Over the last decade, injection drug use in Erie County, Ohio, has caused a major uptick in new hepatitis C virus (HCV) cases along the southern shores of Lake Erie, according to new data from the Ohio State Department of Health, the Sandusky Register reports.

Ohio’s latest HCV figures, which were presented to Erie County’s health board earlier this month, show that hepatitis C diagnoses in the area have quadrupled over the last 10 years, increasing from just 39 cases in 2005 to 169 cases in 2015.

A map from the state health department also shows that Erie County’s hepatitis C rate is relatively high compared with the rest of the Great Lakes region and that nearby Huron County also has disproportionately high HCV rates. However, figures also showed that in southern Ohio, the toll of HCV is even greater.

Local health officials in both regions say a surge in IV drug use across the country is a major contributing factor to the rising hep C rates and that many drug users in the region are spreading the disease by sharing contaminated needles. Health authorities in Ohio are now advising local drug users to get tested for HCV as soon as possible and to avoid reusing or sharing needles or injecting equipment with others.

Today, the U.S. Centers for Disease Control and Prevention (CDC) estimates that up to 4 million Americans are living with a chronic hepatitis C infection and confirms that diagnosis rates of the deadly liver disease have been increasing nationwide since at least 2010.