Neutrophil-to-ferritin ratio can predict hematological causes of fever of unknown origin.

Despite advancements in diagnostic modalities, delineating the etiology of fever of unknown origin (FUO) remains a significant challenge for clinicians. Notably, cases with hematological malignancies often have a poor prognosis due to delayed diagnosis. This study investigated the potential of readily obtainable laboratory markers to differentiate hematological causes from other etiologies during the early stages of FUO. A retrospective analysis was conducted on the medical records of 100 patients who fulfilled the modified FUO criteria between January 2010 and April 2023. Hematological etiologies were identified in 26 of the 100 patients. Peripheral blood neutrophil, lymphocyte, platelet counts, and the systemic immune inflammation (SII) index, were significantly lower in the hematological group compared to the non-hematological group. Conversely, serum ferritin levels were demonstrably higher in the hematological group. ROC analysis identified a neutrophil-to-ferritin ratio (NFR) cutoff value of < 8.53 as optimal for predicting hematological etiology. Subsequent multivariate analysis demonstrated that the NFR was the sole independent predictor of hematological etiology (p = 0.013).This study proposes a novel approach for early diagnosis of a potentially life-threatening subset of FUO patients. The NFR presents as an inexpensive and readily available marker for predicting hematological etiology in FUO cases.

Metagenomic next generation sequencing of plasma RNA for diagnosis of unexplained, acute febrile illness in Uganda.

Metagenomic next generation metagenomic sequencing (mNGS) has proven to be a useful tool in the diagnosis and identification of novel human pathogens and pathogens not identified on routine clinical microbiologic tests. In this study, we applied mNGS to characterize plasma RNA isolated from 42 study participants with unexplained acute febrile illness (AFI) admitted to tertiary referral hospitals in Mubende and Arua, Uganda. Study participants were selected based on clinical criteria suggestive of viral infection (i.e., thrombocytopenia, leukopenia). The study population had a median age of 28 years (IQR:24 to 38.5) and median platelet count of 114 x103 cells/mm3 (IQR:66,500 to 189,800). An average of 25 million 100 bp reads were generated per sample. We identified strong signals from diverse virus, bacteria, fungi, or parasites in 10 (23.8%) of the study participants. These included well recognized pathogens like Helicobacter pylori, human herpes virus-8, Plasmodium falciparum, Neisseria gonorrhoeae, and Rickettsia conorii. We further confirmed Rickettsia conorii infection, the cause of Mediterranean Spotted Fever (MSF), using PCR assays and Sanger sequencing. mNGS was a useful addition for detection of otherwise undetected pathogens and well-recognized non-pathogens. This is the first report to describe the molecular confirmation of a hospitalized case of MSF in sub-Saharan Africa (SSA). Further studies are needed to determine the utility of mNGS for disease surveillance in similar settings.

Fever of unknown origin, blood and cerebrospinal fluid involvement: a leprosy case report.

Leprosy is a chronic infectious disease that mainly affects the skin and peripheral nerves, it can also invade deeper tissues and organs, including mucous membranes, lymph nodes, testes, eyes, and internal organs. Severe cases can result in deformities and disabilities. We encountered the case of a 39-year-old male with unexplained fever, headache and rash. The patient's lesions were taken for histopathological examination and slit skin smear analysis. Further, the patient was detected of Mycobacterium leprae (M.leprae) nucleic acid sequences in the cerebrospinal fluid (CSF) and plasma, and M.leprae gene targets in the skin lesion tissue and blood. The patient was eventually diagnosed with multibacillary leprosy and type II leprosy reaction. These results suggest the possibility of bacteremia in patients with leprosy to some extent, and observation implies the potential invasion of CSF by M.leprae or its genetic material.

An FUO patient diagnosed as appendicitis: a case report.

BACKGROUND: The diagnosis and management of fever of unknown origin pose significant challenges in the field of infectious diseases, as it is influenced by various factors. Infectious diseases have long been recognized as the primary etiology of fever of unknown origin. However, not all infectious diseases can definitively identify the causative pathogen and infection sites. CASE PRESENTATION: we present a case report of an individual with fever, nausea, and anorexia but did not report any abdominal pain. Physical examination revealed no signs of abdominal tenderness. Repeated imaging studies including enhanced CT and color US of the appendix, only one color US suggested the possibility of appendicitis. Despite effective anti-infective treatment, the patient continued to experience low-grade fever, leading to the decision for laparoscopic exploration and subsequent appendectomy. Pathological findings confirmed the presence of appendicitis. After the surgical procedure, the patient's temperature and infectious markers returned to within normal range, ultimately leading to a diagnosis of appendicitis. CONCLUSIONS: The atypical symptoms and signs, along with the negative imaging results, contribute to the under diagnosis of appendicitis and the progression of fever of unknown origin, thereby exacerbating the physical, mental, and economic burden on patients. Consequently, there are valuable insights to be gained regarding the management of both appendicitis and fever of unknown origin.

