HUNTINGTON (AP) — West Virginia heath officials say an active HIV cluster has been confirmed in Cabell County.

A statement from the West Virginia Department of Public Health says there are 28 known cases, primarily among intravenous drug users.

Officials told a local media outlet the cluster represents a sharp increase from the baseline average of eight cases annually over the past five years.

Cabell-Huntington Health Department physician director Michael Kilkenny says it is the first notable HIV cluster in West Virginia where intravenous drug use is identified as the main risk factor.

Although the cases are confined, Kilkenny says officials estimate that Cabell County has more than 1,800 active IV drug users, so introducing HIV into that population is very concerning.