Interferon-Gamma Testing for Bovine Tuberculosis - Monthly Reports from April 2016
Source: environment.data.gov.uk (2022-01-18)

These monthly reports summarise the gamma tests completed / reported during that calendar month. The report also summarises tests for the whole calendar year to the end of the current month.
While all effort is made to ensure the accuracy of the test data, small errors can occur and later corrected in subsequent reports. 

Cattle interferon-gamma (IFNg) tests (and test outcome) carried out between 1st Jan and 31st Dec 2009. Tests are listed by country (England, Wales, Scotland) and by Animal Health Office (AHDO) and the reason for the test. Reports contain test data for the month, the calendar year to date and total tests since rollout (23rd Oct 2006). 

Please note: this dataset consists of 12 monthly reports. Data for this report was compiled from field staff inputs and laboratory test information. Subsequent minor data amendments may have been made after the report was originally compiled, and these corrections would appear in the following month’s report. Each report was checked and deemed correct at the time of release. Attribution statement:

Operational notes on terminology, definitions, re-test and re-samples test
outcomes:
• “Samples” refers to an individual tube of blood taken from an individual animal which is
subsequently submitted for testing. It is generally assumed that the number of samples and
the number of animals are analogous as any duplicate sample blood tube from the same
animal will not be tested. However, minor discrepancies may occur where the same animal is
tested more than once due to a request for a resample or the animal is tested twice under
different categories (for example, as a PAR-RAPID and then as part of a PAR-HERD-S).
• “Submissions” refers to an individual batch or set of samples received for testing.
Submissions may comprise 1 or more samples (for example, if an entire herd is being tested it
is usually sent as 1 submission). It is generally assumed that the number of submissions and
the number of herds are analogous.
• Retests are samples where the first ELISA assay fails and the same sample is retested on a
new ELISA plate. Each sample can be retested only once. A retest is not a reportable test
outcome.
• Resamples are where a sample has been retested and failed a second time, so that the lab
requests a new sample. This is a reportable test outcome.
• Rejects are samples that are not tested by the lab for one of the following reasons: blood
collected into wrong type of vacutainer, samples that have not been maintained at the
appropriate temperature range (22±5C), unlabelled samples, broken or cracked tubes, blood
that is extensively clotted (small clots are OK), samples received after 4pm on the day after
sample collection. Such samples are reported separately in the tables and in figure 5.
• POS (pokeweed mitogen) is a sample positive control reagent which provides a measure of
the quality/viability of the blood sample. A POS fail (< 0.45 optical density reading) may
indicate compromised blood quality as a result of collection/transportation conditions or due
the animal having an unusually low/suppressed cellular immune response.
• NEG (no-antigen control) is a sample negative control which provides a measure of the
background antigen-independent IFN- responses. A NEG fail (> 0.3 optical density reading)
may indicate a laboratory procedures problem (normally resolved during re-test) or that an
animal has unusually high background levels of IFN-g.

0
1
2
3
4
5
6
7
May
June
July
August
September
October
November
December
January
February
March
April
May
2016
2017
%Rejected
%Resampled
% NEG Fail
% POS Fail
% of total
submitted
Figure 5. Rates of resamples including the fail rates broken down for positive
(POS) and negative (NEG) controls.