You may never have heard of the disease lymphatic filariasis, but it affects 120 million people in 70 countries around the world, causing dramatic swelling of the limbs and other parts of the body, known as elephantiasis. It’s caused by tiny parasitic worms, transmitted between people by mosquito bites, which can lie low in the body for many years, hiding from the immune system. But how do they do that? Kat Arney spoke to Michael Kimber from Iowa State University to find out.