A disease eliminated from the western world is steadily growing in New Zealand

Rheumatic fever develops when a sore throat goes untreated - it's common in children with poor access to healthcare.

The College of General Practitioners' medical director warns the disease causes serious heart inflammation.

Medical Director Doctor Bryan Betty says it takes ten years of monthly penicillin injections to get better.

He says in some cases that doesn't work - and the child develops chronic rheumatic heart disease - which is a lifetime of illness.