Immune-mediated Hemolytic Anemia Research Articles

Azathioprine and low dose prednisolone in the therapy of secondary Immune-Mediated Hemolytic Anemia (IMAH) in dogs: case report

Immune-Mediated Hemolytic Anemia (IMHA) is an autoimmune disease characterized by hemolysis of erythrocytes of primary or secondary origin, occurring in dogs and recommended therapy using corticosteroids and immunomodulators. Thus, the objective is to report the association of azathioprine with low-dose prednisolone in the treatment of secondary IMHA pyometra. A female, American Pitbull breed, 8 years old, not castrated, arrived for treatment with anorexia, weight loss and prostration for 7 days; being diagnosed with pyometra after clinical and complementary examinations. Seven days after surgery, the patient returned prostrate with a blood count showing hypochromic normocytic anemia, leukocytosis, reticulocytes with a moderate response and a positive saline agglutination test, confirming AHIM. The therapy adopted was azathioprine (2 mg/kg) and a low dose of prednisolone (0.5 mg/kg), both administered orally every 24 hours. Within twelve days, he was clinically stable with normalization of hematological parameters. It was concluded that the association of azathioprine with low-dose prednisolone was effective in controlling IMHA secondary to pyometra.

Oxidative stress induces plasma membrane phosphatidylserine externalization in canine erythrocytes in vitro, mitigated by thiol antioxidants.

To determine if oxidative stress induces phosphatidylserine (PS) externalization in canine erythrocytes and if exposure to antioxidants prevents such changes. This was an in vitro, experimental study using 5 healthy, adult, purpose-bred research Beagles. Fresh EDTA-anticoagulated blood samples were collected from each dog, and erythrocytes were harvested. For objective 1, erythrocytes were exposed to the pro-oxidant agents tert-butyl hydroperoxide (TBHP) at 2, 3, or 4 mM or 2,2'-azobis(2-amidinopropane) dihydrochloride at 30, 40, or 50 mM. For objective 2, erythrocytes were exposed to 3 mM TBHP and the antioxidant N-acetylcysteine-amide (NACA) at various concentrations (0, 1, or 3 mM). Erythrocytes incubated with benzoylbenzoyl-ATP were used as positive control, whereas erythrocytes incubated with sodium chloride medium with 0.1% bovine serum albumin, DMSO, and NACA were used as negative controls. Erythrocytes were stained with allophycocyanin-conjugated Annexin V, and PS externalization was assessed by flow cytometry. The degree of PS externalization of each sample was recorded as median fluorescence intensity and percentage of PS positivity. TBHP at 3 and 4 mM caused increased PS externalization in canine erythrocytes. 2,2'-Azobis(2-amidinopropane) dihydrochloride at all concentrations caused increased PS externalization. N-acetylcysteine-amide at all concentrations prevented significant PS externalization measured by median fluorescence intensity and percentage of PS positivity from erythrocytes exposed to TBHP. Oxidative stress causes PS externalization in canine erythrocytes, and NACA ameliorates this effect. Future studies are needed to determine if increased PS externalization in erythrocytes occurs in dogs with immune-mediated hemolytic anemia and its role in promoting thromboembolism.

Progression of cyclosporine A-blood levels in experimental cats receiving a high-dose treatment protocol.

Cyclosporine A (CsA) is used as a steroid-sparing or alternative immunosuppressing agent in cats with various immune-mediated diseases such as immune-mediated hemolytic anemia. Daily treatment dosages of 5-20 mg/kg have been described. Interindividual variations in CsA blood levels are known to occur. To determine when steady-state conditions are reached and thus the earliest advisable time for monitoring CsA blood levels during the course of treatment, a prospective experimental study was conducted in six healthy adult Domestic Shorthair cats. Cats were treated with an oral dosage of 7 mg/kg CsA q 12 h for 10 days. On days 1, 2, 3, 5, 7, and 10 after the start of CsA administration (i.e., after 1, 3, 5, 9, 13, and 19 CsA administrations), EDTA blood was collected to measure the CsA level 12 h after the CsA administration (trough values) using high-performance liquid chromatography coupled to mass spectrometry (HPLC-MS/MS). Statistical analysis revealed a significant increase in mean CsA blood levels up to day 5 (2,050 ± 964.2 ng/mL [mean ± SD], 832-3,203 ng/mL [minimum-maximum]; repeated-measures ANOVA: p = 0.0021), while values on days 5 and 7 did not differ significantly from CsA concentrations on day 10. CsA concentrations showed markedly interindividual variability. Cyclosporine A blood levels reached a steady state on day 5 of high dosages of CsA q 12 h (i.e., after nine CsA administrations), indicating that this time point is suitable for monitoring blood levels in clinical patients. Results confirmed the well-known remarkable interindividual variability of CsA, indicating the need for treatment monitoring. The assessed treatment regime resulted in significantly higher mean CsA trough levels than the target range for immunosuppressive therapy (200-600 ng/mL).

