Hemophagocytic Lymphohistiocytosis Associated with Scrub Typhus: Systematic Review and Comparison between Pediatric and Adult Cases

Acute intravascular haemolysis associated with scrub typhus

Scrub typhus, a prevalent tropical infection, may sometimes manifest with unusual complications. Here, we present the case of a young man who was admitted to our facility with a fever for the past 3 days and passage of dark-coloured urine since that morning. On investigation, we identified intravascular haemolytic anaemia. Through meticulous examination, a black necrotic lesion (eschar) was discovered on his right buttock, a pathognomonic sign of scrub typhus infection. Treatment was initiated with oral doxycycline 100 mg two times a day. Subsequently, diagnosis of scrub typhus was confirmed through positive results from scrub typhus IgM via ELISA and PCR analysis from the eschar tissue. The patient responded well to oral doxycycline and his symptoms resolved within the next few days. This case highlights severe intravascular haemolysis associated with scrub typhus infection.

mNGS helped diagnose scrub typhus-associated HLH in children: a report of two cases

Background

Scrub typhus, caused by the Orientia tsutsugamushi (Ot), is a widespread vector-borne disease transmitted by chigger mites. Hemophagocytic lymphohistiocytosis (HLH) is considered to be one of the potentially severe complications. The diagnosis of scrub typhus-associated HLH may be overlooked due to the non-specific clinical characteristics and the absence of pathognomonic eschar.

Case presentation

We obtained clinical data from two patients in the South of Sichuan, China. The first case involved a 6-year-old girl who exhibited an unexplained fever and was initially diagnosed with sepsis, HLH, and pulmonary infection. The other patient presented a more severe condition characterized by multiple organ dysfunction and was initially diagnosed with septic shock, sepsis, HLH, acute kidney injury (AKI), and pulmonary infection. At first, a specific examination for scrub typhus was not performed due to the absence of a characteristic eschar. Conventional peripheral blood cultures yielded negative results in both patients, and neither of them responded to routine antibiotics. Fortunately, the causative pathogen Orientia tsutsugamushi (Ot) was detected in the plasma samples of both patients using metagenomics next-generation sequencing (mNGS) and further confirmed by polymerase chain reaction. Subsequently, they both were treated with doxycycline and recovered quickly.

Conclusion

The unbiased mNGS provided a clinically actionable diagnosis for an uncommon pathogen-associated infectious disease that had previously evaded conventional diagnostic approaches.

Flea-Borne Typhus Causing Hemophagocytic Lymphohistiocytosis: An Autopsy Case

Infection with members of the order Rickettsiales (the genera Rickettsia, Anaplasma, Orientia, and Ehrlichia) is known to cause hemophagocytic lymphohistiocytosis (HLH). The literature is scant on flea-borne typhus (FBT) being implicated in this process. We present a case of autopsy-proven HLH caused by FBT in a 71-year-old diabetic female who was initially suspected of having diabetic ketoacidosis who rapidly suffered decompensated multi-organ failure. Although she was suspected of having FBT and HLH pre-mortem, due to her rapid progression to multi-organ failure, she was transitioned to comfort care by her family five days after admission. A literature search yielded five other cases of HLH secondary to FBT, which are analyzed in this review. The literature on HLH occurring with infection due to other members of the order Rickettsiales is also surveyed.

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.

Hemophagocytic Lymphohistiocytosis secondary to Rickettsial infection: A case report