Disseminated Histoplasmosis Presenting as Pyrexia of Unknown Origin in a Rheumatoid Arthritis Patient.

We present a case of a 56-year-old female with rheumatoid arthritis (RA) who has been on methotrexate for 9 years and has been complaining of high-grade fever for the past 1 month with no localizing signs and symptoms. She was thoroughly evaluated before being labeled as pyrexia of unknown origin. Histoplasmosis was suspected after bone marrow aspiration smear examination. The presence of histoplasma antigen in the urine confirmed our diagnosis. Fever responded after 2 weeks of liposomal amphotericin B and patient discharged in stable condition on tablet itraconazole.

Metagenomic next-generation sequencing in patients with fever of unknown origin: A comprehensive systematic literature review and meta-analysis.

Metagenomic Next-Generation Sequencing (mNGS) holds promise in diagnosing fever of unknown origin (FUO) by detecting diverse pathogens. We systematically reviewed the literature to evaluate mNGS's accuracy, clinical efficacy, and limitations in FUO diagnosis. Nine studies revealed mNGS's positivity rate ranging from 66.7% to 93.5% for bacterial bloodstream infections and systemic infections. Meta-analysis of three studies involving 857 patients, including 354 with FUO, showed a sensitivity of 0.91 (95% CI: 0.87-0.93) and specificity of 0.64 (95% CI: 0.58-0.70). Despite lower specificity, mNGS demonstrated a higher Diagnostic Odds Ratio (DOR) of 17.0 (95% CI: 4.5-63.4) compared to conventional microbiological tests (CMTs) at 4.7 (95% CI: 2.9-7.6). While mNGS offers high sensitivity but low specificity in identifying causative pathogens for FUO, its superior DOR suggests potential for more accurate diagnoses and targeted interventions. Further research is warranted to optimize its clinical application in FUO management.

Approach to fever in children.

BACKGROUND: Fever in children is one of the most common reasons for outpatient visits as well as in-patient evaluation, often causing anxiety among parents and caregivers. Fever can be a standalone feature or be associated with other localising symptoms and signs like rash, lymphadenopathy, or any other organ system involvement with or without a focus of infection. The etiologies of fever vary depending on the clinical setting and epidemiology. India being a tropical country, sees a distinct spectrum of tropical infections. Physicians need to stay updated on the prevalent diseases in their region and the unique factors that may influence the clinical presentations and course of fever in the cohort of children they manage. The challenge lies in balancing the benefit of early treatment for severe diseases versus the harms of unnecessary investigations and treatment for self-resolving illnesses. OBJECTIVES: This review aims to provide a comprehensive overview of fever in children, covering its etiology, clinical features, and management strategies. This review offers an algorithmic approach to fever tailored to the Indian setting to guide physicians in identifying the disease based on clinical symptoms and signs, ordering essential laboratory investigations, and initiating appropriate management promptly. CONTENT: The review categorises fever into various segments like fever with localising signs like rash, lymphadenopathy, fever due to infection localised to a particular organ system, and fever without a focus including fever of unknown origin. It delves into the diverse etiological factors contributing to fever in each of these categories, encompassing infectious and non-infectious origins. It gives pointers to identify the etiology from history, examination, and confirm them with judicious use of diagnostic investigations with emphasis on identifying the red flag signs that require immediate attention, especially in vulnerable groups like neonates and young infants.

Role of urine Gram stain in young febrile infants with a suspected urinary tract infection: a cohort study.

