Evaluation of ante-mortem diagnostic techniques for tuberculosis in New World camelids
Degree Final Project defended by Sofía Cobos Blázquez
July 8th, 2025
In the last years, the popularity of South American camelids or “New World camelids” (NWC), a term which mainly englobes llamas and alpacas, has increased in Europe. They are used for multiple purposes such as wool production, pasture care or trekking. For this reason, veterinary treatment of this species has been gradually developing, with increasing concern for diseases that affect them and those that can be transmitted to humans. Among them is tuberculosis (TB), caused by mycobacterias of the Mycobacterium tuberculosis complex (MTBC) specially M.bovis, causing respiratory clinical signs and even sudden death without prior clinical symptoms. The lesions are pathognomonic and easily identifiable at necropsy, but the problem relies in identifying infected animals before reaching this is stage.
The main issue is the lack of ante-mortem methods to achieve an effective TB diagnosis and the lack of studies in this regarding to NWC. On the other hand, according to Regulation (EU) 2016/429, a valid negative test for TB must be provided prior to any commercial movement and following a 12-month surveillance period. Therefore, the aim of this study is to evaluate the performance of two commercial kits that detect antibodies against MTBC for the diagnosis of TB in serum samples from NWC. For this purpose, samples from both infected (from Spain and Peru) and healthy (from Chile) animals were included. The kits used were INgezim Tuberculosis DR (Eurofins Scientific, Spain) and IDEXX (IDEXX Laboratories, Inc., USA).
The results obtained determined sensitivity (Se) and specificity (Sp) values of 61.53% (95% CI, 60.7-93.1) and 100% (95% CI, 100), respectively, with Ingezim and 76.92% (95% CI, 42.8-80.2) and 98.75% (CI, 97.6-99.8) with IDEXX. Based on the significant increase in Se (91.12%), and maintaining the Sp (98.75%), obtained with when combining both kits and a substantial concordance (kappa value of 0.77) between them, it was concluded that their combined use would be an effective and valid alternative as a diagnostic technique for TB in NWC. Since this would mean a high economic cost, it was determined that the individual use of IDEXX could also be considered as an effective alternative
