Pertussis laboratory tests

Overview
Microscopic identification of whipworm eggs in feces is evidence of infection. Because eggs may be difficult to find in light infections, a concentration procedure is recommended. Because the severity of symptoms depend on the worm burden, quantification of the latter (e.g. with the Kato-Katz technique) can prove useful. Methods used in laboratory diagnosis include culturing of nasopharyngeal swabs on Bordet-Gengou medium, polymerase chain reaction (PCR), immunofluorescence (DFA), and serological methods. The bacteria can be recovered from the patient only during the first three weeks of illness, rendering culturing and DFA useless after this period, although PCR may have some limited usefulness for an additional three weeks. For most adults and adolescents, who often do not seek medical care until several weeks into their illness, serology is often used to determine whether antibody against pertussis toxin or another component of B. pertussis is present at high levels in the blood of the patient.