When one of the pupils at Audley Junior School caught tuberculosis last autumn, his GP notified the authorities as is required by law.
The local public health team swooped on the school, testing the child's classmates and teachers to track down the carrier and detect whether the disease had spread.
For the head teacher, David Braithwaite, the school's TB alert revived vivid memories. As a child he was tested and X-rayed every year for five years from the age of three because his father had caught the illness after the war.
He says: "I remember going to visit him in the sanatorium and later when he came home, the district nurse came round to give him injections of streptomycin. I wasn't worried when it turned up here because I thought I knew this disease personally. . ."
Other members of staff and parents at this Blackburn school were less relaxed. Some teachers could not understand why only a few colleagues were screened for infection when all the staff had been in contact with the boy. Some of the parents wanted to know if they should keep their children at home.
Mr Braithwaite says: "It all boiled down to a lack of information. I didn't know how infectious it was, so I couldn't reassure them and the medical people tended to brush things aside.
"In the end, the nurse came in and spoke to the staff explaining the medical reasons for just testing those who'd been in prolonged and direct contact with the child. But it was a bit late in the day. Some of the apprehensions and fears had already taken hold. With hindsight, I'd probably have held that meeting earlier and sent a letter to every parent giving the nurse's contact number."
Happily, the crisis blew over. No other children were infected, the carrier was never found and the infected child recovered and returned to school 10 weeks later.
Although TB is still rare in this country, it has crept back after decades of being considered a vanquished Victorian disease. Over the past eight years, the number of cases in England and Wales has risen by about 20 per cent to roughly 6,000 a year.
The home-grown variety is eminently treatable with drugs, provided it is caught early. But what is more worrying is that drug-resistant strains of the disease are spreading through the Third World due to the misuse of antibiotics. Among infectious diseases, tuberculosis is the leading killer of adults today. Some medical experts warn that Europe may have as little as a five-year breathing space before TB becomes a menace again. In the popular imagination it is already taking on the status of plague of the future.
Dr Peter Davies, consultant physician at the the CardioThoracic Centre and the Tuberculosis Research Centre in Liverpool, says there is a lot of ignorance about the disease. While the older generation are terrified of infection - they probably knew someone who died of it as a child - it means nothing to the young.
Dr Davies says: "I think we've forgotten what a serious disease it was and could be if it became drug-resistant again. People think they're safe because they're immunised but, in fact, BCG only offers 70 per cent protection and lasts just 15 years."
As for the concerns raised by the Audley Junior School teachers, Dr Davies explains: "It's not a highly-infectious disease such as smallpox where you've just got to be in the same room for a second and you're infected. You catch it by inhaling the germs that the infected person coughs out. You've probably got to be in close and frequent contact, such as sharing a house, to be at serious risk of picking up the infection. Although I suppose there is the rare case where someone sits next to a sufferer on a bus for half an hour and picks it up."
Recent evidence that immunisation is not universal in Britain is a new cause for alarm. Last month a survey of 500 school nurses by the Health Visitors Association had 12 per cent reporting that BCG vaccinations were not being given in their district and a larger number saying that the vaccination was not automatically given.
TB used to be a disease that carried the social stigma of poverty and uncleanliness. Nowadays there is a racial stigma. According to the World Health Organisation, Asian countries with big cities have extremely high rates of TB and account for two-thirds of cases worldwide. The WHO also states that in many parts of Europe and other industrialised areas, half or more cases of TB victims are "foreign born". The disease does not discriminate and having white skin is no guarantee of protection. However, among the most vulnerable are people with contacts or relatives who have travelled from the Third World.
Outbreaks in schools happen only occasionally, but when they do occur they are taken very seriously by public health officials as it is important to stop the disease spreading. In children there is a very small chance they will develop TB meningitis. This is as prevalent and deadly as the meningococcal meningitis.
However, the big risk of TB in schools is not from child to child contact (because forms of tuberculosis in children are generally non-infectious), but when a teacher becomes infected. In the late seventies a teacher with a "smoker's cough" infected 46 children in a Leicestershire primary school in a TB outbreak which was missed by local GPs. The public health authorities were only alerted when the headmaster rang them.
Teachers no longer have the routine chest X-rays which were mandatory in the past. However, Dr Davies says all teachers should see their GP if they develop symptoms such as a cough with weight loss and general debility for more than six weeks. Other signs include fevers, night sweats, constant tiredness and loss of appetite. It is possible to be ill and spreading TB but only have mild symptoms.
The disease can attack any part of the body, but the lungs are the most common target and a person with advanced TB will typically cough up blood-streaked sputum as the substance of the lung is eaten away by bacteria.
Tanygrisiau Primary School in Blaenau Ffestiniog, North Wales had a brush with TB two summers ago. The head teacher, Hazel Hughes, got a phone call from a chest consultant informing her that one of her midday supervisors had TB.
Out of the 90 children in the school, five showed a positive reaction to the Heaf skin test. This indicated they had come in contact with the disease, although this was considered a "normal" percentage. All of the positive children were cleared when given a second test and chest X-ray. Because the supervisor had only been with the children in the open air for a short time the disease had not spread.
Hughes says: "It was not a very nice experience. There was a lot of prejudice because we're in a old slate-quarrying village and there are lots of people with chest illnesses here. Forty or 50 years ago TB used to be a killer here. Some members of the community didn't want to come into the school. They thought they might catch the disease off the walls. Children at the other village school heard the adults talking and didn't want to travel in the same school bus."
Hughes held an open meeting in the school along with a medical team so the parents could ask questions. They went away reassured. This was fortunate because when the press found out about the incident a few weeks later, the school was over-run by reporters and television cameramen filming the children playing. "It was if they were somehow different from any other children, " says Hughes indignantly.
Two years on and the children and staff have largely forgotten the episode. The real casualty according to Hazel Hughes was the midday supervisor: "She was a very sensitive person and the media attention came at a time when she was trying to rest and recover. She'd had a long list of chest problems and she just didn't realise when it became TB. It affected her a great deal. It affected her confidence because obviously she felt worried about the children and upset that she was the cause of it all.
"She hasn't come back to work at the school and it's a shame because she was very good with the children."