The Virulent Factors of Bordetella Pertusis

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Whooping cough is a highly contagious and acute respiratory disease caused by an aerobic Gram negative non-sporulating encapsulated coco-bacillus bacterium, Bordetella pertussis. It is a strict human pathogen with no known animal or environmental reservoirs (Cotter and Miller, 2009) and transmitted through inhalation of bacteria-infected droplets. Consequently colonizing the ciliated cells of the bronchio-epithelium causing disease (Relman, D.A, 1995). Bordetella pertussis disease is characterised by mucus hyper-secretion, epithelial damage and pulmonary edema, with paroxysmal coughing that last for close for a month and post-tussive vomiting. In addition, it is often accompanied by pneumonia, otitis edema, seizures and encephalopathy.

For successful infection to occur, the bacterium should disseminate itself in the lower respiratory tract and evade the host's immune responses. Therefore, the inhaled bacteria droplets attach to the ciliated epithelial cells in the nasal-pharynx and trachea. It is at this point that Bordetella pertussis produces virulent factors to enable its survival in the host. These virulent factors are classified basically into adhesins mediate bacterial attachment to the epithelial cells and toxins that mediate the host immune system. Adhesins include; filamentous haemagglutinin, fimbriae and pertactin while toxins include; pertussis toxin, tracheal cytotoxin, adenylate cyclase toxin and lipo-oligosaccharide (Armirthalingam, 2013). To clearly understand the importance of these virulence factors in Bordetella pertussis pathogenesis and immune evasion, a mouse model system has been used (Carbonetti, 2010). The system suggest that the virulence factors not only alter the host's local environment but also mod...

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... 2013 and Thomas et al., 2000). In England and Wales, pertussis vaccination has been underway since 1957 with rising and falling trends in disease incidences over the years. But with the introduction of a more potent and less toxic acellular vaccine, the disease trend has changed. This vaccine has been used since in 2001, as a booster in the pre-school age group and has provided major protection in infants who are not eligible for vaccination (Armirthalingam et al., 2012). In addition, the accelerated schedule and high vaccine coverage has further lessened the general prevelance. However in April, 2012, there was a national outbreak majorly seen in adults and adolescents. This has led to new vaccination strategies such as: the temporary vaccination programme for expectant mothers as a way of protecting their unborn babies from the disease (Armirthalingam G, 2013).

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