Extraordinary high level of propagation of Babesia divergens in severe human babesiosis.

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.

Clinical tolerance and efficacy of anti-parasitic treatment with albendazole in patients with alveolar echinococcosis: long-term follow-up observation in 117 patients.

Alveolar echinococcosis is the most severe worm disease primarily detected in the liver. This study aimed to determine the clinical tolerance and efficacy of albendazole in patients with alveolar echinococcosis, depending on the volume of previous surgical treatment or its absence and the duration of anti-parasitic therapy. We retrospectively (over the last 15 years) analyzed the data of 117 patients, who were divided into 4 groups according to curability: R0 (radical resection), R1+2 (incomplete resection), Nr (unresectable), and Rr (recurrence). All of them received albendazole from 3 months to 11 years, depending on the volume of resection. We evaluated patients' tolerability of albendazole according to the level of hepatic transaminases and blood cell count. The effectiveness of anti-parasitic treatment was evaluated by imaging studies and the absence of serum antibodies. There was no direct relationship between the frequency of adverse reactions and the duration of taking albendazole (r - 0.20229). Adverse reactions were significantly more often observed in unresectable patients (p < 0.01), which is most likely associated with the general serious condition of the patients and with individual drug intolerance. The effectiveness of the anti-parasitic treatment was manifested in the inhibition of tumor development in 88% of patients in group R1+2 and 60% in group Nr. Follow-up of group R0 patients from 3 to 14 years did not reveal new lesions of the liver and other organs. The chance of a complete cure depends on the early detection of a parasitic tumor and can reach 50%.

The importance of uninterrupted albendazole treatment in patients with unresectable alveolar echinococcosis undergoing liver transplantation.

BACKGROUND: This study focused on the monitoring of patients who had undergone liver transplantation (LT) because of unresectable alveolar echinococcosis (AE). The role of long-term administration of albendazole (ABZ) in patients with residual/recurrent AE lesions and without AE lesions was evaluated. METHODS: Albendazole therapy was prescribed to patients diagnosed with AE 4-6 weeks after LT on the background of continuous suppressive therapy while following the protocol for managing patients after LT. Clinical data (general condition, blood counts, and level of hepatic transaminases), ultrasound scans (USs), magnetic resonance imaging (MRI) or multispiral computed tomography (MSCT), and serological data were collected from four patients with residual/recurrent AE lesions and without AE lesions. The results of the USs, MRI, and MSCT examinations at diagnosis and at the end of follow-up were retrospectively reviewed for all patients. RESULTS: Observation of patients over a long period (up to 10 years) showed that the continuous (without interruption) use of ABZ restrained the development of metacestodes. Interruptions in taking the drug, associated with the manifestation of hepatotoxicity in some patients, led to the development of lesions in other organs in which the parasite had not previously been detected. No new foci were found in the transplanted livers of the patients. CONCLUSION: Liver transplantation, together with continuous anti-relapse chemotherapy, prolongs the patient's life, both in the absence and in the presence of metastases in other organs.

Severe babesiosis caused by Babesia divergens in a host with intact spleen, Russia, 2018.

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%.

Fatal human babesiosis caused by Babesia divergens in an asplenic host.

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.