LONDON — International officials are looking at the bright side of the latest doping scandals to jolt track and field.

The positive tests that nabbed top-name sprinters Tyson Gay, Asafa Powell and Sherone Simpson are disappointing but also proof that global drug-testing efforts are working, the IOC and IAAF said Monday.

The cases, which were disclosed Sunday, come less than a month before the world championships in Moscow and cast another drug shadow over what is considered the marquee sport of the Olympics.

IOC President Jacques Rogge says "I am naturally disappointed, and I would like to reiterate our zero-tolerance policy against doping. ... but these cases do once again show the effectiveness of the strong, sophisticated and continually evolving battle against doping in sport."