Resurgence of Pertussis
Pertussis has made a reemergence in well-vaccinated populations. Pathogenic adaptation and the decrease in strength are most likely the cause of the reemergence of pertussis. There is pressure for vaccine research because of the resurgence of the pathogen. Pertussis remains one of the leading causes of vaccine preventable deaths in infants under 1 year of age. Pertussis is a Gram-negative, bacillus called Bordetella pertussis. This bacterium binds to the ciliated epithelial cells in the nasopharynx of the upper respiratory tract. Disease presentation depends on age and history of previous infection or vaccination. Young infants present apnea and cyanosis, with or without disease symptoms. Adults and teens usually show mild symptoms, and have a typical prolonged cough. The human Bordetellea are classified as monomorphic, but there is evidence of genetic variation in B. pertussis. As far as vaccines, there are two types of licensed pertussis vaccines. The first generation is whole cell vaccines (WCVs), which are killed cells. The second generation is acellular vaccines (ACVs), which contain virulence factors. The WCVs contain whole dead cells that can cause more adverse effects compared to ACVs, which have been gradually replacing WCVs. Some of the virulence factors that the ACV uses are pertactin, filamentous hemagglutinin, two fimbriae serotypes, and chemically detoxified pertussis toxin. WCVs induce type 1 helper T cells, which assist cytotoxic T cells. WCVs also induce a broad antibody response against a range of surface antigens. ACVs induce type 2 helper T cells, which assist B cells. It causes a high antibody response against the vaccine antigens presented. Both of these vaccines give satisfactory long-term protection against pertussis. WCV is estimated to protect for 4-12 years and the AVC could last 5-7 years. Programs to vaccinate began in the 1950s with the WCV. This caused a dramatic drop in mortality and morbidity in children....
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