Opioid overdose deaths in Philadelphia dropped or stayed steady for nine months before rising again this spring, according to the latest numbers.

City officials on Tuesday said the jump indicates that the opioid crisis remains stubbornly persistent in a city where 1,217 people died of overdoses last year.

Overdose deaths between April and June rose by about 11 percent compared with the previous two quarters.

"This still represents a kind of leveling-off in opioid-related fatalities over the last three quarters," said Kendra Viner, manager of the Philadelphia Health Department's opioid surveillance program. "The bad news is that we're not seeing the decline in fatalities we'd really like to see. And if this trend continues, we'll probably end 2018 with maybe just under the total number of fatalities that we saw in 2017."

At current rates, the city expects from 1,100 to 1,150 overdose deaths this year, Viner said.

In the first quarter of the year, between January and March, 257 people died of overdoses, and 85 percent of those deaths were caused by opioids. But in the second quarter, between April and June, 282 people died of unintentional drug overdoses, again with about 85 percent overdosing on opioids.

That's still fewer deaths than in the second quarter of 2017. In the third quarter of 2017, overdose deaths hit an all-time high before dropping in the last three months of the year.

That end-of-year trend is still somewhat encouraging to Viner and other health officials.

"We saw that as a sign we'd peaked," she said. "But it was a sign that we'd reached a lower plateau. Maybe we are on our way down, but it's not a sudden decline. It's a gradual decline."

Fentanyl, the powerful synthetic opioid that has contaminated or replaced most of Philadelphia's heroin supply, is behind the city's persistently high overdose rates, health officials said. The city has employed numerous initiatives, though it's not clear which are most effective, Viner said.

"We're addressing over-prescribing through physician education, increasing access to treatment, increasing distribution of naloxone," the overdose-reversing drug, Viner said. "At the same time, there are a lot of law enforcement efforts to take down the larger dealers and get large quantities of fentanyl. I think all of those factors play a role."

Though the crisis is most visible in neighborhoods like Kensington, where opioid-related homelessness doubled this summer, the city is still struggling to find and treat many people at risk of a fatal overdose. Most of the city's deaths still occur in private homes — 75 percent of last year's overdose victims died at home, officials said.

"The majority of people who are dying are people who are not being seen by other people. We have to figure out how to find those people and prevent that from happening," Viner said.

Nonfatal overdose trends this year were similar to fatal overdose trends, Viner said, but overdose reversals are more difficult to track because not everyone who survives an overdose is treated at a hospital or by paramedics. The city has handed out tens of thousands of doses of the overdose reversal medicine naloxone in Kensington, and many people in active addiction carry it as a matter of course.

“Through just talking with community partners, there’s a lot more naloxone reversal happening by community members than there has been previously, and at the same time [paramedics] are being called less and less of the time,” Viner said. “So this may indicate that there may be more overdoses happening in the community that aren’t being reported to us, but that more fatalities that could have happened are being prevented.”