AVIS - Foot and Mouth Disease

Collection of samples

Vesicular Material

Epithelium from an unruptured or freshly ruptured vesicle should be identified. The area may be washed with phosphate-buffered saline (PBS) or water if heavily contaminated with food (in the mouth) or faeces (on the feet) but disinfectants must NOT be used. It may be advisable to sedate the animal prior to sample collection (e.g., xylazine ‘Rompun’ in cattle and sheep or azaperone ‘Stresnil’ in pigs). This is particularly relevant in pigs and sheep where vesicular material might be scarce. Collect as large a piece of epithelium as possible (2 cm2 is ideal, about the size of a postage stamp). If present, subcutaneous fat or muscle should be trimmed off to leave the epithelium alone. If unruptured vesicles are found, the virus-rich, straw-coloured vesicular fluid can be withdrawn with a syringe and diluted in transport medium. Samples containing vesicular fluid should be labelled as such so that the transport fluid itself is examined for the presence of virus.

Pieces of epithelium and/or vesicular fluid should be suspended in transport medium, a mixture of equal amounts of glycerol and 0.04 M phosphate buffer pH 7.2-7.6, preferably with added antibiotics. There will be considerable loss of infectivity if samples are sent in buffer outside this pH range. When more than one animal is affected it is advisable to sample several animals, preferably in different management groups provided more than one group is affected.