Abstract:

Introduction: Human African trypanosomiasis (HAT) has been targeted for interruption of transmission by 2030. This study was undertaken to assess the sensitivity of a RDT test detecting anti-T. b. gambiense antibodies to PCR testing in domestic animals from HAT foci in Chad.

Method: Blood samples were taken from 443 goats, 339 sheep, 228 dogs, 98 pigs, 1,466 cattle, 155 donkeys and 151 horses. The rapid diagnostic test (RDT) was used to detect trypanosomes. DNA was extracted from buffy coats and T. b. gambiense was identified by PCR.

Results: Of the 2,860 domestic animals sampled, 8.98% were positive for anti-T. b gambiense antibodies. RDT targeting anti-T. b. gambiense antibodies and PCR were simultaneously positive and negative for 257 (9%) and 21 (0.73%) respectively. The RDT was positive in 236 animals (8.25%) that were PCR-negative. For RDT targeting anti-T. b. gambiense antibodies and PCR targeting T. b. gambiense, 549 samples (82.1%) showed concordant results, while discordant results were reported for 120 samples (17.9%). Of the 549 samples with concordant results, 14 (2.6%) and 535 (97.4%) were positive and negative, respectively. Sensitivity and specificity were 66.67% and 91.44% respectively. Comparing the sensitivity of TDR according to the species analyzed, it was found that this value varied from 0% in cattle, 37.50% in sheep, 60% in goats and 100% in other animals (sheep, pigs, donkeys and horses). RDT specificity ranged from 79.74% in Asians to 97% in Cattle.

Conclusion: Results comparing RDT and PCR targeting T. b. gambiense in each animal species were poor. RDT does not appear to be suitable for the reliable identification of T. b. gambiense in domestic animals