| In recent years, polymerase chain reaction (PCR) has been under study as a potential technique to improve the accuracy of diagnosis of suspected central nervous system viral infections. We describe a case of severe encephalitis in a previously healthy 20-year-old woman from new york who presented with headache, fever, and photophobia. Her illness was characterized by progressive worsening of her neurological status, leading to confusion, delirium, and status epilepticus. The diagnosis of Jamestown Canyon encephalitis was established by positive reverse transcriptase (RT)-PCR and nucleic acid sequencing of the band from both cerebrospinal fluid and brain tissue. The nucleotide sequence and the deduced amino acid sequence of the Jamestown Canyon virus from this patient were very similar to Jamestown Canyon virus isolates from mosquito pools in new york. This report suggests that RT-PCR assays could be important tools in the diagnostic workup of cases of encephalitis. ( info) |
2/13. Severe La Crosse encephalitis with significant neurologic sequelae. La Crosse encephalitis, a member of the california arbovirus group, is the most common cause of reported mosquito-borne illness in the united states. Approximately 70 cases of La Crosse encephalitis are reported each year. The principal vector is the mosquito aedes triseriatus. During the summer the virus is amplified horizontally in a cycle among small mammals such as chipmunks and squirrels. Infected female A. triseriatus deposit eggs in the basal holes of hardwood trees, although man-made containers and old tires containing water also supply a suitable breeding site. Some of these eggs infected with la crosse virus hatch the next spring and give rise to infected adult A. triseriatus, and the host-vector cycle is renewed. Only a minority of children infected with the virus become ill. Clinical disease caused by La Crosse is usually mild, and neurologic sequelae are relatively uncommon. In this report we describe six patients with severe La Crosse meningoencephalitis diagnosed within a 4-week period. All patients required intensive care management, and there was a high rate of neurologic sequelae, suggesting that La Crosse is not necessarily a benign meningoencephalitis. ( info) |
3/13. La Crosse encephalitis presenting like herpes simplex encephalitis in an immunocompromised adult. The diagnosis of the precise cause of viral encephalitis can be difficult, hampered by the nonspecific presentation, the number of etiologic viruses, and limited culture and serologic diagnostic methods. Because herpes simplex encephalitis (HSE) can be neurologically devastating and is treatable, timely diagnosis is important. We report an immunocompromised adult with encephalitis clinically consistent with HSE who had serology consistent with recent La Crosse encephalitis (LAC). ( info) |
4/13. The first reported case of california encephalitis in more than 50 years. A recent case of california encephalitis, a rare mosquito-borne viral disease, represents only the fourth ever reported and the first since the initial three cases in 1945. This case was diagnosed retrospectively on the basis of a rise in antibody titer between acute- and convalescent-phase serum samples. ( info) |
5/13. LaCrosse viral encephalitis mimics herpes simplex viral encephalitis. temporal lobe abnormalities, findings commonly associated with herpes simplex virus encephalitis, were observed in a male 10 years of age found to have LaCrosse virus encephalitis. Diagnostic features included magnetic resonance imaging revealing abnormal signal intensity in the bilateral frontotemporal regions, and left-sided periodic lateralizing epileptiform discharges. LaCrosse virus encephalitis should be included in the differential diagnosis of viral encephalitis associated with structural and electrographic temporal lobe lesions, represented by periodic lateralizing epileptiform discharges. The recently developed LaCrosse RNA polymerase chain reaction for cerebrospinal fluid may enable rapid diagnosis, prevent the need for treatment with acyclovir, and give parents an encouraging prognosis. ( info) |
6/13. california serogroup virus infections in the Ryazan region of the ussr. serum samples from 60 people diagnosed in the summer of 1989 as having acute respiratory infections, meningitis or meningoencephalitis, acute pneumonia, Lyme disease, or other illnesses were tested by neutralization and hemagglutination-inhibition with Tahyna, Inkoo, and snowshoe hare viruses of the california serogroup (family bunyaviridae, genus Bunyavirus). Demonstration of a diagnostic increase in antibody titers between paired serum samples from seven people showed that their illnesses were probably caused by Inkoo or Tahyna viruses. The clinical pictures were less specific. One patient had signs of meningoencephalitis, three had signs of meningitis, and three had influenza-like illnesses. These observations and other results suggest that california serogroup viruses are widespread in russia and may account for an unexpectedly large number of presently undiagnosed febrile illnesses, some with central nervous system involvement. ( info) |
7/13. Jamestown Canyon virus (california serogroup) is the etiologic agent of widespread infection in michigan humans. In a sample population of 780 michigan residents tested for neutralizing antibodies to california serogroup viruses, 216 (27.7%) had specific neutralizing antibody to Jamestown Canyon virus. An additional eight (1.0%) had specific neutralizing to trivittatus virus; none had specific neutralizing antibody to La Crosse virus. Significantly more male residents than female residents of the Lower Peninsula had antibody to Jamestown Canyon virus. The frequency of neutralizing antibody titers fits the poisson distribution, suggesting that Jamestown Canyon virus infections occur endemically in residents of michigan. Among 128 sera with specific neutralizing antibody to Jamestown Canyon virus, only two (1.6%) were found to have significant hemagglutination-inhibiting antibody titers with la crosse virus, while 23 of 44 (52%) had significant titers with Jamestown Canyon virus; a single serum had significant antibody by complement fixation tests with both La Crosse and Jamestown Canyon viruses. This study confirms earlier speculation that complement fixation and hemagglutination-inhibition tests with la crosse virus (the only tests for california serogroup virus infections performed by most state diagnostic laboratories) fail to detect antibody to Jamestown Canyon virus. ASPEX computer-drawn maps demonstrated that the distribution of persons with antibody to Jamestown Canyon virus and residing in michigan's Lower Peninsula is closely correlated with the estimated distribution of white-tailed deer in that part of the state, further supporting the hypothesis that white-tailed deer are the primary vertebrate host for Jamestown Canyon virus. ( info) |
8/13. A case of encephalitis in a human associated with a serologic rise to Jamestown Canyon virus. An 8-year-old girl living in rural southwestern michigan experienced sudden onset of symptoms beginning with headache, dizziness and fever which rapidly progressed to central nervous system involvement with seizures and coma. Following 27 days of hospitalization her recovery was uneventful, with no apparent sequelae 15 months after discharge. Serologic studies of paired sera showed a rise in antibody to Jamestown Canyon virus, a member of the california serogroup (family bunyaviridae). Specific IgM anti-Jamestown Canyon virus antibody was detected in sera drawn 9 days after onset. A concomitant rise in complement fixation antibody to herpesvirus was also noted. We believe this is the first reported case of encephalitis associated with Jamestown Canyon virus infection. Reasons are presented for the current inability to routinely detect infection and clinical illness caused by this virus. ( info) |
| A child developed acute hemiparesis due to infarction of basal ganglia and internal capsule. Pleocytosis of cerebrospinal fluid and elevated immunoglobulin M antibodies suggest that california encephalitis virus infection caused the stroke. ( info) |
| arboviruses are mosquitoborne and tickborne agents that persist in nature in complex cycles involving birds and mammals, including humans. Characteristics of arboviral infection include fever, headache, encephalitis, and sometimes death. In 1994, health departments in 20 states reported 100 presumptive or confirmed human cases of arboviral disease to CDC. Of these, 76 were california (CAL) serogroup encephalitis; 20, St. Louis encephalitis (SLE); two, western equine encephalomyelitis (WEE); one, eastern equine encephalomyelitis (EEE); and one, Powassan encephalitis (POW). This report summarizes information about arboviral disease in the united states during 1994. ( info) |