Diagnosis Of Japanese Encephalitis Research Articles

Epidemiology and risk factors of Japanese encephalitis in Taiwan, 2010-2022.

Taiwan introduced a two-dose inactivated Japanese encephalitis (JE) mouse brain-derived (JE-MB) vaccine into routine childhood immunization in 1968, with booster vaccination implemented in 1974 and 1983. In 2017, JE-MB vaccine was replaced by a two-dose live-attenuated chimeric vaccine (JE-CV). After implementation of JE vaccination programs, JE cases have shifted from children to adults. In this study, we described the JE epidemiology and identify high-risk groups to further inform vaccine policy. We extracted data from Taiwan's notifiable disease surveillance database, vital statistics, and employment statistics from 2010 to 2022. Diagnosis of JE was confirmed by JE seroconversion, a four-fold increase in virus-specific antibodies, a positive JE viral nucleic-acid test, or JE virus isolation. From 2010 to 2022, a total of 313 cases of JE were diagnosed, resulting in an overall incidence rate of 0.10 cases per 100,000 person-years and a mortality rate of 0.006 per 100,000 population per year. Among these patients, 64% were male, and the median age was 51 years (range 0-82). Compared with people born in or after 1976 (vaccinated with four doses of JE-MB vaccine or two doses of JE-CV), those born in or before 1962 (unvaccinated) and those born during 1963-1975 (vaccinated with two or three doses of JE-MB vaccine) had a 4.2-fold (95% confidence interval [CI] 3.0-5.7) and 5.9-fold (95% CI 4.3-8.1) higher risk of JE, respectively. The relative risk of working in agriculture, forestry, fishing, or animal husbandry, compared to other occupations, was 5.0 (95% CI 3.5-7.0). In Taiwan, individuals born before 1976 and those employed in agriculture, forestry, fishing, or animal husbandry had a higher risk of JE. We recommend JE vaccination for people in these high-risk groups who have not been fully vaccinated or have an unknown vaccination history.

Teaching NeuroImages: Japanese encephalitis

A 20-year-old woman presented with 3 days' history of fever and deteriorating consciousness. Physical examination showed positive Kerning sign. Brain MRI revealed hyperintensity involving bilateral thalami and substantia nigra (figure). Although CSF tests for white blood cells, protein, glucose, chlorine, and TORCH antibodies were normal, Japanese encephalitis (JE) virus immunoglobulin M antibody was positive. Therefore, a diagnosis of JE was made. The patient recovered from coma, and brain lesions were disappearing after 3 months supportive care (figure). As a common human viral encephalitis in the world, JE is usually very severe with high case-fatality rate.1 Symmetric thalami and substantia nigra involvement are characteristic in JE.2

The Ecology and Evolution of Japanese Encephalitis Virus.

Japanese encephalitis virus (JEV) is a mosquito-borne flavivirus mainly spread by Culex mosquitoes that currently has a geographic distribution across most of Southeast Asia and the Western Pacific. Infection with JEV can cause Japanese encephalitis (JE), a severe disease with a high mortality rate, which also results in ongoing sequalae in many survivors. The natural reservoir of JEV is ardeid wading birds, such as egrets and herons, but pigs commonly play an important role as an amplifying host during outbreaks in human populations. Other domestic animals and wildlife have been detected as hosts for JEV, but their role in the ecology and epidemiology of JEV is uncertain. Safe and effective JEV vaccines are available, but unfortunately, their use remains low in most endemic countries where they are most needed. Increased surveillance and diagnosis of JE is required as climate change and social disruption are likely to facilitate further geographical expansion of Culex vectors and JE risk areas.

