Ehrlichia-Induced Hemophagocytic Lymphohistiocytosis: A Case Series and Review of Literature

Human monocytotropic ehrlichiosis-A systematic review and analysis of the literature

Human monocytotropic ehrlichiosis (HME) is a tick-borne bacterial infection caused by Ehrlichia chaffeensis. Most available data come from case reports, case series and retrospective studies, while prospective studies and clinical trials are largely lacking. To obtain a clearer picture of the currently known epidemiologic distribution, clinical and paraclinical presentation, diagnostic aspects, complications, therapeutic aspects, and outcomes of HME, we systematically reviewed the literature and analyzed and summarized the data. Cases of HME are almost exclusively reported from North America. Human infections due to other (non-chaffeensis) Ehrlichia spp. are rare. HME primarily presents as an unspecific febrile illness (95% of the cases), often accompanied by thrombocytopenia (79.1% of the cases), leukopenia (57.8% of the cases), and abnormal liver function tests (68.1% of the cases). Immunocompromized patients are overrepresented among reviewed HME cases (26.7%), which indicates the role of HME as an opportunistic infection. The incidence of complications is higher in immunocompromized compared to immunocompetent cases, with ARDS (34% vs 19.8%), acute renal failure (34% vs 15.8%), multi organ failure (26% vs 14.9%), and secondary hemophagocytic lymphohistiocytosis (26% vs 14.9%) being the most frequent reported. The overall case fatality is 11.6%, with a significant difference between immunocompetent (9.9%) and immunocompromized (16.3%) cases, and sequelae are rare (4.2% in immunocompetent cases, 2.5% in immunocompromised cases).

Hemophagocytic Lymphohistiocytosis (HLH) in Patients with Tick-Borne Illness: A Scoping Review of 98 Cases

Hemophagocytic lymphohistiocytosis (HLH) secondary to tick-borne infections is a rare but potentially life-threatening syndrome. We performed a scoping review according to PRISMA guidelines to systematically analyze the existing literature on the topic. A total of 98 patients were included, with a mean age of 43.7 years, of which 64% were men. Most cases, 31%, were reported from the USA. Immunosuppression was present in 21.4%, with the most common cause being previous solid organ transplantation. Constitutional symptoms were the most common, observed in 83.7% of the patients, while fever was reported in 70.4% of cases. Sepsis was present in 27.6%. The most common laboratory abnormalities in this cohort were thrombocytopenia in 81.6% of patients, while anemia, leukopenia, and leukocytosis were observed in 75.5%, 55.1%, and 10.2%, respectively. Liver enzyme elevation was noted in 63.3% of cases. The H-score was analyzed in 64 patients, with the mean value being 209, and bone marrow analysis was performed in 61.2% of patients. Ehrlichia spp. was the main isolated agent associated with HLH in 45.9%, followed by Rickettsia spp. in 14.3% and Anaplasma phagocytophilum in 12.2%. Notably, no patient with Powassan virus infection or Lyme borreliosis developed HLH. The most common complications were acute kidney injury (AKI) in 35.7% of patients, shock with multiple organ dysfunction in 22.5%, encephalopathy/seizure in 20.4%, respiratory failure in 16.3%, and cardiac complications in 7.1% of patients. Treatment included antibiotic therapy alone in 43.9%, while 5.1% of patients were treated with immunosuppressants alone. Treatment with both antibiotics and immunosuppressants was used in 51% of patients. Appropriate empiric antibiotics were used in 62.2%. In 43.9% of cases of HLH due to tick-borne disease, patients received only antimicrobial therapy, and 88.4% of those recovered completely without the need for immunosuppressive therapy. The mortality rate in our review was 16.3%, and patients who received inappropriate or delayed empiric therapy had a worse outcome. Hence, we suggest empiric antibiotic treatment in patients who are suspected of having HLH due to tick-borne disease or in whom diagnostic uncertainty persists due to diagnostic delay in order to minimize mortality.

