Research has identified the first inter-species signaling pathway between an arthropod parasite and host, where molecules in the blood of a host animal triggers the immunity and development of a parasite. The study showed that when ticks feed on the blood of mice infected with the bacteria Borrelia burgdorferi, which causes Lyme disease, a protein from the mouse immune system binds to receptors on tick cell surfaces and signals organs to develop more rapidly, producing an immune response long before the bacteria itself can begin to infect the tick.