Parasite burden and red blood cell exchange transfusion for babesiosis.

BACKGROUND: The association between parasite burden and end-organ dysfunction in subjects with Babesia microti infection has not been extensively studied, nor has the optimal role of red blood cell exchange (RCE) transfusion in babesiosis treatment. This retrospective chart review evaluates the associations between parasitemia, end-organ dysfunction, and outcomes in babesiosis patients treated with antimicrobial agents and RCE compared to those treated with antimicrobial agents alone. MATERIALS AND METHODS: We evaluated adults (≥18 years of age) with laboratory-confirmed babesiosis who were admitted between 2011 and 2017 to Yale New Haven Hospital, located in a Babesia-endemic region of the Northeastern United States. Patient demographics, parasitemia levels, clinical and laboratory indicators of end-organ dysfunction, and outcomes were examined. RESULTS: Ninety-one subjects (mean age 65.1 years, 69.2% male) were studied. Subjects were stratified according to peak parasitemia: <1% (n = 34), 1-5% (n = 24), 5-10% (n = 15), and >10% (n = 18). Laboratory measures indicating degrees of hemolysis, coagulopathy, and pulmonary, renal and hepatic dysfunction differed significantly across peak parasitemia levels. Median length of hospital stay increased with each successive peak parasitemia level (P < .001). These results indicate a strong association between peak parasitemia level and disease severity. Nineteen subjects underwent RCE, all with peak parasitemia ≥9% and some degree of end-organ dysfunction. CONCLUSIONS: Babesia microti parasitemia is closely associated with disease severity, though not all subjects with end-organ dysfunction had high-grade parasitemia. Our data suggest that the use of parasitemia >10%, coupled with clinical status, is a reasonable indicator for RCE in babesiosis patients.

Adjunctive treatment of clinically severe babesiosis with red blood cell exchange: a case series of nineteen patients.

BACKGROUND: Infection with the protozoan parasite Babesia, the causative agent of babesiosis, can result in asymptomatic to life-threatening illness. Severe cases of babesiosis are characterized by high levels of parasitemia (>4%-10%) and commonly treated with adjunctive red blood cell exchange (RCE) in addition to antimicrobial therapy. The efficacy of RCE in this context is unknown. STUDY DESIGN AND METHODS: Blood bank records were examined for requests for RCE during a 10-year period from 2007 to 2017. Relevant clinical and laboratory variables were extracted from medical records from presentation to 35 days after RCE and analyzed in univariate and multivariate models. RESULTS: Nineteen cases of babesiosis were identified in which RCE was performed. The median age of patients was 77 years, 74% of whom were male. A total of 37% of patients were asplenic. RCE was performed on average 1.3 days after presentation, with procedural urgency driven mainly by the level of parasitemia. Mean pre- and post-RCE levels of parasitemia were 12.9 and 3.4%, respectively, resulting in a mean percent reduction in parasitemia of 75%. Preprocedural parasitemia (p = 0.047) and age (p = 0.028) were both significant predictors of postprocedural hospital length of stay (post-RCE LOS). Neither postprocedural parasitemia (p = 0.12) nor percent reduction in parasitemia (p = 0.72) correlated with post-RCE LOS. Four patients died, none of whom were asplenic. Mortality was not correlated with hematologic, parasitologic, or clinical variables analyzed. CONCLUSIONS: Reduction in the level of parasitemia is the only known benefit of RCE in severe babesiosis.

Repeat exchange transfusion for treatment of severe babesiosis.

We report a case of severe babesiosis presenting with 43% parasitemia in a 73-year-old splenectomized woman on etanercept for rheumatoid arthritis. She initially was treated aggressively with clindamycin and quinine and exchange transfusion. Despite a post-exchange drop in parasitemia to 7.6%, it rebounded to 11.4% on hospital day 5 accompanied by new onset high fevers and hypoxia. She improved after a second exchange transfusion and ultimately resolved her infection after 12 weeks of antibabesial antibiotics. Although exchange transfusion is commonly used in immunocompromised hosts, there is a dearth of information about repeat exchange transfusion, including the risk for and outcome of repeat exchange. We performed a literature search for other cases of repeat exchange transfusion for severe Babesia microti infection and compared our case with those in other published reports.

