Christine Lord's son Andrew died of the disease in 2007
Two women whose sons died from variant Creutzfeldt-Jacob Disease say they do not believe official figures for the number of people killed by the disease.
Christine Lord, of Southsea, Hampshire, lost her son Andrew Black, 24, to vCJD in 2007 while Rose Smith's son Billy, of London, died aged 21 in January.
Since 1990, 168 people have died from vCJD and the Department of Health said it had never manipulated the figures.
Ms Lord and Ms Smith were at a memorial event in London on Saturday.
To mark Human BSE Memorial Day, Ms Lord also published a list of names on her website
Justice for Andy
of hundreds of people who have died, been diagnosed with or affected by the human form of mad cow's disease.
Ms Lord said: "Since Andrew died I've actually been in contact, interviewed and filmed dozens of people who have lost a loved one through variant CJD.
"Many of these victims have never appeared on the official government statistics.
"What I'm finding increasingly, again and again, is that there is a deliberate massaging and manipulation of just actually how many people have and are dying of variant CJD and have been affected by the disease.
"This gives the appearance that the disease has disappeared.
"One death is one death too many of a totally avoidable disease and the government are spinning the truth.
"They are rewriting the statistics in order to escape the unacceptable reality and protect those responsible."
Ms Smith, of Eltham, south-east London, added: "Be honest open and transparent about the true numbers of people dying, diagnosed and affected by vCJD.
"We are still not being told the truth about vCJD. How many have and are dying."
A spokesperson for the Department of Health said: "The statistics [for vCJD]are gathered independently, according to internationally agreed criteria - and using those we build the most accurate picture we can."
Variant CJD has been linked to eating beef infected with mad cow disease.