What samples are needed for the diagnosis of FMD?
• FMD is usually diagnosed by detecting virus or virus antigen. The best sample for this is material from fresh lesions, because this contains large amounts of virus and positive results can be confirmed just a few hours after the test is set up at the laboratory. Antigen can also be detected in samples of milk and of whole heparinised blood, in the early stages of infection. The sample most useful for detecting virus in subclinically infected sheep (and in carrier animals) is cells and fluid (oesophageal -pharyngeal fluid sample) taken from the back of the throat using a metal cup on a rod – a probang cup. Just a nasal swab is needed for a new test which has recently been developed but is not yet used in the UK. As the disease progresses and the animal’s immune system responds the amount of virus decreases (some may be left in the back of the throat (pharynx area) of carriers). In the later stages of disease and after the period of clinical signs, clotted blood samples are taken and t
