0.03) was significantly more in JE. Sequelae were observed at 6 weeks follow up in 18.8% of JE and 13.9% of non-JE.

CONCLUSION

JE was the most common cause of viral encephalitis in eastern Nepal and should be suspected in encephalitic patients having pig rearing at home and neurological sequelae. Although duration of hospitalization and complication were higher in JE, final outcome was similar to non-JE. Longer duration of fever in JE and shorter duration of fever in non-JE correlated with recovery, while altered sensorium and focal neurological deficit were independent predictors of sequelae at 6 weeks only in JE and not in non-JE.

Echovirus 30, Jiangsu Province, China

An outbreak of aseptic meningitis occurred in the northern area of Jiangsu Province in China from January to July in 2003. A total of 1,681 cases were involved in this outbreak, and 99% of patients were <15 years of age. To identify the etiologic agent, 66 cerebrospinal fluid specimens were tested by cell culture. Eighteen showed an enteroviruslike cytopathic effect on MRC-5 human fetal diploid lung cells. An enterovirus primer-mediated reverse transcriptase-polymerase chain reaction, a standard neutralization assay, and sequencing of the complete capsid-encoding (VP1) gene identified the 18 isolates (FDJS03) as echovirus 30. At least a 10% difference was seen in nucleotide sequences of VP1 between FDJS03 isolates and other global strains of echovirus 30. Phylogenetic analysis based on complete sequences of VP1 was performed to further characterize the FDJS03 isolates. This report is the first to identify a distinct lineage of echovirus 30 as a probable cause of this outbreak.

New initiatives for the control of Japanese encephalitis by vaccination: minutes of a WHO/CVI meeting, Bangkok, Thailand, 13-15 October 1998

Japanese encephalitis (JE) is a leading cause of viral encephalitis in Asia that, in several countries, has been controlled effectively through national vaccine programs. However, in recent years, transmission has been recognized or has intensified in new locations where the available vaccines are either unaffordable or unlicensed. In addition, the near-eradication of poliomyelitis from Asia has elevated JE in the public health agenda of preventable childhood diseases, and surveillance of acute neurological infections to confirm polio eradication, simultaneously, has led to a greater awareness of the disease burden attributable to JE. The only internationally licensed JE vaccine, an inactivated mouse-brain derived vaccine, is efficacious but is problematic from the perspectives of reactogenicity, requirement for numerous doses, cost and reliance on a neurological tissue substrate. A live-attenuated vaccine distributed only in China also is efficacious and requires fewer doses; however, production and regulatory standards are unresolved. Several approaches toward developing novel JE vaccines that could fill the gap in JE vaccine need are under pursuit. The minutes and recommendations of a meeting of experts to discuss these issues, jointly sponsored by the World Health Organization and the Children's Vaccine Initiative in Bangkok, Thailand, 13-15 October, 1998, are presented.

Nested PCR for rapid detection of mumps virus in cerebrospinal fluid from patients with neurological diseases

In this study, we have developed a reverse transcription (RT)-nested polymerase chain reaction (n-PCR) for the detection of mumps virus RNA in cerebrospinal fluid (CSF) from patients with neurological infections. A specific 112-bp fragment was amplified by this method with primers from the nucleoprotein of the mumps virus genome. The mumps virus RT-n-PCR was capable of detecting 0.001 PFU/ml and 0.005 50% tissue culture infective dose/ml. This method was found to be specific, since no PCR product was detected in each of the CSF samples from patients with proven non-mumps virus-related meningitis or encephalitis. Mumps virus RNA was detected in all 18 CSF samples confirmed by culture to be infected with mumps virus. Positive PCR results were obtained for the CSF of 26 of 28 patients that were positive for signs of mumps virus infection (i.e., cultivable virus from urine or oropharyngeal samples or positivity for anti-mumps virus immunoglobulin M) but without cultivable virus in their CSF. Overall, mumps virus RNA was detected in CSF of 96% of the patients with a clinical diagnosis of viral central nervous system (CNS) disease and confirmed mumps virus infection, while mumps virus was isolated in CSF of only 39% of the patients. Furthermore, in a retrospective study, we were able to detect mumps virus RNA in 25 of 55 (46%) CSF samples from patients with a clinical diagnosis of viral CNS disease and negative laboratory evidence of viral infection including mumps virus infection. The 25 patients represent 12% of the 236 patients who had a clinical diagnosis of viral CNS infections and whose CSF was examined at our laboratory for a 2-year period. The findings confirm the importance of mumps virus as a causative agent of CNS infections in countries with low vaccine coverage rates. In summary, our study demonstrates the usefulness of the mumps virus RT-n-PCR for the diagnosis of mumps virus CNS disease and suggests that this assay may soon become the "gold standard" test for the diagnosis of mumps virus CNS infection.

Molecular detection of enteroviruses from an outbreak of hand, foot and mouth disease in Malaysia in 1997

Enterovirus 5'UTR sequences were detected by RT-PCR in 22 out of 47 suspected hand, foot and mouth disease (HFMD) patients during an outbreak of the disease with incidences of fatal brainstem encephalomyelitis in Malaysia in 1997. Genetic and phylogenetic analyses of the isolates 5'UTR sequences suggest the presence of predominantly enteroviruses with high sequence similarities to Echovirus 1 and Coxsackievirus A9 in the Malaysian peninsula. No fatal cases, however, were associated with these isolates. The remaining isolates, including all (4/4) isolates of the fatal cases from the Malaysian peninsula and Sarawak shared very high sequence identity with enterovirus 71MS (EV71). These findings suggest that several enteroviruses were circulating in Malaysia during the outbreak period, with only EV71 causing fatal infections.

Absence of seven human herpesviruses, including HHV-6, by polymerase chain reaction in CSF and blood from patients with multiple sclerosis and optic neuritis

Several members of the herpesvirus family have been implicated in the pathogenesis of multiple sclerosis (MS). Recently, HHV-6 viral antigen has been demonstrated in association to MS plaques, as well as DNA from human herpesvirus 6 (HHV-6) in cerebrospinal fluid from a few MS patients by polymerase chain reaction (PCR). In the present study, CSF from patients with MS, optic neuritis and other neurological diseases, as well as consecutive CSF and serum samples from MS patients included in a clinical trial with acyclovir, were analysed by nested PCR for the presence of DNA from herpes simplex virus 1 and 2, Epstein-Barr virus, varicella zoster virus, cytomegalovirus, human herpesvirus 6 and 7. No virus DNA was found in any CSF (n = 115) or serum (n = 116) sample. These findings argue against a continuous disseminated herpesvirus infection in MS, but do not rule out a lesion-associated, low-grade herpesvirus infection within the MS brain.