As intravenous drug use continues to rise across the country, health officials, doctors and advocates are speaking out about the “epidemic of epidemics”—with overdoses, hepatitis C virus (HCV) and deadly bacterial infections rising in tandem with the addiction crisis, Vox reports.

U.S. health officials often measure the severity of the opioid crisis in the number of drug overdose deaths, which totaled nearly 64,000 in 2016 alone. However, advocates are now arguing that a number of related health crises are often overlooked—namely, increases in hepatitis C and dangerous bacterial infections, such as endocarditis, an inflammation of the heart that can be deadly. Doctors also fear the United States may be on the brink of increasing HIV outbreaks, sparked by injection drug use and lack of access to clean needles.

“This really is an epidemic of epidemics,” said Michael Brumage, MD, executive director at the Charleston city health department in West Virginia—one of the country’s hardest-hit states. “The number of overdoses does not convey the full scope of the tragedy that is playing out in front of us.”

Meanwhile, syringe exchange clinics are popping up throughout the United States, hoping to slow the spread of infections and encourage patients to seek treatment. But these harm reduction centers, working on the front lines of the crisis, are often underfunded and understaffed because of the persistent stigma attached to addiction and addiction services. 

In response, lawmakers and federal officials cite $45 billion as the amount needed to address the U.S. opioid epidemic. But the real cost of treatment for the diseases caused by rising injection drug use—which includes direct-acting antivirals for hepatitis C and open-heart surgery for bacterial endocarditis—could be four times that amount. Thus far, Congress has approved only around $6 billion in funding to address both opioid abuse and mental health treatment.

Advocates say that without further action, these overlapping epidemics, a phenomenon known as a “syndemic,” will likely burden the U.S. health infrastructure for years to come. The United States has seen a threefold increase in hepatitis C cases over the past five years. Another study found that the prevalence of drug-induced endocarditis and other serious infections nearly doubled between 2002 and 2012.