[Intro]   I’m Hank Green, and this week, SciShow News brings you the latest from Melbourne, Australia, where thousands of scientists from around the world are meeting for the 20th International AIDS Conference to share new insights into the fight against HIV and AIDS.   And I’m happy to report that some promising findings have been announced there.   The first of which is: We appear to be winning.   Based on new data released Tuesday, by nearly every measure, HIV is in decline in much of the world.   According to the Institute for Health Metrics and Evaluation, the global incidence of HIV has declined by nearly 33% from its peak, with 1.7 million new cases having been reported last year, compared to 2.8 million new cases in 1997, when the rate of new infections was at its highest.   Similarly, the number of deaths by HIV is down by about 25%, with 400,000 fewer deaths worldwide last year than in 2005, when mortality reached its peak.    The scientists credit much of this success to improved antiretroviral treatments, better results in stopping the transmission of HIV from mothers to children, and more widespread use of HIV prevention programs.    But of course, these gains haven’t been made equally.   In the U.S., HIV infection rates have fallen more than 33% overall in the past ten years — although it’s worth pointing out that they actually increased by that same amount among young men between 13 and 24.   But the biggest disparities, the Center reports, are between industrialized nations and those in the developing world.    HIV rates are substantially higher in Thailand and Papua New Guinea than elsewhere in Southeast Asia, for example, while in Europe they remain well above average in Ukraine and Kazakhstan.    And by far the highest concentrations worldwide remain in southern Africa, particularly Botswana, Lesotho, and Swaziland, where the total incidence of HIV is still above 12%.     But some other interesting data coming out of Melbourne are about how we can make the most of one of our most surprising weapons against HIV: circumcision.   A number of studies have shown that circumcised men have significantly lower risk of HIV infection from heterosexual sex than uncircumcised men.   I’m talking 50 to 75% lower risk of infection.    In fact, while this was being researched among men in Africa in the mid-2000s, the effects of circumcision become so clear so quickly that the studies were actually stopped, so that the control groups of uncircumcised men could go get circumcised if they wanted to.   The results seem to stem from the fact that skin cells on the inside of the foreskin are different from the rest of most other parts of the body.    These cells have less of the protective protein keratin in them than other skin cells, for one thing.   But they also include high concentrations of specialized cells that communicate with our immune systems -- called Langerhans cells -- which seem to be prime targets for the HIV virus.   So, circumcision has been a promising strategy in combating HIV and AIDS so far. But the challenge has been 1) persuading grown men to have penis surgery, while also making it clear that, if you do get circumcised, you still have to practice safe sex.   But two new reports out of Melbourne show that these problems might not be as bad as experts thought.   One study from the University of Chicago tracked men who took part in Kenya’s national circumcision program which was voluntary, to be clear.    The research surveyed 1,600 men who had been circumcised, and 1,600 who chose to not have the procedure.    Over the course of two years, the surveys showed that both groups of men actually used condoms more as time went on, while risky sexual behavior -- like casual sex, or sex with multiple partners -- decreased among both groups.    So there was no evidence to suggest that circumcised men were taking more risks with themselves or their partners.   Meanwhile, another study from the University of North Carolina investigated the same Kenyan program to figure out what might be keeping men from getting circumcised.    And it’s not what I would think!   It turns out that men were less concerned about the procedure itself than about missing work, and therefore losing money.   So a series of test projects have showed that simply offering compensation for lost wages made men significantly more likely to have the procedure done.    Men who were offered food vouchers for as little as $9 to $15 were quick to take up the offer, with as many as 10% having it done in the first two months, particularly older men and married men with families.   So yes, obviously, the fight against HIV and AIDS is far from over. But we are making progress.    Thanks for watching SciShow News! If you want to help us keep teaching the world about stuff, just go to subbable.com and become a contributing member. If you want to keep getting smarter yourself, just go to youtube.com/scishow and subscribe!