Zoonotic Bacterial Infections Triggering Cytokine Storm Syndrome

Zoonotic infections can result in life-threatening complications that can manifest with hemophagocytic lymphohistiocytosis (HLH)/cytokine storm syndrome (CSS). Bacteria constitute the largest group of zoonotic infection-related HLH cases. The growing list of zoonotic bacterial infections associated with HLH/CSS include Brucella spp., Rickettsia spp., Ehrlichia, Coxiella burnetii, Mycobacterium spp., and Bartonella spp. Patients most commonly present with fever, cytopenias, hepatosplenomegaly, myalgias, and less frequently with rash, jaundice, and lymphadenopathy.

Secondary hemophagocytic lymphohistiocytosis in children (Review)

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition characterized by hyperinflammation in an uncontrolled and ineffective immune response. Despite great improvement in diagnosis and treatment, it still represents a challenge in clinical management, with poor prognosis in the absence of an aggressive therapeutic approach. The present literature review focuses on secondary HLH at pediatric age, which represents a heterogeneous group in terms of etiology and therapeutic approach. It summarizes the most recent evidence on epidemiology, pathophysiology, diagnosis, treatment and prognosis, and provides a detailed description and comparison of the major subtypes of secondary HLH. Finally, it addresses the open questions with a focus on diagnosis and new treatment insights.

Ehrlichia-Induced Hemophagocytic Lymphohistiocytosis (HLH) With No Response to Doxycycline Treatment

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening condition characterized by the persistent activation of antigen-presenting cells and multisystemic inflammation. Ehrlichiosis is a tick-born infection that primarily infects the white blood cells and can present with a variety of symptoms, including fever, fatigue, and multisystemic complications. Here, we present a 58-year-old female hospitalized for a urinary tract infection. Her hospital course was complicated by HLH, which was later discovered to be precipitated by an Ehrlichia chaffeensis infection. The patient did not respond to the doxycycline treatment, developed multiorgan failure, and passed away after a few weeks of treatment trials.

Cytokine Storm Syndrome

Cytokine storm syndrome (CSS), which is frequently fatal, has garnered increased attention with the ongoing coronavirus pandemic. A variety of hyperinflammatory conditions associated with multiorgan system failure can be lumped under the CSS umbrella, including familial hemophagocytic lymphohistiocytosis (HLH) and secondary HLH associated with infections, hematologic malignancies, and autoimmune and autoinflammatory disorders, in which case CSS is termed macrophage activation syndrome (MAS). Various classification and diagnostic CSS criteria exist and include clinical, laboratory, pathologic, and genetic features. Familial HLH results from cytolytic homozygous genetic defects in the perforin pathway employed by cytotoxic CD8 T lymphocytes and natural killer (NK) cells. Similarly, NK cell dysfunction is often present in secondary HLH and MAS, and heterozygous mutations in familial HLH genes are frequently present. Targeting overly active lymphocytes and macrophages with etoposide and glucocorticoids is the standard for treating HLH; however, more targeted and safer anticytokine (e.g., anti-interleukin-1, -6) approaches are gaining traction as effective alternatives.

Secondary hemophagocytic lymphohistiocytosis due to Heartland virus

An older man from the mid-Southeastern USA presented with acute onset of fever, fatigue, and non-bloody diarrhoea. There was high suspicion for tick-borne illness given exposure history, clinical presentation and laboratory abnormalities. Despite prompt treatment with doxycycline, the patient clinically worsened. He was diagnosed with secondary hemophagocytic lymphohistiocytosis (HLH) due to Heartland virus (HRTV). This is the second documented case of secondary HLH due to HRTV, and the first in a relatively immunocompetent patient. Furthermore, though HRTV has been primarily concentrated in the Central USA, our case provides evidence of further geographic expansion of HRTV, mirroring the increased range of the Lone Star tick. Clinicians should consider HRTV when a patient with a clinical presentation consistent with tick-borne illness fails to respond to doxycycline. Furthermore, healthcare providers should be aware of the geographic expansion of HRTV and the potential of HRTV to lead to secondary HLH.

