The number of cases in the UK rose to 460 on Wednesday, up from 373 on Tuesday morning, the Department of Health said. Six British patients have died of the disease in the UK.
Earlier, the department confirmed that Ms Dorries had first exhibited symptoms on Thursday, when she attended a reception in Downing Street with Prime Minister Boris Johnson.
Ms Dorries, who has placed herself in self-isolation, has met hundreds of people in Westminster over the past week.
Number 10 officials said Mr Johnson was not suffering symptoms and would not be tested for coronavirus. They added that he had not been in close contact with the health minister and that current advice stated you had to be within two metres of someone to pass the disease on.
Officials are urgently seeking to identify the names of everyone with whom Ms Dorries has come into contact in recent days and Public Health England will contact anyone they believe to be at risk. Ms Dorries sent a message to a WhatsApp group of Conservative MPs on Wednesday in which she said a member of her staff was also unwell.
Kelly Holmes, the Olympic gold medallist, was present at the Downing Street reception on Thursday. Liz Truss, the international trade secretary, and Anne-Marie Trevelyan, the international development secretary, were also present.
On Wednesday a Labour MP said she was self-isolating following a meeting with Ms Dorries. Rachael Maskell, Labour’s shadow employment minister, wrote on Twitter that she had taken the step after calling the health service’s medical helpline. “NHS111 have advised that I self-isolate as a result of a meeting I had with [Ms Dorries] last Thursday who has subsequently tested positive for coronavirus,” she said. “Thankfully I am asymptomatic. It is so important that we all follow all public health advice.”
The authorities in Westminster said: “At present there are no plans to suspend parliament.”
Matt Hancock, the health secretary, said: “Really sorry to hear Nadine has tested positive for coronavirus. She has done the right thing by self-isolating at home, and both NHS and PHE staff have been brilliant. We all wish her well as she recovers.”
Ms Dorries said in a tweet: “Thanks for so many good wishes. It’s been pretty rubbish but I hope I’m over the worst of it now. More worried about my 84yo mum who is staying with me and began with the cough today. She is being tested tomorrow. Keep safe and keep washing those hands, everyone.”