Meningococcal disease can strike with frightening speed. Its victims can present with symptoms in the morning and be dead by nightfall.

A 22-month-old boy is in a stable condition in a Sydney hospital where he is being treated for meningococcal disease. The New South Wales Health Department says his condition is improving.

About 20 children from a preschool on Sydney's northern beaches will be treated with antibiotics to prevent an outbreak of meningococcal disease. The move comes after a toddler from the centre was admitted to hospital with symptoms of the disease.

Tests have confirmed a case of meningococcal disease on the New South Wales south coast. The tests, undertaken by the public health unit at the South-Eastern Sydney and Illawarra Health Service, have found that a 57-year-old Wollongong woman died of meningococcal disease.