Theileria parva is a protozoan parasite that primarily infects cattle and is transmitted by Rhipicephalus (Boophilus) microplus ticks. It is responsible for a disease known as East Coast fever, which can lead to severe health issues in affected animals, including fever, lymphadenopathy, and ultimately death if untreated. This parasite invades and multiplies within the host's white blood cells, disrupting the immune system. Control measures include vaccination and tick management strategies to reduce transmission. Understanding Theileria parva is crucial for livestock health and agricultural productivity in regions where it is prevalent.