Babesia

Babesia, also called Nuttallia, is an Apicomplexan parasite that infects red blood cells, transmitted by ticks. Originally discovered by the Romanian bacteriologist Victor Babeș, over 100 species of Babesia have since been identified. Babesia species infect livestock worldwide, wild and domestic vertebrate animals and occasionally humans where it causes the disease babesiosis. In the United States, B. microti is the most common strain of the few which have been documented to cause disease in humans. Babesia is a protozoan parasite found to infect vertebrate animals, mostly livestock mammals and birds, but also humans. Common names of the disease, which Babesia microti causes are Texas cattle fever, redwater fever, tick fever, and Nantucket fever. The disease it causes in humans, babesiosis, is also called piroplasmosis. Due to historical misclassifications, the protozoan has been labeled with many names, including Nuttallia; the microbiological community changed the name Babesia to Theileria based on evidence from 2006. The sequence published in 2012 shows, that the species belongs to neither Babesia nor Theileria but instead to a separate genus. For centuries, the animal disease was known to be a serious illness for wild and domesticated animals, especially cattle. In 1888 Victor Babeș first identified the causative agent in Romania and believed it to be due to the bacterium he named Haematococcus bovis. He documented the disease by describing signs of a severe hemolytic illness seen uniquely in cattle and sheep. In 1893, Americans Theobald Smith and Fred Kilborne identified the parasite as the cause of Texas cattle fever, the same disease described by Babeș. They also identified the tick as the transmitting agent, a discovery which first introduced the concept of arthropods functioning as disease vectors. It was believed to be a disease that only affected nonhuman mammals, but in 1957 the first case of babesiosis was seen in a human. The person had been splenectomized, as were all people diagnosed with babesiosis until 1969, when the first case of babesiosis was diagnosed in a person who still had their spleen. This proved the parasite was a potential pathogen in anyone. Babesia show host specificity, allowing many different subspecies of Babesia to emerge, each infecting a different kind of vertebral organism. While B. bovis and Babesia bigemina prefer to infect cattle in tropical environments, they can infect other animals, such as the white-tailed deer. Therefore, while the organism has the capacity to display host specificity, and thus increase transmission effectiveness, it can still infect a variety of hosts. It achieves this through mutations and natural selection. In different environments, individual protozoa may develop mutations which when they increase their fitness allow the population to increase their numbership. It explains why there is such great genetic diversity for this organism.