In Wales, the chief veterinary officer of the National Assembly wrote to agricultural college heads "suggesting strongly" that they should temporarily close their doors.
Llysfasi College of Agriculture has closed on veterinary advice. Classes are suspended and work that does not involve being on the land will be relocated to a site in Wrexham. The college will need to find alternative accommodation for about 300 students.
"We are waiting with bated breath. This is having a terrible effect on confidence and students' morale about careers in the countryside," said principal Ed Cunningham.
Northumberland College at Kirkley Hall has closed as a precaution. It is in a five-mile exclusion zone, "so no one is coming in or going out." said a spokesman. It is drawing up an emergency timetable.
Moulton College, Northamptonshire, has been closed temporarily.
Howard Petch, of the NAPEO, which represents agricultural colleges, said closure could it finances and students' achievement, and not just for land-based students as colleges had diversified outside agriculture.
Chris Dyke, agricultural education adviser for NATFHE, the lecturers' union, said: "Students are being segregated. Those not living on site are being told not to come in. This could knock two to three months off the teaching programme."
At half-term, all students at Sparsholt College, in Hampshire, were told not to return if they lived in a vulnerable area. The farm has been sealed off at Bishop Burton College, in Humberside. Otley College in Suffolk is questioning visitors about previous movements.
The public is barred at Kingston Maurward, in Dorset. At Askham Bryan College in North Yorkshire, the farm has been closed to all but essential people. "We have not ruled out complete closure," said Kevin Kendall, head of agriculture.
Essential staff are wearing body suits at Capel Manor horticultural centre in Enfield, London (see picture, left). Steve Dowbiggin, principal said:
"It is scary. The next seven days will be crucial. If we had to close, with 800 students on the premises, it would be like World War Two."