People affected by the foot-and-mouth crisis in 2001 suffered symptoms close to post-traumatic stress disorder for months afterwards, a report has said.
Humans suffered as well as livestock, researchers say
Flashbacks, nightmares, and conflict in communities were among problems found by Lancaster University researchers.
They studied weekly diaries kept for 18 months from December 2001 by 54 people including farmers, vets and doctors.
Distress was experienced beyond the farming community, the report published in the British Medical Journal said.
The 54-strong "rural citizens' panel", which also included small business owners and others in rural areas, completed diaries, gave interviews and took part in group discussions.
"The study shows that life after the foot-and-mouth disease epidemic has been accompanied by distress, feelings of bereavement, fear of a new disaster, loss of trust in authority and system of control and by the undermining of the value of local knowledge," the report said.
Uncontrollable emotions and increased social isolation were also identified by the Lancaster University Institute for Health Research.
There was evidence in the longer term of anxieties about emissions from disposal sites where animal bodies were burned and buried, as well as confusion, bitterness and increased fear of unemployment.
BBC rural affairs correspondent Tom Heap said foot-and-mouth had been a "watershed event which was not only commercially devastating, but horrifically graphic for those who lived amongst it".
"The result is close to post-traumatic stress disorder," he said.
The report said: "People who have experienced a disaster may not be sick as a result, but they need careful and appropriate support to rebuild lives and regain confidence."
Statutory and voluntary groups had a more complex and lasting role to play than had been previously understood, it said.
The researchers said: "Distress is not a medical problem... unless it becomes pathological, when it is re-categorised as depression or post-traumatic stress disorder - if it is treated it is counted.
"Otherwise those who are suffering are expected to recover using their own resources and networks."
The epidemic forced the closure of much of the countryside for months and the slaughter of between 6.5 million and 10 million animals.