Hemophagocytic Lymphohistiocytosis (HLH) is a rare life-threatening condition characterized by widespread activation of the immune system leading to tissue damage all over the body. It is divided into primary HLH due to inborn error in lymphocytes, T cells, and macrophages and secondary HLH which is mostly due to infections, systemic connective tissue diseases, and lymphoid malignancies. Here, we report a 34-year-old man with a history of high-grade fever, chills, and rigor, eschar, splenomegaly with the laboratory findings of thrombocytopenia, hypochromic RBCs with anisocytosis and basophilic stippling, elevated transaminases, and a positive Weil Felix test along with positive PCR results for Orientia tsutsugamushi and the presence of IgG and IgM antibodies. A detailed workup was done to rule out other etiology for fever. Diagnosis of HLH secondary to Rickettsia infection was made with a thorough history, clinical evaluation, and a variety of investigations. The patient was treated with Doxycycline, Ciprofloxacin, Etoposide, and Dexamethasone but unfortunately, the patient died during treatment due to multiorgan failure. Patients with scrub typhus typically respond well to therapy; therefore, early detection and antibiotic treatment can help avoid serious complications. Scrub typhus with the hemophagocytic syndrome can result in DIC and multiorgan failure. Despite its rarity, scrub typhus may be lethal; as a result, practitioners must be aware of the necessity of detecting and treating suspected cases as soon as possible. We learned that a systematic diagnostic approach, use of diagnostic criteria, and prompt treatment are very crucial in this disease.

Unusual clinical presentations of scrub typhus, a neglected tropical disease: A case series from north India

BACKGROUND & OBJECTIVES

Scrub typhus is a neglected tropical disease common in Asia and Africa. It usually presents with non-specific symptoms like fever, rashes, and lymphadenopathy. It has a varying range of clinical picture that often leads to misdiagnosis and initiation of non-specific treatment. This disease is thus associated with high morbidity and mortality. We aim to highlight the uncommon presentations of this common disease to create awareness regarding the unusual presentations of scrub typhus.

METHODS

This prospective study was performed over a period of two months enrolling eleven adult patients with serological evidence of anti-scrub typhus IgM antibodies.

RESULTS

All enrolled 11 cases [5 males (45.5%) and 6 females (54.5%)] were positive for anti-ST IgM antibodies and negative for other tested microbial agents. 7/11 (63.6%) patients were admitted with a clinical diagnosis of acute encephalitis syndrome (AES as per standard WHO definition), 3/11 (27.3%) patients presented with jaundice and 1/11 (9.1%) patients presented with rashes. Two out of 7 (28.6%) AES cases had developed peripheral gangrene of extremities.

INTERPRETATION & CONCLUSION

Scrub typhus is a common tropical disease that can have various unusual clinical presentations like meningoencephalitis, vasculitis, acute kidney injury, jaundice, MODS. It closely mimics other infective etiologies making its diagnosis difficult. A high index of suspicion and clinical awareness is required in clinical practice to identify the different presentations of this disease so that early treatment can be initiated to reduce morbidity and mortality associated with this disease.

Scrub Typhus-Associated Hemophagocytic Lymphohistiocytosis: Not a Rare Entity in Pediatric Age Group

BACKGROUND

Our goal was to study the demographic, clinical and laboratory profile and outcome of scrub typhus-associated hemophagocytic lymphohistiocytosis (HLH) in the pediatric age group.

METHODS

We conducted a prospective observational study in a tertiary care teaching hospital over a period of 1 year. Children in the age group of 1 month to 12 years with IgM ELISA positive for scrub typhus were included in the study. HLH was diagnosed using HLH-2004 criteria. Demographic, clinical and laboratory profile, treatment and outcome of HLH patients were noted and also compared with non-HLH scrub typhus patients.

RESULTS

Among 58 children with scrub typhus infection, 18 had HLH. The mean age of patients with HLH was 35.3 ± 44.8 months and 61% were male. Anemia, thrombocytopenia and hyperferritinemia were seen in all the patients. Hypertriglyceridemia, hypofibrinogenemia and coagulopathy were noted in 78%, 56% and 44%, respectively. All the patients were treated with intravenous doxycycline for an average duration of 9.5 days. Intravenous immunoglobulin and methylprednisolone were given in 33% and 22% cases, respectively. Complications like acute respiratory distress syndrome (ARDS) (p = 0.001) and MODS (p = 0.004) were significantly high in the HLH group. Younger age (<3 years), fever > 7 days, presence of convulsion, ARDS and MODS were the clinical predictors of scrub typhus-associated HLH.

