Infection with a Babesia-Like Organism in Northern California

Abstract

A newly identified babesia-like organism causes infections in humans in the western United States. The clinical spectrum associated with infection with this protozoan ranges from asymptomatic infection or influenza-like illness to fulminant, fatal disease.

Transmission of Tropical and Geographically Restricted Infections during Solid-Organ Transplantation

“…Babesia microti has been found most frequently in human cases from the United States, although recently, other species of Babesia (types WA1, CA1, and MO1) have also been described (142,165,290). In Europe, Babesia infections are caused mainly by Babesia divergens (142).…”

“…Definitive diagnosis is obtained after the parasites are demonstrated inside red blood cells in a Giemsa-stained peripheral blood film. Serological tests, mainly the measurement of antibodies by indirect immunofluorescence (IFAT), have been demonstrated to be both specific and sensitive for the diagnosis of B. microti infection, especially in chronic infections (84), but the persistence of antibodies does not necessarily reflect active infection, and the possibility of false-positive and false-negative results may occur (290).…”

Shared features in the pathobiology of babesiosis and malaria

“…P. falciparum generally causes more severe disease than the other species of Plasmodium (P. vivax, P. malariae, P. ovale) or than the Babesia species that infect humans (B. divergens, B. duncani [Washington1 or WA1], B. microti, EU1 [European Union1], MO1 [Missouri1], and TW1 [Taiwan1]). A pattern of disease similar to that of malaria might occur, however, in people experiencing severe babesiosis [22,39,40]. Although individual manifestations are described as discrete entities, patients experiencing fulminant P. falciparum malaria or babesiosis might suffer simultaneous complications of several organ systems with similar pathologic findings [6,41].…”

“…Renal failure has been reported in $5% of severe B. microti human infection and even more frequently in patients experiencing severe B. duncani infection [39,40]. On autopsy of patients dying of malaria, several distinct pathologic patterns are noted in the kidneys, with erythrocyte sequestration and exposure to products of lysed red blood cells contributing to the pathology [67].…”

Susceptibility of Chinese Hamsters (Cricetulus griseus) to the Infection of Babesia microti

“…Babesiosis caused by B. microti arouses interest also as an emerging zoonosis in humans [12]. The cases have been reported especially in North America, where human babesiosis is caused mainly by B. microti and occasionally by a newly recognized species of parasite called WAI piroplasma [3,20]. However, in Europe, the human babesiosis is rather infrequent but more lethal and mostly caused by B. divergens [19].…”