**2.2. Pertussis genetic changes**

Genetic changes in *B. pertussis* may be one of the factors that have contributed to the recent reappearance of whooping cough. In the USA, isolated cases of *Bordetella pertussis* without pertactin have increased from 14% in 2010 to 85% in 2012. The effectiveness of the acellular vaccine appears to remain the same, but surveillance for the adaptations and mutations of the bacteria must be enhanced, as new genotypes have been reported [26, 27].