Challenges of Diagnosing Severe Ehrlichiosis in Orthotopic Liver Transplant Recipients

In recent solid organ transplant recipients, acute febrile illness is usually a source of grave concern and a diagnostic dilemma, especially if no response is noted after initiation of broad antimicrobial therapy. Human Monocytic Ehrlichiosis (HME) is a tick-borne illness caused by Ehrlichia chaffeensis and is not considered an opportunistic infection in immunocompromised patients such as solid organ transplant patients. Ehrlichiosis in immunocompromised patients can be life-threatening, and a strong index of suspicion is needed, especially in patients who live in endemic areas, for proper treatment initiation with doxycycline. We report a case of a 40-year-old male who received an orthotopic liver transplant six months earlier secondary to primary sclerosing cholangitis, on chronic immunosuppressive medication, who presented with complaints of sudden onset fever associated with nausea, vomiting, and diarrhea. Initial extensive infectious workup was negative and no response to empiric antimicrobials. There was suspicion for ehrlichiosis prompting empiric doxycycline use. Subsequently, E. chaffeensis polymerase chain reaction (PCR) was positive, and the antibiotic regimen was de-escalated to only doxycycline with complete resolution of his symptoms and progressive improvement in previously abnormal biochemical indices.

Ehrlichiosis and anaplasmosis subcommittee report to the Tick-borne Disease Working Group

Ehrlichioses and anaplasmosis have undergone dramatic increases in incidence, and the geographic ranges of their occurrence and vectors have also expanded. There is marked underreporting of these diseases owing to deficient physician awareness and knowledge of the illnesses as well as limited access to appropriate diagnostic tests. Human monocytic ehrlichiosis and anaplasmosis are life threatening diseases with estimated case fatality rates of 2.7 and 0.3%, respectively. However, knowledge of their full range of signs and symptoms is incomplete, and the incidence of subclinical infections is unknown. Currently available laboratory diagnostic methods are poorly utilized, and with the exception of nucleic acid amplification tests are not useful for diagnosis during the acute stage of illness when timely treatment is needed. The Ehrlichiosis and Anaplasmosis Subcommittee of the Tick-Borne Disease Working Group recommended active clinical surveillance to determine the true incidence, full clinical spectrum, and risk factors for severe illness, as well as standardized surveillance of ticks for these pathogens, and enhanced education of primary medical caregivers and the public regarding these diseases. The subcommittee identified the needs to develop sensitive, specific acute stage diagnostic tests for local clinical laboratories and point-of-care testing, to develop approaches for utilizing electronic medical records, data mining, and artificial intelligence for assisting early diagnosis and treatment, and to develop adjunctive therapies for severe disease.

Donor-derived ehrlichiosis: two clusters following solid organ transplantation

Ehrlichiosis has been infrequently described as transmissible through organ transplantation. Two donor derived clusters of ehrlichiosis are described here. During the summer of 2020, two cases of ehrlichiosis were reported to the Organ Procurement and Transplantation Network (OPTN) and the Centers for Disease Control and Prevention (CDC) for investigation. Additional transplant centers were contacted to investigate similar illness in other recipients and samples were sent to CDC. Two kidney recipients from a common donor developed fatal ehrlichiosis-induced hemophagocytic lymphocytic histiocytosis (HLH). Two kidney recipients and a liver recipient from another common donor developed ehrlichiosis. All three were successfully treated. Clinicians should consider donor-derived ehrlichiosis when evaluating recipients with fever early after transplantation after more common causes are ruled out, especially if the donor has epidemiological risk factors for infection. Suspected cases should be reported to the organ procurement organization (OPO) and the OPTN for further investigation by public health authorities.

A 58-Year-Old Man With Acute Encephalopathy, Fever, and Multi-Organ Dysfunction

CASE PRESENTATION

A 58-year-old man with a medical history of type 2 diabetes mellitus and COPD presented with fever, chills, nausea, vomiting, left upper quadrant abdominal pain, and altered mental status for the past week. His mental status rapidly deteriorated and work of breathing increased, which required intubation and mechanical ventilation. The patient's wife reported recent exposure to tick bites after finding several ticks while changing the sheets in their bedroom.

