A Systematic Review on the Risk Factors Associated with the Resurgence of Pertussis in Highly Immunized Countries within the Last Ten Years  (2004-2014)
Creators: name: Philip, Lindsey
Publisher: name: Georgia State University
Year: 2014

description: BACKGROUND:  Bordetella pertussis, otherwise known as whooping cough, is a highly contagious respiratory disease that was once a significant source of childhood morbidity and mortality. The availability and distribution of the pertussis vaccine beginning in the 1940s and onwards has helped to decrease transmission of infection, resulting in a major decline in pertussis incidence among highly immunized countries over time. However, there has been a reemergence of pertussis within highly immunized communities, with rates progressively increasing over the last 30 years and an observed epidemiological shift of higher incidence among adolescent and adult populations. Negative health outcomes in pertussis infected children less than one year of age continue to remain a major public health concern as intensity of symptoms and delay of recovery in this population often leads to hospitalization and even death.
OBJECTIVES: This systematic review examines published literature in the last ten years to provide an up-to-date analysis of the risk factors associated with the resurgence of pertussis among highly immunized populations.
METHODS:  A literature search was conducted using PUBMED and EBSCO databases using combination searches with the key words pertussis, whooping cough, resurgence, reemergence, recurrence, and comeback. Retrieved articles were refined based on the date of publication and on the country in which the study was conducted. Only primary studies with data collected between 2004-2014 from highly immunized countries with equal to or greater than 90% of three doses of infant pertussis immunization coverage were included in this review.
RESULTS: Three main groups of risk factors contributing to pertussis reemergence were identified among fourteen primary studies. The first category included four studies assessing the risk factor of waning immunity. The second category comprised of six studies focused on the risk factor of bacterial mutations. A third grouping of articles based on immunization status and diagnosis recognition included one article associated with each of the following risk factors: non-medical exemptions, inadequate childhood immunizations, household transmission, and inadequate provider awareness.
CONCLUSION: Pertussis resurgence is a complex public health issue involving various components and interrelated risk factors. Research into the associated waning immunity through use of acellular vaccines and increased understanding of bacterial mutations contributing to vaccine ineffectiveness will be important to improving current available vaccines and should be a focus of continued efforts through collaboration among multiple disciplines. Emphasis on the importance of up to date immunizations among the general population and educational interventions directed toward health care providers and patients will be key to reducing pertussis transmission in highly immunized countries until new vaccines become available.