Bordetella pertussis is the bacterium that causes whooping cough – the main clinical feature of which is a severe lingering cough that can last for weeks or even months. Right now we are in the midst of an epidemic of pertussis cropping up in pockets throughout the US, most notable California. According to the CDC:
During January 1– June 30, 2010, a total of 1,337 cases were reported, a 418% increase from the 258 cases reported during the same period in 2009. All cases either met the Council of State and Territorial Epidemiologists definitions for confirmed or probable pertussis or had an acute cough illness and Bordetella pertussis–specific nucleic acid detected by polymerase chain reaction from nasopharyngeal specimens.
In addition, if the trends continue through the end of this year, which they are likely to do, this will be the highest incidence of pertussis in almost 50 years. These numbers are not in question, but there is some discussion about what, exactly, is causing it.