Babesia

The prevalence of Babesia microti infections varies depending on the endemic geographic region. Over the past 30 years, an increasing number of confirmed Babesia infections have been documented in the United States. This is likely due to the growing deer population and the increase in outdoor activities. An endemic area for babesiosis has been identified by the Centers for Disease Control and Prevention in New Jersey, USA. A significant number of confirmed infections have also been observed in the US states of Washington, California, Missouri, and Connecticut. In Europe, isolated cases of babesiosis have been described, with seroprevalences ranging from 4% to 13%.

The pear-shaped, Plasmodium-like parasites were first discovered by Victor Babes in 1888 in cattle suffering from bovine redwater fever. Nearly 100 subspecies of Babesia have since been described, some of which can infect humans. Human babesiosis can be life-threatening and is an increasingly tick-borne disease, primarily caused by Babesia microti. However, human infections with Babesia divergens, Babesia duncani, Babesia gibsonii, Babesia WA1, and CA1 have also been reported.