The Indiana State Department of Health says four more people have tested positive for HIV in an area of southern Indiana that has been the center of the worst outbreak in state history.

State officials said Monday that the total number of cases is now 188. Officials say the newly diagnosed cases were identified as people who are contacts of cases previously identified in the outbreak.

Indiana State Health Commissioner Jerome Adams says progress has been made to slow the spread of HIV in southern Indiana but more people likely will be diagnosed as testing continues.

Nearly all of the cases have occurred in Scott County, about 30 miles north of Louisville, Kentucky. The outbreak has been largely driven by needle-sharing among people injecting a liquefied form of the painkiller Opana.

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