OBJECTIVE: To analyse the performance of the urine Gram stain for predicting a positive urine culture (UC) in young infants with fever without source (FWS) and pyuria. DESIGN: Observational study; secondary analysis of a prospective registry-based cohort study. SETTING: Paediatric emergency department; tertiary teaching hospital. PATIENTS: Infants ≤90 days old with FWS, pyuria and urine Gram stain requested seen between 2010 and 2022. MAIN OUTCOME MEASURE: Performance of the Gram stain, defined as positive if any bacteria were seen, for predicting urinary tract infection (UTI: UC by urethral catheterisation growing >10 000 CFU/mL of a single bacterial pathogen). RESULTS: Among 367 febrile infants with pyuria, 281 (76.6%) had a positive Gram stain and 306 (83.3%) had a positive UC (277; 90.5% Escherichia coli).Rates of positive UC in patients with positive and negative Gram stains were 97.2% and 38.4%, respectively (p<0.01), showing a sensitivity of 89.2% (95% CI: 85.2% to 92.2%) and a specificity of 86.9% (95% CI: 76.2% to 93.2%). Sensitivity was lower for diagnosing UTIs caused by bacteria other than E. coli (69.0% vs 91.3% for UTIs caused by E. coli; p<0.01).Two (2.1%) of the 86 infants with negative Gram stains were diagnosed with bacteraemia unrelated to a UTI (Streptococcus pneumoniae and Staphylococcus aureus). CONCLUSIONS: Around a third of infants with pyuria and a negative Gram stain will eventually be diagnosed with a UTI. These patients have a higher rate of UTIs caused by bacteria other than E. coli. Bacterial infections other than UTIs should also be considered in such cases.

[The 506th case: fever of unknown origin, negative PET-CT and hemoperitoneum].

A 48-year-old male was admitted to Peking Union Medical College Hospital presented with intermittent fever for two years. The maximum body temperature was 39 ℃, and could spontaneously relieve. The efficacy of antibacterial treatment was poor. He had no other symptoms and positive signs. He had a significant weight loss, and the serum lactate dehydrogenase increased significantly. It was highly alert to be lymphoma, but bone marrow smear and pathology, and PET-CT had not shown obvious abnormalities. Considering high inflammatory indicators, increased ferritin and large spleen, the patient had high inflammatory status, and was treated with methylprednisolone. Then the patient's body temperature was normal, but the platelet decreased to 33×109/L. During hospitalization, he had suddenly hemoperitoneum and hemorrhagic shock. He was found spontaneous spleen rupture without obvious triggers, and underwent emergency splenectomy. The pathological diagnosis of spleen was diffuse large B-cell lymphoma.

[Workplace-associated fever]. / Arbeitsplatzassoziiertes Fieber oder wenn es doch das Zebra ist .

INTRODUCTION: Febrile conditions often have an infectious etiology. However, there are also fevers associated with occupational exposures. A detailed occupational history can hold the key to the diagnosis. In the case of exposure to organic dusts, the development of hypersensitivity pneumonitis (HP) is possible. Thus, HP should be considered in the presence of interstitial lung disease of unclear etiology. Failure to recognize this can have dramatic consequences and, in extreme cases, lead to lung transplantation. Differentially, organic dust toxic syndrome (ODTS) must be considered. The syndrome of metal fume fever provoked by inhalation of inorganic substances is usually benign and self-limiting. The disease manifests with fever, cough, and flu-like sensations.

[Fever in rheumatological diseases]. / Fieber bei rheumatologischen Erkrankungen.

Fever is a frequent and important symptom in patients with rheumatological diseases and can be an expression of activity of the underlying rheumatological disease. There is great variability in the incidence of fever as a symptom of the disease between individual diseases. The growing understanding of the molecular signatures of the diseases can help to explain these discrepancies: A genetic overactivation of potently pyrogenic cytokines is the reason why fever is nearly always present in autoinflammatory syndromes. In contrast, fever is less common in polyarthritis and myositis and mostly limited to severe courses of disease. In the diagnostic work-up of fever, frequent differential diagnoses, such as infections, malignancies, side effects of drugs and hypersensitivity reactions should be considered. This article provides an overview of the physiology of the development of fever, describes the relevance of fever in individual rheumatological diseases and proposes a workflow for the clinical clarification of rheumatological patients who present with fever.

[Infections and fever]. / Infektion und Fieber.

Fever can be due to infectious or noninfectious causes and results from the body's natural response to exogenous or endogenous pyrogens. Laboratory tests including complete blood count, differential blood count, C­reactive protein, erythrocyte sedimentation rate and procalcitonin do not have sufficient sensitivity and specificity to definitively detect or rule out an infectious (bacterial, viral, parasitic) cause of fever. Blood cultures should be carried out when bacteremic or septic illnesses are suspected. Fever is not always present in infections and can be absent, especially in older and immunocompromised patients. If fever is suspected, core temperatures should be taken, e.g., rectally, orally or invasively. Depending on the clinical situation, infectious causes must be excluded as the most likely cause of an acutely occurring fever. The investigation of long-standing fever (fever of unknown origin, FUO) can be complex and some infectious diseases should first be ruled out, whereby a syndromic classification often helps to clarify the cause of the fever.

Performance of Febrile Infant Algorithms by Duration of Fever.