CONCLUSION

HLH in scrub typhus infected children is being increasingly recognized. Younger age, prolonged fever, presence of convulsion, ARDS and MODS should alert clinicians of the risk of HLH. Treating the primary cause usually cures the disease and immunomodulator therapy need not be routinely administered.

A Brief History of the Major Rickettsioses in the Asia-Australia-Pacific Region: A Capstone Review for the Special Issue of TMID

The rickettsioses of the "Far East" or Asia-Australia-Pacific region include but are not limited to endemic typhus, scrub typhus, and more recently, tick typhus or spotted fever. These diseases embody the diversity of rickettsial disease worldwide and allow us to interconnect the various contributions to this special issue of Tropical Medicine and Infectious Disease. The impact of rickettsial diseases-particularly of scrub typhus-was substantial during the wars and "police actions" of the last 80 years. However, the post-World War II arrival of effective antibiotics reduced their impact, when recognized and adequately treated (chloramphenicol and tetracyclines). Presently, however, scrub typhus appears to be emerging and spreading into regions not previously reported. Better diagnostics, or higher population mobility, change in antimicrobial policies, even global warming, have been proposed as possible culprits of this phenomenon. Further, sporadic reports of possible antibiotic resistance have received the attention of clinicians and epidemiologists, raising interest in developing and testing novel diagnostics to facilitate medical diagnosis. We present a brief history of rickettsial diseases, their relative importance within the region, focusing on the so-called "tsutsugamushi triangle", the past and present impact of these diseases within the region, and indicate how historically, these often-confused diseases were ingeniously distinguished from each another. Moreover, we will discuss the importance of DNA-sequencing efforts for Orientia tsutsugamushi, obtained from patient blood, vector chiggers, and rodent reservoirs, particularly for the dominant 56-kD type-specific antigen gene (tsa56), and whole-genome sequences, which are increasing our knowledge of the diversity of this unique agent. We explore and discuss the potential of sequencing and other effective tools to geographically trace rickettsial disease agents, and develop control strategies to better mitigate the rickettsioses.

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.

Association of Scrub Typhus With the Risk of Autoimmune Diseases: A Population-Based Cohort Study

Infection plays a major role in the development of autoimmune diseases. In this study, we investigated the relationship between scrub typhus and systemic autoimmune diseases. We enrolled 6,928 hospitalized patients with scrub typhus between 2000 and 2012 from the Taiwan National Health Insurance Research Database, and we compared them with 27,712 selected inpatients who had never been diagnosed with scrub typhus (1:4 ratio, matched by age, sex, and index year) in relation to the risk of developing autoimmune diseases. Cox proportional hazards regression analysis was used to analyze the risk of autoimmune diseases by sex, age, and comorbidities, with hazard ratios and 95% confidence intervals. The adjusted hazard ratio for autoimmune diseases for the scrub typhus group was 2.4 (95% confidence interval: 1.66, 3.48, P < 0.0001) compared with the control group. Subgroup analysis showed that women aged <40 years had a significant higher risk of autoimmune diseases. The risk was significantly higher within 3 years after scrub typhus infection. In conclusion, a higher risk of autoimmune diseases was found among the scrub typhus group, especially for female patients, those aged <40 years, and within the first 3 years after getting scrub typhus.

Disseminated CMV infection and HLH in a patient with well-controlled HIV and ulcerative colitis

We present a case of haemophagocytic lymphohistiocytosis (HLH) in the context of disseminated cytomegalovirus (CMV) viraemia in a 50-year-old man with well-controlled HIV infection and ulcerative colitis (UC), for which he was receiving azathioprine. Peak CMV viral load was 371 000 copies/ml with evidence of end-organ CMV in the lungs and colon. A bone marrow biopsy showed evidence of haemophagocytosis of platelets, neutrophils and erythrocytes. The azathioprine was stopped, and he received intravenous ganciclovir and corticosteroids with suppression of the CMV viral load and resolution of the HLH.