Pertussis in Individuals with Co-morbidities: A Systematic Review.

Pertussis is a highly contagious disease of the respiratory tract caused by Bordetella pertussis. Although the burden of pertussis is highest in children, available data suggests that pertussis in the elderly and those with underlying chronic conditions or illnesses can result in significant morbidity, mortality and costs. We undertook a comprehensive review to assess the association between pertussis and chronic conditions/illnesses. A search was undertaken on 17 June 2019 across EMBASE, Medline and BIOSIS. Citations were limited to those in English, in humans and published since 1 January 1990. There were 1179 papers identified with an additional 70 identified through a review of the reference lists. Of these, 34 met the inclusion criteria. Papers included were categorised in groups, those which reported: associations between prior pertussis and subsequent chronic conditions or illnesses; a link between chronic conditions/illnesses and subsequent risk of pertussis; and those which reported on the effect of the chronic conditions/illnesses on pertussis complications or exacerbations. Pertussis appears to increase the likelihood of developing some chronic conditions/illnesses, but also appears to decrease the likelihood of developing some haematological cancers. There were several chronic conditions/illnesses where the study results were mixed, and several studies that found no association with previous pertussis. There were also studies which showed that having some comorbid health condition(s) might increase the risk of developing pertussis. Three studies showed pertussis can lead to increased exacerbations of chronic conditions/illnesses and associated hospitalisations, although one study showed it reduced the effects of chronic bronchitis. Previous pertussis appears to contribute to the increased likelihood of developing some respiratory conditions like asthma, and conversely those with asthma or COPD are at increased risk of severe pertussis requiring further intervention. Further research is required to confirm or disprove these associations, and to characterise the pathophysiological mechanisms behind the potential associations with pertussis.