What is the definition or description of: pertussis found on nasal swab (dfa)?

Rapid screening test: Dfa--direct fluorescent antibody test--a rapid diagnostic test done in the lab that takes 1-2 days to screen for pertussis (whooping cough). While much faster than a culture, this test is not as reliable. A nasal swab is inserted gently into the nostrils toward the throat (posterior nasopharynx). Then fluorescently labeled antibodies are exposed to the sample looking for pertussis antigens/markers.

Posiitive test: Dfa (direct fluorescent antibody) positive for pertussis means the person has a positive test for whooping cough.