Contact tracing successful at diagnosing HIV in partners of those with acute infection

Contact tracing for individuals with acute HIV infection can successfully lead to the diagnosis of other individuals with HIV, investigators from North Carolina report in the online edition of the Journal of Acquired Immune Deficiency Syndromes, and yields a higher number of new diagnoses than tracing the contacts of chronically infected individuals. A quarter of the partners of individuals with acute HIV infection contacted were also found to have acute infection.

“Identifying persons with acute HIV infection is vital to controlling the spread of HIV. Phylogenetic and epidemiological analyses among other populations have demonstrated the crucial role this group plays in forward transmission,” comment the investigators.

In 2002, the North Carolina Department of Public Health began using nucleic acid amplification testing (NAT) to identify individuals with acute HIV infection. Investigators hypothesised that individuals who were found to have acute infection would be able to identify more sex or drug use partners than individuals with established HIV infection.

To test this hypothesis, the investigators compared the number of partners identified by individuals with acute infection who were reached by contact-tracing services to the number named by patients with established HIV infection. The period of the study was 2002 to 2007.

Individuals with acute HIV infection were interviewed by trained counsellors within a day of their diagnosis, whereas those with established HIV infection were interviewed within an average of a week of being told that they had HIV. Patients with acute infection were asked to name sexual partners in the previous six months, and those with established infection to identify partners in the preceding year.

Information from 120 patients with acute infection and 9044 individuals with established infection were analysed.

Patients with acute infection reported a median of two partners in the six months before interview, whereas those with established infection reported a median of one partner. The median number of named partners for both groups was one.

Approximately 50% of the named partners who were contacted had previously been tested for HIV. A quarter of the contacted partners already knew they were HIV-positive.

The investigators found that the partners of individuals with acute HIV infection were more likely to be tested than the partners of patients with established infection (50% vs 39%, p < 0.01). Similar proportions of partners for both groups were newly diagnosed as having HIV (twelve of 264 [5%] vs 468 of 7899 [6%]).

However, of the newly-diagnosed partners with acute infection, 25% were also found to have acute infection, compared to below 1% of partners of individuals with established infection.

Statistical analysis showed that individuals with acute infections identified over twice as many total named partners as did those with chronic HIV infection.

Moreover, 9% of the partners of individuals recently infected with HIV were themselves HIV-positive compared to 5% of the partners of patients who had HIV infection for a year of more. This difference was significant (p = 0.03).

The investigators calculated that acutely infected individuals identified 1.93 times as many newly diagnosed partners than did individuals with established HIV infection.

“This is the first population-based study to demonstrate that persons with acute HIV infection identify higher numbers of named partners per index case than persons with established infections,” write the investigators. They add, “persons with acute HIV infection also have a higher proportion of partners who get tested for HIV.”

“The results of this analysis”, conclude the authors, “lend additional support for routine identification of acute HIV infections as a means to increase the number of partners reached by [contact tracing] and the number of new infections identified.”