Ms Dorries, the first MP to test positive, said she had taken all the advised precautions after finding out and had been self-isolating at home.
It comes as a sixth person died from the virus in the UK, which has a total of 382 cases.
The latest person to die was a man in his early 80s who had underlying health conditions.
Meanwhile, NHS England said it was scaling up its capacity for testing people for the infection, with the number of cases set to rise.
That will mean 10,000 tests a day can be done - currently 1,500 are being carried out.
Confirmation of any positive test results will also be accelerated with most people getting a result back within 24 hours.