Ehrlichia-induced hemophagocytic lymphohistiocytosis after autologous stem cell transplant

Hemophagocytic lymphohistiocytosis (HLH) causes multiorgan failure due to the release of multiple cytokines mediating widespread inflammation. We present a patient with multiple myeloma on maintenance chemotherapy with the anti-CD38 monoclonal antibody daratumumab after autologous stem cell transplant (ASCT) who developed fatal HLH secondary to Ehrlichiosis.

A Case of Hemophagocytic Lymphohistiocytosis Associated With Mediterranean Spotted Fever in a Healthy 29-Year-Old Female

A 29-year-old female presented with fever, headache, and epigastric pain. Though her initial presentation was benign and nonspecific, she soon developed a full-blown cytokine storm with disseminated intravascular coagulation. She was diagnosed with hemophagocytosis secondary to Rickettsia conorii infection. A good outcome was achieved thanks to prompt diagnosis and proper treatment.

Incidence and treatment of hemophagocytic lymphohistiocytosis in hospitalized children with Ehrlichia infection

We report a large cohort of pediatric patients with human monocytic ehrlichiosis (HME), enabling an estimated incidence of secondary hemophagocytic lymphohistiocytosis (HLH) in hospitalized children with HME. Among 49 children with PCR-confirmed Ehrlichia infection, 8 (16%) met current criteria for HLH. Those with HLH had more significant hematologic abnormalities and longer durations from symptom onset to admission and definitive anti-infective therapy. Among these eight, three received chemotherapy plus doxycycline, one of whom died; the other five were treated with doxycycline without chemotherapy, and all survived without HLH recurrence. Our findings demonstrate that antimicrobial therapy alone can successfully resolve Ehrlichia-associated HLH.

Hemophagocytic Lymphohistiocytosis Secondary to Ehrlichia Chaffeensis in Adults: A Case Series From Oklahoma

Hemophagocytic lymphohistiocytosis (HLH) is a syndrome of pathologic immune activation that occurs as either a familial disorder or as a sporadic condition in association with a variety of triggers. Infections are the most common cause of HLH in adults and should be searched for as early treatment usually results in a favorable outcome. Human monocytotropic ehrlichiosis (HME) is a very rare cause of HLH. Failure to consider ehrlichiosis can result in misdiagnosis and an increased length of hospitalization and healthcare cost as described in our report. Treatment for secondary HLH is aimed at reducing hypercytokinemia and eradicating inflammatory and infected cells. It is important to promptly initiate doxycycline when tick-borne diseases are being entertained as a possible trigger, as the antibiotic is effective, safe and inexpensive.

Ehrlichiosis Presenting as Hemophagocytic Lymphohistiocytosis in an Immunocompetent Adult

Hemophagocytic Lymphohistiocytosis (HLH) is a fatal, immunologic syndrome characterized by dysregulated tissue inflammation. HLH can be either primary or secondary; with the latter typically resulting from an infection. Diagnosis requires five or more of the following: fever, splenomegaly, cytopenia, hypertriglyceridemia, hemophagocytosis via biopsy, low natural killer (NK) cell activity, elevated ferritin and soluble CD25 level (sCD25). We present a case of HLH related to ehrlichiosis.

In order to mount an effective immune response against microbes such as Ehrlichia chaffeensis, the host must have preserved NK cell function. Being that HLH Is characterized as a state of depleted NK cell function, It is crucial to investigate the role NK cell function has in the setting of HLH on the infectivity of Ehrlichia species.

Human Monocytic Ehrlichiosis Associated With Myocarditis and Hemophagocytic Lymphohistiocytosis

We present 3 cases at a single institution of human monocytic ehrlichiosis resulting in myocarditis and hemophagocytic lymphohistiocytosis. Contrary to previously published studies in which case fatalities were only as high as 1%, 2 of the 3 patients we discuss experienced a fulminant course resulting in death despite appropriate doxycycline treatment. Human monocytic ehrlichiosis is rarely a cause of myocarditis and hemophagocytic lymphohistiocytosis, but a high degree of suspicion is important because early empirical therapy may decrease morbidity and mortality. (Level of Difficulty: Intermediate.)

