When the city health department ordered 39 testing labs to report any cases of multi-drug resistant HIV that match or are similar to the virus that infected one New York City gay man, it sent the labs “a specific nucleotide sequence” taken from the man’s virus in an effort to get an exact match.

But Dr. Scott E. Kellerman, assistant commissioner for HIV/AIDS Services at the city health department, said that matching the sequence to one taken from HIV in another person does not guarantee that the two individuals are infected with the same virus.

“In these type of situations you have the laboratory matches, but you also have to make sure that there is an epi link,” he said in an April 1 interview. “Laboratory matches can certainly happen by chance.”

The “epi link” would be established by interviewing individuals with matched sequences to determine if they were sex partners with the New York City man or part of a network of sex partners and so were likely to be infected with the same virus.

The search for such individuals has been intensive since Dr. Thomas Frieden, the city health commissioner, announced on February 11 that a gay man in his 40s had recently become infected with multi-drug resistant HIV and had rapidly progressed to AIDS.

“You want to make sure, but sometimes folks don’t want to talk to you about that stuff so you go with the best evidence you have,” Kellerman said.

To date, the department has found no other cases. When pressed, Kellerman said that while a match could occur by chance that would be unusual.

“It would be quite a circumstance if it were to occur by chance,” he said. “There are a lot of nucleotides in that virus so if you get a complete match it’s pretty compelling. Can you say it with certainty 100 percent of the time? Frankly, there’s not much in my life that I can say with certainty 100 percent of the time.”

The New York City man may have been infected as recently as October of last year or as long ago as May of 2003 and rapidly progressed to AIDS. Typically, the progression from HIV positive to AIDS takes years. The man’s virus is resistant to many anti-HIV drugs though he appears to be responding to treatment currently.

Nucleotides are the building blocks of DNA or RNA. The health department is assuming that the nucleotide sequence is unique to or characteristic of the man’s virus and that a match would be “pretty suggestive,” according to Kellerman.

“It’s a tough case,” he said. “Even if this doesn’t turn out to be as dire as might have been predicted a month or two ago, this still is a harbinger of things to come. There is an increase in unsafe sex out there. There is an increase in the use of crystal meth and other powder drugs… That concerns me and I hope that concerns the community.”

—Duncan Osborne