Researchers at UCSD’s school of medicine have mapped the transmission network of human immunodeficiency virus (HIV) in San Diego, allowing researchers to explore the likelihood of new transmissions and identify persons at the greatest risk for transmitting the virus.
The findings are published online in the June 5 issue of the journal PLOS ONE.
“The more we understand the structure and dynamics of an HIV transmission network, the better we can identify ‘hot spots’ of transmission,” said Susan Little, professor of medicine at the UCSD AntiViral Research Center and lead author of the study.
“Not everyone who is HIV infected is equally likely to transmit the infection to others. There are clusters of more active disease transmission. We can use this information to target treatment interventions to those most likely to transmit the virus to others and markedly reduce the number of new infections.”
The researchers analyzed data from recently infected persons and their sexual and social contacts in San Diego between 1996 and 2011. The data were collected as part of routine HIV genetic testing used to determine if a virus is resistant to certain classes of HIV medications. The data compared genetic similarities between viral sequences infecting different people. Viruses from two people with high genetic similarity were suggestive of a transmission link. The scientists noted that viral similarity does not independently prove that a transmission occurred, only that the individuals are part of a closely connected transmission network.
Within the transmission network, researchers calculated a score to estimate the risk of transmission from a newly diagnosed individual to a new partner. Participants with a high score were significantly more likely to develop a close linkage to another person within their first year of infection, suggesting onward transmission. Using this information resulted in a significantly greater likelihood of reduced new transmissions.
“Focusing our prevention and treatment resources to the populations at greatest risk of transmission could dramatically reduce the number of new infections associated with these populations,” Little said. “Used in conjunction with traditional partner services, TNS-guided treatment and prevention interventions could markedly lower rates of new HIV infection in our community.”
Co-authors include Sergei L. Kosakovsky Pond, Christy M. Anderson, Jason Young, Joel O. Wertheim and Sanjay R. Mehta, UCSD; Susanne May, University of Washington; Davey M. Smith, UCSD and Veterans Affairs San Diego Healthcare System. – Staff and contributions