BACKGROUND: Inflammatory processes have fundamental roles in stroke in both the 
etiology of ischemic cerebrovascular disease and the pathophysiology of cerebral 
ischemia. We summarize clinical data on infection and inflammation as risk or 
trigger factors for human stroke and investigate current evidence for the 
hypothesis of a functional interrelation between traditional risk factors, 
genetic predisposition, and infection/inflammation in stroke pathogenesis.
SUMMARY OF REVIEW: Several traditional vascular risk factors are associated with 
proinflammatory alterations, including leukocyte activation, and predispose 
cerebral vasculature to thrombogenesis on inflammatory stimulation. Furthermore, 
accumulation of inflammatory cells, mainly monocytes/macrophages, within the 
vascular wall starts early during atherogenesis. During later disease stages, 
their activation can lead to plaque rupture and thrombus formation, increasing 
stroke risk. Inflammatory markers (eg, leukocytes, fibrinogen, C-reactive 
protein) are independent predictors of ischemic stroke. Chronic infections (eg, 
infection with Chlamydia pneumoniae or Helicobacter pylori) were found to 
increase the risk of stroke; however, study results are at variance, residual 
confounding is not excluded, and causality is not established at present. In 
case-control studies, acute infection within the preceding week was a trigger 
factor for ischemic stroke. Acute and exacerbating chronic infection may act by 
activating coagulation and chronic infections and may contribute to 
atherogenesis. Genetic predisposition of the inflammatory host response may be 
an important codeterminant for atherogenesis and stroke risk.
CONCLUSIONS: Inflammation contributes to stroke risk via various interrelated 
mechanisms. Infectious diseases, traditional risk factors, and genetic 
susceptibility may cooperate in stimulating inflammatory pathways. Final proof 
of a causal role of infectious/inflammatory mechanisms in stroke pathogenesis is 
still lacking and will require interventional studies.