ANEMIA HEMOLÍTICA IMUNOMEDIADA SECUNDÁRIA A ERLIQUIOSE

Ehrlichiosis is an infectious and contagious disease that can be transmitted to humans and is therefore considered a zoonosis. During the development of the disease, immune- mediated haemolytic anemia occurs, characterized by a decrease in red blood cells due to the action of the phagocytic system in association with the presence of immunoglobulins. This research is based on the relationship between immune-mediated hemolytic anemia and Ehrlichiosis, with the aim of understanding both diseases, relating how they develop in the body, as well as their etiology, symptoms, laboratory changes, treatment and prophylaxis. To achieve this goal, data was collected through bibliographic research, and the results indicated the importance of controlling and preventing the disease through measures linked to the use of ticks and periodic monitoring by the veterinarian, since immune-mediated hemolytic anemia occurs secondary to this hemoparasitosis.

Immune Mediated Haemolytic Anaemia Associated with Haemoparasitic Infections in Dogs

A haematological condition known as Immune-Mediated Haemolytic Anaemia (IMHA) affects dogs and is caused by antibodies directly destroying red blood cells in the bloodstream. It can be primary (idiopathic) or secondary (caused by neoplastic or infectious illnesses). An attack on circulating red blood cells by the immune system is the hallmark of IMHA, a potentially fatal autoimmune disease. Though the disease occurs naturally in both humans and dogs, it is significantly more prevalent in dogs. The aim of this review was to methodically assess the available data on the disease's clinico-pathology, its therapy and utilize the results to derive recommendations that may be implemented in broader veterinary medicine.

Clinical presentation, outcome and prognostic factors in dogs with immune-mediated haemolytic anaemia: a retrospective single-centre study of 104 cases in Ireland (2002–2020)

BackgroundImmune-mediated haemolytic anaemia (IMHA) has a high mortality rate within the first weeks to months of diagnosis. Identifying dogs at increased risk of death may help guide decision-making for owners and veterinarians. Prior studies have identified several but inconsistent prognostic factors. The objectives of the study were to describe the clinical presentation and outcome of canine immune-mediated haemolytic anaemia in Ireland and to assess for independent factors associated with survival including long-term survival. Medical records from a single centre were reviewed between 2002 and 2020 to identify dogs with immune-mediated haemolytic anaemia using the American College of Veterinary Internal Medicine (ACVIM) consensus statement algorithm. Survival analysis was performed using univariable Cox proportional hazards regression models with Breslow method for ties to identify prognostic factors.ResultsOne hundred and four cases were included. The diagnosis of immune-mediated haemolytic anaemia was classified as definitive, supportive and suspicious in 42 (40%), 50 (48%), and 12 dogs (12%) respectively. Twenty-two dogs (21%) were diagnosed with associative IMHA and 82 dogs were diagnosed with non-associative IMHA (79%). 65% of the cases received more than one immunosuppressive medication during the course of treatment. The mortality rate at one and three months was 16% (95% confidence interval [CI] 9–26) and 31% (95% CI 21–43) respectively. Excluding dogs that died within three months, the median survival time was 2664 days. The relapse rate during the follow-up period was 7%. Survival did not improve over the course of the study period. Thrombocytopenia and hyperbilirubinaemia were identified as negative prognostic indicators (Hazard ratio 2.2 and 2.5, 95% CI 1.1–4.1 and 1.1–5.6, respectively).ConclusionsExcluding dogs that died within three months, the outcome was good in dogs with non-associative immune-mediated haemolytic anaemia in Ireland. The relapse rate was low regardless of the presence of associative causes. Thrombocytopenia and hyperbilirubinaemia were the only independent negative prognostic factors. The one-month and three-month mortality rates were similar compared to prior studies and survival did not improve over time during the study period: the mortality rate of canine immune-mediated haemolytic anaemia remains high in the acute phase.

