Impact of infection on risk of Parkinson's disease: a quantitative assessment of case-control and cohort studies.

Identifying modifiable risk factors for Parkinson's disease (PD) to help prevent this disease has attracted increasing interest in recent years for the limited effective drugs at present. Despite many studies indicated that infection acts as a risk factor for PD, there is no quantitative assessment of the impact of viral and bacterial infections on the risk of developing PD. The present study performed a meta-analysis on the basis of 38 datasets from 13 studies covering 287,773 PD cases and 7,102,901 controls to ascertain the association between PD and infection and the differences in the strength of the viral and bacterial infections. The overall meta-analytic results indicated that individuals with infection had a 20% increased risk of PD compared with controls (OR 1.20, 95%CI 1.07-1.32). The subgroup analysis according to the type of infection found that bacterial infection had a significant impact on increased risk of PD (OR 1.40, 95%CI 1.32-1.48). The present analysis indicated that infection could increase the risk of developing PD, and physician should be aware of the risk of developing PD in subjects with infection.