A report of cerebral malaria treated with automated red blood cell exchange.

BACKGROUND: Adjunctive automated whole blood or red blood cell exchange (RBCEx) can rapidly decrease malarial hyperparasitemia. Several case reports and series suggest improvement in clinical symptomatology; however, recent Centers of Disease Control and Prevention (CDC) recommendations concluded that RBCEx has no efficacy as an adjunctive therapy. We present a case of mental status changes secondary to cerebral malaria treated with automated RBCEx resulting in rapid and dramatic neurologic improvement. CASE REPORT: An 84-year-old Somali woman presented with a 3-day history of altered mental status, spiking fevers, chills, bilateral leg pain and weakness, and intermittent diarrhea. Her travel history included a recent trip to Kenya for 1 month without antimalarial chemoprophylaxis. During the hospital stay, her health declined, and she became obtunded. Physical examination revealed fever, tachypnea, hypertension, hypoxia, and no response to verbal or physical stimuli. Her hemoglobin decreased from 12.6 to 6.5 g/dL with 12% intraerythrocytic parasitemia by thin smear. Intraerythrocytic trophozoites and banana-shaped gametocytes were present consistent with Plasmodium falciparum. An emergent 1.5-volume RBC mass automated RBCEx and quinidine infusion decreased her parasitemia to 2%. The patient's mental status improved throughout the procedure, and after the 2½-hour procedure, the patient was alert, oriented, and speaking coherently. The patient continued to receive quinidine and artesunate 1 day later from CDC. CONCLUSION: Automated RBCEx transfusion reduced the parasite burden and restored neurologic functioning in a patient with cerebral malaria while awaiting definitive treatment with artesunate.

Babesia parasitemia rebound after red blood cell exchange.

Babesiosis is an increasingly recognized disease which may benefit from therapeutic apheresis (Category II/Grade 2C). Vulnerable populations include the splenectomized, those aged >50, those with malignancies, and the immunocompromised. In the setting of parasite levels > 10%, significant anemia, renal impairment, pulmonary compromise, or hepatic dysfunction, RBC exchange can rapidly reduce parasite burdens and decrease the bioavailability of proinflammatory cytokines. No previous report has shown such a rapid rebound in parasitemia despite adequate organism removal. Herein, we report a case of severe babesiosis in a splenectomized 56 year old male with a past medical history significant for benign multiple sclerosis. Following a week of flu-like symptoms, the patient presented to an outside hospital with anemia, elevated bilirubin, thrombocytopenia, and 15% of his RBCs containing Babesia forms on a peripheral smear. Despite initiation of appropriate antimicrobials, subsequent transfer to our facility revealed worsening parasitemia (25%), tachypnea, and hypoxia. An emergent two volume RBC exchange was performed, resulting in 15% post-exchange parasitemia. Twelve hours later, the parasitic burden had climbed to 30%. A second RBC exchange reduced the parasite burden to 1.5%. His post-procedural course was significant for diminishing periodic increases in parasitemia despite continued antimicrobial therapy. Rapid increases in parasitic burden following RBC exchanges can occur and post-procedural surveillance of parasitemia should be closely monitored to expedite additional exchanges.