Analysis of cross-reactivity between flaviviruses with sera of patients with Japanese encephalitis showed the importance of neutralization tests for the diagnosis of Japanese encephalitis

Japanese encephalitis (JE) is one of the most important viral encephalitis in Asia. JE is caused by the Japanese encephalitis virus (JEV), which belongs to the genus Flavivirus, family Flaviviridae. The diagnosis of JE is usually based on serological assays, and it has been reported that cross-reactivity between flaviviruses has complicated the interpretations of results from serological assays. Therefore, analysis of the cross-reactivity is an important subject for serological diagnosis of JE and other diseases caused by flaviviruses. In the present study, the cross-reactivity of the sera of patients with JE to other flaviviruses was analyzed using enzyme-linked immunosorbent assay (ELISA) and neutralization tests. Sixteen serum samples were collected from patients with JE and were tested for: i) IgM antibody against West Nile virus (WNV), dengue virus (DENV), zika virus (ZIKV), and tick-borne encephalitis virus (TBEV) using IgM-ELISA, ii) IgG antibody against DENV and TBEV using IgG-ELISA, and iii) neutralization tests with DENV 1–4, ZIKV, TBEV, and WNV. Out of the 16 samples tested using ELISA, 11 and 14 samples were positive for IgM and IgG, respectively, against at least one of the other flaviviruses. In neutralization tests, neutralizing potency against DENV, ZIKV, or TBEV was not detected in any samples. Although 13 samples showed neutralizing potency against WNV, their neutralizing antibody titers were equal to or less than one-eighth of those against JEV. These results show that neutralization tests are more specific than ELISA, indicating the importance of the neutralization tests in the diagnosis of JE.

The characteristics of cranial magnetic resonance imaging in adult Japanese encephalitis

Objective To analyze the magnetic resonance imaging (MRI) images of patients with adult Japanese encephalitis (JE), and to investigate the diagnostic value of MRI for the disease. Methods Thirty-two adult JE patients who underwent cranial MRI at General Hospital of Ningxia Medical University between August 2016 and September 2018 were enrolled. All patients had disease onset between August and September and they aged 17 to 83 years old. The clinical data, laboratory results, MRI signal characteristics of each scanning sequence and the distribution of the brain lesions were retrospectively analyzed. Results Of the 32 adult JE patients, 29 (90.6%) cases had acute onset, 28 (87.5%) cases had unconsciousness and cognitive impairment, 26 (81.2%) cases had intracranial hypertension, 3 (9.4%) cases had meningeal irritation, 3 (9.4%) cases had Parkinson-like symptoms, 10 (31.2%) cases had epilepsy, and 15 (46.9%) cases had decreased muscle strength. Twenty patients were positive for JE virus-specific IgM antibodies. Twenty-eight patients underwent cerebrospinal fluid examination, 15 (53.6%) cases showed intracranial pressure ≥180 mmH2O (1 mmH2O=0.009 8 kPa), 7 (25%) cases developed lymphocyte reaction, and 16 (57.1%) cases showed mixed cell reaction. Twenty-three cases (71.9%) showed lesions of brain on MRI, including thalamus (17 cases, 73.9%), hippocampus (13 cases, 56.5%), cerebral peduncle (6 cases, 26.1%), cortical and subcortical (4 cases, 17.4%), basal ganglia (2 cases, 8.7%), brainstem (1 case, 4.3%) and splenium of corpus callosum (1 case, 4.3%). Positive T1 weight image (T1WI) and T2 weight image (T2WI) results were found in 21 patients, respectively, 23 patients had positive T2-fluid attenuated inversion recovery (FLAIR) images, and 20 patients had positive diffusion weighted imaging (DWI) images. Among them, T2-FLAIR and DWI images showed more lesions, wider range of lesions and clearer boundary of cortical involvement range than T1WI and T2WI images. Conclusions Bilateral thalamus and hippocampus are often involved in adult JE. T2-FLAIR and DWI sequences are more sensitive to detect lesions. Combining MRI images with epidemiological characteristics, clinical manifestations, and laboratory tests is of great assistance for early diagnosis of JE. Key words: Encephalitis, Japanese; Adult; Magnetic resonance imaging; MRI spectrum; Clinical spectrum

