Babesiosis is a malaria-like parasitic disease caused by infection with Babesia, a genus of protozoal piroplasms. Ticks transmit the human form of babesiosis, so it often presents with other tick-borne illnesses such as Lyme disease. In addition to transmission by a tick, babesia can be transmitted from mother to unborn child or through a contaminated blood transfusion. Currently, most blood banks do not screen donated blood for babesia. Symptoms of babesiosis are similar to those of Lyme disease but babesiosis more often starts with a high fever and chills. As the infection progresses, patients may develop fatigue, headache, drenching sweats, muscle aches, chest pain, hip pain and shortness of breath. 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.
The first case of babesiosis was reported from Nantucket Island, Massachusetts, in 1969. Since the late 1980s, the disease has spread from the islands off the New England coast to the mainland. Cases have also been reported across the United States, Europe, and Asia.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. In Europe, B. divergens is the primary cause of infectious babesiosis and is transmitted by I. ricinus. In Australia, babesiosis of types B. duncani and B. microti has recently been found in symptomatic patients along the eastern coastline of the continent.
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 the ribosomal RNA of Babesia in thin blood smears. The lab can also test the patient’s blood for antibodies to Babesia. Babesiosis is typically treated with a combination of anti-malarial drugs and antibiotics. Relapses sometimes occur after treatment and must be retreated.