Human babesiosis

Abstract

Human babesiosis is a worldwide emerging tick-borne disease that is increasing in frequency and geographic range. It is caused by an intraerytrocytic piriform parasitic microorganism Babesia also called Piroplasma (Apicomplexa: Babesiidae). Out of more than 100 Babesia species described so far, only some were diagnosed in infected humans, mostly B. microti in USA, B. divergens and B. venatorum (Babesia sp. EU1) in Europe. B. divergens is transmitted by I. ricinus ticks (larvae, nymph and imago) with cattle as the primary reservoir hosts. I. ricinus also serves as a reservoir host because parasite is transmitted by transovarial (and transstadial) transmission. Infection in humans may be asymptomatic or mild but is of a particular risk for asplenic individuals, those with congenital or acquired immunodeficiencies, and elderly. Death from babesiosis occurs in up to 50 percent of these groups. On the territory of Russia and the former Soviet Union 3 cases of babesiosis provoked by B. divergens resulting in the death of patients were reported. Diagnosis was confirmed by identification of typical intraerythrocytic parasites on a stained blood smear or Babesia DNA using PCR. Treatment included atovaquone and azithromycin or clindamycin and quinine, and erythrocyte transfusion in severe cases. Personal and community protection can can reduce the risk of Babesia infection, but stopping transmission is unrealistic due to the zoonotic nature of the infestation. The purpose of this publication is to attract the attention of specialists to epidemiology, prevention, laboratory diagnosis of human babesiosis.