Hemophagocytic lymphohistiocytosis associated with Epstein-Barr virus infection: case report and literature review

Hemophagocytic lymphohistiocytosis (HLH) is rare and life threatening syndrome. There are only a few reported cases of HLH with GI symptoms. We describe the case of an 18 months old boy who presented with a history of fever for 40 days, abdominal distention and hepatosplenomegaly. Abdominal x-ray showed a pneumoperitoneum. Urgent laparotomy was done which revealed an isolated cecal perforation. The histopathological findings in the subsequent resected bowel was HLH with evidence of positive EBV Barr infection.

Human ehrlichiosis at a tertiary-care academic medical center: Clinical associations and outcomes of transplant patients and patients with hemophagocytic lymphohistiocytosis

BACKGROUND

Ehrlichiosis is an acute febrile tick-borne disease which can rarely be a trigger for secondary hemophagocytic lymphohistiocytosis (HLH).

METHODS

We reviewed our experience with Ehrlichia infections at a tertiary-care academic medical center.

RESULTS

Over 10 years, 157 cases of ehrlichiosis were identified. Ten patients (6.4%) had infection with E. ewingii, 7(4.5%) of whom were transplant patients as compared to 3(1.9%) non-transplant patients (p = .035). Transplant patients were more likely to have leukopenia and elevated creatinine compared to immunocompetent patients; length of hospital stay and early mortality were not different between the two groups. Ten patients met the HLH-2004 diagnosis criteria, which could be an underestimation of HLH occurrence as most patients were not completely evaluated for these criteria. We calculated the H-Score to find the probability of HLH; 25 patients scored high making the occurrence rate of HLH at least 16%. Ehrlichia-induced HLH patients (N = 25) had more anemia, thrombocytopenia, elevated creatinine and AST. Moreover, they had a significantly longer hospital stay (median 9 days) compared to patients without HLH (median 4 days) (p = .006).

CONCLUSIONS

Ehrlichia-induced HLH is a potential serious complication with relatively high occurrence rate; patients manifest severe disease with end-organ damage requiring longer hospital stay.

Severe Human Granulocytic Anaplasmosis With Significantly Elevated Ferritin Levels in an Immunocompetent Host in Pennsylvania: A Case Report

Human granulocytic anaplasmosis (HGA) is a tick-borne, infectious disease caused by Anaplasma phagocytophilum that generally presents with nonspecific symptoms such as fever, chills, headache, malaise, and myalgia. If not treated immediately, HGA can cause hemophagocytic lymphohistiocytosis (HLH), a well-documented but underrecognized sequela of severe HGA. In this article, we report a case of severe HGA with hyperferritinemia in a 74-year-old male from Central Pennsylvania who initially presented with recurrent fevers, nausea, and malaise to our emergency department and was subsequently discharged home that same day. Ten days later, the patient returned with acute kidney injury, elevated liver transaminases, and profound hyperferritinemia to 5130 ng/mL. Empiric doxycycline was administered for suspected tick-borne disease and serologies eventually came back positive for anti–Anaplasma phagocytophilum antibodies. The patient returned to baseline status 15 days after discharge. Our case shows the challenges in the timely diagnosis of HGA and highlights the role of serum ferritin in aiding this diagnosis. Although our patient did not fulfill the HLH diagnostic criteria, our report demonstrates the importance of recognizing HGA as a reversible cause of HLH.

Emerging Infections and Pertinent Infections Related to Travel for Patients with Primary Immunodeficiencies

In today's global economy and affordable vacation travel, it is increasingly important that visitors to another country and their physician be familiar with emerging infections, infections unique to a specific geographic region, and risks related to the process of travel. This is never more important than for patients with primary immunodeficiency disorders (PIDD). A recent review addressing common causes of fever in travelers provides important information for the general population Thwaites and Day (N Engl J Med 376:548-560, 2017). This review covers critical infectious and management concerns specifically related to travel for patients with PIDD. This review will discuss the context of the changing landscape of infections, highlight specific infections of concern, and profile distinct infection phenotypes in patients who are immune compromised. The organization of this review will address the environment driving emerging infections and several concerns unique to patients with PIDD. The first section addresses general considerations, the second section profiles specific infections organized according to mechanism of transmission, and the third section focuses on unique phenotypes and unique susceptibilities in patients with PIDDs. This review does not address most parasitic diseases. Reference tables provide easily accessible information on a broader range of infections than is described in the text.

