Stroke is among the most common causes of death and persisting disability and therefore represents a great social and economic burden worldwide. In order to lower this burden it is essential to identify risk factors and respective preventive strategies. Besides the established stroke risk factors (e.g. hypertension, diabetes, hypercholesterolemia, atrial fibrillation) both acute and chronic infectious diseases have emerged as risk factors for stroke.
Mainly acute respiratory tract infection but also urinary tract infections independently increase the risk of ischemic stroke. Such additional risk was shown to be highest for infection within 3 days before ischemia and the risk steadily declines with increasing time intervals between infection and stroke. Associations between stroke incidence and mortality and influenza epidemics have been demonstrated. Observational studies showed an inverse association between influenza vaccination and stroke risk; however, interventional studies in this field have not been performed so far. Chronic infections, presently discussed as stroke risk factors mainly include periodontitis and infections with Helicobacter pylori (Hp) and Chlamydia pneumoniae (Cp). Although most respective studies identified these infectious diseases as independent stroke risk factors interventional trials have not been performed so far and causality is not proven, yet. There is preliminary evidence that the number of pathogens to which a subject had been exposed to rather than single pathogens are associated with the risk of stroke or other cardiovascular diseases.
Chronic infectious diseases are treatable conditions and their identification as causal contributors to stroke risk could offer new avenues in stroke prevention.