Detection of Trypanosoma evansi in brains of the naturally infected hog deer by streptavidine-biotin immunohistochemistry

Twenty-four percent of hog deer (Cervus porcinus) that ranged free on a far m in Samut Prakarn province, Thailand, died showing nervous signs between S eptember 1997 and February 1998. The nervous signs shown by most of them in cluded ataxis, paresis of hind limbs, lateral recumbency, excitation and co nvulsion. Six animals and one carcass were submitted for diagnosis at the N ational Institute of Animal Health, Bangkok. Trypanosoma evansi was detecte d in blood and cerebrospinal fluid of four and five animals, respectively. Antibodies to T. evansi were found in all the hog deer by indirect enzyme-l inked immunosorbent assay. Histopathological observation revealed a general ised non-suppurative meningoencephalitis affecting the white and grey matte r at all levels of the brain. Typically, there were broad perivascular cuff s of mononuclear inflammatory cells, including lymphocytes, and some Mott c ells. No trypanosomes were found in any tissue examined by conventional his topathology. However, numerous T. evansi were demonstrated by streptavidine -biotin immunohistochemistry in neuropil and Virchow-Robin spaces of brain in three animals. (C)2000 Elsevier Science B.V. All rights reserved.