Federal public health officials are joining Massachusetts health officials in investigating a large cluster of reported HIV cases in Lawrence and Lowell.
The Centers for Disease Control and Prevention agreed to help the Massachusetts Department of Public Health with investigating the cases, which it said involves people who inject drugs and are homeless.
Preliminary data from DPH showed 52 new HIV cases in 2017 among those who use opioids, compared to 23 cases the year before.
The CDC's involvement in the investigation will bring resources to determine underlying factors in the infection clusters and why this spike is happening now after a decade of increasing intravenous drug use related to the ongoing opioid epidemic.
There will also be additional help with field interviews of those infected with HIV and their needle-sharing and sexual partners.
Assistance from the CDC is expected to begin later in April.
"The sooner we can discover why these infections are happening now, the sooner we can use the most effective prevention interventions based on the evidence," Dr. Al DeMaria, DPH's infectious disease medical director and state epidemiologist, said in a statement.
Dr. Thomas Stopka, who teaches at Tufts University School of Medicine and studies how one epidemic can lead to another, previously told NBC10 Boston he believed the presence of fentanyl in the Merrimack Valley could be a factor in the increase as addicts tend to use more because of its potency.
"If they're injecting more frequently, there's increased chance for syringe sharing," he said.
Drug overdoses are now the leading cause of death among Americans under 50, according the CDC, and hepatitis C cases related intravenous drug use have increased by 300 percent across the country.
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Meanwhile, U.S. Surgeon General Dr. Jerome Adams has issued his office's first national public health advisory in 13 years after recommending Americans carry the overdose antidote naloxone, commonly referred as Narcan, on Thursday.
"You don't have to be a policeman or a firefighter or a paramedic to save a life," he said.