As Drug-Resistant HIV Spreads, Its Implications Are Still a Mystery

The number of men turning up in King County with drug-resistant HIV is growing. In February, public-health officials announced that a monitoring program had found four men whose strain of the human immunodeficiency virus showed resistance to at least 15 of the 29 available AIDS drugs. In the two months since, two more men have tested positive for the same strain. "It's not going away," says Susan Buskin, the health department's epidemiologist in charge of analyzing tests for drug resistance.

It sounds scary, and indeed the health department's announcement back in February aroused new fears of an HIV "superbug," as reporters referred to it when they called into King County from all over the country. But in fact, it's far from clear how much alarm is warranted.

"We're sort of dealing a little in gray areas," says Bob Wood, head of the health department's HIV/AIDS program. "We're not sure how significant all this stuff is."

He says he has no reason to believe that the strain will bring on AIDS more quickly. In fact, one of the six men has been on drugs for years—including some of the drugs his virus is purportedly resistant to—and they appear to be working. "You have to keep in mind that when we do resistance testing, we're testing one drug at a time," says epidemiologist Buskin. In real life, however, patients take a cocktail of drugs.

Still, doctors believe that drug-resistant HIV is harder to treat, even if they don't know exactly how much harder. Dr. Bob Harrington of Harborview Medical Center's Madison Clinic, which treats HIV and AIDS patients, says a drug-resistant patient may have to take more drugs in all—along with injections—rather than the one pill a day many HIV patients are now able to take. He adds that it's not uncommon for patients to develop resistance to drugs over many years of treatment. As a result, "These people with brand-new [drug-resistant] infections are starting out way behind the eight ball."

Given those facts, "We felt we had a duty to warn people that risk behavior is risky," Wood says.

"It was not a climate of undue fear or paranoia," says Gay City Health Project's executive director, Fred Swanson, of the health department's announcement and its aftermath. At the same time, he says, "We definitely heard from people who came in and said, 'I'm here to get tested because of all this stuff I read in the news about drug-resistant HIV.'"

King County is trying to puzzle out the significance of this strain in the wake of a famous New York City case. Two years ago, the health department there announced that it had found a man with a drug-resistant strain of HIV who had progressed rapidly to full-blown AIDS. The notion of a "superbug" took hold.

But new research published in the May 1 edition of The Journal of Infectious Diseases debunks that idea. Two papers detail how New York's health department tracked down the person who infected the New York man with the supposed superbug. It turned out that neither that person nor his partner (who had the same strain of HIV) had progressed rapidly to AIDS. This led researchers to conclude that it was something about the New York man—a weakened immune system due to his drug use, perhaps—that brought on AIDS more quickly, rather than the virus itself.

The examination revealed another, less encouraging finding. The source's partner had been "superinfected" with the drug-resistant strain of HIV; that is, he'd already had HIV and then got infected with the drug-resistant variety—a "cautionary tale," as one of the journal papers put it.

Researchers had previously believed that drug-resistant HIV, while more virulent, was at least harder to transmit. But Seattle's news brings more evidence debunking that notion. Analysis of the RNA sequence in the virus of all six King County cases shows unusual similarity; it appears that the same strain was passed among a group of people. In light of these cases, Davey Smith, a professor specializing in infectious diseases at University of California, San Diego, says a question to consider is whether the drug-resistant strains are actually more transmissible than other forms of the virus.

All of which makes it more important that researchers be able to locate men who may have been exposed. Finding those people, however, is a big challenge.

The health department runs a partner-notification program, which has an aim of alerting everyone who has recently had sex with someone who tests positive for HIV. But the department has to negotiate difficult terrain. Consider this: Officials don't even know for sure whether any of the six in the drug-resistant cluster have had sex with each other. That's because it's illegal to reveal someone's HIV status. So officials can't just show a picture and ask, Have you had sex with this guy? Instead, they have to ask the men to recall names of sex partners and see if any of the other five names pop up. They have not.