High transmission risk among recently-infected people

Press Release from Infectious Diseases Society of America
Source: News-Medical.Net 09 Mar 2007 – 19:00 PST

New evidence suggests that the risk of HIV transmission may be highest in the early stages of infection. According to a study published in the April 1 issue of The Journal of Infectious Diseases, now available online, early infection accounted for nearly half of all transmission occurrences in an HIV-infected population in the province of Quebec, Canada.

Bluma Brenner, PhD, and Mark Wainberg, PhD, of the McGill AIDS Centre in Montreal, and colleagues from several hospitals and health clinics in Canada studied HIV transmission through phylogenetic analysis – essentially, drawing the virus’s family tree. The technique follows the history of a virus as it spreads from one person to another by looking at the evolution of viral genetic material in infected individuals.

Drs. Brenner, Wainberg, and colleagues found that 49 percent of early infections formed phylogenetic clusters – very close branches on the family tree. This indicated that a large portion of HIV acquisition could be attributed to individuals transmitting the virus who were themselves in the early stages of infection, before the virus had had time to mutate much. Therefore, early infection – also known as primary infection – which represented “less than 10 percent of the total samples, disproportionately accounted for about half of subsequent transmission events.”

A high viral load associated with early HIV infection is what makes newly infected individuals so infectious, according to Drs. Brenner and Wainberg. In an editorial accompanying the article, authors Deenan Pillay, MD, of the Health Protection Agency and University College London, and Martin Fisher, MD, of the Brighton and Sussex University Hospitals, pointed out that diagnosis of HIV reduces the risk of transmission. But, they note, symptoms of primary HIV infection are non-specific. Only a small proportion of infected individuals are diagnosed in early infection, thus compounding the difficulties in preventing transmission at that stage of infection.

“The early infection stage can be entirely asymptomatic,” Dr. Wainberg added. “This is why people who are recently infected may not know it, and will probably often test negative by conventional antibody screening. Hence, we must do a much better job of identifying recently infected people if we are to be able to counsel them to modify high-risk sexual behavior and desist from transmitting the virus.”

He suggested the development of affordable tests such as polymerase chain reaction assays to directly monitor the presence of the virus, instead of relying on the current method of antibody screening.

In addition, Dr. Pillay and Fisher asserted that more innovative and effective prevention strategies are needed to stem HIV transmission during primary infection and block the spread of drug-resistant viruses.

Victoria’s HIV cases at highest level in 20 years

By Carol Nader, The Age  (10 March 2007)

NEW reports of HIV have reached their highest level in Victoria in 20 years, prompting criticism that State G0overnment efforts to reduce the numbers have failed.

The Department of Human Services was notified of 334 cases of HIV last year, 17 per cent higher than the 285 in 2005 and the highest number since 1987.

But the Government says 70 of the notifications were for people who had first tested HIV-positive in another state or country. A doctor tested them again here and by law must alert the department.

When that is taken into account, there were 264 new diagnoses last year and 242 in 2005 — a rise of 9 per cent. The figure is double the number of new diagnoses in 1999.

The latest rise has prompted Michael Wooldridge, chairman of the Federal Government’s advisory committee on sexually transmissible infections (STIs), to say: “The effort in Victoria has been an abject failure.”

In NSW, the number of new cases has been stable since they peaked at 414 in 2003. They fell to 391 in 2005, and the AIDS Council of NSW expects the final 2006 figure to reflect a further reduction of at least 10 per cent to about 346.

Dr Wooldridge, a former Howard Government health minister, praised the “spectacularly successful” efforts of NSW.

“There’s a great challenge for the Victorian Government to show leadership here, and NSW has shown that leader- ship in this area can make an enormous difference,” he said.

Victorian Health Minister Bronwyn Pike said the rise in HIV notifications was concerning and authorities would have to examine ways of spreading the safe-sex message. The State Government announced an extra $2.7 million in funding for HIV and other STIs in October.

But the money still hasn’t been allocated because tendering is under way.

The executive director of the Australian Federation of AIDS organisations, Don Baxter, said the NSW Government had taken action to reduce new HIV infections as soon as the numbers started to rise.

However, the Victorian Government had been slow in allocating new funding.