Bordetella pertussis Toxin (PT) Antibody (IgG), Immunoassay details

Pertussis toxin is a protein produced by Bordetella pertussis, the bacterium that causes whooping cough. This blood test measures IgG antibodies against the toxin, which your immune system makes after infection and also after vaccination. It is mainly used when you have had a long-lasting cough for several weeks, when tests that look for the bacterium itself are less likely to be positive. A high result can point to a recent pertussis infection, while a low result makes recent infection less likely. Because vaccines also raise these antibodies, results are hard to interpret within about a year of a pertussis vaccine and are always read against your symptoms and vaccination history.