Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health, has been at the forefront of battling AIDS for decades. He is scheduled to talk tomorrow, Wednesday, at the XVII International AIDS Conference in Mexico City, and wrote a column on CNN's website today which summarizes tomorrow's presentation.

Dr. Anthony S. Fauci says that while advancements are made all the time, HIV is probably not going to be tackled with for good in the near future, due to its very nature which makes the virus very hard to attack. The virus mutates rapidly, hides from the immune system, and targets and destroys the immune system cells that successfully defend against most other viruses, Dr. Fauci reminds. Thus he remains "cautiously optimistic" about the upcoming HIV treatments.

At the end of his column, the scientist pushes for Universal Action Now, reminding of the necessity to deliver proven tools of HIV prevention and therapy to communities around the globe.

A study presented today at the XVII International AIDS Conference in Mexico City has concluded that heterosexual activity may be associated with higher risks of contracting HIV than previously thought. The standard estimates of 1/1000 chance of getting HIV in a heterosexual encounter is much higher in reality because it doesn't make use of risk factors.

As expected, the highest risk among heterosexual contacts is anal sex, which carries a risk of 1 in 3.1 contacts of getting HIV. At the other end of the spectrum, there were even zero transmission cases after 100 normal penile-vaginal intercourse acts. Circumcision lowers the risk of contracting the disease, whereas lesions such as genital ulcers significantly increase the risks.

Meanwhile, two HIV world-renowned physicians have apparently disappeared in Iran after being arrested for participation in subversive activities.