Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. Human babesiosis is an uncommon but emerging disease in the Northeastern and Midwestern United States and parts of Europe, and sporadic throughout the rest of the world. It occurs in warm months.
Symptoms of babesiosis are similar to those of Lyme disease but babesiosis more often starts with a high fever and chills. Babesiosis is often so mild it is not noticed but can be life-threatening to people with no spleen, the elderly, and people with weak immune systems. Complications include very low blood pressure, liver problems, severe hemolytic anemia, and kidney failure.
In the United States, the majority of babesiosis cases are caused by B. microti, and occur in the Northeast and northern Midwest from May through October. Areas with especially high rates include eastern Long Island, Fire Island, Nantucket Island, and Martha's Vineyard.In Europe, B. divergens is the primary cause of infectious babesiosis and is transmitted by I. ricinus. Babesiosis has emerged in Lower Hudson Valley, New York since 2001. In Australia, babesiosis of types B. duncani and B. microti has recently been found in symptomatic patients along the eastern coastline of the continent. Sometimes, babesia can be detected in blood examined under a microscope. However, this method is reliable only in the first two weeks of the infection. Commercial tests currently detect only two strains of Babesia and there are likely many strains yet to be discovered. The PCR(polymerase chain reaction) test can detect babesia DNA in the blood. The FISH (Fluorescent In-Situ Hybridization) assay can detect theribosomal RNA of Babesia in thin blood smears.