A new study suggest that infection with seasonal influenza, may increase the risk of developing Parkinson's disease.Most cases of Parkinson's have no known cause and researchers continue to debate and study possible factors that may contribute to the disease.Now, researchers at Thomas Jefferson University in the US suggest that a certain strain of influenza virus predisposes mice to developing pathologies that mimic those seen in Parkinson's disease.
 
      "Here we demonstrate that even mice who fully recover from the H1N1 influenza virus responsible for the previous pandemic (also called 'swine flu') are later more susceptible to chemical toxins known to trigger Parkinson's in the lab," said Smeyne.Previously, researchers showed that a deadly H5N1 strain of influenza (so-called bird flu) that has a high mortality rate (60 per cent of those infected died from the disease) was able to infect nerve cells, travel to the brain and cause inflammation that would later result in Parkinson's-like symptoms in mice.

       Inflammation in the brain that does not resolve appropriately, such as after traumatic injury to head, has also been linked to Parkinson's.The researchers looked at a less lethal strain, the H1N1 "swine flu," that does not infect neurons, but which still caused inflammation in the brain via inflammatory chemicals or cytokines released by immune cells involved in fighting the infection.