| Veterinary TB
VETERINARY TB
Veterinary Microbiology 122 (2007) 108-115. Tuberculosis outbreak in a dromedary racing herd and rapid serological detection of infected camels. U. Wernery, J. Kinne, K.L. Jahans, H.M. Vordermeier, J. Esfandiari, R. Greenwald, B. Johnson, A. Ul-Haq, K.P. Lyashchenko
Editorial by Les Stutzman
A recent TB outbreak in a dromedary racing herd provided an opportunity to compare Chembio’s lateral-flow antibody based blood assay – CamelidTB STAT-PAK Assay – to the more traditional intradermal skin testing. The herd of 57 camels were serologically and skin tested (i.e., SITT – single intradermal tuberculin test & SCITT – single comparative intradermal tuberculin test using EU regulation 64/432/EEC using bovine PPD and avian PPD).
Results showed detection of serum antibodies in two infected dromedaries by CamelidTB STAT-PAK in addition to the infected index case camel and negative tests for all presumed non-infected camels using pre-skin test serum samples. Two subsequent CamelidTB STAT-PAK tests on each of the “non-infected” 55 member herd were consistently serologically negative. The antibody responses found in the three infected camels were unaffected by the tuberculin skin tests.
Skin tested animals using 3 different sites for tuberculin injection further substantiated the CamelidTB STAT-PAK positive reactions on the two members (the index case was already euthanized). However in addition to the two positives cases, there were four (4) other suspects and two more reactors on SITT as well as another positive on SCITT found in the herd. To date these seven dromedaries continued to be monitored via both serological and skin tests, but are presumed to be false positive by skin testing until such time as they either succumb or are euthanized and necropsied to confirm their true TB status. Serological testing remains negative to date.
This study demonstrates that a rapid test (RT) such as Chembio’s CamelidTB STAT-PAK Assay has the potential to improve surveillance and ante mortem diagnosis of TB in camels. In this study the CamelidTB STAT-PAK produced no false positive results and detected all confirmed infected animals. Skin testing did detect the two infected animals in the 57 member herd, but also signaled as many as 7 false positives that are still presumed to be negative until necropsied. In dromedaries skin testing appears to lack the sensitivity and specificity of serological humoral antibody testing as observed with Chembio’s CamelidTB STAT-PAK Assay.
CamelidTB STAT-PAK is a simple and easy-to-use animal-side test that can use serum, plasma, or whole blood to provide a qualitative screening answer as to whether or not there are circulating humoral antibodies to TB (M. bovis or M. tuberculosis) within 20 minutes. The devices can be stored at room temperature for up to 18 months and do not require skilled personnel to perform, specialized laboratory equipment, or an environment. Furthermore, single and repeat testing can be performed without the necessary intervening wait period of 60 days, as is required between succeeding skin tests.
The publication concludes with an assessment that Chembio’s CamelidTB STAT-PAK Assay can improve on current skin testing technologies for TB screening in camelids and perhaps may with further studies prove to be the preferred standalone diagnostic test for program management and control of TB in camelids.
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