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PubMed1977

Biological and immunological studies on two substrains, c-1 and c-3, derived from the Nakayama-NIH strain of Japanese encephalitis virus.

A comparative analysis was performed on two substrains, c-1 and c-3, derived from the Nakayama-NIH strain of Japanese encephalitis virus. The infectivity of the two substrains was inactivated at similar rates by treatment with Tween 80 and Tween 20 but not by treatment with Tween 60. However, hemagglutinating activity as measured at pH 6.8 of the c-3 substrain treated with Tween 80 was more labile than that of the c-1 substrain treated with Tween 80. Also, the immunogenicity (neutralizing and hemagglutination-inhibiting antibodies) was different between the two substrains in sensitivity to low pH (6.8) and to Tween 80. With the c-1 substrain a combination of these treatments reduced the immunogenicity, but each treatment applied singly did not materially reduce it. The immunogenicity of the c-3 substrain was reduced by single as well as combined applications of the two treatments. Evidence was obtained which suggested that the part of the antigen sensitive to these treatments was strain-specific, whereas the resistant antigen was common among the Japanese encephalitis-St. Louis encephalitis complex members.

Animals↗
PubMed2004

Post-infectious encephalomyelitis associated with St. Louis encephalitis virus infection.

Neurologic illness associated with acute St. Louis encephalitis, West Nile, and Japanese encephalitis virus infection includes acute aseptic meningitis, encephalomyelitis, and a poliomyelitis-like syndrome. Few post-infectious immune-mediated neurologic events associated with flaviviral infection have been reported. The authors report on a woman with apparent post-infectious encephalomyelitis associated with recent St. Louis encephalitis virus infection, suggesting that neurologic illness from flaviviruses may also be seen in the post-infectious period following mild clinical illness.

Brain↗
PubMed2003

Vector competence of Australian mosquitoes (Diptera: Culicidae) for Japanese encephalitis virus.

Australian mosquitoes were evaluated for their ability to become infected with and transmit a Torres Strait strain of Japanese encephalitis virus. Mosquitoes, which were obtained from either laboratory colonies and collected using Centers for Disease Control and Prevention light traps baited with CO2 and octenol or reared from larvae, were infected by feeding on a blood/sucrose solution containing 10(4.5 +/- 0.1) porcine stable-equine kidney (PS-EK) tissue culture infectious dose50/mosquito of the TS3306 virus strain. After 14 d, infection and transmission rates of 100% and 81%, respectively, were obtained for a southeast Queensland strain of Culex annulirostris Skuse, and 93% and 61%, respectively, for a far north Queensland strain. After 13 or more days, infection and transmission rates of > 90% and > or = 50%, respectively, were obtained for southeast Queensland strains of Culex sitiens Wiedemann and Culex quinquefasciatus Say, and a far north Queensland strain of Culex gelidus Theobald. Although infection rates were > 55%, only 17% of Ochlerotatus vigilax (Skuse) and no Cx. quinquefasciatus, collected from far north Queensland, transmitted virus. North Queensland strains of Aedes aegypti L., Ochlerotatus kochi (Dönitz), and Verrallina funerea (Theobald) were relatively refractory to infection. Vertical transmission was not detected among 673 F1 progeny of Oc. vigilax. Results of the current vector competence study, coupled with high field isolation rates, host feeding patterns and widespread distribution, confirm the status of Cx. annulirostris as the major vector of Japanese encephalitis virus in northern Australia. The relative roles of other species in potential Japanese encephalitis virus transmission cycles in northern Australia are discussed.

Animals↗
PubMed2002

Immunization with heterologous flaviviruses protective against fatal West Nile encephalitis.

Prior immunization of hamsters with three heterologous flaviviruses (Japanese encephalitis virus [JEV] SA14-2-8 vaccine, wild-type St. Louis encephalitis virus [SLEV], and Yellow fever virus [YFV] 17D vaccine) reduces the severity of subsequent West Nile virus (WNV) infection. Groups of adult hamsters were immunized with each of the heterologous flaviviruses; approximately 30 days later, the animals were injected intraperitoneally with a virulent New York strain of WNV. Subsequent levels of viremia, antibody response, and deaths were compared with those in nonimmune (control) hamsters. Immunity to JEV and SLEV was protective against clinical encephalitis and death after challenge with WNV. The antibody response in the sequentially infected hamsters also illustrates the difficulty in making a serologic diagnosis of WNV infection in animals (or humans) with preexisting Flavivirus immunity.

