A multi-centre evaluation of the card indirect agglutination test for trypanosomiasis (TrypTect CIATT)

Abstract

A version of the card indirect agglutination test for trypanosomiasis, the TrypTect CIATT, was evaluated for the diagnosis of Trypanosoma brucei gambiense and T. b. rhodesiense sleeping sickness. The results of this antigen-detection test indicated high relative sensitivity (99.3%) and specificity (99.4%), and also much higher prevalences of infection in the general population of endemic foci (27.9% for T. b. gambiense and 21.8% for T. b. rhodesiense) than detected by parasitological diagnosis (1.6% and 1.1%, respectively). TrypTect CIATT detected (and could therefore be used for the diagnosis of) non-patent infections. Among the suspected cases (i.e. those initially found to be parasite-negative but to be antigen-positive), trypanosomes were detected in 29 (4.2%) of those checked at a 3-month follow-up, and 17 more such suspects when they were followed up at 6-18 months. Moreover, a high proportion of blood samples from a random sample of the rest of the suspects tested positive for trypanosome-specific DNA by PCR (79.9% for T. b. gambiense and 13.9% for T. b. rhodesiense). ELISA also demonstrated the presence of anti-trypanosome antibodies in many of the suspects tested (63%, 38%, 24% and 66.9% of those in Cameroon, Côte d'Ivoire, Tanzania, and Malawi, respectively). A follow-up of 164 patients treated with melarsoprol revealed that, by 9 months post-treatment, 113 (69.0%) had no detectable trypanosome antigens in their peripheral blood. The test could therefore be used for evaluating chemotherapeutic cure, as well as for diagnosis.