Clinical profiles and some associated factors of Japanese encephalitis in Bali

Background Japanese Encephalitis (JE) is a mosquito-borne vi-ral disease that can affect the central nervous system and causeseveral complications and death. In Indonesia, particularly in Bali,studies of JE in humans are still very limited.Objective To assess the clinical manifestations and outcome ofJE in Bali and to identify some possible associated factors andmonthly distribution of admission to the hospitals.Methods A cross-sectional study was conducted in 8 district hospi-tals, army hospital, and Sanglah central hospital, as surveillance cen-ters in Bali, from July 2001 through January 2003. Subjects less than12 years of age and residences of Bali province who were suspectedof having acute viral encephalitis, aseptic meningitis, and acute flac-cid paralysis referred from all health facilities were included in thisstudy. The diagnosis of JE was established by detection of virus-spe-cific IgM in CSF and serum, with IgM capture enzyme-linkedimmunosorbent assay (MAC ELISA)Results During the study, 158 subjects with encephalitis were in-cluded; 55 (34.8%) were caused by JE and 103 (65.2%) were causedby non-JE. It showed that pig owning and rice farming were signifi-cantly associated with JE (PR= 3.02, 95% CI 1.29; 7.10; P= 0.009and PR= 2.86, 95% CI 1.30; 6,31, P= 0.008, respectively). Mostsubjects (46.2%) were under 2 years old with mean age of 37.24(SD 32.24) months. Forty-two (26.6%) subjects had nuchal rigidity,and all of them had aseptic meningitis. Denpasar had the highestprevalence of non-JE cases. Bangli and Klungkung had the lowestprevalence of JE and non-JE. The highest prevalence of JE was inGianyar. Peak prevalences of JE were in April and May 2002. Peakprevalences of non-JE were during August-October 2001 and inMarch-April 2002. Four (7.3%) subjects of JE group and 25 (24.3%)subjects of non-JE died. There were 25 (45.5%) out of 55 subjectswho survived with disability. Twenty-four (43.6%) JE subjects and34 (33.0%) non-JE subjects had good outcome.Conclusions Around one third of the subjects were positively di-agnosed as JE. The highest prevalence of JE was found in Gianyar.Peak prevalences of JE are in April and May 2002. Pig owning andrice farming are associated factors. Almost half of JE subjects sur-vived with disability

Seroprevalence of Cysticercus Antibodies in Japanese Encephalitis Patients in Upper Assam, India: A Hospital Based Study.

Co-infection of Japanese Encephalitis (JE) and Cysticercosis is attributed mainly to the common epidemiological features between the two diseases. Not much is known about the clinical implications of one infection over the other. The study aimed at establishing whether JE-Cysticercosis co-infection is prevalent in the Upper Assam districts and to explore additional details about such co-infections both clinically and epidemiologically. The present study was a retrospective cross-sectional hospital based study conducted between July 2013 and June 2014 and included 272 Acute Encephalitis Syndrome (AES) patients. Out of this, 137 JE positive and 135 non-JE Acute encephalitis patients were taken as cases and controls respectively. The diagnosis of JE and Cysticercosis was established by ELISA. EpiInfo ver. 7 was used for statistical analysis. Chi-square was used and p-value < 0.05 was considered to be statistically significant. The association of Cysticercosis with JE was found to be statistically significant (14.6%, p = 0.0019) in the cases with reference to the controls (3.7%). Moreover, the co-infections were found to be more common in case of adults (19.32%, p = 0.0360); with males having a greater odds (5.25, p = 0.0008) of harbouring the parasite as compared to females. The study proves that the association of Cysticercosis and JE holds true in this region.

