No, absolutely not. I had glandular fever myself as an adult, it's usually not dangerous but it is a severe illness nonetheless if you get it as an adult. MDMA has been proven to have a tremendous dampening effect on your immune system, that's why you often get sick after rolling at a rave. He runs the risk of having his illness turned up a few notches. There is also potential for liver damage with glandular fever. All in all he should not be using drugs until it completely passes, which takes weeks, it is a very stubborn illness. MDMA is a bad choice when you're sick. Can't speak for ketamine but, from my limited knowledge it appears the lesser evil, though as said I strongly discourage him using drugs at all at the moment
