Pertussis
Also known as whooping cough, pertussis is a respiratory disease caused by the bacterium Bordetella pertussis. The introduction of the whole-cell vaccines in the middle of the last century resulted in dramatic decrease in disease incidence.
The virulence factors of Bordetella pertussis can be divided into adhesions, such as pertactin and toxins, such as pertussis toxin. Adhesins attachment to the host and toxins are involved in immune evasion and possible resource extraction.
The infection is characterized by bacterial colonization of ciliated respiratory in the trachea and bronchi. The incubation period is 6 – 20 days.
Classical pertussis is an illness of three stages. It starts with a catarrhal stage, with nonspecific symptoms similar to those of the common cold (duration 1 to 2 weeks). At the paroxysmal stage (duration 2 to 6 weeks), the cough becomes more prominent with staccato attacks, postussive whooping, and vomiting.
At the convalescent stage (duration several weeks), the frequency and severity of coughing attacks gradually decrease. The most severe cases of whooping cough occur in unvaccinated children under 1 year of age. This group accounts for most deaths.
Whooping cough is presently one of the 10 most common causes of death from infectious disease. The WHO estimates it to cause 50 million illnesses and over 350,000m deaths worldwide each year.
After introduction of whole-cell vaccines in the 1950s, its morbidity and mortality were significantly reduced in the developed world, whereas in the developing countries whooping cough has remained a major cause of infant mortality.
In highly vaccinated communities, Bordetella pertussis and Bordetella parapertussis infections often go undiagnosed because pertussis is thought to be rare and adequate laboratory diagnostic tests are not used or available.
Pertussis
