MIAMI—In three months hundreds of thousands of soccer fans are expected to descend on nine South African cities for the 2010 World Cup. But for so many visitors going to a country where more than 10 percent of the population is estimated to have HIV/AIDS, many public health experts are worried that the event will kick off a spike in transmission. South Africa, in turn, has responded by requesting one billion condoms for the year (many of which will be supplied by the U.K.)—more than twice as many as usual, the BBC noted.

"Jo'burg is awash in condoms," Myron Cohen, of the University of North Carolina at Chapel Hill, said of Johannesburg. Cohen made his remarks here Thursday at the 14th annual International Congress on Infectious Diseases.

The trouble is, however, people don't always practice safe sex, he noted. Despite increasing global awareness of prevention measures, HIV continues to infect more than two million people annually, many of whom get the virus through sexual contact.

The full biology behind transmission is still a bit mysterious to virologists. Even though an infected male can transmit thousands of unique virus particles during sex, just one particle is usually responsible for an ensuing infection. Nevertheless, Cohen noted, "transmission is not inefficient." In South Africa, some 31 percent of women (and 5.8 percent of men) have HIV by age 21. And getting to the bottom of this dynamic will likely shed new light on keeping infection from occurring in the first place.

Recent research has shown that contagion rates for men with HIV vary greatly depending on the stage of infection they have and whether they are experiencing another sexually transmitted disease or infection—which can increase inflammation and thus transmission likelihood, Cohen explained.

New data, reported by the World Health Organization in January, also showed that male circumcision increases protection by about 60 percent (though as Cohen noted, such studies aren't perfect, as "you can't do a randomized double-blinded controlled trial—people will know if they're circumcised"). A previous study examining this same effect had been so successful that it was stopped early to recommend circumcision to males in the control group.

And since the release of promising Thai vaccine trial data in November 2009, there has been renewed interest in developing a protective vaccine. Although the protection shown in the study was only slight, "we at least have some hint that we can prevent HIV," noted Stanley Plotkin, a scientific advisor to vaccine maker Sanofi Pasteur.

Ongoing trials are investigating other ways to decrease the rate of transmission, including anti-retrovirals for those who expect to be exposed or those who think they might have recently been exposed to HIV.

Treatment of infected individuals might also be a successful way to decrease transmission. If those with HIV remain on their treatment regimen, they appear to be less contagious. And with some 25 different drugs, including many protease inhibitors and nucleoside analogue reverse transcriptase inhibitors, now available, noted Pedro Cahn of the University of Buenos Aires, therapy can be both more effective and more tolerable.

The number of people with HIV/AIDS, however, continues to climb worldwide, and now totals approximately 33 million. Particularly because of the many children who acquire it at birth, there is what Cohen calls "the treatment mortgage"—a long and expensive road ahead to keep these individuals on therapy for the rest of their lives unless alternative treatments are developed.

Even though there is currently no cure, cautioned Cohen, "do not believe this is an incurable infection." Instead, he noted, a major part of the quest comes down to effectively reducing the disease manifestation in those who have the virus, much as oncologists have been able to do in many cancers. As Cohen concluded, "the HIV field needs to learn from the cancer field."

In the meantime, he noted, the World Cup condoms might be worth procuring—not just for safe sex, but also, if virologists continue to make strides toward pushing transmission rates closer to zero, as a collector's item.

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