Ysgol y Strade pupils in Llanelli offered TB screening
Screening for tuberculosis (TB) will be offered to 124 pupils at a comprehensive school in Carmarthenshire after a staff member was diagnosed with the infection.
Letters have been sent to parents at Ysgol y Strade, Llanelli, saying their children will be offered a blood test next Thursday.
Health officials say the risk that the infection has spread to pupils is low.
Precautionary screening is also being offered to 21 members of staff.
They are those identified as being close contacts of the patient.
Sion Lingard, acting consultant in health protection for Public Health Wales (PHW), said TB is difficult to catch and is treatable with antibiotics.
"We are emphasising to pupils, parents and staff that it is very rare for TB to be transmitted within a school environment and so we are offering screening as a precaution," he said.
"Close contact with an infectious individual over a long time period, such as living in the same household, is usually required for a person to become infected with TB."
Another four cases of TB had been identified in the Llanelli area over the last year, he said, but none of these have links to the school.
"Investigations into these cases are continuing with the involvement of Hywel Dda Health Board with treatment, advice and screening offered where appropriate," Mr Lingard added.
TB is an infection usually found in the lungs, but any part of the body can be affected.
People can catch TB by breathing in the bacteria in tiny droplets sneezed or coughed out by someone who has the infection in their lungs.
The most common symptom of TB is a persistent cough for more than three weeks, with spit which can sometimes be blood-stained.
Other symptoms can include weight loss, a high temperature, and sweating, particularly at night.
Public Health Wales said anyone who is concerned about their health should speak to their GP or contact NHS Direct Wales on 0845 46 47.