P. vivax Malaria presenting as Thrombotic Microangiopathy.

INTRODUCTION: Acute kidney injury (AKI) is reported to occur in patients with falciparum malaria but not uncommon with vivax malaria. AKI, anemia, thrombocytopenia and jaundice is a recurrent finding in severe malaria and can mimic as thrombotic microangiopathy (TMA). Relationship of malaria with TMA is unclear till date however evidences suggest their association. METHODS & MATERIAL: We reviewed our electronic database to evaluate relationship of malaria with TMA, of cases of malaria, jaundice and AKI. RESULTS: 4 patients found to have P. vivax malaria and histopathologically confirmed TMA. All had fever, oliguria, jaundice at presentation. The time between onset of symptoms and admission ranged from 7 to 14 days. All had parasitemia at presentation so were treated with Artesuanate. Hemodialysis and Plasmapheresis was done in all patients. On follow-up all patients recovered and asymptomatic urinary abnormality persisting in one patient. CONCLUSION: High index of suspicion should be kept for TMA in a patient who has nonrecovering AKI with persistent anemia and thrombocytopenia even after clinical and laboratory evidences of recovery from malaria, as response to plasmapheresis seems excellent in this subset of malarial AKI. There could be a pathogenetic link between P.vivax and TMA though yet to be confirmed in larger studies.

From genome screening to creation of vaccine against Trypanosoma cruzi by use of immunoinformatics.

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, and activation of CD8(+) T cells is crucial for a protective immune response. Therefore, the identification of antigens with major histocompatibility complex class I epitopes is a crucial step for vaccine development against T. cruzi. Our aim was to identify novel antigens and epitopes by immunoinformatics analysis of the parasite proteome (12 969 proteins) and to validate their immunotherapeutic potential in infected mice. We identified 172 predicted epitopes, using NetMHC and RANKPEP. The corresponding protein sequences were reanalyzed to generate a consensus prediction, and 26 epitopes were selected for in vivo validation. The interferon γ (IFN-γ) recall response of splenocytes from T. cruzi-infected mice confirmed that 10 of 26 epitopes (38%) induced IFN-γ production. The immunotherapeutic potential of a mixture of all 10 peptides was evaluated in infected mice. The therapeutic vaccine was able to control T. cruzi infection, as evidenced by reduced parasitemia, cardiac tissue inflammation, and parasite burden and increased survival. These findings illustrate the benefits of this approach for the rapid development of a vaccine against pathogens with large genomes. The identified peptides and the proteins from which they are derived are excellent candidates for the development of a vaccine against T. cruzi.

Out with the bad and in with the good; red cell exchange, white cell reduction, and platelet reduction.

Automated techniques for red cell [red blood cell (RBC)] exchange or depletion of malignant cells from the peripheral blood have allowed patients with life-threatening conditions to survive long enough to receive definitive treatment. Examples of such conditions include acute chest syndrome in sickle cell disease (SCD) or acute respiratory insufficiency due to leukostasis in acute leukemia. Conversely, other patients with SCD undergo RBC exchanges on a chronic basis to maintain a reasonable quality of life and prevent another stroke. In this review, we will discuss the techniques as well as indications for RBC exchange, leukocytapheresis, and thrombocytapheresis. To illustrate the uses of these therapeutic apheresis procedures, the authors included a summary of the most common diagnoses that comprise their use.

Can we trust measures of healthcare utilization from household surveys?

BACKGROUND: The research community relies heavily on measures of healthcare utilization from household surveys to understand health seeking choices and to evaluate interventions in developing countries. Such measures are known to suffer from recall problems but there is limited evidence of whether the method of data collection affects evaluation findings. We compared the results of a randomized trial of free healthcare using utilization data from two sources. METHODS: Data are from a study in Ghana, in which 2,194 households containing 2,592 children under 5 y old were randomized into a prepayment scheme providing free primary and some referral care, or to a control group whose families paid user fees for healthcare. Data on morbidity and health seeking behaviour were collected using a standard household survey administered at endline and a pictorial diary given to households over a six month period, collected at monthly intervals. RESULTS: Self-reported measures of morbidity and healthcare utilization were substantially lower in the household survey than the pictorial diary when the recall period was over a month. Introducing free healthcare had a positive effect on primary care visits based on the pictorial diary and a non-significant negative effect according to the household survey. Using any clinic visit in the past month as the outcome, the difference in the effect of free care between the two data collection methods was 3.6 percentage points (p = 0.078). CONCLUSIONS: The findings raise methodological concerns about measures of healthcare utilization from household surveys, particularly in the evaluation of health financing interventions.

