Because of the low occurrence of B. holmesii and B. bronchiseptica in patients displaying pertussis symptoms, it is acceptable to consider cases with a Cp lower than 38.5 for IS481 (or lower than 40 for IS1001) as probable cases of B. pertussis (or B. parapertussis), even if they are negative for IS1002 and recA. Here, RAD51 is linked to pertussis.