MRI Findings of the Japanese Encephalitis

Japanese encephalitis (JE) is a disease caused by the mosquito-borne Japanese encephalitis virus (JEV). It is prevalent in Southeast Asia and East Asia. Diagnosis of JE is generally accomplished by testing of serum or cerebrospinal fluid (CSF) to detect virus-specific antibodies. Magnetic resonance imaging (MRI) is a useful adjunct for the diagnosis. Thalamic invasion is classical findings of MRI. Other areas in the brain may be invaded are midbrain, pons, cerebellum, basal ganglia, cerebral cortex. Case 1: A 60-year-old man presented with headache and fever. Neurological examination showed consciousness Kernig’s sign. CSF: JEV HI antibodies: X320. (Figure 1) Axial T2-weighted MR image (4 days after onset) shows high intensity area in the left thalamus (arrow) and the left putamen (curved arrow). Case 2: A 91 year-old woman presented with deteriorated consciousness. CSF: JEV CF antibodies: X32, JEV HI antibodies: X160. (Figure 2) Axial T2-weighted MR image (8 days after onset) shows high intensity area in the bilateral thalamus (arrow).

Public health laboratory surveillance and diagnosis of Japanese encephalitis: Time to revisit

We assessed detection of recent Japanese encephalitis virus infection using recommended strategy. Cross-sectional community-based study conducted in 12 villages in Kushinagar, Uttar-Pradesh, India in 2012-13. Recent infection with Japanese encephalitis virus in 239 healthy children aged 1-15 year was detected using a combination of serology and molecular methods. 24 (10%) children showed recent infection; 2 by serology and 22 by molecular method. Symptomatic cases were estimated as 626 in Kushinagar against reported 139 in all age groups across the state. Lower positivity using recommended serology suggests major gap in existing surveillance and diagnostic protocols and estimation of burden of Japanese encephalitis.

Japanese Encephalitis and its Epidemiology

Japanese encephalitis (JE) is among the most common cause of viral encephalitis in human beings and is found worldwide. JE, a zoonotic disease, is caused by JE virus (JEV), a mosquito-borne flavivirus and belongs to the family Flaviviridae. About 1% of human JEV infections result in JE, but 20–30% of these cases are fatal and 30-50% of survivors have significant neurologic or psychiatric sequelae. WHO estimated that approximately 67 900 JE cases occur annually in the 24 JE-endemic countries with an overall incidence of 1.8 per 100 000 population and 75% of these cases occur in children aged 0-14 years, which gives an estimated overall annual incidence of 5.4 per 100 000 in this age group. Five genotypes of JEV (1 to 5), based on structural protein sequences, with geographically distinct distributions, have been described. Diagnosis of JE can be made by virus isolation in cell/ tissue culture, antigen detection, and antibody detection. There is no specific treatment of JE, and only supportive care is provided to patient thus prevention of JE is considered as an important intervention in JE. Hence a strong surveillance system along with implementation of high quality vaccination program for children is the key ingredients to reduce the number of JE cases in endemic areas.

Concurrent infection of Japanese encephalitis and mixed plasmodium infection

Japanese encephalitis (JE) and malaria would coexist in the areas where both illnesses are endemic with overlapping clinical pictures, especially in a case of febrile encephalopathy with hepatosplenomegaly. However, there are no published data till date showing concurrent infection of these two agents despite both diseases being coendemic in many areas. We report a case of concurrent infection of JE and mixed plasmodium infection, where the case, initially diagnosed as cerebral malaria did not improve on antimalarials and alternative diagnosis of JEV encephalitis was thought which was confirmed by a serological test. To the best of our knowledge, this is the first case report of concurrent Japanese encephalitis with mixed plasmodium infection. We report a case of 3-year-old male child, who presented with febrile encephalopathy with hepatosplenomegaly. Based on a rapid diagnostic test and peripheral smear examination, a diagnosis of mixed P.Vivax and P.falciparum infection was made and the patient was treated with quinine and doxycycline. However, besides giving antimalarials the patient did not improve and an alternative diagnosis of JE was considered as the patient was from the endemic zone of Japanese encephalitis. Cerebrospinal fluid (CSF) of the patient was sent for a virological study which came out to be positive for JE IgM in CSF, which is confirmatory of JE infection. In a patient with febrile encephalopathy with hepatosplenomegaly especially in areas coendemic for JE and malaria, the possibility of mixed infection should be kept in mind.