A case of imported severe plasmodium falciparum malaria in the emergency department and the current role of exchange transfusion treatment.

BACKGROUND: The role of exchange transfusion in the management of severe malaria is not well documented in Emergency Medicine literature. OBJECTIVES: The goal of this article is to review the importance of considering malaria in the differential diagnosis of the febrile returned traveler and to discuss the role of exchange transfusion in the management of severe Plasmodium falciparum malaria. CASE REPORT: A 59-year-old woman presented to the Emergency Department (ED) with severe P. falciparum malaria. Her physical examination was remarkable for scleral icterus, dry mucous membranes, and tachycardia. Her complete blood count revealed a white blood cell count of 6.9 k/uL, with 71% segmented neutrophils, 19% bands, a hemoglobin level of 11.9 g/dL, hematocrit of 37.2%, and a platelet count of 9 k/uL. Hepatorenal impairment was present and malaria parasites with ring form were seen on malaria prep in 18% of red blood cells. The patient was treated with fluids, platelets, quinidine gluconate, doxycycline, and exchange transfusion with significant improvement in the patient's clinical condition. CONCLUSIONS: The high level of parasitemia presenting with acute kidney injury, hyperbilirubinemia, and thrombocytopenia supported the use of exchange transfusion as adjunct therapy. Exchange transfusion was a reasonable consideration in this case and was well tolerated by our patient. Institutions that are equipped with apheresis units should evaluate each case individually in concert with Centers for Disease Control experts and local consultants and weigh the risks and benefits of the use of exchange transfusion as an adjunct in the treatment of severe P. falciparum malaria.

Automated red blood cell exchange as an adjunctive treatment for severe Plasmodium falciparum malaria at the Vienna General Hospital in Austria: a retrospective cohort study.

BACKGROUND: Severe falciparum malaria is associated with considerable rates of mortality, despite the administration of appropriate anti-malarial treatment. Since overall survival is associated with total parasite biomass, blood exchange transfusion has been proposed as a potential method to rapidly reduce peripheral parasitaemia. However, current evidence suggests that this treatment modality may not improve outcome. Automated red blood cell exchange (also referred to as "erythrocytapheresis") has been advocated as an alternative method to rapidly remove parasites from circulating blood without affecting patients' volume and electrolyte status. However, only limited evidence from case reports and case series is available for this adjunctive treatment. This retrospective cohort study describes the use of automated red blood cell exchange for the treatment of severe malaria at the Medical University of Vienna. METHODS: Epidemiologic data for imported malaria cases in Austria are reported and data of patients treated for malaria at the General Hospital/Medical University of Vienna were extracted from electronic hospital records. RESULTS: Between 2000 and 2010, 146 patients were hospitalized at the Medical University of Vienna due to malaria and 16 of those were classified as severe malaria cases. Eleven patients of this cohort were potentially eligible for an adjunctive treatment with automated red blood cell exchange. Five patients eventually underwent this procedure within a period of seven hours (range: 3-19 hours) after hospital admission. Six patients did not undergo this adjunctive treatment following the decision of the treating physician. The procedure was well tolerated in all cases and rapid reduction in parasite counts was achieved without occurrence of haemodynamic complications. One patient died within seven days, whereas four patients survived without any sequelae. DISCUSSION AND CONCLUSION: Automated red blood cell exchange was a safe and efficient procedure to rapidly clear peripheral parasitaemia. Whether the fast reduction in parasite biomass may ultimately improve patient survival remains however unclear. Randomized controlled trials are needed to conclusively appreciate the value of this adjunctive treatment.

Apoptotic lymphocytes treated with IgG from Trypanosoma cruzi infection increase TNF-alpha secretion and reduce parasite replication in macrophages.

