Case 114. Encephalitis japonicum (5 y-o M)
         
   
Autopsied brain of a child with acute consciousness disturbance in summer
   
         
   
Key words : Japanese encephalitis virus, arbovirus, Flavivirus
   
         
   
zoonosis
   
     
 
     
Marked inflammatory edema provokes a spongy necrosis in the cerebral cortex. Mononuclear infiltration is noted around small vessels (HE, low power).   Typical features of neuronophagia, a cluster of microglia around a necrotic neuron, are shown (HE, high power).
     
 
     
In the focus of spongy necrosis, accumulation of foamy macrophages is observed (HE, high power). No inclusion body is recognized.   Autopsy record in the summer of early 1960's in a university hospital in Tokyo
Many of the autopsy diagnoses in this season were encephalitis epidemica (Japanese encephalitis). Fourteen were pediatric cases, while four were adult cases (not younger than than 19 y-o). Japanese encephalitis is now endemic in the India though southeastern Asia. The pig is a reservoir of this Flavivirus (arbovirus), which is transmitted by the mosquito, Culex tritaeniorhynchus Giles.
     
 
     
Reference case 114A
Acute lethal encephalitis of unknown etiology seen in a 45 y-o male (HE, low power). Histologically, perivascular infiltration of mononuclear cells and inflammatory edema are observed in the necropsy specimen (HE, low power).
  Reference case 114A
Acute lethal encephalitis of unknown etiology seen in a 45 y-o male (HE, high power). A few glial cells show intranuclear inclusions (HE, high power). Viral antigens of herpes group were all negative.