Methylprednisolone alone or combined with cyclosporine or mycophenolate mofetil for the treatment of immune-mediated hemolytic anemia in dogs, a prospective study.

Benefit of adding a second-line immunosuppressive drug to glucocorticoids for the treatment of non-associative immune-mediated hemolytic anemia (naIMHA) in dogs has not been defined prospectively. Evaluate the effectiveness of different immunosuppressive protocols in naIMHA dogs. Forty-three client-owned dogs. Open label, randomized, clinical trial. Dogs were treated with methylprednisolone (M-group), methylprednisolone plus cyclosporine (MC-group) or methylprednisolone plus mycophenolate mofetil (MM-group). Dogs were defined as responders by disappearance of signs of immune-mediated destruction and hematocrit stabilization. Frequency of responders was compared between M-group and combined protocols (MC and MM-group evaluated together), and among the 3 different therapeutic groups at 14 (T14), 30 (T30), 60 (T60) days after admission. Frequency of complications, length of hospitalization and relapse were also compared. Death rate was evaluated at discharge, T60 and 365 (T365) days. Proportion of responders was not significantly different between M-group and combined protocols (MC and MM-groups), nor among the 3 therapeutic groups at T14, T30, and T60 (P > .17). Frequency of relapse, complications, and length of hospitalization were not significantly different between M-group and dogs treated with combined protocols, nor among the 3 treatment groups (P > .22). Death was significantly more common only for MM-group compared with MC-group at T60 (+42.8%; 95% CI: 11.5-67.4; P = .009), and at T365 (+50%; 95% CI: 17.5-73.2; P = .003). Combined immunosuppressive therapy did not improve hematological response in naIMHA.

A Bibliometric Analysis of Thromboelastography in Veterinary Clinical Use

The evaluation of coagulation with thromboelastography (TEG) has been of high interest for the last two decades in veterinary medicine. The main cause is the ability to detect hypo-, normo- and hypercoagulative states in a single TEG analysis. In clinical veterinary medicine, the importance of coagulation in terms of course and outcome in many diseases had been realized through research over time. TEG studies had gained importance as traditional coagulation tests were inadequate, especially in cases complicated with hypercoagulation. The bibliometric analysis determined topics, researchers and countries of studies in veterinary clinical use of TEG. According to the Web of Science database, a total of 371 documents in this research field were identified between 1998 and 2023. In 2012, with 39 articles, the highest number of studies were published. The most relevant author was Kristensen A.T. with 39 articles. In the list of corresponding authors’ countries, the first country with 189 authors was determined as the USA. Trend topics and their distribution over time have shown that dogs were the most studied animal species in this field. A high number of studies on the topic hypercoagulability and immune-mediated hemolytic anemia were detected, but in the last 3 years new topics like antithrombotics and rational use were involved. The bibliometric analysis carried out showed the changes over time and the currentness of the subject. The results of the present study could be used in planning future studies in the field of veterinary clinical use of TEG.

A Case of Immune-Mediated Coombs-Negative Hemolytic Anemia in a Patient with Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an auto-immune connective tissue disorder that can involve any organ in the body. The American College of Rheumatology criteria (ACR) include autoimmune hemolytic anemia with reticulocytosis as one of the criteria in the diagnosis of SLE. Anti-erythrocyte antibodies in SLE are mainly warm-type IgG. We present a case of systemic lupus erythematosus presenting with immune-mediated Coombs-negative hemolytic anemia. This case highlights the possibility of autoimmune hemolysis occurring with a negative Coombs test, where the autoantibody levels are too low to be detected by a conventional direct antiglobulin test. (DAT)

Donor/recipient Rh-mismatched allogeneic hematopoietic stem cell transplantation: transfusion strategy and allo-immunization to red blood cell antigens.

