Your granddaughter has probably been told that she must have a test for tuberculosis (TB) in order to work in the Head Start program. In most states, those who work with children in day care centers, camps, schools, hospitals and other settings are required to demonstrate that they have a negative TB test, on a yearly basis.
The TB test is called the Mantoux test, or intradermal PPD. Testing is done by injecting a tiny amount of protein from the tuberculosis bacterium under the skin on the forearm, and then checking 48 to 72 hours later to see whether a reaction has occurred. If a person has been infected with tuberculosis, the injection site will be a large, red, painless lump the size of a nickel or quarter. If there has been no contact with TB in the past, there will be no reaction at all — a negative test.
Your granddaughter has probably had Mantoux testing in the past, but she has probably not had a TB immunization. An immunization against tuberculosis, called BCG immunization, does exist and is given in Europe and other countries but is not generally given in the United States.
A yearly Mantoux test is not detrimental to health, and it will very definitely promote health by identifying TB in the earliest stages, when it can be effectively treated.