Health minister Nadine Dorries has become the first MP to have tested positive for coronavirus.
The former nurse, who recently helped to draw up legislation to tackle covid-19, said she is currently self-isolating - while officials were working to identify how she came into contact with the virus.
It comes as the number of cases in the UK rose to 382 on Tuesday and a sixth death was confirmed.
In a statement, Ms Dorries said: "I can confirm I have tested positive for Coronavirus.
"As soon as I was informed I took all the advised precautions and have been self-isolating at home."
"Public Health England has started detailed contact tracing and the department and my parliamentary office are closely following their advice."
On Twitter, Ms Dorries said she hopes she is over the worst of it and was more concerned for her 84-year-old mother who is currently living with her.
She said: "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."
Health Secretary Matt Hancock tweeted saying Ms Dorries "has done the right thing by self-isolating."
On Wednesday, Labour MP Rachael Maskell tweeted that she was self-isolating after coming in to contact with Ms Dorries on Thursday.
The York Central MP said she was showing no symptoms of Covid-19 and urged others to "follow all public health advice" on coronavirus.
Mr Hancock continued: "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."
He added: "I understand why people are worried about this disease. We will do all we can to keep people safe, based on the best possible science."
ITV News Political Correspondent Paul Brand tweeted saying Ms Dorries has been in "close proximity to hundreds of MPs.
He said: "Nadine Dorries voted in the Commons twice last Wednesday, meaning she will have been in close proximity to hundreds of other MPs, if only briefly.
"Will be a huge job to trace all those she’s been in contact with, as she now self-isolates and recovers at home."
The UK may experience its peak number of coronavirus cases within the next fortnight, England's deputy chief medical officer has admitted.
Dr Jenny Harries defended the Government's decision to delay closing schools and the introduction of other tactics, adding experts are assessing new cases on an hourly basis to ensure a "balanced response".
Coronavirus: Everything you need to know