African Trypanosomiasis

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Clinical features:

• Endemic areas are the tropical forest near rivers.

• Transmitted by insect bite.

• Congenital form also exists.

Pathogen: Trypanosoma ganbiense and T. rhodesiense.

Anatomic locations:

• Cerebral and cerebellar white matter, basal ganglia and brain stem tend to be most affected.

• Cerebral cortex is relatively spared.

Macroscopic changes may be scanty or absence even in fatal cases.

Histology:

• Diffuse meningoencephalitis consisting of lymphocytes, histiocytes, and plasma cells around blood vessels and in the subarachnoid space.

• Diffuse microglial hyperplasia, proliferation of large astrocytes, and formation of microglial nodules Morular cells (plasma cells distended with immunoglobulin) occur in perivascular spaces.

• Trypanosomes have never been described in tissue sections of African trypanosomiasis cases, but parasites can be seen in blood or CSF as flagellates.

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