In the case of donor/recipient rhesus (Rh)-incompatibility after allogeneic hematopoietic stem cell transplantation (alloHSCT), the transfusion policy in France is to transfuse red blood cells (RBC) in the donor's Rh phenotype from the day of transplantation, leading to a risk of allo-immunization, either of donor or recipient origin. In this single-center retrospective study, the incidence of donor/recipient Rh incompatibility was 7.1% over an 8-year period including 1012 alloHSCT. Six of 58 evaluable patients (10.3%) developed alloantibodies to RBC antigens within one year of alloHSCT. None of these allo-immunizations were directed against the donor-mismatched Rh antigens and none could have been prevented by the transfusion of recipient and donor Rh-compatible RBC units. None of these allo-immunizations led to immune-mediated hemolytic anemia. We observed a statistically significant higher incidence of chronic GVHD among patients with anti-RBC allo-immunization. In the context of donor/recipient Rh incompatibility, the transfusion of packed RBC units in the donor's Rh phenotype from the day of alloHSCT is feasible and not associated with a high risk of allo-immunization. The generalization of this strategy could be discussed even when donor and recipient Rh phenotypes could be respected, to allow the preservation of units of infrequent phenotypes for other indications.

Idiopathic Immune Mediated Haemolytic Anaemia (IMHA) in a 2.5-Month-old Puppy: A Case Report

Background: A 2.5-month-old puppy was presented to the Veterinary Clinical Complex of the College of Veterinary Sciences and AH, Jalukie, Nagaland with a complaint of emesis for one week, inappetence, icterus of the lower abdominal area and other visible mucous membrane. Detailed clinical history was collected and clinical examination was conducted. Methods: 4 ml blood peripheral blood was collected from the cephalic vein in the Lev-Lock blood clot activator vacutainer to harvest serum for biochemical analysis. Another 2 ml of whole blood was also collected in Lev-Lock K3 EDTA vacutainer for complete blood count, blood smear examination for blood parasites, morphological changes in the RBC and IDEXX SNAP 4Dx Plus test kit was also used for diagnosis of the blood parasites test. Result: Peripheral blood smear examination and IDEXX SNAP 4Dx Plus test were found to be negative for blood parasites, but spherocytosis could be observed in the blood smears. A complete blood count (CBC) examination revealed severe anaemia of macrocytic normochromic type, neutrophilic leucocytosis and thrombocytopenia. Serum biochemistry revealed a decrease in blood urea nitrogen (BUN) and creatinine with normal alanine transaminase (ALT). Treatment with whole blood transfusion, corticosteroid and other supportive therapy was successful in this case. Based on the clinical presentation, laboratory findings and its response to the treatment with prednisolone, it was diagnosed as an idiopathic immune-mediated haemolytic anaemia (IMHA) with an extravascular mechanism of haemolysis. A follow-up review after 1 year and 4 months post-treatment reported that the dog was still alive and healthy.

Managing severe anaemia with a blood transfusion in a suspected IMHA case

This article discusses a challenging case from initial presentation, stabilisation and treatment to relapse. The case had an inconclusive diagnosis and differentials of hemangiosarcoma or immune-mediated haemolytic anaemia. The case progression included intensive medical management and a whole-blood transfusion with an excellent outcome. The patient, Patch (8-year-old male neutered Jack Russell Terrier), presented with history of lethargy and sudden onset of inappetence. Clinical symptoms alongside a MPCV 19%, RBC 0.25, haemoglobin 63, high platelets and borderline basophils.

Stem cell therapy for dogs with immune-mediated hemolytic anemia

Stem cell therapy for dogs with immune-mediated hemolytic anemia

Comparison of timing of relapse in dogs with nonassociative immune-mediated hemolytic anemia, thrombocytopenia, or polyarthritis.

Relapse is a clinical concern in dogs diagnosed with immune-mediated hemolytic anemia (IMHA), thrombocytopenia (ITP), or polyarthritis (IMPA). The average time to relapse is unknown, and evidence that vaccination is associated with disease relapse is lacking. Compare the incidence of relapse in groups of dogs with IMHA, ITP, or IMPA over a 24-month period after diagnosis and compare proportions of dogs that received vaccines in those dogs that did and did not relapse. One hundred sixty client-owned dogs (73 with IMHA, 55 with ITP, 32 with IMPA). Medical records of dogs were reviewed with the goal of following cases for a minimum of 2 years. Incidence of relapse was calculated for each disease, and relapse rates in dogs that were or were not vaccinated after diagnosis were compared. Relapse rates at 12 months differed significantly among disease groups (P = .02), with a higher rate for IMPA (35%) compared to IMHA (11%) or ITP (11%). Relapse rate at 24 months was 41% for IMPA, 18% for IMHA, and 23% for ITP. Ninety percent of IMPA relapses occurred in the first 12 months after diagnosis, compared with 56% for IMHA and 50% for ITP. Vaccine administration after diagnosis was not associated with relapse (P = .78). Risk of disease relapse in IMPA is highest in the first year after diagnosis, with a higher relapse rate compared with IMHA and ITP. The role of vaccination in disease relapse remains unclear.

