MINNEAPOLIS (WCCO) – The Minnesota Department of Health is investigating an outbreak of human immunodeficiency virus (HIV) infections among people who inject drugs.

There have been 18 cases reported between December 2018 and January 2020, with 13 in Hennepin County and five in Ramsey County, according to the department.

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In contrast, there are usually about zero to three cases of HIV per year in Hennepin and Ramsey counties among people who inject drugs.

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Experts say the outbreak has the potential to spread quickly, due to blood-to-blood contact.

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Many of the infected individuals have experienced homelessness. According to a health advisory, many of them are also “co-infected with hepatitis C virus.”