Malaria is evolving resistance to the commonly used drugs in many parts of the world, most especially in Asia, where already it has become very difficult to treat malaria. The most familiar anti-malaria drug, chloroquine, now can barely combat the pathogen in any part of the world. (See maps below.) Now there are also reports in UK of malaria surviving the commonly used combination of drugs. Cases have recently been reported of malaria recurring in 4 patients who were treated with artemether and lumefantrine.
Not to forget that the problem is worsened by the evolving resistance of many vector mosquitoes to different insecticides. (The most common vector for malaria is the female anopheles mosquito, shown above, which is now hard to control is many parts of the world.)