For years, Camden has ranked as one of America's most violent cities. Since 2012, the city's bloodiest year on record, crime rates have fallen. Just when it seemed Camden was turning a corner, the city's opiate crisis took off.

On average, nine people overdose daily in Camden. On one day in August, EMTs responded to 16 overdoses in one hour. Adding to its escalating opiate problem, Camden has not had clean needles in over a year. The local syringe exchange closed in August 2016.

Opiates do not kill only by way of overdose. Without access to clean needles, people driven by addiction and desperate to avoid the symptoms of withdrawal resort to sharing. Shared needles efficiently spread bloodborne infections such as HIV and hepatitis C. Even one dirty needle can spark an outbreak of disease.

In the year before it closed, Camden's syringe exchange provided over 400,000 clean needles to more than 7,000 people. The syringe exchange, run by an organization called Camden Area Health Education Center (AHEC), was privately funded as state law prohibited use of government dollars to purchase needles. In September 2016, in response to the worsening opiate crisis, the New Jersey Legislature passed a law allowing state funding for clean syringes. But it was too late for AHEC. Camden's exchange had closed the month prior after its building was sold off.

Syringe-exchange programs decrease rates of new HIV and hepatitis infections without increasing drug use. In addition to providing clean needles, exchanges offer HIV and hepatitis C testing, make referrals to doctors, and offer substance-abuse treatment. People on HIV medications are not only healthier, they do not transmit the virus to others, even if they share needles or have unprotected sex. Hepatitis C is curable with medications. People who use syringe-exchange programs are five times more likely to get treatment for addiction and have higher rates of successfully stopping IV drug use than those who do not use exchanges. And these programs cut costs. While a sterile syringe costs pennies, the Centers for Disease Control and Prevention estimates that the lifetime cost of caring for a patient with HIV is more than $400,000. The cost of the medications needed to treat hepatitis C is about $40,000 per individual infected.

Camden has not had clean needles for a year, but it may only now begin to see the full public health effects of needle sharing. While deaths by overdose immediately spike when rates of heroin use climb, an epidemic of HIV and hepatitis C can spread undetected for months or even years. Both viruses work slowly: wearing down the immune system in the case of HIV, or damaging the liver, in the case of hepatitis C. Symptoms that might lead to medical care and eventual diagnosis do not develop until years into illness. And many intravenous drug users avoid doctors' offices and hospitals where they might undergo screening, fearing the legal consequence of admitting to their addiction. Despite the lag between transmission and visible symptoms, both HIV and hepatitis C are contagious within days to weeks of infection and are most likely to spread in the time between infection and diagnosis.

Addiction is a lifelong disease, and ending the opiate epidemic in Camden and across the country will take decades. But powerful, local, short-term solutions are possible.

Clean needles are to the opiate epidemic what condoms are to AIDS — cheap, simple ways to prevent the spread of disease and to save lives. According to the CDC, more than 65,000 people died of drug overdoses between March 2016 and March 2017. Without access to clean needles, many more will suffer the effects of HIV and hepatitis C infection. And if AHEC fails to reopen, Camden, whose motto is "the city invincible," is about to face yet another challenge — that of an AIDS epidemic.

Cecilia Fix MD is a recent graduate of the Internal Medicine Residency Program at Columbia University Medical Center and an HIV doctor in Camden New Jersey.