Philadelphia Mayor Jim Kenney said Friday that the man accused of raping at least three women in South Philadelphia is HIV positive.

"That is an issue and we are doing the best we can to make sure people get what they need in terms of treatment and information," Kenney said in response to a question from NBC10. "Thankfully, this guy is off the street."

Kenney's comments came less than 24 hours after NBC10 first reported new developments in the case.

Safien Williams, a 37-year-old Philadelphia Streets Department employee, was charged with multiple counts of rape, aggravated assault, sexual assault, false inprisonment, criminal trespassing, unlawful restraint and burglary, among other charges.

The rapes occured on Mifflin, Morris and Bancroft streets; an indecent assault also occurred on South 16th Street.

Philadelphia police indicated Williams might be responsible for other attacks.

In each known case, Williams followed the victims during late-night or early-morning hours, investigators said. Surveillance video showed a man on a bicycle approaching homes and circling South Philly streets.

At least one victim might be an undocumented resident of Philadelphia, according to police. Officials encouraged other victims, including those concerned about approaching law enforcement authorities because of their immigration status, to report assaults.

"Irrespective of what you're status may be or whether you're not a resident of this country, don't worry about that. You're a victim," Philadelphia Police Commissioner Richard Ross said earlier this week. "Come forward."

The Philadelphia Police Department, however, and the Philadelphia District Attorney's Office did not comment on Williams' HIV diagnosis.

Williams was assigned a public defender but the Defender's Association of Philadelphia declined to comment for this story.

More than 30 states across the country have laws that make it a crime to not disclose an HIV-positive status prior to sexual contact. Pennsylvania, however, does not.

Criminalizing the spread of HIV would only add to stigma, according to Ronda Goldfein, executive director of the AIDS Law Project of Pennsylvania.

"In a case like this, there is an allegation of a very serious crime and we don't need to add an added element," she said. "A person's health status does not become an element of that crime [because] we don’t know the impact of a person’s health on an alleged victims’ health."

HIV is no longer the death sentence it once was, she added.

"With access to medication, [HIV] is a chronic and manageable condition. We don't want that important factor to get lost," Goldfein said. "We have made great progress in regards to science and medicine, but stigma still runs rampant."

The Philadelphia Department of Public Health did not comment on the Williams case, but said in a statement that "all the victims who have come forward are being offered the appropriate counseling and medical care."

Sexual assault victims who seek medical treatment immediately or shortly after an assault are less likely to transmit the virus, according to Dr. Sara Schultz, an infectious disease specialist at Drexel University College of Medicine.

"Time is of the essence," she said. "After a sexual assault, it is unlikely but possible to transmit HIV depending on various factors ... including how much HIV [the attacker] had."

An estimated 1.1 million people in the United States are currently living with HIV, according to the Centers for Disease Control and Prevention. In Philadelphia, about 19,000 people have the virus.

Advancements in medicine have also made it possible for HIV-positive patients to live into their 70s. The average life expectancy for a patient undergoing treatment is 71 years compared to 79 years for Americans who are not infected, according to the CDC.

HIV is spread through blood, semen, breast milk and other bodily fluids. Sharing needles or having unprotected anal sex puts people at especially high risk of infection.

If an HIV patient's status is undetectable, then transmission is less likely, according to Schultz. But if someone with HIV is not on medication, has not been diagnosed or very recently contracted HIV, then the transmission risk increases.

People exposed to the virus can drastically reduce their risk of transmission by taking a medication every day for 28 days. Nonoccupational postexposure prophylaxis, or nPEP, is most effective when taken within 72 hours.

"The sooner this is started after an assault, the better," Schultz said.

Go to the City of Philadelphia's website for more information and available resources.