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

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.

Infections and Acute Kidney Injury: A Global Perspective

Globally, there are an estimated 13.3 million cases of acute kidney injury (AKI) annually. Although infections are a common cause of AKI globally, most infection-associated AKI occurs in low- and lower-middle-income countries. There are marked differences in the etiology of infection-associated AKI across age groups, populations at risk, and geographic location. This article provides a global overview of different infections that are associated commonly with AKI, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human immunodeficiency virus, malaria, dengue, leptospirosis, tick-borne illnesses, and viral hemorrhagic fevers. Further discussion focuses on infectious conditions associated with AKI including sepsis, diarrheal diseases and pregnancy, peripartum and neonatal AKI. This article also discusses the future of infection-associated AKI in the framework of climate change. It explores how increased investment in achieving the sustainable development goals may contribute to the International Society of Nephrology's 0 by 25 objective to curtail avoidable AKI-related fatalities by 2025.

Ehrlichiosis-Associated Hemophagocytic Lymphohistiocytosis: A Case Series and Review of the Literature

Background

Human monocytic ehrlichiosis (HME) is a potentially life-threatening tick-borne illness. HME-associated hemophagocytic lymphohistiocytosis (HLH) is a rare entity with a paucity of published literature regarding treatment and outcome. We present the clinical features, treatment, and outcomes of 4 patients at our institutions with HME-associated HLH. This review also summarizes the current literature regarding the presentation, treatment, and outcome of this infection-related HLH.

Methods

We searched the PubMed database for case reports and case series. All cases were diagnosed according to the HLH-04 criteria.

Results

Four cases of HME-associated HLH were included from our institutions. The literature review yielded 30 additional cases. About 41% of the cases were in the pediatric population; 59% were female; and all patients had fever, cytopenia, and elevated ferritin. Most patients were immunocompetent; all but one patient with available data were treated with doxycycline, and eight of the patients with available data received the HLH-94 treatment protocol. The mortality rate was 17.6%.

Conclusions

HME-associated HLH is a rare but serious syndrome with significant mortality. Early treatment with doxycycline is critical, but the role of immunosuppressive therapy is individualized.

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.

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.

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.

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 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.

Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis is a life-threatening disorder characterized by unbridled activation of cytotoxic T lymphocytes, natural killer (NK) cells, and macrophages resulting in hypercytokinemia and immune-mediated injury of multiple organ systems. It is seen in both children and adults and is recognized as primary (driven by underlying genetic mutations that abolish critical proteins required for normal function of cytotoxic T cells and NK cells) or secondary (resulting from a malignant, infectious, or autoimmune stimulus without an identifiable underlying genetic trigger). Clinical and laboratory manifestations include fever, splenomegaly, neurologic dysfunction, coagulopathy, liver dysfunction, cytopenias, hypertriglyceridemia, hyperferritinemia, hemophagocytosis, and diminished NK cell activity. It is treated with immune suppressants, etoposide, and allogeneic hematopoietic stem cell transplantation; more than 50% of children who undergo transplant survive, but adults have quite poor outcomes even with aggressive management. Newer agents directed at subduing the uncontrolled immune response in a targeted fashion offer promise in this highly morbid disease.