This city, where the rate of drug overdose deaths is nearly 10 times the national average, has done more than most to fight the heroin and prescription painkiller epidemic. Local police have been diverting drug users to specialized drug courts for treatment. The city opened a syringe exchange program to reduce the spread of infectious diseases among drug users. And doctors and nurses from a local hospital have developed a model facility to care for the hundreds of opioid-dependent infants born to heroin-addicted mothers. But instead of getting better, Huntington’s opioid problem is getting worse. In just one afternoon last month, 28 people in this city of 50,000 overdosed on heroin. Since January, 773 people have overdosed on opioids (including prescription painkillers and heroin), a 24 percent increase over last year. An estimated 8,000 Huntington residents are addicted, mostly to opioids.