Animals↗
PubMed2003

Viral encephalitis in England, 1989-1998: what did we miss?

We analyzed hospitalizations in England from April 1, 1989, to March 31, 1998, and identified approximately 700 cases, 46 fatal, from viral encephalitis that occurred during each year; most (60%) were of unknown etiology. Of cases with a diagnosis, the largest proportion was herpes simplex encephalitis. Using normal and Poisson regression, we identified six possible clusters of unknown etiology. Over 75% of hospitalizations are not reported through the routine laboratory and clinical notification systems, resulting in underdiagnosis of viral encephalitis in England. Current surveillance greatly underascertains incidence of the disease and existence of clusters; in general, outbreaks are undetected. Surveillance systems must be adapted to detect major changes in epidemiology so that timely control measures can be implemented.

Adult↗
PubMed2001

Murray Valley encephalitis virus surveillance and control initiatives in Australia. National Arbovirus Advisory Committee of the Communicable Diseases Network Australia.

Mechanisms for monitoring Murray Valley encephalitis (MVE) virus activity include surveillance of human cases, surveillance for activity in sentinel animals, monitoring of mosquito vectors and monitoring of weather conditions. The monitoring of human cases is only one possible trigger for public health action and the additional surveillance systems are used in concert to signal the risk of human disease, often before the appearance of human cases. Mosquito vector surveillance includes mosquito trapping for speciation and enumeration of mosquitoes to monitor population sizes and relative composition. Virus isolation from mosquitoes can also be undertaken. Monitoring of weather conditions and vector surveillance determines whether there is a potential for MVE activity to occur. Virus isolation from trapped mosquitoes is necessary to define whether MVE is actually present, but is difficult to deliver in a timely fashion in some jurisdictions. Monitoring of sentinel animals indicates whether MVE transmission to vertebrates is actually occurring. Meteorological surveillance can assist in the prediction of potential MVE virus activity by signalling conditions that have been associated with outbreaks of Murray Valley encephalitis in humans in the past. Predictive models of MVE virus activity for south-eastern Australia have been developed, but due to the infrequency of outbreaks, are yet to be demonstrated as useful for the forecasting of major outbreaks. Surveillance mechanisms vary across the jurisdictions. Surveillance of human disease occurs in all States and Territories by reporting of cases to health authorities. Sentinel flocks of chickens are maintained in 4 jurisdictions (Western Australia, the Northern Territory, Victoria and New South Wales) with collaborations between Western Australia and the Northern Territory. Mosquito monitoring complements the surveillance of sentinel animals in these jurisdictions. In addition, other mosquito monitoring programs exist in other States (including South Australia and Queensland). Public health control measures may include advice to the general public and mosquito management programs to reduce the numbers of both mosquito larvae and adult vectors. Strategic plans for public health action in the event of MVE virus activity are currently developed or being developed in New South Wales, the Northern Territory, South Australia, Western Australia and Victoria. A southern tri-State agreement exists between health departments of New South Wales, Victoria and South Australia and the Commonwealth Department of Health and Aged Care. All partners have agreed to co-operate and provide assistance in predicting and combatting outbreaks of mosquito-borne disease in south-eastern Australia. The newly formed National Arbovirus Advisory Committee is a working party providing advice to the Communicable Diseases Network Australia on arbovirus surveillance and control. Recommendations for further enhancement of national surveillance for Murray Valley encephalitis are described.

Animals↗
PubMed1980

Antigenuria in St. Louis encephalitis.

Patients with St. Louis encephalitis may have urinary tract symptoms when they develop manifestations related to involvement of the central nervous system. During 1976, 12 patients with St. Louis encephalitis were studied for the presence of antigenuria, and compared to controls. Although virus isolation attempts were negative indirect immunofluorescence, electron microscopy, and immune electron microscopy demonstrated the presence of viral antigen in urine. Further study of antigenuria in St. Louis encephalitis is needed to delineate the pathophysiology of the lower urinary tract symptoms and to determine whether this phenomenon might furnish the basis for a rapid diagnostic test for the disease.

