HIV Resistance Tracking Stepped Up

New York state health officials collect data with potential for investigating sex partner networks

With little public comment, the New York state health department has ordered labs across the country to report results from tests that show which anti-HIV drugs a patient’s virus is resistant to.

Such tests are used to guide treatment decisions, but that data could also identify people who are infected with strains of HIV that are similar or identical, potentially allowing health authorities to find and intervene in clusters of people where new HIV infections are happening.

While that could be a powerful new tool in slowing the spread of HIV, it could also been seen as government monitoring of the sex lives and needle-sharing practices of taxpayers.

“I think it is always very valuable to identify outbreaks,” said Dr. James Koopman, a professor of epidemiology at the University of Michigan.

One type of drug-resistance testing, called genotyping, produces what is effectively a map of the genetic make-up of at least part of the virus. Maps from different people can be compared to identify viruses that are the same or similar. Koopman said the data could be used to create a “genetic tree” and the “clusters of branches” would be those viruses that are similar.

Using a computer program that compares these genetic maps, the city health department, which gets the test results from the state, might observe a new cluster. It could find the individuals in that cluster to offer counseling, ask them who their sex or needle-sharing partners are, and then find the partners to urge them to get tested for HIV or to get counseling.

Some researchers, including Koopman, argue that HIV is spread in discrete groups, or mini-outbreaks, and each cluster could be one of these. Individuals in those groups who are newly infected may be making a significant contribution to the spread of the virus. People who are newly infected are highly infectious, but they often do not know that they have HIV. If newly-infected people can be identified, tested, and counseled that could end their role in any further virus transmission.

“My vision is the way that transmission dynamics are happening is that we have these repeated and sporadic outbreaks,” he said. “I suspect that there are outbreaks ranging in size from 10 to 20 to 50. It would be really important to determine how these things go on… I believe that we can do that.”

Any cluster tracing effort might be limited by the data that the labs give to the state. Only that portion of the genetic map that shows the drug resistance is reported. Asked if that provided enough data to make comparisons for cluster tracing, Dr. James I. Mullins, a professor of microbiology at the University of Washington at Seattle, said, “I don’t believe so.”

Mullins used genetic mapping in cases where authorities wanted to determine who was responsible for an HIV infection. He worked on the case of Dr. David Acer, a Florida dentist, who is believed to have infected six of his patients. The best known of the six was Kimberly Bergalis who died in 1991, after a firestorm of publicity broke out about the case. Acer died in 1990.

Similarly, Dr. Christopher D. Pilcher, assistant professor of medicine at the University of North Carolina at Chapel Hill, said the resistance data was insufficient.

“You really need the whole sequence,” he said. “It could be done, but it would require that they get the entire sequence.”

Koopman said he thought that the resistance data was enough to identify clusters as did Dr. Martin Markowitz, a researcher at the Aaron Diamond AIDS Research Center. Markowitz pointed to a 2003 ADARC study that tested 85 newly-infected individuals. The resistance data showed that seven of the cases were linked. A more complete genetic mapping confirmed those links and identified “14 previously unrecognized links.”

The city health department could supplement any shortcomings in the resistance data with other information. Initial HIV diagnoses are reported to the state, and shared with the city, as are AIDS diagnoses. Other information in these reports can include where the patients live, their age, sex, race, ethnicity, and their sex or needle-sharing partners.

The city health department is aware that this genetic mapping, or nucleotide sequencing as it is also known, can be used to identify clusters of people who have similar HIV though it is not currently using this data to do cluster tracing.

“We don’t routinely use viral nucleotide sequence tests for those purposes,” a spokesperson wrote in an email. “We are continuing discussions about when it would be prudent to do so.”

Last year, the city health department required 39 testing labs across the country to report any results that matched or were similar to the nucleotide sequences in the virus that infected one New York City gay man. That man had rapidly progressed from being HIV-positive to having an AIDS diagnosis and his HIV has shown resistance to many anti-HIV drugs.

Whether New Yorkers would be comfortable with this data being used for cluster tracing is another question. Some might find the monitoring intolerable; many people object when information they give to the government or a private company for one purpose is used for another without their knowledge or consent.

“In terms of accomplishing public health goals, it’s so important to have this trust between public health authorities and the populations that they serve,” Koopman said. “If, in fact, it breaks down that trust, it’s a problem… At the beginning of the epidemic there was no trust with the gay male community. We’re beginning to get some now.”

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