TB screening for 62 after Torfaen pupil tests positive
More than 60 adults and children are being screened after a student at a school in Torfaen was diagnosed with TB.
Public Health Wales (PHW) said 52 children and 10 adults, including pupils and staff at the unnamed school, were being offered the "precautionary" tests.
In a statement, officials said the risk of contracting TB was "very low".
Officials added that there was no wider public health risk.
Public Health Wales is notified of around 200 cases of TB each year in Wales.
Dr Lika Nehaul, consultant in communicable disease control, 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.
"The infection is difficult to catch but easy to treat."
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.