You may be familiar with the antibiotic properties of resveratrol and other polyphenol molecules from red wine. These compounds come from the skins, where the grapes form them as part of their natural environmental defense. Plants, and especially ripening fruit, are vulnerable to bacteria, viruses and fungus just as animal are, and this explains the broad spectrum of antibiotic capabilities of resveratrol. Wine’s use as a means of purifying drinking water over the past few thousand years is likely based as much on this as its alcohol content. Parasites such as the malaria bug are more difficult to suppress, and so the activity of resveratrol was unexpected.
One reason for this is that resveratrol’s inhibition of malaria works indirectly, by altering the red blood cells that contain the bug. In order for the more sever manifestations of malaria to occur, the blood cells need to adhere to the lining of the blood vessels, which resveratrol prevents (this is actually related to how it helps prevent heart attacks). So the idea isn’t that resveratrol can eradicate the parasite, but rather to mitigate the more severe effects of it while treating with anti-malarial drugs.
Since malaria is most common in tropical climates and developing countries, any effect of wine consumption would be a difficult association to discover. The British, during the Raj turned to quinine and the now-classic gin & tonic rather than claret for the same practical reasons. It is a bit difficult to picture fine Bordeaux becoming the standard prophylaxis in sub-Saharan Africa, but it may well hold the key to minimizing a lot of suffering.