Trypanosomosis agglutination card test for Trypanosoma brucei rhodesiense sleeping sickness

Objective: To develop a simple field test for diagnosis of Trypanosoma bruc ei rhodesiense in man, Design: Trypanosomosis Agglutination Card Test (TACT) was developed for the diagnosis of sleeping sickness due to Trypanosoma brucei rhodesiense infec tion, based on stabilised procyclic forms derived from Utat 4.1, Procyclics were fixed in buffered formalin at 4 degrees for 24 hours and further stab ilised in acid/alcohol mixture for 30 minutes, The fixed antigen was staine d with Coomassie blue and suspended in 0.1M PBS/sodium azide buffer pH 7.2 at a concentration of 1 x 10(8) trypanosomes/ml and kept at room temperatur e, This antigen was used to screen 100 sera from rabbits infected with T. b . rhodesiense, eight from normal rabbits, and 220 only sera 60 of which wer e from sleeping sickness patients, 50 from normal persons and 110 from othe r parasitic infections, Setting: Laboratory testing of the antigen types against the rabbit and hum an sera infected with cloned variable antigen types of T,b, rhodesiense, wa s routinely carried on test cards under room temperature. Subjects/participants: Serum samples from normal and infected rabbits and h uman subjects, Results: All sera from infected rabbits and 59 from sleeping sickness patie nts reacted strongly with the antigen showing agglutination reaction which ranged from 1:4 to 1:1024 serum dilution. There was minimal cross reaction with other parasitic infections its follows: one out of 20 malaria patients none of the 20 hookworm patients, one out of 30 for schistosomiasis patien ts, none of the 10 amoebiasis patients and one out of 20 for filariasis pat ients, Agglutination titres from all these non-sleeping sickness patients w ere below 1:16, Based on rabbit positive and negative sera, TACT gave a sen sitivity and specificity of 100% and 80% while for human sera a sensitivity of 98.3 % and specificity of 96% were observed, Conclusion: These preliminary results show that TACT could be a promising s creening field test for T,b, rhodesiense sleeping sickness.