I have been in discussions with folks at DEFRA/APHA with regard to TB testing in camelids. Here are a few points to note in case you find yourself with a suspect TB animal on your farm.
What is a suspect TB animal?
- Any animal that has a positive skin test or blood test result from voluntary screening (eg pre-movement test or surveillance testing):
- An animal that is submitted for routine PM and suspicious lesions are found at post-mortem.
- It seems that a proper post-mortem report will NOT be routinely produced if the animal is culled under suspicion of TB, while it might be produced if the animal is submitted for routine PM and suspicious lesions are found. Please ALWAYS ask at time of submission for a proper PM report (with descriptions of lesions) if you would like one. I have had trouble getting a report in the first instance as the pathologists are apparently not required to write one. I have argued that this should be routine, but I believe they don’t want to waste time (or money) once it becomes a TB suspect as the animal falls into the situation of being a surveillance specimen and there are limited resources at this point. I believe that this unfortunately leads potentially to a “failure to diagnose” – if cultures are negative, you still don’t know what caused it. ALWAYS ask to see the TB report at the very least if you can’t acquire a proper PM report.
- You may ask for a PCR test to be done on suspect tissues. This gives you some sort of answer typically within a week, rather than having to wait up to 14 weeks for culture results. In recent cases I’ve been involved with, it has been able to specify whether or not M bovis is involved, although not necessarily the exact species. This has been very useful information to the owners affected. The PCR test can be done at APHA Starcross, but another lab at Liverpool will also do this and they give a detailed report which is helpful. You will need to ASK for this at the time of submission to ensure that they save sufficient sample but also so that it is sent off in a timely manner. This test will need to be paid for by yourself (approx. £55 or so) and will not be covered by APHA, even if the animal is culled under suspicion of TB (due to positive skin or blood test). Note that the test is not officially validated yet, so will not free you from movement restrictions (at this time) but is extremely helpful in allowing you some sleep at night…
- If a case is a TB suspect, APHA/DEFRA do not necessarily submit other tests. This appears to depend upon the pathologist conducting the PM. If a case actually isn’t TB, and you have to wait 14 weeks for a culture result to be reported as negative, it may be too late to submit other tests. This highlights the importance of getting a proper PM report and having your vet evaluate the results as a clinical case – it may be something else and you will need to ask for routine cultures as they will need to be done under the same special conditions down at Starcross (since they are potentially hazardous).
For the time being, if you want other cultures or PCR testing, there is no formal process allowing this to be requested by APHA folks in regional centres. It is in process, but apparently takes a few months for codes to be set up and added to their system. In the meantime, if you have a camelid post-mortem’ed under suspicion of TB, or suspicious lesions are found at PM and this results in samples being sent for further testing, please contact me! I can then contact the right person to ensure that tests are done as it is currently difficult for regional centres to find out how to do this. I can also help you and your vet negotiate the vortex of information deficit (while you wait for results!) if you find yourselves in the unfortunate position of having a suspect TB case on your farm.