Detection of specific cysticercus antigen in the urine for diagnosis of neurocysticercosis

Neurocysticercosis (NCC) is an important zoonotic infection, and a significant cause of morbidity and mortality in India. Immunodiagnosis plays an important role in the early, rapid, and specific diagnosis of the condition. The aim of the present study was to detect specific cysticercal antigen excreted in the urine for the diagnosis of NCC. The objective was to develop and evaluate staphylococcal Co-agglutination (Co-A) test for the detection of urinary cysticercal antigen. In the present study, urine samples were collected from 9 cases of clinically suspected NCC, 8 cases of CT/MRI proven cases of NCC, 11 of non-cysticercal CNS infection controls, and 25 healthy control subjects. Polyclonal antisera raised in rabbits against porcine complete cysticercus homogenate antigen, was used in the Co-A test to detect cysticercal antigen. The Co-A detected excreted cysticercal antigen in the urine of five of nine (55.5%) clinically diagnosed NCC and in five of eight (62.5%), CT/MRI proven cases of NCC. A false positive reaction was observed with 1 of 11 (9%) of control urine specimens from non-cysticercal CNS infection controls. No false positivity was demonstrated with 25 urine samples collected from healthy controls. Results of the present study shows that the Co-A test can be employed as a moderately sensitive and specific test for detection of urinary antigen in the diagnosis of NCC in poorly equipped laboratories.