A virus long thought to be harmless may actually play a role in Parkinsons disease, a condition that affects more than one million Americans.Northwestern Medicine scientists discovered Human Pegivirus (HPgV) in the brains and spinal fluid of people with Parkinsons, but not in those without the disease. The results challenge decades of assumptions about the virus."HPgV is a common, symptomless infection previously not known to frequently infect the brain," Dr. Igor Koralnik, chief of neuroinfectious diseases at Northwestern, said in a press release."We were surprised to find it in the brains of Parkinsons patients at such high frequency and not in the controls."TRAINED DOGS CAN SMELL PARKINSON'S DISEASE BEFORE SYMPTOMS SHOW UP, STUDY FINDSThe findings were published in the journal JCI Insight.Researchers examined post-mortem brain tissue from 10 Parkinsons patients and 14 people who died of other causes. The virus appeared in five of the 10 Parkinsons brains and none of the 14 controls.NEW WEEKLY INJECTION FOR PARKINSON'S COULD REPLACE DAILY PILL FOR MILLIONS, STUDY SUGGESTSIt also turned up in spinal fluid samples, suggesting the virus could be active in the nervous system. Patients carrying HPgV showed more advanced brain changes tied to Parkinsons, including protein buildup and altered brain chemistry.The team didnt stop at brain tissue. Using blood samples from more than 1,000 participants in a project led by The Michael J. Fox Foundation, researchers saw the same immune system changes linked to the virus.Even more striking: patients with a Parkinsons-related mutation in the LRRK2 gene responded differently to HPgV than those without the mutation."This suggests it could be an environmental factor that interacts with the body in ways we didnt realize before," Koralnik said."It may influence how Parkinsons develops, especially in people with certain genetic backgrounds."STANFORD SCIENTISTS 'TOTALLY SURPRISED' BY POTENTIAL PARKINSON'S TREATMENT DISCOVERYParkinsons disease is the second most common brain disorder after Alzheimers, according to the National Institute of Neurological Disorders and Stroke. While a small percentage of cases are inherited, most patients dont have a family history, and the cause has remained unknown.If HPgV truly plays a role, it could help explain why some people develop Parkinsons while others do not. It could also open the door to new treatments targeting viruses or the immune system."The study detected traces of HPgV more often in brains of people with Parkinsons disease than in controls. This raises the possibility of a link between viral exposure and Parkinsons, but its far too early to say the virus causes the disease," Dr. Joel Salinas, a behavioral neurologist and associate professor at NYU Grossman School of Medicine, told Fox News Digital.LIVING NEAR A GOLF COURSE IS LINKED TO PARKINSONS RISK IN NEW STUDY AS SOME CITE LIMITATIONSSalinas, who was not involved in the study, also said that much larger and longer-term studies will be needed to determine whether this association has real clinical significance."For now, people should know this is early research and not a reason to worrytheres no overwhelming evidence yet that this virus causes Parkinsons, similar to how work on herpesviruses in Alzheimers has suggested a possible link but remains to be fully established."According to the Parkinsons Foundation, nearly 90,000 Americans are diagnosed every year. That number is expected to reach 1.2 million by 2030.MORE IN HEALTH NEWSThe Northwestern team plans to expand their study to see how often HPgV is found in people with Parkinsons versus healthy controls, and whether other viruses may be involved."For a virus that was thought to be harmless, these findings suggest it may have important effects in the context of Parkinsons disease," Koralnik said.CLICK HERE TO SIGN UP FOR OUR HEALTH NEWSLETTER"We also aim to understand how viruses and genes interact; insights that could reveal how Parkinsons begins and could help guide future therapies."