People with Hepatitis C are nearly 30% more likely to develop Parkinson's disease, say researchers. Scientists followed nearly 250,000 people for 12 years in Taiwan to discover the link.

Researchers from China Medical University investigated the link between Hepatitis C - a blood-borne virus which is most commonly found in West Asia and Central Africa -, and the neurological disorder, Parkinson's disease. They found that after controlling for sex, age, and diabetes, people with Hepatitis C were 30% more likely to develop Parkinson's disease than those without Hepatitis.

"Many factors clearly play a role in the development of Parkinson's disease, including environmental factors," said Chia-Hung Kao, author of the study. "This nationwide study, using the National Health Insurance Research Database of Taiwan, suggests that hepatitis caused specifically by the hepatitis C virus may increase the risk of developing the disease. More research is needed to investigate this link."

The study, published in Neurology, followed the medical history of 49,967 people with hepatitis, and 199,868 without it. Of the people with hepatitis, they were sub-grouped into those with hep' B, hep' C, and those with both.

After 12 years, the researchers collected data for those that had developed Parkinson's since the beginning of the study. The resulting statistical analysis then showed that those with hepatitis C were 30% more likely to develop Parkinson's.

Few people that have hepatitis C show symptoms, especially at the beginning. The World Health Organisation estimates though, that between 130 and 150 million people have the hepatitis C virus – that is equivalent to about 1 in every 50.

The most common cause of infection is through sharing needles or the virus being passed on by mothers at birth. Despite treatment success rates of between 40 and 80% depending on the strain of the virus, a full vaccine is still considered a significant amount of time away from development.