Antibodies, Viral↗
PubMed1983

Surveillance for California encephalitis group virus illness in Wisconsin and Minnesota, 1978.

During the summer and fall of 1978, active surveillance for encephalitis in southwestern Wisconsin and southeastern Minnesota resulted in the detection of the largest number of cases of California encephalitis group (CEG) virus infections ever documented in that region, where CEG virus is known to be endemic. A total of 75 laboratory-confirmed and eight presumptive cases of CEG virus infections were identified as a result of serologic testing completed in the Wisconsin and Minnesota State Laboratories. Cases included 46 residents of Wisconsin, 25 of Minnesota, 10 residents of Iowa and two from Illinois. The outbreak peaked during the last half of August and the first half of September. Eighty percent of patients were less than 10 years of age; only one case was documented in an adult (greater than or equal to 18 years). The clinical picture in patients ranged from mild aseptic meningitis to encephalitis with coma; convulsions occurred in 31% (22/72) of patients. One patient, a 3-year-old girl, died. The high incidence of infection detected in this investigation may be representative of the endemic incidence of CEG illness in the region and suggests that CEG infections in children residing in endemic areas in Wisconsin and Minnesota may be a greater public health problem than previously recognized.

Adolescent↗
PubMed1983

Occurrence of La Crosse (California serogroup) encephalitis viral infections in Illinois.

La Crosse (LAC) virus (California encephalitis serogroup) was identified as the etiologic agent of disease in 61 cases of California encephalitis (CE) that occurred in Illinois between 1976 and 1980. This group represented 54% of all 114 laboratory-diagnosed cases of CE between 1966 and 1980. Key epidemiologic observations included: 88% of the 61 cases had onset in July, August, or September; the 5- to 9-year-old age group represented 48% of the cases; the male:female sex ratio was 2:1; 97% of the cases occurred in the northern half of the state; and 61% of the cases occurred in Peoria County. Four instances of probable common source of exposure were reported. Average length of hospitalization was 8.3 days (range 3-31 days). Hospitalization costs were estimated at $3,967-$5,750 per case. An "average" year in Illinois yields 12 cases of LAC encephalitis with direct hospitalization costs of $47,604-$69,000.

Adolescent↗
PubMed1985

Fatal outcome in Japanese encephalitis.

Forty-nine consecutive patients with laboratory-confirmed acute Japanese encephalitis were studied to identify risk factors present at hospital admission which were associated with a fatal outcome. Sixteen patients (33%) died. The following constellation of findings correlated with a fatal outcome: infectious virus in cerebrospinal fluid (CSF), low levels of Japanese encephalitis virus-specific IgG and IgM in both CSF and serum, and a severely depressed sensorium. Age, sex, days ill before admission, distance from home to the hospital, past medical history, CSF protein content, and CSF leukocyte count were not significant risk factors. Among patients hospitalized for acute Japanese encephalitis, a vigorous virus-specific immunoglobulin response, both systemically and locally within the central nervous system, is a good marker for survival, and may be an inherently important factor in recovery from illness.

Adolescent↗
PubMed1999

Safety, immunogenicity, and protective efficacy of NYVAC-JEV and ALVAC-JEV recombinant Japanese encephalitis vaccines in rhesus monkeys.

Two poxvirus-vectored vaccines for Japanese encephalitis (JE), NYVAC-JEV and ALVAC-JEV, were evaluated in rhesus monkeys for safety, immunogenicity, and protective efficacy. The vaccines were given to four monkeys each on study days 0 and 28 along with saline placebo on day 7. For controls, the licensed BIKEN JE vaccine and a saline placebo were given to other groups of four monkeys on days 0, 7, and 28. No systemic effects were observed. All injection site reactions were mild. All vaccines elicited appreciable JE-specific neutralizing antibody responses. However, a more rapid increase and higher peak level of antibody were seen in the BIKEN group as compared with the NYVAC-JEV and ALVAC-JEV groups. The peak neutralizing antibody level in the NYVAC-JEV group was higher than that of the ALVAC-JEV group. Antibody persisted in all four BIKEN recipients through 273 days of follow-up, whereas, the antibody level decreased to the threshold of detection in two NYVAC-JEV and all four ALVAC-JEV recipients by day 120. On day 273, all monkeys were given a booster dose. A rapid increase in neutralizing antibody was seen in all vaccine recipients by seven days. Two months after the booster dose, all monkeys were challenged intranasally with one 90% effective dose of JE virus. Four recipients of saline, three of ALVAC-JEV, one of NYVAC-JEV, and one of BIKEN experienced encephalitis. This study suggests that the NYVAC-JEV and ALVAC-JEV vaccines are safe and immunogenic in monkeys and that the NYVAC-JEV and BIKEN vaccines are effective in protecting monkeys from encephalitis.

