Five deaths have been reported so far, with the advent of Influenza and Adino viruses.
The government's Information Department quoting medical officials said the Karapitiya Teaching Hospital in Galle had been experiencing an increase in the number of patients who arrived with a fever over the past few days, Xinhua news agency reported.
According to doctors, patients who were admitted included children aged two to three years old as well as infants who were less than six months old.
Aruna De Silva of the Pediatric Unit at Karapitiya Hospital said they examined the matter and had identified that the situation arose as a result of a virus that causes pneumonia.
He added that the disease was caused by the Influenza and Adino viruses and affects children who are less than two years old.