When gallbladder oedema comes as a chronic disease – diagnosis and treatment

Diagnosis of the gallbladder oedema is difficult during the clinical examination because the clinical signs are not specific for this disease. The causes of this pathology are multiple and can be divided into emergencies (such as anaphylactic shock, right-sided hearth failure, pericardial effusion) and chronic pathologies (such cholecystitis, pancreatitis or immune-mediated hemolytic anemia). Imagistics methods complete the information of the clinical exam and ultrasound is considered the golden standard for diagnosing this pathology. Normally, at the ultrasound exam, the gallbladder has a hyperechoic wall, with a diameter of 2-3 mm; while in case of gallbladder oedema, the wall is thick and has a triple stratification, with 2 hyperechoic rows, separated by a hypoechoic line. This pathognomonic description of the gallbladder oedema is also known as the ‘Halo Sign’ or ‘Double Rim Effect’. Making a correct differential for the appearance of the sign is vital for the outcome of the case. The main focus is to exclude every emergency cause in order to start treating the chronic pathologies. This paper presents the pathologies leading to gallbladder oedema, met at the Radiology and Emergencies Departments from the Faculty of Veterinary Medicine Iasi during the period march 2020 – may 2022. The clinical case presented was diagnosed and treated at the Center of Endoscopy and Minimally Invasive Surgery Bucharest.

A retrospective review of cats with suspected false positive results in point-of-care feline leukemia virus tests and concurrent immune-mediated anemia.

To describe clinical findings, diagnosis, treatment, and survival in 18 cats with anemia of suspected immune-mediated origin (ASIMO) and conflicting results using FeLV diagnosis tests, and to suggest an accurate way to assess their FeLV diagnosis. 18 cats. Medical records from 5 veterinary institutions were retrospectively reviewed to identify cats with ASIMO, positive results on p27 SNAP ELISA, and negative results on pro-virus PCR testing in peripheral blood, in the absence of other identified triggers. Follow-up was recorded from diagnosis to the time of writing, and survival analysis was performed to assess similarities with previous published data. 18 cats were enrolled from referral centers in Spain, Italy, and the United Kingdom. Both peripheral immune-mediated hemolytic anemia (IMHA; 12/18) and precursor targeted immune-mediated anemia (PIMA; 6/18) were described. When the SNAP ELISA test was rechecked in patients with disease control, SNAP ELISA positive results had become negative. Two cats had a relapse of the ASIMO, and the FeLV SNAP ELISA tested positive again. Other signs of FeLV disease did not appear in any of these patients despite immunosuppression. 14 cats (14/18 [78%]) were alive at the time of writing, and the mean estimated survival time was 769 days. This study describes incongruent FeLV results in cats with ASIMO. It supports the necessity to confirm FeLV SNAP ELISA positive results using additional tools, such as pro-virus PCR testing, as different p27 point-of-care and external serological tests may be inconsistent.

Immune-mediated hemolysis after administration of human intravenous immunoglobulin in a dog: a case report

A 10-year-old spayed female Maltese presented with purpura and hematemesis. Initial laboratory evaluation revealed immune-mediated thrombocytopenia, but evidence of hemolytic anemia was not identified. Three milligrams of human intravenous immunoglobulin (hIVIG) was administered for 3 hours following prednisolone and mycophenolate mofetil. A pale mucous membrane was identified, and the packed cell volume decreased by 3%. Blood film examination revealed significant spherocytosis with auto-agglutination. Blood transfusions and immunosuppression were continued for 4 days, and hIVIG was discontinued. This report describes a case of increased immune-mediated hemolysis after hIVIG administration, possibly due to new-onset immune-mediated hemolytic anemia or enhanced immunogenicity.

