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At least 19 recordsLinked to original sources
PubMed1994

Comparison of chickens and pheasants as sentinels for eastern equine encephalitis and St. Louis encephalitis viruses in Florida.

Pheasants and chickens were compared as sentinels for monitoring the transmission of arboviruses of public health significance in Florida during 1991-93. Results suggest that pheasants are better sentinels for eastern equine encephalitis (EEE) virus. They detected virus transmission 3-6 weeks earlier in epizootic years, 2-4 times more frequently during the season, and twice as many birds within a flock seroconverted during a given week. Pheasants detected virus transmission at 2 sites during 2 interepizootic years when chickens failed. Although pheasants detected St. Louis encephalitis (SLE) virus activity somewhat later than did chickens, they had greater seroconversion rates than did chickens. Although both bird species can be used to monitor EEE and SLE viruses, pheasants are more sensitive than chickens as sentinels for EEE virus and as sensitive as chickens as sentinels for SLE virus.

Animals↗
PubMed2001

St. Louis Encephalitis and West Nile Virus Encephalitis.

St. Louis encephalitis virus is a major cause of epidemic arboviral encephalitis in the US. Transmitted by a mosquito vector, this virus is an annual public health concern during the late summer and early fall in much of the midwest and southeast. The characteristic epidemic features of this viral encephalitis coupled with public health surveillance and vector monitoring programs have made the diagnosis readily accessible during the past decade. Recently, however, the arboviral landscape in the US changed dramatically with the emergence and persistence of West Nile virus and associated human neurologic illness in New York and the Northeast. In its New York presentation, West Nile virus encephalitis exhibited clinical and laboratory similarities to St. Louis encephalitis. Not surprisingly, this led to initial confusion in establishing the diagnosis. In anticipation of the potential geographic spread of West Nile virus beyond the northeastern US, neurologists must now consider West Nile virus along with St. Louis encephalitis when diagnosing patients with suspected epidemic mosquito-borne viral encephalitis or meningoencephalitis. Although no specific antiviral agents are yet available, patients will benefit from close monitoring during the initial phase of illness, supportive critical care, and appropriate rehabilitation.

Journal Article↗
PubMed1983

Comparative vector competence of Culex tarsalis and Culex quinquefasciatus from the coachella, imperial, and San Joaquin Valleys of California for St. Louis encephalitis virus.

St. Louis encephalitis (SLE) virus has continued to be active in the Colorado Desert region of Southern California (Coachella and Imperial Valleys) since 1973, while it has virtually disappeared from the Sacramento and San Joaquin Valleys of Central California. Consequently, comparative vector competence studies were undertaken from 1978 to 1981 to evaluate the susceptibility of populations of Culex quinquefasciatus and Culex tarsalis from the San Joaquin and Coachella/Imperial Valleys to oral infection with representative SLE viral strains from each geographical area. Culex quinquefasciatus females from both areas were equally susceptible to infection with both viral strains by the pledget and viremic chick feeding techniques. Although susceptibility profiles were similar by both feeding techniques, infection thresholds (i.e., ID50S) obtained with Cx. quinquefasciatus females were at least 10,000-fold lower when fed on viremic chicks than on virus soaked pledgets. Culex tarslis females from the two geographical areas were equally susceptible to infection with the indigenous viral strain by feeding on pledgets, and were uniformly more susceptible than sympatric populations of Cx. quinquefasciatus. Thus, differences observed in SLE viral activity in different geographical areas of California since 1973 cannot be explained by differences in the susceptibility of Cx. quinquefasciatus or Cx. tarsalis to oral infection with SLE virus.

Animals↗
PubMed1974

Cross-protection between group B arboviruses: resistance in mice to Japanese B encephalitis and St. Louis encephalitis viruses induced by Dengue virus immunization.

Albino Swiss mice, immunized with any of several types and strains of dengue viruses, were afforded substantial protection against peripheral Japanese B encephalitis or St. Louis encephalitis virus challenge. Dengue-2 (New Guinea "C")-immunized mice showed, 10 and 20 weeks after immunization, undiminished resistance with concomitant cyclophosphamide treatment and virus challenge. Examination of the effects of immunization on Japanese B encephalitis virus pathogenesis, after virus challenge with concomitant cyclophosphamide treatment, indicated that protection was associated with decreased viremia and virtually no virus replication in the brain as compared with controls. These effects could be demonstrated before detection of any neutralizing antibody to the challenge virus. From the applied aspect, the data support the hypothesis, based on epidemiological evidence and experiments in hamsters, that prior exposure of man to dengue viruses can confer some degree of protection against Japanese B encephalitis or St. Louis encephalitis disease.

Animals↗
PubMed1986

Comparison of proteins specified by Murray Valley encephalitis, West Nile, Japanese encephalitis and St. Louis encephalitis viruses.

The relationships among proteins specified by Murray Valley encephalitis (MVE), West Nile (WN), Japanese encephalitis (JE) and St. Louis encephalitis (SLE) viruses were examined by peptide mapping. [3H]methionine-labelled tryptic peptides of viral proteins were separated by reverse phase high performance liquid chromatography (HPLC) and the separation profiles for a given protein specified by the different viruses were compared. Analyses of the non-structural protein NV5 (P98 or NS5) suggested that WN and SLE were the most closely related pair of viruses, and that JE was the virus most distant from the other three. Analyses of the structural proteins C and E failed to show the close relationship between WN and SLE indicated by the NV5 results, but did suggest that NV5 was the most conserved and E the least conserved of the three proteins.

Encephalitis Viruses↗
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↗
PubMed2003

Wicking assays for the rapid detection of West Nile and St. Louis encephalitis viral antigens in mosquitoes (Diptera: Culicidae).

