Doctors document case of HIV reinfection

February 2, 2000
Web posted at: 7:30 p.m. EST (0030 GMT)

(CNN) -- The first case of an HIV positive patient being reinfected with a second strain of HIV has been documented by doctors in Ottawa Canada, according to data presented Wednesday at the annual Conference on Retroviruses in San Francisco.

Experts believe this case proves what has been suspected all along -- HIV positive people can be reinfected even years after their initial exposure to the virus. And it raises concerns about difficulties in developing a vaccine against HIV.

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The first case of an HIV positive patient being reinfected with a second strain of HIV has been documented by doctors in Ottawa. Real 28K 80K Windows Media 28K 80K

According to doctors, the Ottawa Hospital patient was reinfected after a sexual relationship with another HIV positive patient who was being treated at the hospital. They became suspicious when the patient stopped responding to anti-viral therapy and informed them of the relationship.

"Initially we noticed that he was getting worse," said Ottawa Hospital's Dr. Jonathan Angel. "His immune system appeared to be getting weaker, and the amount of virus in his blood stream appeared to be getting higher without any explanation."

This superinfection has been seen in chimpanzees and in anecdotically in some humans. The Ottawa data is still preliminary and experts say reinfection may not cause everyone to deteriorate as rapidly as the patient in this case.

"Conceivably, this is the reason why the person had a progressively deteriorating course," said Dr. Anthony Fauci of the National Institutes of Health. "But since it's only one patient, we've got to be careful that we don't jump to any conclusions about the frequency of superinfection or double infection."

Doctors say this is a reminder of the importance of safe sex, even if both people in the relationship are HIV positive.

"The belief that reinfection is not possible or does not occur is a contributing factor to unprotected sex, particularly between individuals who are both HIV positive," said Ronald Johnson, associate executive director of the Gay Men's Health Crisis.

But what concerns experts most about the Ottawa data is its impact on vaccine development and effectiveness.

"Here's a person who had a relatively good immune response, because they were not advanced in their disease," Fauci said. "They had a virus in them that was continually stimulating their immune system, and yet, they still got infected with another virus."

Fauci pointed out that a vaccine is never as potent as a replicating virus in protecting a person against infection from another virus. "If this replicating virus (HIV) can't do it (fight off another HIV virus) then a vaccine is going to have a tough time doing it," Fauci said.