Protocol for blood sampling for bovine TB using the Enferplex test.
Please be aware that the following represents best practice. Serological samples are relatively tolerant of sub-optimum conditions but if maximum sensitivity and specificity are to be achieved then they need to be handled appropriately.
1. Collect samples at the beginning of the working week, to allow the samples to get to SureFarm Ltd by Tuesday or early Wednesday morning at the latest.
2. Cleanly take a blood sample, minimum of 3 ml, into a serum (red top) glass vacutainer tube.
3. Clot the blood at room temperature (20 +/- 4 degrees Celcius) for 2-3 hours to allow good clot formation and initial clot retraction. Beware taking samples over prolonged period of time in very cold temperatures as this can result in a problem with clot retraction.
4. Store Cool to 4-8 degrees Celcius and keep at that temperature until they arrive at the destination lab. Transport should be in an approved transport container with samples appropriately labelled / supported so they don’t shake about too much. Avoid having the samples delayed in the transport system over a weekend.
Selection of animals to be tested
Any age of animal can be tested. There is no minimum age.
To avoid excessive cost, in larger herds it has been accepted that it will be reasonable to sample a statistically derived proportion of the herd. This proportion will be calculated by SureFarm Ltd based on the number in the whole herd and using the same inputs in terms of prevalence, sensitivity and specificity as used for the statistical package used to interpret the results as discussed above. Clearly, not sampling all animals does increase the risk that infection may be missed and, where targeted sampling occurs, the owner will have to sign that they accept this risk.
Given the inherent difficulties in predicting where bovine tuberculosis (bTB) might exist in a herd, there are no specific answers as to how to determine which animals should be tested where whole herd sampling is not performed. The general advice is that the sampling of animals should be designed to target the specific cohorts that exist in the herd in terms of age and group i.e. ideally samples should be taken from all the different groups of animals and to reflect the age structure of that group. Please consult your veterinary surgeon on the approach to sampling in your herd.
As this is a voluntary scheme, there is no compulsion on the owner to present specific groups but ultimately it is in the owner’s interest to ensure that freedom of disease is tested for as thoroughly as possible.