Introduction

Bacterial, viral and parasitic infections are associated with stroke in several ways. First, at least 20% of strokes are preceded by a bacterial infection in the month prior to stroke. Second, many pathogens that affect the central nervous system are able to directly cause stroke. Third, patients who suffer a stroke are prone to develop infectious complications due to post-stroke immunodepression and impaired swallow and cough reflexes.

In this chapter, we will briefly summarize available evidence on how bacterial infections can trigger stroke. Then, specific infectious diseases are reviewed that are a direct cause of stroke, such as endocarditis, vasculitis and chronic meningitis. Furthermore, aspiration pneumonia is discussed, as an example of an early infectious complication that arises within the first week after stroke. Late infectious complications, occurring later than a week after stroke, such as ventilator-associated pneumonia or catheter-related infections, will not be covered since they are common infections in the hospital with no specific link to stroke.

Infections preceding stroke

Recent infection and stroke

Several studies have supplied evidence that acute infection in the week preceding stroke is an independent risk factor for cerebral infarction (odds ratio 3.4–14.5) [1–3]. Especially bacterial respiratory and urinary tract infections can trigger ischemic stroke [4]. Since a heterogeneous group of microbial pathogens is involved, the systemic inflammatory response is probably more important than microbial invasion per se. However, a detailed molecular understanding of events that lead to a higher susceptibility to cerebral infarction is lacking.