Administration, Intranasal↗
PubMed1976

Murray Valley encephalitis, 1974: clinical features.

Of the 58 patients who developed Murray Valley encephalitis (MVE) during 1974, 22 were admitted to Fairfield Hospital, Melbourne. The patients were of all ages, but the disease was most common in children. Calculations suggest that the incubation period of MVE is from one to four weeks. The severity of brain damage varies considerably; 11 patients recovered almost completely, seven had severe residual damage and four patients died. There are no special features which distinguish MVE from any other form of encephalitis. The survival of five of eight patients who required artificial respiration suggests that patients with suspected MVE should be transported at an early stage to a hospital where artificial respiration is available if necessary. There is no evidence that infection with the MVE virus can cause clinical manifestations of a disease other than acute encephalitis.

Adolescent↗
PubMed2000

Characterization of tick-borne encephalitis virus from Latvia.

Viruses of the tick-borne encephalitis (TBE) antigenic complex, within the family Flaviviridae, cause a variety of diseases including uncomplicated febrile illness, encephalitis, meningo-encephalitis, hemorrhagic fever and chronic disease in humans, domesticated animals or wildlife species. TBE is a serious problem in Latvia with up to a 1,000 patients confirmed serologically annually 1994-1995. No previous data had been reported on the causative agent of TBE in Latvia. In the present study, a virus was isolated from serum of a patient with clinical symptoms of an acute TBE infection. Nucleotide sequence information obtained by direct reverse transcription-polymerase chain reaction (RT-PCR) and the serological characteristics of the isolated virus strain, designated TBE-Latvia-1-96, indicated a closer relationship to the Vasilchenko strain, isolated in Novosibirsk (Siberia, Russia), as compared to the western European or far eastern subtypes of TBE viruses. In a mouse neurovirulence assay, a significant difference in survival rates (days) was shown between Latvia-1-96 and the western European TBE virus subtype.

Animals↗
PubMedDate not supplied

[A cultured concentrated inactivated vaccine against tick-borne encephalitis studied during the immunization of children and adolescents].

The word deals with the results obtained in the study of the reactogenicity and immunological activity of concentrated and inactivated tissue-culture tick-borne encephalitis vaccine, manufactured by the Chumakov Institute of Poliomyelitis and Viral Encephalitides, in the immunization of children and adolescents. The vaccine proved to be moderately reactogenic and exhibited pronounced immunological activity. In 91.5% of the immunized children the fourfold increase of the antibody level was observed. On the basis of the data obtained in this study the tick-borne encephalitis vaccine was recommended for use in medical practice for the prophylaxis of tick-borne encephalitis among children and adolescents.

Adolescent↗
PubMed1999

The first report on human cases serologically diagnosed as Japanese encephalitis in Indonesia.

Although Japanese encephalitis (JE) virus was isolated from mosquitos in 1974, human JE cases have never been reported in Indonesia in spite of the prevalence of anti-JE antibodies among human and pig populations as well as abundant JE vector mosquitos. In this report, we describe serological diagnosis of JE cases in Bali. Indonesia. using IgM-capture ELISA both on serum and cerebrospinal fluid (CSF) of the patients. In the first series of our investigation (Series 1), we examined serum specimens from 12 patients with clinical diagnosis of viral encephalitis, meningitis or dengue hemorrhagic fever (DHF), and found 2 possible JE cases. In the next series (Series 2), we examined both serum and CSF from encephalitis patients and gave laboratory diagnosis of JE. One of them was suspected to have concomitant or recent infection with dengue virus, probably type 3. These results strongly indicated that JE has been prevalent in Bali, Indonesia.

Child, Preschool↗
PubMedDate not supplied

[Involvement of the common shrew, Sorex araneus (Insectivora, Soricidae), in circulation of the tick-borne encephalitis virus in south-western Siberia].

