(Reuters) - The number of confirmed and presumed HIV cases stemming from abuse of intravenous prescription drugs has increased to 142 in a rural part of southeastern Indiana and more cases are being identified every day, a state health official said on Friday.

The HIV outbreak, the biggest in state history, is centered on Scott County near the Kentucky border and now includes at least five cases in neighboring Jackson County, officials said.

"We likely haven't reached the peak of this outbreak, but we hope to soon through the continued comprehensive response made possible by the joint efforts of so many people and organizations," state Health Commissioner Jerome Adams said in a statement.

The 142 confirmed and preliminary positive cases is up from 106 cases two weeks ago. Typically, Scott County has fewer than five new HIV cases in a year.

Indiana bans needle exchange programs, but Indiana Governor Mike Pence, a Republican who opposes such programs, launched one in Scott County in early April to stem the outbreak. The program was due to end Friday, but he extended it by 30 days.

Needle exchange programs provide drug users with sterile needles to try to stop infections from spreading through the sharing of contaminated needles.

Human immunodeficiency virus (HIV), can cause AIDS, or Acquired Immune Deficiency Syndrome. More than 1.2 million people in the United States are living with HIV, according to the U.S. Centers for Disease Control and Prevention.

(Reporting by David Bailey in Minneapolis; Editing by Doina Chiacu)