Studies on serological cross-reaction in sequential flavivirus infections.

Acute- and convalescent-phase sera from patients with dengue (DEN) hemorrhagic fever (DHF) and Japanese encephalitis (JE) that contained pre-existing flavivirus antibodies were tested for cross-reacting antibodies to DEN, JE and yellow fever (YF) viruses by a neutralization (N) test. A fourfold or greater rise in N antibody titer in the convalescent-phase was considered significant. Of 39 DHF cases, obtained at Chiang Mai University Hospital, Thailand, 15 (38.5%) showed a rise in DEN antibody titer, while another 15 (38.5%) showed a significant rise in both DEN and JE N antibody titers. On the other hand, eight (61.5%) of 13 JE cases obtained at the same Hospital, showed a significant rise in JE antibody titer, while two (15.4%) showed a significant rise in both DEN and JE antibody titers. Sucrose gradient centrifugation and fractionation of these two cross-reactive JE sera revealed that IgM class antibody was specific for JE, while IgG class antibody was cross-reactive. Of three JE cases with pre-existing YF antibody obtained in Okinawa, Japan, two showed a significant rise in YF and JE antibodies. Both IgM and IgG class antibodies to YF virus were elevated. These results indicate that the cross-reactivity among flaviviruses in different subgroups (complexes), was observed quite often, even by the N test, in sequential flavivirus infection.

Japanese encephalitis in children in northern Thailand.

Fifty-nine children with Japanese encephalitis admitted in Maharaj Nakhon Chiang Mai Hospital since 1984-1985 were studied. The male to female ratio was 1.18:1. The age range was between 1 to 14 years old with 74% in the age range of 6-14 years. The symptoms included change of consciousness (100%), fever (96%), headache (76%), convulsions (59%) and vomiting (52%). The neurologic signs, namely positive meningeal signs (61%), hyperreflexia (61%), positive Babinski's sign (49%) hemiplegia (42%), papilledema (22%), and other cranial nerve palsies (23%) were seen. Abnormal respiration were found in 23% and 8% of cases had hypertension. Most children (81%) had blood leukocytosis with predominant neutrophils. The average CSF white blood cell count was 200 cells per mm. with lymphocytosis in 76 percent of the patients. The average CSF protein was higher than normal. Almost all cases had normal CSF sugar levels. The JEV antibody response, mostly primary type, Occurred in about 62 percent of cases. All children received symptomatic and supportive treatment, such as antipyretics, anticonvulsants, anticerebral edema agents, adequate respiration and nutrition and physical and occupational therapies. Associated complications were treated according to the individual's need. The mortality rate and neurological sequelae were found in 17% and 57% of cases respectively. Eighteen percent of the patients suffered severe neurological sequelae. The neurological sequelae included memory deficit (46%), mental retardation (42%), hemiplegia (34%), emotional and behavioral disturbance (24%), epilepsy (20%), motor aphasia (16%), cranial nerve palsies (16%), involuntary limb movement (8%) and blindness (2%).

Symptomatic neuroepithelial cysts in the posterior cranial fossa. Immunohistochemical and electron-microscopic studies.

A 2-year-old boy had increased intracranial pressure and convulsions because of two extraventricular cysts in the posterior cranial fossa. Releasing the watery cyst contents resulted in disappearance of such clinical manifestations. Immunohistochemically, the epithelial cytoplasm of the cyst was strongly positive for glial fibrillary acidic protein. Electron-microscopically, the cells that lined the cysts had microvilli which were coated with finely granular material to represent "fuzzy" coat, intercellular junctions linking the plasma membranes of adjacent cells, and numerous cytoplasmic glial filaments. The strong positivity for glial fibrillary acidic protein, then, is well correlated with an abundance of the latter. Cilia were also identified. Thus, the cysts were unequivocally neuroepithelial (ependymal) cysts. Only nine cases of neuroepithelial cysts in the posterior cranial fossa, including the current one, have been reported. Three patients were children; six were adults. The age of the patients ranged from 7 months to 60 years. The average age was 21.7 years The sex was known in eight patients with a male to female ratio of 3:5. The pathogenesis of these neuroepithelial cysts was proposed as related to developmental anomalies.