Clinical utility of soluble interleukin-2 receptor in hemophagocytic syndromes: a systematic scoping review

The serum-soluble interleukin-2 receptor (sIL-2r) level is considered an important diagnostic test and disease marker in hemophagocytic syndromes/hemophagocytic lymphohistiocytosis (HPS/HLH). However, this cytokine receptor is rarely measured in clinical practice and has been excluded from recent diagnostic/classification criteria such as the HScore and macrophage activation syndrome (MAS) 16. We performed a systematic scoping review of 64 articles (1975-2016) examining the clinical utility of sIL-2r in HPS/HLH. Twenty-two articles describe sIL-2r as a sensitive diagnostic marker for HLH, but only three distinct datasets actually address sensitivity. The original HLH-2004 Guidelines reported sensitivity of 93% and specificity of 100% for sIL-2r ≥ 2400, based on a pediatric dataset (n = 152) which is published for the first time in this review. Two pediatric studies reported sensitivity of 89% for sIL-2r ≥ 2400 in diagnosis of MAS complicating juvenile idiopathic arthritis (JIA) (n = 27) and 88% for secondary HLH in acute liver failure (n = 9). Twenty articles described sIL-2r as a dynamic marker of disease activity that falls with response to treatment, and 15 described high initial sIL-2r levels >10,000 U/mL as a poor prognostic marker. The ability of sIL-2r to distinguish between subtypes of HPS/HLH was inconsistent. This review confirms the importance of soluble IL-2r as a diagnostic and disease marker in HPS/HLH, but also reveals the need for more primary data about its performance characteristics, particularly in adults. More emphasis should be made in including this simple, inexpensive test in clinical practice and studies of HPS/HLH.

Cytopenias and clonal expansion of gamma/delta T-cells in a patient with anaplasmosis: a potential diagnostic pitfall

Human granulocytic anaplasmosis is a rare, tick-borne infectious disease caused by Anaplasma phagocytophilum. Herein, we report a rare case of human granulocytic anaplasmosis associated with cytopenias and clonal expansion of gamma/delta T-cells in the bone marrow. A 77-year old man presented multiple times to the emergency department complaining of muscle weakness. Complete blood count detected cytopenias and peripheral blood smear showed pseudo Pelger-Huet neutrophils. These findings prompted bone marrow evaluation with ancillary studies including flow cytometry, karyotyping and T-cell rearrangement studies. Careful examination of peripheral blood smear revealed very rare neutrophils with intracytoplasmic inclusions, suggestive of ehrlichiosis/anaplasmosis. Bone marrow evaluation showed dyserythropoiesis, dysmegakaryopoiesis and prominence of hemophagocytic histiocytes. Furthermore, an increased number of T-cells was seen in the bone marrow and flow cytometry showed excess of gamma/delta T-cells, while T-cell rearrangement studies detected a T-cell clone. Serologic evaluation confirmed the diagnosis of anaplasmosis. This case nicely illustrates hematologic sequelae of infection with Anaplasma and potential diagnostic pitfalls, such as myelodysplastic syndrome and T-cell lymphoproliferative disorder. To our knowledge, this is the first reported case of clonal expansion of gamma/delta T-cells associated with anaplasmosis. Pathologists should be careful and vigilant when screening peripheral blood smears, as they are often the first to raise the suspicion of anaplasmosis.

Human monocytic ehrlichiosis complicated by hemophagocytic lymphohistiocytosis and multi-organ dysfunction syndrome

Human monocytic ehrlichiosis can manifest as a disease causing multi-organ failure. Rarely, it can cause secondary hemophagocytic lymphohistiocytosis (HLH). Early diagnosis and initiation of treatment for both ehrlichiosis and HLH is lifesaving. Therefore, clinical suspicion of HLH must remain high in the setting of an ehrlichiosis infection.