OBJECTIVES: To analyze the performance of commonly used blood tests in febrile infants ≤90 days of age to identify patients at low risk for invasive bacterial infection (bacterial pathogen in blood or cerebrospinal fluid) by duration of fever. METHODS: We conducted a secondary analysis of a prospective single-center registry that includes all consecutive infants ≤90 days of age with fever without a source evaluated at 1 pediatric emergency department between 2008 and 2021. We defined 3 groups based on caregiver-reported hours of fever (<2, 2-12, and ≥12) and analyzed the performance of the biomarkers and Pediatric Emergency Care Applied Research Network, American Academy of Pediatrics, and Step-by-Step clinical decision rules. RESULTS: We included 2411 infants; 76 (3.0%) were diagnosed with an invasive bacterial infection. The median duration of fever was 4 (interquartile range, 2-12) hours, with 633 (26.3%) patients with fever of <2 hours. The area under the curve was significantly lower in patients with <2 hours for absolute neutrophil count (0.562 vs 0.609 and 0.728) and C-reactive protein (0.568 vs 0.760 and 0.812), but not for procalcitonin (0.749 vs 0.780 and 0.773). Among well-appearing infants older than 21 days and negative urine dipstick with <2 hours of fever, procalcitonin ≥0.14 ng/mL showed a better sensitivity (100% with specificity 53.8%) than that of the combination of biomarkers of Step-by-Step (50.0% and 82.2%), and of the American Academy of Pediatrics and Pediatric Emergency Care Applied Research Network rules (83.3% and 58.3%), respectively. CONCLUSIONS: The performance of blood biomarkers, except for procalcitonin, in febrile young infants is lower in fever of very short duration, decreasing the accuracy of the clinical decision rules.

Unraveling the mystery of fever of unknown origin: a remarkable journey towards the diagnosis of peripheral T-cell lymphoma-T follicular helper type: A rare case report.

INTRODUCTION: Fever of unknown origin (FUO) remains one of the most challenging clinical conditions. It demands an exhaustive diagnostic approach, considering its varied etiologies spanning infectious, autoimmune, inflammatory, and malignant causes. PATIENT CONCERNS: This report shows the journey of diagnosing a 28-year-old male who presented with persistent fever and lower-extremity weakness over 9 months. Despite seeking care at multiple hospitals, a definitive diagnosis remained elusive. DIAGNOSIS: The patient underwent a series of evaluations in various specialties, including gastroenterology, infectious diseases, rheumatology, hematology, and cardiology. Multiple tests and treatments were administered, including antiviral therapy for hepatitis B and antibiotics for suspected infections. INTERVENTIONS: After an initial misdiagnosis and unsuccessful treatments, a positron emission tomography-computed tomography scan and lymph node biopsy ultimately led to the diagnosis of peripheral T-cell lymphoma-T follicular helper type (PTCL-TFH) lymphoma. The patient was referred to the hematology clinic and initiated on CHOEP (cyclophosphamide, vincristine, etoposide, and prednisone) chemotherapy. OUTCOMES: The patient showed a positive response to CHOEP therapy, as indicated by a posttreatment positron emission tomography-computed tomography scan. He reported a significant improvement in his quality of life. Additional rounds of the same regimen were planned to further manage the lymphoma. CONCLUSION: This case emphasizes the importance of a comprehensive and persistent diagnostic approach in managing FUO. Initially, the focus on infectious causes led to extensive treatments, but the disease's progression and complications shifted attention to other specialties. The eventual diagnosis of PTCL-TFH lymphoma highlights the significance of advanced imaging techniques and multidisciplinary collaboration in uncovering elusive diagnoses. Thorough surveillance, timely reassessments, and repeated testing can uncover definitive changes critical for diagnosis. PTCL-TFH lymphoma, although rare, should be considered in the differential diagnosis of FUO, especially when initial evaluations are inconclusive.

Predictive model for diagnostic yield of bone marrow examination in patients with HIV infection having fever of unknown origin.

