RESUMEN

Babesias are obligate apicomplexan parasites that affect the red blood cells (RBCs) of animals. Humans can serve as accidental hosts for them. Asexual reproduction of a parasite occurs in a vertebrate host through asynchronous binary fission, yielding a complex pleomorphic population of intraerythrocytic forms. In natural hosts (Bos taurus), paired pyriforms ('figure 8') of Babesia divergens are usual, but tetrads ('Maltese Cross') are very rare (only in 0.02% infected erythrocytes); in humans, however, up to 5% of infected erythrocytes show tetrads. The current study shows that B. divergens proliferating in an accidental human host can promote extraordinarily high level of fission. This phenomenon is expressed as the simultaneous division of the parasite into 6 and possibly a greater number of merozoites, forming a 'daisy head' (vs the usual 2, less often 4 merozoites). Reproduction is possible without egressing merozoites from the erythrocyte, which results in multi-occupancy of an RBC (≥5 parasites per RBC). An unusually high polyparasitism ­ up to 14 parasites developed in the affected erythrocytes ­ was observed. This phenomenon is rare in natural hosts (usually ≤5), but when B. divergens is cultured in vitro it can be 10­12.

Asunto(s)

Babesia , Babesiosis , Enfermedades de los Bovinos , Animales , Babesiosis/parasitología , Bovinos , Enfermedades de los Bovinos/parasitología , Eritrocitos/parasitología , Humanos , Reproducción

RESUMEN

We report a case of severe babesiosis caused by the bovine pathogen Babesia divergens with the development of multisystem failure in a splenic host. Immunosuppression other than splenectomy can also predispose people to B. divergens. There was heavy multiple invasion of up to 14 parasites inside the erythrocyte, which had not been previously observed even in asplenic hosts. The piroplasm 18S rRNA sequence from our patient was identical B. divergens EU lineage with identity 99.5-100%.

Asunto(s)

Babesia/aislamiento & purificación , Babesiosis/diagnóstico , Bazo/parasitología , Anciano , Babesia/clasificación , Babesiosis/fisiopatología , Eritrocitos/parasitología , Resultado Fatal , Femenino , Humanos , Moscú , ARN Protozoario/análisis , ARN Ribosómico 18S/análisis

RESUMEN

We report a fatal case of human babesiosis caused by bovine pathogen Babesia divergens in Russia. Falciparum malaria was falsely diagnosed due to the presence of small ring forms in the blood smear. Laboratory diagnosis can distinguish between babesiosis and malaria according to the examination of stained blood smears.