Queen Elizabeth II has been admitted to hospital in London.

A spokesman says the 86-year-old monarch has been experiencing symptoms of gastroenteritis or a stomach bug. Her hospitalization is said to be a precautionary measure & is expected to last 2 days.

Gastroenteritis can be picked up through contact with an infected person or contaminated food. The bug irritates the stomach lining & intestines, leading to symptoms like vomiting, fever & stomachache.

On Saturday, the Queen cancelled an engagement to mark Wales' national day so she could recover at Windsor Castle.

Ontario Lieutenant Governor David Onley tweeted his well wishes for the monarch, "On behalf of all Ontarians, I wish Her Majesty The Queen a speedy recovery." Prime Minister Stephen Harper tweets "Laureen and I are sending our best wishes to Her Majesty for a speedy recovery".

Governor General David Johnston issued the following statement Sunday afternoon:

"My wife, Sharon, and I were distressed to receive word that Her Majesty Queen Elizabeth II has been hospitalized.  As our reigning monarch, Her Majesty The Queen is a shining example of dedicated public service.  On behalf of all Canadians, we offer our best wishes to The Queen for a quick and full recovery."

All of the Queen's upcoming commitments, including a trip to Rome have been called off. She rarely cancels engagements, the last one she did was 5 months ago due to a bad back.

Queen Elizabeth II marked 60 years on the throne last year.

(With files from The BBC & The Associated Press)