Japanese viral encephalitis mimicking stroke with an initial manifestation of hemiplegia

Japanese encephalitis (JE) is an endemic disease in Taiwan. After the program to vaccinate children against JE was implemented in 1968, the incidence of JE gradually started to decrease, but it is still an important infectious disease here. Neurological manifestations in JE vary highly during the initial stage of the disease. Focal neurological symptoms, such as hemiplegia, are rarely reported. A 46-year-old male with the initial presentation of abrupt hemiplegia and fever developed mental confusion after 1 day. No bacterial pathogen was isolated from the blood or cerebrospinal fluid (CSF). A diagnosis of JE was confirmed based on the presence of JE virus-specific immunoglobulin M in the CSF and serum samples. It is necessary to consider JE when a patient presents with abrupt hemiplegia with fever followed with mental confusion and seizure, especially if the patient comes from a JE-endemic area.

Japanese encephalitis (JE). Part I: clinical profile of 1,282 adult acute cases of four epidemics

Japanese encephalitis (JE) is numerically the most important global cause of encephalitis and so far confirmed to have caused major epidemics in India. Most of the reported studies have been in children. This largest study involving only adults, belonging to four epidemics, is being reported from Gorakhpur. The aim of this study is to detail the acute clinical profile (not viral) outcome and to classify the sequelae at discharge. This prospective study involved 1,282 adult patients initially diagnosed as JE admitted during the epidemics of 1978, 1980, 1988, and 1989, on identical clinical presentation and CSF examination. In the meantime, the diagnosis of JE was confirmed by serological and/or virological studies in only a representative number of samples (649 of 1,282 cases). Eighty-three left against medical advice (LAMA) at various stages, so 1,199 of 1,282 were available for the study. Peak incidence of [1,061 of 1,282 (83%)] of clinically suspected cases was from September 15 to November 2. Serum IgM and IgG were positive in high titers in 50.87% (330 of 649) and IgM positive in CSF in 88.75% (109 of 123) of the cases. JE virus could be isolated from CSF and brain tissue in 5 of 5 and 4 of 5 samples, respectively. Altered sensorium (AS) in (96%), convulsions (86%), and headache (85%) were the main symptoms for hospitalization by the third day of the onset. Other neurological features included hyperkinetic movements in 593 of 1,282 (46%)-choreoathetoid in 490 (83%) and bizarre, ill-defined in 103 (17%). The features of brain stem involvement consisted of opsoclonus (20%), gaze palsies (16%), and pupillary changes (48%) with waxing and waning character. Cerebellar signs were distinctly absent. Dystonia and decerebrate rigidity was observed in 43 and 6%, respectively, paralytic features in 17% and seizures in 30%. Many non-neurological features of prognostic importance included abnormal breathing patterns (ABP) (45%), pulmonary edema (PO) (33%), and upper gastrointestinal hemorrhage (UGIH) (16%). Injection dexamethasone was used in 1978 in all 208 cases, including 21 of PO. Patients were later randomized alternately in dexa and non-dexa groups. Forty-six cases of PO from the non-dexa group were transferred to the dexa group as an ultimate life-saving measure. Thus, it was administered in 737 of 1,199 patients including 529 patients from the later epidemics in doses of 4 mg IV every 8 h for 7 days. Of 1,199, 462 did not receive it. There was no significant difference in mortality (p > 0.05) between the dexa (42.47%) and the non-dexa group (42.86%). All PO cases expired; so after the exclusion of the PO cases from dexa group, the difference of 6.14% (42.86 and 36.72) became significant (p < 0.01) (511 of 1,199 (43%) expired, [320 of 511 (63%) died within 3 days of hospitalization]). Out of a total of 1,199 patients treated, 688 (57%) were discharged; 23 of 688 (3%) without any sequelae and 665 of 688 (97%) with neuropsychiatric deficits classified into nine groups. During the four epidemics, the diagnosis of JE was basically on identical clinical presentation of acute encephalitic syndrome (AES) consisting of (1) abrupt onset of fever, headache, and AS, (2) dystonias and various movement disorders, (3) opsoclonus and gaze palsies, (4) CSF findings, and (5) the presence of residual neuropsychiatric and neurological features in the survivors.