Phagocytic removal of apoptotic lymphocytes exacerbates replication of Trypanosoma cruzi in macrophages. We investigated the presence of Ab against apoptotic lymphocytes in T. cruzi infection and the role of these Ab in parasite replication. Both control and chagasic serum contained IgG Ab that opsonized apoptotic lymphocytes. Treatment of apoptotic lymphocytes with purified IgG from chagasic, but not control serum, reduced T. cruzi replication in macrophages. The protective effect of chagasic IgG depended on Fcgamma receptors, as demonstrated by the requirement for the intact Fc portion of IgG, and the effect could be abrogated by treating macrophages with an anti-CD16/CD32 Fab fragment. Chagasic IgG displayed increased reactivity against a subset of apoptotic cell Ag, as measured by flow cytometry and immunoblot analyses. Apoptotic lymphocytes treated with chagasic IgG, but not control IgG, increased production of TNF-alpha, while decreasing production of TGF-beta1 by infected macrophages. Increased control of parasite replication required TNF-alpha production. Previous immunization with apoptotic cells or injection of apoptotic cells opsonized with chagasic IgG reduced parasitemia in infected mice. These results indicate that Ab raised against apoptotic cells could play a protective role in control of T. cruzi replication by macrophages.

Automated erythrocytapheresis for severe falciparum malaria.

We describe a case of severe falciparum malaria with hyperparasitaemia. Treatment with automated erythrocytapheresis, in conjunction with parenteral artesunate, produced a rapid and sustained fall in parasite burden. Several poor prognostic features were present at admission. Despite the development of a severe headache with abnormal cerebrospinal fluid parameters and transient pulmonary oedema, a complete recovery was observed. Erythrocytapheresis can be considered in selected cases where facilities exist and has theoretical and practical advantages over traditional methods of red cell exchange transfusion. The paucity of systematic or trial evidence convincingly demonstrating a benefit in terms of morbidity or mortality has limited its application. However, the lack of robust trial data should not in itself invalidate considering this therapeutic option in the appropriate context.

Red Cell Exchange as Adjunctive Therapy for Babesiosis: Is it Really Effective?

Human babesiosis is a parasitic disease prevalent in the Northeastern and Midwestern United States (US). Treatment with antibiotics is the standard of care but red cell exchange (RCE) has been used as an adjunctive treatment in more severe disease. Data for the efficacy of RCE in the treatment of babesiosis has been based on case reports and case series. An English language literature search was conducted for cases of babesiosis treated with RCE since 1980 and relevant laboratory and clinical outcome data were extracted. Similar data were obtained on severe cases of babesiosis referred for RCE in our hospitals in the time period 2000 to 2020. Fifty reports including forty-one individual case reports and nine case series were retrieved. There were 108 patients that underwent RCE with an overall mortality rate of 20%. Some patients had more than one RCE. The patients varied in the level of anemia and evidence of compromise of renal or pulmonary function. The pre-RCE level of parasitemia varied between 1.7% to 85% with the vast majority >10%. The post-RCE level of parasitemia varied between 1% to 10%. Since 2000, 32 patients were referred for RCE in our hospitals and RCE was performed on 23 of 32. There were more patients treated with RCE in the second decade as compared to the first decade, 19 versus 4 respectively. The overall mortality was 22% similar to the national data. Comparing the cohort treated with RCE to the 9 patients who were treated only with antibiotics, there were similar levels of parasitemia and laboratory parameters. The overall number of days needed to achieve a parasite count <1% was similar between the two cohorts and mortality for the antibiotics only cohort was 0%. More than 40 years after the first reported case of RCE in severe babesiosis it cannot be concluded that this adjunctive therapy favorably influences the clinical outcome. Since there is largely equipoise, a registry of severe patients treated with or without RCE could identify a benefit or otherwise.

In vivo antimalarial activity of a probiotic bacterium Lactobacillus sakei isolated from traditionally fermented milk in BALB/c mice infected with Plasmodium berghei ANKA.

