Marion County has joined 35 Iowa counties in legal action against pharmaceutical companies over the marketing of prescription opioid painkillers. Aggressive and fraudulent marketing has led to a drug epidemic in Iowa and throughout the nation, according to the suit announced Friday in Des Moines. According to the lawsuits, prescription opioid overdose deaths in Iowa have quadrupled in the past 20 years, making it only one of four states with such a dramatic increase. Polk County made up 25 percent of those deaths. The majority of opioid-related deaths in Iowa involve prescription opioids. At least 646 Iowans died due to prescription use between 2009 and 2014, the firm said. In Iowa, opioid-related emergency room visits have tripled over the last decade. In 2006 there were only 519 such incidents; there were 1,555 in 2014. Beyond its human cost, the crisis has financially strained the services that counties provide to residents and employees. It affects human services, social services, hospitals, courts, law enforcement and medical examiners.