Coinfection of Japanese Encephalitis with Neurocysticercosis: An Imaging Study

Coinfection of neurocysticercosis (NCC) and Japanese encephalitis (JE) has been advocated as more than a chance occurrence resulting in poor outcome. We undertook this study to determine whether the association of the 2 infections is more than a chance occurrence, to define the imaging characteristics of coinfections, and to explore the synergistic effect of NCC in JE. Sixty-two patients with JE were studied by MR imaging and CT. CT was done in 53 and MR imaging in 53 patients. The diagnosis of JE was established by CSF JE virus immunoglobulin M capture (MAC) enzyme-linked immunosorbent assay (ELISA). NCC was diagnosed from imaging. A control group of 385 patients was evaluated by imaging for prevalence of NCC in the general population. A significantly high association of NCC with JE (19.3%) was observed in comparison with prevalence of NCC in control subjects (1.04%; P = .0003). JE lesions in coinfection were significantly asymmetric with lateralization to the side of the brain having the maximum NCC or a cyst with edema. The JE lesions in coinfections were more florid, with a significantly higher proportion of abnormal CT scans and more abnormal MR imaging. Coinfections were significantly more common in children. Significantly lower CSF MAC-ELISA units in patients with coinfection reflected low CSF IgM levels, suggesting altered immune status. In our series, there was a strong association between JE and NCC, and, thus, this coinfection was more than a chance occurrence.

Acute Flaccid Paralysis as an Unusual Presenting Symptom of Japanese Encephalitis: A Case Report and Review of the Literature

Japanese encephalitis (JE) is an endemic disease in Taiwan. Acute JE virus infection characterized by acute flaccid paralysis in an adult has never been reported in Taiwan. We report a young adult man who received four doses of JEV (Nakayama strain) vaccination in childhood, but still developed acute JE virus infection, characterized with acute flaccid paralysis.He presented with fever, headache, progressive muscle weakness, and respiratory paralysis requiring mechanical ventilator. Deep tendon reflexes were decreased except for the Achilles reflex. After supportive care, he was weaned from the mechanical ventilator and at discharge 1 month later, his muscle power level and deep tendon reflexes recovered partially. The diagnosis of JE was based on the presence of anti-JE virus IgM in the CSF and seroconversion of IgM and IgG by the ELISA method. Electrophysiological findings were described. From the experience of this case, we caution that a history of vaccination for JE with the Nakayama strain may not provide a complete protection against natural infection in the community; and in Taiwan or any area where JE remains an endemic disease, Japanese virus encephalitis infection should be considered as a differential diagnosis in any adult presenting with acute flaccid paralysis.

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.

Diffusion-Weighted MR Imaging in Japanese Encephalitis

This study was performed to evaluate the role of diffusion-weighted imaging (DWI) in the diagnosis of Japanese encephalitis (JE) and to look for any relationship of the apparent diffusion coefficient (ADC) values with duration of the illness. We performed DWI in fourteen patients of JE. T2 weighted (T2W) and DWI were compared for number and location of lesions in all patients. Based on imaging patients were divided in three groups: group 1 (n=9) showing more lesions on DWI compared with T2W images, group 2 (n=3) with equal number of lesions on T2W and DWI and group 3 (n=2) with lesions more pronounced on T2W than DWI. ADC values were computed for all the lesions. The time interval between onset of neurologic signs/symptoms and MRI were charted and correlated with ADC values. DWI was helpful in making early diagnosis of JE by showing characteristic involvement of bilateral thalami in four patients. Nine out of fourteen patients showed additional lesions on DWI. ADC from lesions in groups I, II and III measured 0.648 +/- 0.099 x 10 mm/s, 0.739 +/- 0.166 x 10 mm/s and 1.123 +/- 0.185 x 10 mm/s respectively. The ADC from the lesions in group 1 was significantly lower compared with group 2 (P value <0.05) while it was higher in group 3 lesions compared with the other two groups. There was a significant direct correlation of ADC values with the disease duration in these cases (r=0.847, P <0.01). DWI is helpful in early diagnosis and characterization of the duration of the lesions in JE.