ETHNOPHARMACOLOGICAL RELEVANCE: Milk production, processing and consumption are integral part of traditional practices in Fulani tribe of Cameroon. It has been observed that Fulani are resistant to malaria. Dairy products traditionally processed by Fulani are intensively used in the ritual treatment of malarial, inflammations and behavioural disorders. Many studies have demonstrated that fermented milk is a rich source of probiotic bacteria. However, the antimalarial activity of probiotics isolated from this natural source has not been experimentally tested. AIM OF THE STUDY: Hence, this study was therefore aimed at evaluating the antimalarial activity of a probiotic bacterium Lactobacillus sakei isolated from traditionally fermented milk in mice infected with chloroquine sensitive Plasmodium berghei ANKA. MATERIALS AND METHODS: The probiotic bacterium was isolated from the Cameroonian Mborro Fulani's traditionally fermented milk and identified using the 16S r RNA gene sequencing. The schizontocidal activity of Lactobacillus sakei on established malaria infection was evaluated. Eighty-four healthy young adult Balb/c mice infected with Plasmodium berghei parasite were randomly divided into two sets of seven group of six mice each, and were given three different doses of Lactobacillus sakei, chloroquine and sulfadoxine/pyrimethamine for seven and fourteen days respectively. The level of parasitaemia, body temperature, survival time and haematological parameters were evaluated. RESULTS: The parasite growth inhibition was observed to increase with increasing dose of probiotic bacterium with maximum suppression being 100 % at dose 3 on day 20. Also, the probiotic bacterium significantly prevented body weight loss and was associated with body temperature reduction and prevented (p<0.05) a decrease in haematological parameters compared to that untreated malaria infected mice. CONCLUSION: The results obtained suggest that Lactobacillus sakei is a probiotic bacterium with antimalarial activity in mice infected with chloroquine sensitive Plasmodium berghei.

Pre-clinical evaluation of a whole-parasite vaccine to control human babesiosis.

Babesia spp. are tick-transmitted intra-erythrocytic protozoan parasites that infect humans and animals, causing a flu-like illness and hemolytic anemia. There is currently no human vaccine available. People most at risk of severe disease are the elderly, immunosuppressed, and asplenic individuals. B. microti and B. divergens are the predominant species affecting humans. Here, we present a whole-parasite Babesia vaccine. To establish proof-of-principle, we employed chemically attenuated B. microti parasitized red blood cells from infected mice. To aid clinical translation, we produced liposomes containing killed parasite material. Vaccination significantly reduces peak parasitemia following challenge. B cells and anti-parasite antibodies do not significantly contribute to vaccine efficacy. Protection is abrogated by the removal of CD4+ T cells or macrophages prior to challenge. Importantly, splenectomized mice are protected by vaccination. To further facilitate translation, we prepared a culture-based liposomal vaccine and demonstrate that this performs as a universal vaccine inducing immunity against different human Babesia species.

Considerations on the use of adjunct red blood cell exchange transfusion in the treatment of severe Plasmodium falciparum malaria.

BACKGROUND: Travelers returning to the United States from malaria-endemic areas are at increased risk of a potentially fatal infection from Plasmodium falciparum, which requires prompt and aggressive treatment. STUDY DESIGN AND METHODS: Described is a case of a 7-year-old boy who was infected by P. falciparum while in Africa and developed features of severe infection, including hyperparasitemia, altered neurologic status, and malarial hepatitis. RESULTS: A single automated erythrocytapheresis procedure reduced parasitemia from 14% to less than 1%. Along with intravenous quinidine, this reduced parasite level was maintained throughout the hospitalization and the patient recovered. CONCLUSION: Exchange transfusion (ET) is an effective adjunct therapy to reduce the parasite load in cases of severe P. falciparum malaria. When performed in certain defined settings, the benefits can outweigh the risks of the procedure. Discussed are the medical and technical considerations on the use of adjunctive ET for severe P. falciparum infection and a review of the literature of the use of adjunct ET in the treatment of severe P. falciparum malaria.