The recent outbreaks of West Nile (WN) encephalitis and St. Louis encephalitis (SLE) in the United States have highlighted the need for rapid and specific methods of detecting arboviral antigens in mosquitoes. We evaluated rapid, field-usable assays for detecting and differentiating WN and SLE viruses in mosquito pools, based on a patent-pending, immunochromatographic technology (VecTest) formatted on a dipstick. The device provides results in less than 20 min and can be used in laboratories with adequate containment facilities. In laboratory assessments, both the SLE and WN virus tests demonstrated sensitivity comparable with that of an antigen capture ELISA, but less than can be achieved with Vero cell plaque or reverse-transcriptase polymerase chain reaction assays. There was no evidence of cross-reaction when tested with high concentrations of heterologous flavivirus antigens or with Eastern equine encephalitis or Western equine encephalitis viruses. Both the WN and SLE dipstick tests delivered a clear positive result with a single positive specimen in a pool of 50 mosquitoes. This virus assay technology reduces the time required to obtain test results and will allow rapid medical threat assessment and effective targeting of vector control measures.

Animals↗
PubMed1978

St. Louis encephalitis in children.

St. Louis encephalitis is not an uncommon cause of seasonal meningoencephalitis in children. The clinical presentation is variable and may range from inapparent infection to a severe illness with diverse neurologic signs. A review of three recent cases of St. Louis encephalitis in children in Phoenix, Arizona, stresses the need to consider this type of encephalitis in patients with signs of brain stem dysfunction or acute cerebellar ataxia. The appearance of these clinical signs is supported by the pathologic changes that have been documented to occur, most frequently in the thalamus and brain stem. The importance of serologic identification to facilitate early vector control is emphasized.

Arizona↗
PubMed2002

The neurobehavioural consequences of St. Louis encephalitis infection.

BACKGROUND: St. Louis encephalitis (SLE) is a relatively common cause of neurological illness, yet little is known about its cognitive and psychosocial consequences. PURPOSE: To describe the cognitive, emotional, psychophysiological, and psychosocial consequences of SLE infection. METHOD: A comprehensive neuropsychological and psychophysiological evaluation of a high functioning woman 6 weeks and 1 year after acute SLE infection is presented. The focus and course of rehabilitation is also examined. RESULTS: The primary cognitive consequences of SLE infection involved attention, working memory, speed of processing, and cognitive efficiency. Depression was also observed. Psychometric testing suggested that these deficits largely resolved after 1 year. CONCLUSIONS: SLE produces neurocognitive deficits which are reflected in both psychometric and psychophysiologic measures and functional status. Psychometric and vocational improvement were observed over 1 year. However, the normal vocational return came at a significant psychosocial cost. This case emphasizes the importance of a comprehensive neuropsychological evaluation and illustrates the importance of an integrated rehabilitation programme.

Adult↗
PubMed2003

Previous infection protects house finches from re-infection with St. Louis encephalitis virus.

Antibody titers against St. Louis encephalitis virus (SLE) measured by a plaque reduction neutralization test (PRNT) decreased rapidly in house finches (Capodacus mexicanus) after initial infection, whereas antibodies measured by enzyme immunoassay (EIA) remained detectable in all birds for the length of the experiment, indicating long-term persistence and greater assay sensitivity of the EIA. After 52 wk, birds were challenged by subcutaneous inoculation with the same strain of SLE virus. Virus was not detected for 1-4 d postchallenge in blood samples tested by plaque assay and RT-PCR or by xenodiagnosis in Culex tarsalis fed concurrently and then held for 11 d at 26 degrees C. Virus was detected by all three methods in control birds infected concurrently for the first time. Challenge with SLE produced a rapid and marked ananmestic rise in both neutralizing and EIA antibody titers that exceeded the primary response in the same birds or in concurrently inoculated control birds. At necropsy 4 wk postchallenge, 3 of 7 challenged and 1 of 2 positive control birds were chronically infected, with viral RNA detected by RT-PCR in brain, spleen, lung, and/or kidney tissues. Our results indicated that persistence of protective antibody prevents reinfection during the following season and may prevent the recrudescence of infectious virus in chronically infected birds.

Animals↗
PubMed1984

Immunoglobulin M antibody capture enzyme-linked immunosorbent assay for diagnosis of St. Louis encephalitis.

Sera from patients with St. Louis encephalitis were tested with an immunoglobulin M (IgM) antibody capture enzyme immunoassay (MAC ELISA). The assay used five reagents: antihuman IgM, test serum, sucrose-acetone-extracted mouse brain antigen, broadly cross-reactive flavivirus monoclonal antibody conjugated to alkaline phosphatase, and substrate (p-nitrophenyl phosphate). MAC ELISA endpoint titers correlated (r = 0.893) with the absorbance value of a 1:100 dilution of patient serum. Significant (fourfold or greater) changes in the endpoint titers between paired sera corresponded to a critical ratio (ratio of absorbance values at the 1:100 dilution) of greater than or equal to 1.3. IgM antibodies were detected in 71% of patients bled at 0 to 3 days after the onset of illness, in 99% bled at 4 to 21 days, and in 91% bled at 22 to 67 days. Thereafter, the IgM seropositivity rate declined; however, 29% of sera were still positive at 115 to 251 days after the onset of illness. MAC ELISA titers were significantly correlated with hemagglutination inhibition (r = 0.258) and neutralization (r = 0.711) titers. Because IgM antibodies appeared early and waned rapidly, a diagnosis was made on the basis of a decrease in titer more often by MAC ELISA than by hemagglutination inhibition, complement fixation, or neutralization tests. IgM antibodies generally showed a high degree of specificity; heterologous cross-reactions were, however, present in 4 of 14 sera examined. The MAC ELISA is useful for the rapid, early diagnosis of St. Louis encephalitis.

Antibodies, Viral↗