INDIANAPOLIS — Health officials are warning of an explosion of HIV cases in Southeast Indiana and beyond as they identify more people who’ve been exposed to the virus that causes AIDS.

Deputy State Health Commissioner Jennifer Walthall said the number of cases could quickly move into the hundreds.

Many of those infected with HIV in Scott County had sexual contact or shared intravenous needles through drug use with multiple others — up 50 people, in some instances — before learning they were infected.

“There is potential for this to exponentially explode,” Walthall said at a Wednesday hearing at the Statehouse where health officials urged a needle exchange to slow the spread of the virus.

As of yesterday, 72 cases of HIV had been confirmed in Scott County since December, with a number of other cases identified but awaiting confirmation.

Among those infected are women who worked as prostitutes at truck stops along Interstate 65. One of those women reported having sex with up to 75 truckers between the time of her infection and her diagnosis, according to local health official, Jeanni McCarty, who testified Wednesday.

Walthall said the HIV outbreak, which she described as a “crisis” of a historic nature, should prompt an extraordinary response from the state, including implementation of a targeted, temporary needle exchange program in Scott County.

“We’re prepared to take decisive action,” she said during the hearing of the House Public Health Committee.

Walthall made clear that her boss, Gov. Mike Pence, strongly opposes such programs as a response to the rising problem of intravenous drug use in Indiana.

When pressed by legislators to explain Pence’s position, she said she “couldn’t speculate.”

But Walthall said the current crisis demands a “surgical strike” of resources for testing and treatment.

Health officials from Southeast Indiana are calling on lawmakers to go beyond an emergency order by Pence, expected Thursday, to allow a needle exchange in Scott County and send resources to the area.

“This will explode everywhere in Indiana,” said Dr. Shane Avery, a Scott County family physician who has patients who’ve been newly diagnosed with HIV. “It just started in Scott County.”

The U.S. Centers for Disease Control and Prevention, which dispatched a team of HIV experts to Scott County earlier this week, endorses needle-exchange programs as a tool to slow the spread of the virus.

It’s not a cure-all, said Dr. Deepak Azad, a former president of the Indiana State Medical Association. But it will help stem a crisis that he and others predict will continue to grow in places where IV drug abuse is a chronic problem.

“Keeping a needle exchange program just to Scott County is not going to solve the problem,” Azad said. “This is spreading too fast.”