Efficacy and safety of exchange transfusion as an adjunct therapy for severe Plasmodium falciparum malaria in nonimmune travelers: a 10-year single-center experience with a standardized treatment protocol.

BACKGROUND: Even in circumstances where optimal antimalarial and supportive treatment is available, severe Plasmodium falciparum malaria is still associated with a significant case fatality. Although exchange transfusion (ET) has been considered as a controversial adjunct therapy, we have not encountered any case fatality since ET was introduced as a standard adjunct therapy for patients with severe malaria. STUDY DESIGN AND METHODS: In this retrospective cohort study of 25 patients with severe malaria, the efficacy and safety of ET as an adjunct to parenteral antimalarial treatment (which was implemented in our hospital starting in 1998) were evaluated and compared with 31 historical control patients who were treated with conventional parenteral antimalarial treatment in the period before ET was added to the standard of care for severe malaria (generally before 1997). RESULTS: The parasite clearance times (PCT)(25%), PCT(50%), PCT(75%) and PCT(90%) were all significantly shorter for patients treated with ET than for patients treated with parenteral quinine only. The shorter PCTs in the ET group were the result of a more rapid parasite clearance in the early phases after initiation of ET. CONCLUSION: No case fatalities were observed in the ET group. The complications that were observed with ET were more likely related either to the multiorgan dysfunction associated with severe malaria or to side effects of parenteral quinine rather than to the ET procedure. ET may be safely executed in a setting with intensive care facilities and availability of safe blood products and should be considered as a beneficial adjunct treatment to parenteral antimalarial therapy.

Red cell exchange transfusion for babesiosis in Rhode Island.

We report four cases of clinically severe tick borne babesiosis treated with chemotherapy and adjunctive red cell exchange (RCE) at two Rhode Island hospitals from 2004 to 2007. All RCE procedures were performed using a Cobe Spectra device and were well tolerated without complications. The volume of allogeneic red cells used in the exchange was determined using the algorithm in the apheresis device with the input variables of preprocedure hematocrit, weight, height, an assumed allogeneic red cell hematocrit of 55 and a desired post procedure hematocrit of 27. The preprocedure level of parasitemia varied between 2.4% and 24% and the postprocedure level of parasitemia between 0.4 and 5.5% with an average overall percent reduction in parasitemia of 74%. Retrospectively, application of a new formula to calculate red cell mass appeared to correlate better with the percent reduction in parasitemia. Previous reports of RCE in babesiosis were reviewed. The reported reduction in parasitemia varied from 50% to >90%. Although a preprocedure level of parasitemia of 10% is sometimes used as a threshold for RCE in clinically severe babesiosis, this threshold does not have a firm empirical basis. No postprocedure desired level of parasitemia is indicated nor the mass of allogeneic red cells needed to achieve such a level. We conclude that current estimates of the dose of allogeneic red cells used in RCE are probably inaccurate, advocate a new formula to estimate this dose and suggest that a 90% reduction in parasitemia should be the minimally desired target of RCE in babesiosis.

Was the First Malaria Vaccine Tested in 1898?

Early trials of killed, whole-cell typhoid vaccine indicated a paradoxical, positive effect on malaria infections. British soldiers in India in 1898 reported > 90% decrease in malaria recurrences after receiving an investigational typhoid vaccine despite no intention or expectation to observe such an outcome. In the 1940s, multiple doses of intravenous typhoid vaccine appeared to control parasitemia and limit reinfection in three syphilis patients purposefully infected with Plasmodium vivax. Several modern vaccines (against human papillomavirus, hepatitis B virus, and malaria) use a detoxified lipid A derived from Salmonella as an immune adjuvant. Early typhoid vaccines could have plausibly functioned as an innate immune stimulus, leading to some protection against malaria.