The home secretary, Priti Patel, has expressed “shock and disgust” and said she felt “a lot more wary” in public after an internet troll who racially abused her on Facebook was jailed.

Gerard Traynor was arrested in January after posting a string of racist messages to the MP’s Facebook page. On Friday he was jailed for 22 months at Manchester crown court after admitting to sending offensive messages between October and December 2018.

The 53-year-old, who was born in Dublin, also trolled the DUP leader, Arlene Foster, with a series of rambling, hate-filled Facebook posts that included graphic threats and offensive language against Protestants, Muslims and Jews.

In a statement to police, Patel said: “I converse with the public on a daily basis this can provoke debate and I am faced with criticism. This incident has taken acceptable behaviour to serious criminality, the content was shocking and disgusting in its nature and the messages were racist, grossly offensive, hugely upsetting and caused me to feel intimidated.

“It had a huge impact on both my personal and professional life, I am a lot more wary of my surroundings when I am in public.”

Foster said: “I expect a degree of commentary but these messages overstep the mark of free speech. I don’t know the sender, where he was or what his intentions were. I was concerned about my own movements, but at least I am in control of my own movements … My concerns were for my family and those around me.”

John Marsh, defending, cited aspects of Traynor’s “dreadful life” as mitigation, including his childhood spent in a nunnery and adoption by a strict Irish Catholic couple, along with his difficulties with Asperger’s syndrome.

Traynor has 11 previous convictions for similar offences stretching back to 2004, including a suspended sentence in 2017 for racially or religiously aggravated common assault.

Sentencing Traynor, the judge, Simon Bryan, said: “This was not the exercise of the democratic right to free speech or the type of critical commentary that all politicians face on a day to day basis. On the contrary the messages are deeply offensive and threatening.”

He refused to give Traynor’s “bigoted hatred the oxygen of publicity” in his sentencing remarks, describing it as “debased language that has no place in our multicultural society and was designed to demean and incite racial hatred.”