Meningococcal meningitis is an infection that causes inflammation of the membranes covering the brain and spinal cord. Most cases of meningococcal meningitis occur in children, from infancy to adolescence. Most at risk are children up to the age of 5, and teenagers and young adults, aged 15 - 26. The infection occurs more often in winter or spring and may cause local epidemics at boarding schools, college dormitories, or military bases.
It struck for a fourth time in less than two weeks at Lucindale Area School in South Australia.
A 16-year-old male student is in a satisfactory condition in hospital after three other cases from the same school were reported to the Health Department about 10 days ago.
They have since been discharged from hospital.
All were boarders, except the most recent victim, who is a day student. Family members and about 60 students and staff have been prescribed preventive antibiotics. It is understood a football team also would receive antibiotics.
The Health Department acting chief medical officer Professor Paddy Phillips said the 16-year-old was not given antibiotics at the time of the first three cases because he had not been in close contact with them.
Professor Phillips was confident the appropriate procedures had been followed but was unclear how the last case had occurred. "It's clearly worrying for the community and one of our staff has been down there helping," he said.
Although a bacterial illness, symptoms of meningococcal disease can be similar to viral conditions, such as colds and influenza.
Professor Phillips said "significant" leg pain, cold hands and feet and abnormal skin colour were signs suggestive of meningococcal disease.
Southern Australia has now recorded 11 meningococcal cases for the year. There were 11 reported cases to the same time last year and a total of 18 in 2006.
A baby girl was rushed to hospital in Sydney in New South Wales last week after doctors at the Batemans Bay Hospital suspected she had contracted the disease.
The nine-month-old had been taken to the hospital with some of the symptoms, including fever and a rash.
Health authorities have treated the family and others who may have been in contact with them with antibiotics.
Tracey Oakman from the Greater Southern Area Health Service says parents and doctors remain to be aware of the risk of meningococcal disease at this time of the year.
"It's difficult to say where it may have come from. About 10 per cent of the population carries the bacteria in their nose and throat and they don't know what the mechanism is that makes that bacteria either become invasive or be fine in one person and then when it's transferred to another person becomes invasive," she said.