Immune-mediated hematological disease in dogs is associated with alterations of the fecal microbiota: a pilot study

BackgroundThe dog is the most popular companion animal and is a valuable large animal model for several human diseases. Canine immune-mediated hematological diseases, including immune-mediated hemolytic anemia (IMHA) and immune thrombocytopenia (ITP), share many features in common with autoimmune hematological diseases of humans. The gut microbiome has been linked to systemic illness, but few studies have evaluated its association with immune-mediated hematological disease. To address this knowledge gap, 16S rRNA gene sequencing was used to profile the fecal microbiota of dogs with spontaneous IMHA and ITP at presentation and following successful treatment. In total, 21 affected and 13 healthy control dogs were included in the study.ResultsIMHA/ITP is associated with remodeling of fecal microbiota, marked by decreased relative abundance of the spirochete Treponema spp., increased relative abundance of the pathobionts Clostridium septicum and Escherichia coli, and increased overall microbial diversity. Logistic regression analysis demonstrated that Treponema spp. were associated with decreased risk of IMHA/ITP (odds ratio [OR] 0.24–0.34), while Ruminococcaceae UCG-009 and Christensenellaceae R-7 group were associated with increased risk of disease (OR = 6.84 [95% CI 2–32.74] and 8.36 [95% CI 1.85–71.88] respectively).ConclusionsThis study demonstrates an association of immune-mediated hematological diseases in dogs with fecal dysbiosis, and points to specific bacterial genera as biomarkers of disease. Microbes identified as positive or negative risk factors for IMHA/ITP represent an area for future research as potential targets for new diagnostic assays and/or therapeutic applications.

Immune-Mediated Hemolytic Anemia and Clinically Suspected Acute Pancreatitis in Dogs, a Pilot Study

Acute pancreatitis can be a complication of massive hemolysis, above all when intravascular in nature. Therefore, the aim of this study was to investigate the association between canine immune mediated hemolytic anemia (IMHA) and clinically suspected acute pancreatitis (CSAP) and the role of calculated free plasma hemoglobin (Hbfp) in CSAP occurrence/development. In this cohort study the records of 95 dogs with IMHA and 95 sick dogs with pathologies other than IMHA were compared for CSAP occurrence/development. At presentation, 12/95 dogs with IMHA met criteria for CSAP, while only 3/95 sick control dogs met these criteria (χ2 =1.58, P = .008). Within 7 days of hospitalization 9 additional dogs with IMHA had developed CSAP. The Hbfp was calculated and compared for dogs with IMHA that had/developed CSAP and for those without CSAP. In dogs with IMHA, a calculated Hbfp concentration ≥ 0.08 g/dL resulted in an increased relative risk (RR) of having/developing CSAP (RR = 2.54, 95% CI, 1.51-4.29; P = .003). No significant effect on short-term prognosis in dogs with IMHA was found between those having/developing CSAP and those without CSAP. This study showed that dogs with IMHA have an increased risk of having CSAP and Hbfp concentration may be involved in the pathogenesis of acute pancreatitis.

Regenerative response in dogs naturally and experimentally infected with Babesia rossi.

The regenerative response following Babesia rossi infection in dogs is mild, despite severe hemolytic anemia. We aimed to compare the admission absolute reticulocyte count (ARC) and reticulocyte indices in 103 dogs naturally infected with B. rossi with 10 dogs suffering from immune-mediated hemolytic anemia (IMHA) and 14 healthy control dogs. The regenerative response was also evaluated in five dogs experimentally infected with B. rossi. This is a retrospective observational study of records generated on the ADVIA 2120 hematology analyzer. The median hematocrits (HCT) of the B. rossi and IMHA groups were significantly lower than the control group (p < .001 for both); however, no differences were seen between the B. rossi and IMHA groups. Compared with the control group, the median ARC was significantly higher in the B. rossi (p = .006) and IMHA (p = .019) groups but significantly lower in the B. rossi group than the IMHA group (p = .041). In the experimentally infected dogs, there was a sudden decrease in the ARC approximately 48 h after the detection of peripheral parasitemia, which was followed by an increase after treatment. Reticulocytes of naturally infected B. rossi dogs were larger, with more variation in cellular volume. The reticulocytes of the experimentally infected dogs decreased in size with decreasing hemoglobin concentrations as the study progressed. The regenerative response in dogs naturally infected with B. rossi is inadequate, given the severity of the anemia observed, and it might be a result of direct suppressive action by the parasite or host response on the bone marrow.