PORTLAND — The number of people using Maine’s needle exchange programs has jumped dramatically in recent years, something public health officials call a mixed blessing.

The Portland Press Herald reports that according to a report the Department of Health and Human Services, the number of enrollees in Maine’s needle exchange programs has more than tripled in five years — from 1,238 in 2010 to 4,050 last year.

Experts say the increased abuse of heroin is a major factor in the rising number of needle exchanges, which are meant to keep used needles off the streets and slow the spread of HIV, hepatitis and other diseases.

Health officials say the growing demand for needle exchange programs indicates more injection drug use but is also a sign that outreach efforts are working.