Cause of Pertussis
Whooping cough is caused by a bacteria called Bordatella pertussis.
Bordetella pertussis is viewed as the most important species belonging to the genus Bordetella because it infects only humans and causes the most severe symptoms.[3] Bordetella pertussis is a fastidious gram-negative aerobic coccobacillus that is found microscopically alone or in pairs. It is a nonmotile organism that is transferred from host to host through aerosolized droplets generated from the coughing of infected individuals.
Once its presence is established in the host, B. pertussis initiates destruction of airway tissue through a four-step process of attachment, avoidance of host defense, cellular destruction, and systemic effects.
Bordetella pertussis produces a number of toxins and biologically active substances that influence its pathogenicity. Pertussis toxin is viewed as the most virulent factor due to its mitogenic activity. Pertussis toxin affects the circulation of lymphocytes and serves as an adhesion site for bacterial binding to respiratory ciliated cells. Although the role of pertussis toxin in the pathogenesis of pertussis is not fully understood, it has been shown to cause lymphocytosis, hyperinsulinemia, and possibly encephalopathy.
On the outer surface of the cell, B. pertussis contains filamentous hemag-glutinin, pertactin, and fimbriae. The primary pathogenic role of these substances is to aid adherence to epithelial cells within the respiratory tract.
Bordetella pertussis produces several other toxins that enhance its pathogenicity. These toxins include adenylate cyclase toxin, which impairs host immune cell function, and tracheal cytotoxin, which causes respiratory epithelial damage.
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