On this day 115 years ago, the British medical researcher Sir Ronald Ross discovered how Malaria is transmitted. Here’s an excerpt from his journal that day. “…The 20 August 1897—the anniversary of which I always call Mosquito Day – was, I think, a cloudy, dull, hot day. I went to hospital at 7am, examined my patients and attended to official correspondence… After a hurried breakfast at the Mess I returned to dissect the cadaver (Mosquito 36) but found nothing new in it… At about 1pm I determined to sacrifice the seventh Anopheles (A. stephensi) of the batch fed on the 16th, Mosquito 38, although my eyesight was already fatigued. Only one more of the batch remained. The dissection was excellent and I went carefully through the tissues, now so familiar to me, searching every micron with the same passion and care as one would search some vast palace for a little hidden treasure. Nothing. No, these new mosquitoes also were going to be a failure: there was something wrong with the theory. But the stomach tissue still remained to be examined – lying there, empty and flaccid, before me on the glass slide, a great white expanse of cells like a large courtyard of flagstones, each one of which must be scrutinised—half an hour’s labour at least. I was tired and what was the use? But the Angel of Fate fortunately laid his hand on my head; and I had scarcely commenced the search again when I saw a clear and almost perfectly circular outline before me of about 12 microns in diameter. The outline was much too sharp, the cell too small to be an ordinary stomach- cell of a mosquito. I looked a little further. Here was another, and another exactly similar cell. The afternoon was very hot and overcast; and I remember opening the diaphragm of the sub-stage condenser of the microscope to admit more light and then changing the focus. In each of these cells there was a cluster of small granules, black as jet and exactly like the black pigment granules of the Plasmodium crescents… I laughed, and shouted for the Hospital Assistant – he was away having his siesta… Then I made rough drawings of nine of the cells on page 107 of my notebook, scribbled my notes, sealed my specimens, went home to tea (about 3 p.m.) and slept solidly for an hour…” That’s from Reuters’ YouTrust.org, which put together an excellent package to commemorate the 115th anniversary of Mosquito Day. So, over a century later, where does the world stand in the fight against malaria? According to the World Health Organization there were 216 million cases of malaria and an estimated 655,000 deaths last year. By far, most of these infections are in sub-saharan Africa; children under 5 years old make up the majority of malaria’s victims. That said, the world has made good progress against the disease. Global mortality rates have fallen by more than 25% since 2000, and 33% in Africa. The advent of the Global Fund to Fight AIDS, TB and Malaria has helped channel resources to prevention and treatment in some of the hardest hit places. Treating malaria requires a proper diagnosis, which now can be administered on-the-spot with a rapid diagnostic test. (There’s even an app for that.) Once properly diagnosed, the patient must go on some form of Artimisinin Combination Therapies (ACTs) for a set period of time. Prevention is the second side of malaria control. There are two basic forms: the first is called indoor residual spraying (basically, spraying a non-toxic insecticide in people’s homes, huts or bedrooms.) The other effective prevention method is sleeping under an insecticide treated bednet. The term of art for this is: Long Lasting Insecticide treated Net (LLIN). This is a highly effective method of malaria control. (Via our friends at Nothing But Nets, anyone can help send a bednet to a malaria-endemic region for as little as $10.) When communities use bed nets, malaria rates can be reduced by as much as 90%. Thanks to Sir Ronald Ross, we know where malaria comes from. And thanks to hundreds of researchers around the globe, we know how to treat and prevent the disease. What we have not been able to do is scale up successful treatment and prevention programs to rid the world of this terrible disease once and for all.