Published Tuesday, 30 June 2009
The P2 pupil at St Ronan's primary school in Newry, Co Down, has mild symptoms and is at home, Michael McGimpsey added.
This is the third case in a child.
St Ronan's was closed as a precaution after the first child and a younger brother developed the illness following a family holiday to Mexico.
Fellow pupils have been offered anti-virals.
Mr McGimpsey told the Assembly: "As these figures illustrate the number of new cases continue to grow, doubling in the UK every seven days."
"Although the disease appears to be spreading quickly I would again reassure members and the public that to date the swine flu symptoms are generally mild in most cases but can be severe in a small minority."
There are more than 70,000 confirmed cases in 112 countries and 311 deaths.
Across the UK there are around 6,538 and three deaths.
There are 33 confirmed cases in Northern Ireland and 40 in the Republic.
Mr McGimpsey added most cases in Northern Ireland were travel-related.
With many families heading off on holiday there are expected to be more.
Northern Ireland has a stock of anti-viral drugs to cover half the population and the minister wants to increase it to 80%.
Mr McGimpsey said: "Emerging clinical experience of this virus suggests that for many people the symptoms of swine flu can be treated the same way as a normal cold or seasonal flu, by staying at home, taking paracetamol and cold remedies to reduce symptoms, drinking fluids and resting and only contacting your GP if your symptoms are not improving."
"If we were to adopt this approach as with seasonal flu it would mean that we would rely more on symptoms rather than swabs to diagnose the illness."