Hepatitis C infection may increase Parkinson's risk-Research

The virus is transmitted through sharing needles, needle stick injuries in health care providers and passed on at birth from infected mothers.

In Taiwan during the time of the study, blood transfusions were the most common cause of the virus. In the US, all donated blood has been screened for the virus since 1992.

The study involved 49,967 people with hepatitis and 199,868 people without hepatitis. Participants with hepatitis were placed into three groups: those infected with the hepatitis B virus (71 per cent), those with hepatitis C (21 per cent), and those who had both viruses (8 per cent).

The participants were followed for an average of 12 years to see who developed Parkinson's disease. Of those with hepatitis, 270 developed Parkinson's disease, including 120 people with hepatitis C.

Among those who did not have hepatitis, 1,060 developed Parkinson's disease.

Once researchers controlled for factors such as age, sex, diabetes and cirrhosis, they found that people with hepatitis C were nearly 30 per cent more likely to develop Parkinson's disease than the people who did not have hepatitis.

People with hepatitis B and those with both viruses were not more or less likely to develop Parkinson's than those who did not have hepatitis.