The number of drug- and alcohol-related overdose deaths in Maryland in the first half of the year jumped more than 50 percent from the same period last year, according to new data from the state Department of Health and Mental Hygiene.

From January to June, there were 920 fatal overdoses this year, compared with 601 last year, an escalation of the opioid overdose epidemic that startled even some working in public health.

Heroin accounted for the most deaths. But fatalities related to the powerful synthetic painkiller fentanyl, which is often mixed in heroin, unbeknownst to users, saw the biggest spike.

Heroin deaths rose 68 percent to 566 in the first half of the year, and fentanyl deaths rose 268 percent to 446. Deaths from prescription opioid-based painkillers rose 10 percent to 210. Users who have overdosed and died are often found to have more than one drug in their system.

Although many in public health expected the epidemic to worsen before it abated, few expected it would reach current levels, said Caleb Alexander, co-director of the Center for Drug Safety and Effectiveness at the Johns Hopkins Bloomberg School of Public Health.

“I'm surprised by the magnitude of the increase,” he said. “The fact that you see such a large number of fentanyl-related deaths demonstrates the need for greater resources dedicated to identifying and treating opioid dependence.”

He added, however, that there was “no single intervention” that would significantly curb addiction and overdoses. And, he said, in addition to more treatment, another focus should be on tackling the overprescribing of opioid painkillers, where many addicts get their start.

Others say users need to be warned about the dangers of fentanyl, which federal Drug Enforcement Administration officials have said is typically not the kind used as a painkiller in medical settings but rather synthetic versions made in labs in Asia and shipped illegally to the United States.

Some dealers are cutting heroin with such fentanyl because of its potency, to make their heroin more attractive to buyers.

Public health officials locally and across the country already have been sounding the alarm about fentanyl since last year, when deaths began to climb.

“Fentanyl is a rising and very concerning problem,” said Dr. Leana Wen, Baltimore City health commissioner. “It's many times stronger than heroin, and it's being mixed in with heroin and other drugs such as cocaine, and users are taking what they think is their usual amount and they are dying from overdose. The rise is really remarkable and really shocking.”

The city Health Department has begun deploying teams to overdose “hot spots” identified by emergency responders to alert drug users and addiction treatment providers that fentanyl is likely being sold in those areas. The department, as well as others around the state, also has been training people in the use of the opioid overdose antidote naloxone and pushing for more treatment.

Baltimore City recorded the most overdose deaths in the state in the first half of the year, with 290, an increase of about 54 percent from a year earlier. But increases in overdose fatalities are being recorded statewide.

The fatalities were up by more than 50 percent in a dozen counties. Allegany, Charles, Kent, Talbot, Wicomico and Worcester counties recorded double or triple the number of deaths.

Only four, mostly rural, counties saw decreases in overdose deaths (Washington, Garrett, Carroll and Somerset). Two counties had no change (St. Mary's and Queen Anne's).

“Fentanyl continues to be a grim factor in the scourge we've seen grip Maryland in recent years,” said Dr. Howard Haft, state deputy secretary for public health, in a statement. “Users are buying and consuming fentanyl when they might think they are about to take something else. And they're dying.”

The Rev. Milton Williams of Baltimore, founder of The Turning Point Clinic in East Baltimore, knows this firsthand.

He said his medical staff, and even his security officers, have administered naloxone on the clinic property. It's frustrating, he said, because those overdosing are frequently the same people locked in a cycle of getting a fentanyl-induced “super high,” overdosing, getting revived and then overdosing again later the same day, or soon after.

“This is not the answer,” he said of addicts being saved by repeated naloxone doses. “When this man or this woman is ready to make a change in their life, the doors of treatment need to be ready and waiting and have the capacity to bring them in immediately. They require medication and counseling and, in my philosophy, the help of almighty God.

“This is where we stand. This is not going away.”