Prognosis of Japanese encephalitis patients with dystonia compared to those with parkinsonian features only

Objectives: A number of movement disorders have been reported in Japanese encephalitis (JE). The prognostic significance of these movement disorders, however, has not been evaluated. The present study reports the...

The development and application of the latex agglutination test to detect serum antibodies against Japanese encephalitis virus.

The attenuated SA14-14-2 strain of Japanese encephalitis virus (JEV) was cultured in BHK-21 cells. The viral supernatant was purified and concentrated with PEG (MW 20,000). A suitable concentration of JEV antigen was used to sensitize latex to prepare the latex antigen. The specificity, sensitivity and stability of the antigen were assessed. A latex agglutination test (LAT) was developed for rapidly detecting antibody against JEV infection. The LAT and haemagglutination inhibition (HI) assay were compared by simultaneously testing 35 porcine serum samples from five farms. Ninety per cent (20/23) of the samples were seropositive by both assays. No significant difference was found between the two methods (p > 0.05). Furthermore, when 1,613 porcine sera from 120 farms were tested by LAT, the number of positive sera was 652, while that of negative sera was 961, ranging from 20% to 50% positive throughout the year. These results indicate that LAT is an appropriate candidate method for epidemiological surveys for and diagnosis of Japanese encephalitis.

Seizures in Japanese encephalitis

Objective: Although Japanese encephalitis (JE) has been reported to be associated with seizures, there is no report on its frequency, pattern and severity and their correlation with electroencephalography (EEG) and radiological findings. In this communication, the analysis of seizures in 65 JE patients seen during 1991–1999 is presented. Methods: The diagnosis of JE was based on clinical, radiological and serological criteria. The patients were subjected to a detailed clinical evaluation. Frequency and pattern of seizures and other neurological findings were recorded. Cranial CT scan or MRI was carried out in all the patients. Electroencephalograph was recorded using the 10–20 system of electrode placement. Patients' outcome was defined, on the basis of clinical status for 3 months, into poor, partial and complete recovery. The relationship between seizures and other clinical, radiological and EEG parameters was evaluated by the Z test of proportion using the two-tail approach. Results: The patient's age ranged between 2 and 57 years, 24 were females and 19 were below 13 years of age. Thirty patients had seizures within the first week of encephalitis. The seizures were generalised tonic–clonic in 17 patients and partial motor with secondary generalization in 13 patients. Eleven patients had a single seizure, 8 had two seizures and 11 had multiple seizures. Two patients were presented with status epilepticus. Interictal EEG in the patients with seizures revealed theta to delta slowing in all patients and epileptiform discharges in four patients only. MRI revealed thalamic lesions bilaterally in 24, cortical in 7, basal ganglia in 8 and brainstem in 3 patients out of 26 patients with seizure. In the seizure group, three patients died, nine had poor, eight had partial and nine had complete recovery. Upon comparison of the JE patients with and without seizures, Glasgow coma scale (GCS) score, focal weakness, EEG slowing and cortical and thalamic lesion on CT or MRI were significantly related to the occurrence of the seizures; however, it was not associated with poor outcome. Conclusions: JE is associated with seizures in 46% of the patients in the acute stage of encephalitis which is easily controlled by monotherapy. Patients with severe encephalitis were associated with higher frequency of seizures.