Human babesiosis

Abstract

The first demonstrated case of human babesiosis in the world was reported in Europe, in 1957. Since then, a further 28 babesial infections in man have been reported in Europe. Most (83%) of the infections were in asplenic individuals and most (76%) were with Babesia divergens, a cattle parasite. Parasitaemias varied from l%–80% of red blood cells. The usual clinical manifestations of severe B. divergens infection were severe intravascular haemolysis with haemoglobinuria. The most efficient treatment consisted of a massive blood-exchange transfusion, followed immediately by chemotherapy with clindamycin.

Hundreds of cases of human infection with Babesia spp. have been reported in the U.S.A. Most cases were infected by ticks carrying the rodent parasite B. microti, but other emerging Babesia spp. (currently known as WA₁, CA₁ and MO₁) are increasingly involved. Several cases were the result of blood transfusion. In terms of clinical manifestations, human infections with B. microti varied widely, from asymptomatic infection to a severe, rapidly fatal disease. Parasitaemia ranged between <1% and 85%. The splenectomized, the elderly, the immunocompromised and HIV-infected patients were predisposed to severe infection. Infections with B. microti often remained subclinical or asymptomatic and were only detected through serological surveys. The currently recommended treatment of symptomatic cases is quinine plus clindamycin.

A few other cases of human babesial infection have been described in China, Egypt, Mexico, South Africa and Taiwan.