Evaluation of antigen detection and antibody detection tests for Trypanosoma evansi infections of buffaloes in Indonesia

Abstract

Two Ag-ELISAs, an IgG-specific antibody detection ELISA (IgG ELISA) and a card agglutination test (CATT) for the detection of Trypanasoma evansi infections in buffaloes in Indonesia, were compared. Diagnostic sensitivity estimates were obtained by testing sera from 139 Indonesian buffaloes which had been found to be infected by parasitological tests. Diagnostic specificity was estimated by testing sera from 263 buffaloes living in Australia. Response-operating characteristic curves were constructed, and optimal ELISA cut-off values, which minimized the number of false–negative and false–positive results, were chosen. The IgG ELISA had the highest sensitivity (89%) and the CATT had the highest specificity (100%). There was a significant difference between the sensitivities (71 and 81%), but not between the specificities (75 and 78%), of the two Ag-ELISAs. The four tests were further compared by calculation of post-test probabilities of infection for positive and negative test results using a range of prevalence values, and likelihood ratios. The results suggested that the CATT was the best test to ‘rule-in’ infection (i.e. the highest probability of infection in test-positive animals) and the IgG ELISA was the best test to ‘rule-out’ infection (i.e. the lowest probability of infection in test-negative animals).

Evaluation of Diagnostic Tests for Trypanosoma evansi in Experimentally Infected Pigs and Subsequent Use in Field Surveys in North Vietnam and Thailand

“…Several of these serological tests have been used successfully in water bu¡alo (Davison et al, 1999;Holland et al, 2002) and camels (Dia et al, 1997). Except for limited ¢eld trials with CATT/T.…”

“…Serological tests for detection of T. evansi speci¢c antibodies, based on the predominant variable antigen type (VAT) RoTat 1.2 (Bajyana Songa and Hamers, 1988;Verloo et al, 2001) have been used extensively in water bu¡alo (Davison et al, 1999;Verloo et al, 2000;Holland et al, 2002). A card agglutination test (CATT), a latex agglutination test (LATEX) using serum or blood, and ELISA and immune trypanolysis tests (TL), both using either serum or blood eluted from ¢lter paper, have been evaluated using samples from experimentally infected bu¡alo and naturally infected animals (Verloo et al, 2000;Holland et al, 2002).…”

Polypeptide profiles of South Indian isolate of Trypanosoma evansi

“…Antigen detection ELISA have been used in various animal species (Kashiwazaki et al 1998). However, proper evaluation of the diagnostic parameters in these assays showed poor results (Davison et al 1999). Surra has a wide host spectrum, the main host species varies with the geographical region.…”

Antigenic characterization of Trypanosoma evansi using sera from experimentally and naturally infected bovines, equines, dogs, and coatis

“…The diagnosis of "Mal de Cadeiras" remains problematic and commonly used tests have important limitations (DAVISON et al, 1999). Diagnosis of trypanosomes by direct parasitological techniques is not reliable, specially for naturally occurring field cases, where parasitemias are often low and sporadic (RAE;LUCKINS, 1984;BENGALY;KANWE;DUVALLET, 1995;NANTULYA, 1994).…”

“…Antigen detection ELISAs have been used in various animal species (DIALL et al, 1992;MONZON;HOYOS;JARA, 1995;KASHIWAZAKI et al, 1998). However, proper evaluation of the diagnostic parameters in these assays showed poor results (DAVISON et al, 1999).…”