OBJECTIVE: Bone marrow examination is valuable for identifying the cause of fever of unknown origin (FUO) in HIV-infected patients. Based on the outcomes of bone marrow examination of patients with FUO, we aimed to develop a predictive model for identifying the factors that can increase the diagnostic yield of bone marrow examination. DESIGN: For this retrospective cohort study, we enrolled HIV-infected patients, aged more than 15 years and diagnosed with FUO, at Songklanakarind Hospital in Southern Thailand, between January 2009 and December 2019. METHODS: Evaluations were based on bone marrow aspiration, biopsy, and culture; any missing data were imputed with regression imputation. RESULTS: Among the final 108 included patients, 44 (40.74%) showed positive bone marrow results. The diagnoses mainly comprised histoplasmosis, penicilliosis, and tuberculosis. Bone marrow examination led to treatment modifications in approximately 33% patients. Platelet count less than 150 000 cells/µl, alkaline phosphatase (ALP) level at least 200 U/l, and no previous antibiotic treatment were significantly associated with higher diagnostic yields. The HIV bone marrow (HIVBM) model, comprising of spleen size, hematocrit (Hct), platelet count before bone marrow examination, ALP level at admission, and previous antibiotic treatment, was generated as a nomogram to predict the diagnostic yield of bone marrow examination in HIV-infected patients with FUO. CONCLUSION: The results of this study indicate that the HIVBM model can be used to predict the diagnostic yield of bone marrow examination, and therefore assist in clinical decision-making regarding bone marrow procedures, to be performed for identifying the origin of fever in HIV-infected patients.

Incidence and outcomes of fever of unknown origin after kidney transplant in the modern era.

BACKGROUND: While presumably less common with modern molecular diagnostic and imaging techniques, fever of unknown origin (FUO) remains a challenge in kidney transplant recipients (KTRs). Additionally, the impact of FUO on patient and graft survival is poorly described. METHODS: A cohort of adult KTRs between January 1, 1995 and December 31, 2018 was followed at the University of Wisconsin Hospital. Patients transplanted from January 1, 1995 to December 31, 2005 were included in the "early era"; patients transplanted from January 1, 2006 to December 31, 2018 were included in the "modern era". The primary objective was to describe the epidemiology and etiology of FUO diagnoses over time. Secondary outcomes included rejection, graft and patient survival. RESULTS: There were 5590 kidney transplants at our center during the study window. FUO was identified in 323 patients with an overall incidence rate of .8/100 person-years. Considering only the first 3 years after transplant, the incidence of FUO was significantly lower in the modern era than in the early era, with an Incidence Rate Ratio (IRR) per 100 person-years of .48; 95% CI: .35-.63; p < .001. A total of 102 (31.9%) of 323 patients had an etiology determined within 90 days after FUO diagnosis: 100 were infectious, and two were malignancies. In the modern era, FUO remained significantly associated with rejection (HR = 44.1; 95% CI: 16.6-102; p < .001) but not graft failure (HR = 1.21; 95% CI: .68-2.18; p = .52) total graft loss (HR = 1.17; 95% CI: .85-1.62; p = .34), or death (HR = 1.17; 95% CI: .79-1.76; p = .43. CONCLUSIONS: FUO is less common in KTRs during the modern era. Our study suggests infection remains the most common etiology. FUO remains associated with significant increases in risk of rejection, warranting further inquiry into the management of immunosuppressive medications in SOT recipients in the setting of FUO.

Multidisciplinary approach to diagnosis and management of fever of unknown origin: A case report.

INTRODUCTION: Fever of unknown origin (FUO) poses a diagnostic challenge, often requiring a systematic evaluation to uncover its elusive cause. This case study delves into the presentation of a 42-year-old Chinese male with persistent fever, muscle pain, and a perplexing rash. PATIENT CONCERNS: The patient's symptoms included a prolonged fever, chills, muscle pain, and throat discomfort, with a history of pulmonary tuberculosis. Initial diagnoses of upper respiratory infection and unspecified infection were followed by antibiotic treatments, yet the fever persisted, accompanied by an exacerbating rash. DIAGNOSIS: Extensive diagnostic investigations, including laboratory tests, imaging studies, and skin dermoscopy, provided valuable insights. The patient exhibited elevated inflammatory markers, hepatosplenomegaly, lymphadenopathy, and lung nodules. Differential diagnoses included adult-onset Still disease and drug-induced hypersensitivity syndrome. INTERVENTIONS: The patient received a series of antibiotic treatments, which initially had limited success. Upon considering an autoimmune etiology, corticosteroids were introduced, followed by cyclosporine. The patient exhibited a positive response to this immunosuppressive therapy. OUTCOMES: Treatment adjustments were made, and the patient responded positively to a combination of corticosteroids and cyclosporine. His fever subsided, and laboratory markers normalized. One month after discharge, the patient showed continued improvement. CONCLUSION: FUO cases often demand a multidisciplinary approach, considering rare and uncommon diseases. This case underscores the importance of thorough evaluation, collaboration between specialties, and vigilant monitoring of treatment responses. The patient's unique presentation emphasizes the need to consider drug-induced reactions, even when symptoms deviate from typical disease patterns, highlighting the complexities in diagnosing and managing FUO.