We presented the data on the abundance of immature instars of the taiga tick Ixodes persulcatus Schuize on the common shrews Sorex araneus L. in natural foci of tick-borne encephalitis in the south of Western Siberia. Basing on the results of virological and serological studies we demonstrated a low effectiveness of this host species as a donor of disease agent strains, which are predominant in the territory under study, for ticks feeding on shrews. The analysis of samples taken from the young shrews in winter and spring using reverse RNA transcription with polymerase chain reaction and ELISA revealed occurRence of subvirion components of the tick-borne encephalitis (RNA and capsid protein E) ether in brain, liver or spleen in 90 percent of shrews (n = 42). Neither hemagglutination antigen nor infectious virus have been detected. We discussed a possible epizootic role of the maintenance of non-infectious tick-borne encephalitis virus in overwintering animals.

Animals↗
PubMed2002

[Mental disorders in the course of lyme borreliosis and tick borne encephalitis].

BACKGROUND: Lyme borreliosis is a chronic, multisystem disease, of prolong course with three consecutive stages, caused by a tick-transmitted spirochete Borrelia burgdorferi. Tick Borne Encephalitis (TBE) is neuroinfection caused by Tick Borne Encephalitis Virus (TBEV). OBJECTIVE: We evaluated the occurrence of psychiatric manifestations in the early phase of borreliosis-erythema migrans and neuroboreliosis as well as in its late phase--in arthritis and in the Tick-Born Encephalitis. The aim of the study was to single out the most frequent psychiatric symptoms and psychopathological syndroms and to determine their dynamics. METHODS: The study was carried out between 1999 and 2000 and comprised 174 patients of the Department of Psychiatry and Department of Infectious and Neuroinfectious Diseases of Medical Academy in Bialystok. Seventy seven patients diagnosed with arthritis, 20 with neuroborreliosis, 26 with skin manifestation-erythrema migrans and 51 with KZM participated. All subjects underwent psychiatric evaluation twice--during hospitalization and six month after discharge. Mental status examinations included general psychiatric examination and battery of scales and tests: Mini Mental State Examination, Beck Depression Inventory, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Reitan's Trail Making Test, Choynowsky Memory Scale, Symptoms Inventory and neuropsychological testing. RESULTS: Both in the course of TBE and Lyme borreliosis the majority of patients experienced psychiatric problems in the acute phase of disease as well as in the late phase--3, 6 months after the onset of the disease. The most common psychiatric manifestations were depressive disorders--episodes of depression or organic mood disorders, and cognitive deficits which manifest themselves as mild cognitive disorder or dementia. CONCLUSION: Psychiatric assessment is important in early stage of kzm and borreliosis but first of all after termination of acute symptomatology.

Borrelia burgdorferi↗
PubMed2002

Mycoplasma pneumoniae encephalitis in childhood.

Mycoplasma pneumoniae is an important etiologic agent of acute childhood encephalitis. We retrospectively reviewed 17 cases of M. pneumoniae encephalitis at the Pediatric Department of the National Taiwan University Hospital from April 1997 through March 2000. These cases were diagnosed as having positive immunoglobulin M antibodies (94%), a minimum 4-fold change of complement-fixation antibody titers (47%), or nested polymerase chain reaction. The ages of these patients ranged from 1.5 to 10.9 years (mean, 5.3 years) with a male-to-female ratio of 8:9. The clinical manifestations included fever (94%), altered consciousness (65%), seizure (41%), personality or behavior changes (29%), meningeal sign (24%), visual hallucination (24%), ataxia (12%), Guillain-Barré syndrome (6%), blurred vision (6%), and aphasia (6%). Respiratory symptoms and signs were found in 76% of the patients. Abnormal electroencephalogram and neuroimage were observed in all cases, while abnormal cerebrospinal fluid examination was noted in about one-third of the patients. Five (29%) patients required intensive care because of intractable seizure or respiratory failure. Fourteen (82%) patients recovered completely, but 3 (18%) had sequelae including epilepsy, hydrocephalus, and global neurologic deficits with brain stem dysfunction. In Taiwan, M. pneumoniae should be considered an etiologic pathogen of acute childhood encephalitis if fever and respiratory symptoms and signs are observed with or without abnormal cerebrospinal fluid findings. Supportive treatment is the basis of management.

Child↗