Foot and Mouth Disease Virus

HL Deb 23 April 2001 vol 625 cc10-1WA

The Countess of Mar

asked Her Majesty's Government:

What is the lowest pH level at which the foot-and-mouth disease virus will survive; and what is the pH range of air in the United Kingdom atmosphere. [HL1563]

Baroness Hayman

The viability of foot and mouth disease virus depends on pH and temperature. The virus is most stable at neutral pH levels, but will not survive indifinitely. Acidic or basic pH levels decrease the survival time, as do high temperatures. As an example, in laboratory conditions, foot and mouth disease virus survives at pH 6.0 for only two minutes.

As pH is a measurement of the acidity or basicity of aqueous or other liquid solutions, it is not possible to give the pH range of air. We assume that the question refers to airborne spread of the virus. The factors that affect airborne spread include wind direction, wind speed, wind veer, ambient temperature and relative humidity.

The Countess of Mar

asked Her Majesty's Government:

What is the normal pH of living animal tissue; what pH levels are achieved by rigor mortis; and whether the reduced levels are maintained during the decay of carcasses. [HL1564]

Baroness Hayman

The normal pH of living animal tissues is approximately neutral. Duringrigor mortis, the pH in skeletal muscle falls below 6.0, which is sufficient to inactivate foot and mouth disease virus. The exact value depends on the species of animal and type of muscle. Viable virus can still be isolated, however, from the bone marrow and lymph nodes of carcasses. The pH levels during decay depend on many factors and may rise after rigor mortis; however the virus cannot be reactivated by a rise in pH levels.

The Countess of Mar

asked Her Majesty's Government:

Whether pH levels achieved in meat from healthy slaughtered animals, frozen or chilled without the carcass being hung, are sufficiently low to kill foot-and-mouth disease virus. [HL1565]

Baroness Hayman

To inactivate the virus in meat, it is essential that a pH level below 6.0 has been reached before deboning. This can be achieved by chilling at 2 degrees C for 24 hours or by electrical stimulation. If the meat is frozen before the pH levels drop duringrigor mortis, then the foot and mouth virus can survive for long periods, but may be inactivated during the thawing process.