These images are of the parasite Toxoplasma gondii infecting human cells. In humans, Toxoplasma infection can cause devastating brain inflammation in people without an immune system and can cause miscarriage. It does this by rapidly replicating inside human cells, eventually busting them and going on to infect further cells. Here, I have imaged heavily infected cells showing how hundreds of parasites can grow inside one human cell. In blue the nucleus (containing the DNA) of both the human cell and the parasites can be seen. The skeleton of the human cell (in this case a protein called tubulin) can be seen in magenta or white, occasionally wrapping around the replicating parasites. Individual parasites, only about 0.005 mm long, are illuminated in white, cyan or orange/red. In some of these parasites, Toxoplasma has been caught in act of building two daughters which will later burst out of the mother.