Strongyloides stercoralis hyperinfection in an immunocompetent patient with extreme eosinophilia

Human strongyloidiasis: complexities and pathways forward

Strongyloidiasis is a World Health Organization neglected tropical disease usually caused by Strongyloides stercoralis, a parasitic worm with a complex life cycle. Globally, 300-600 million people are infected through contact with fecally contaminated soil. An autoinfective component of the life cycle can lead to chronic infection that may be asymptomatic or cause long-term symptoms, including malnourishment in children. Low larval output can limit the sensitivity of detection in stool, with serology being effective but less sensitive in immunocompromise. Host immunosuppression can trigger catastrophic, fatal hyperinfection/dissemination, where large numbers of larvae pierce the bowel wall and disseminate throughout the organs. Stable disease is effectively treated by single-dose ivermectin, with disease in immunocompromised patients treated with multiple doses. Strategies for management include raising awareness, clarifying zoonotic potential, the development and use of effective diagnostic tests for epidemiological studies and individual diagnosis, and the implementation of treatment programs with research into therapeutic alternatives and medication safety.

Severe strongyloidiasis: a systematic review and meta-analysis of 339 cases

Strongyloidiasis is a parasitosis representing a significant public health problem in tropical countries. It is often asymptomatic in immunocompetent individuals but its mortality rate increases to approximately 87% in severe forms of the disease. We conducted a systematic review, including case reports and case series, of Strongyloides hyperinfection and dissemination from 1998 to 2020 searching PubMed, EBSCO and SciELO. Cases that met the inclusion criteria of the Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist were analysed. Statistical analysis was performed using Fisher's exact test and Student's t-test and a Bonferroni correction for all the significant values. A total of 339 cases were included in this review. The mortality rate was 44.83%. The presence of infectious complications, septic shock and a lack of treatment were risk factors for a fatal outcome. Eosinophilia and ivermectin treatment were associated with an improved outcome.

Clinico-epidemiological spectrum of strongyloidiasis in India: Review of 166 cases

Strongyloidiasis is frequently asymptomatic but can cause disseminated disease and variable presentations. Diagnosis is often delayed or misdirected either due to poor degree of clinical suspicion or clinical imitation of other gastrointestinal conditions. This infection is not infrequent and several cases from all over India have been reported barring few states from central India. We reviewed 166 cases published in English literature from India; from 2001 till 2018 including 2 recent cases from our institute. The mean age of presentation was 35 years with male female ratio of 2.8:1. The duration of disease at the time of presentation varied from 15 days to 10 years. Most important predisposing factor identified in the study was HIV (13.3%) and steroid therapy (6.6%). Most common modality of diagnosis was by stool microscopy (69.3%). Radiological investigations were ordered in 33.7% patients before stool microscopy. Ivermectin was the most common treatment regimen with cure rate of 97.6%. Better awareness and early clinical suspicion of the disease with stool microscopy and adequate therapy are necessary to improve the outcome. Strongyloidiasis is rather widely prevalent infection with variable symptomatology and calls for a close coordination from family physicians and microbiologists.

Strongyloides stercoralis hyperinfection syndrome: a deeper understanding of a neglected disease

Strongyloides stercoralis hyperinfection syndrome (SHS) is a life-threatening condition that warrants early detection and management. We describe the pathogenesis, organ-specific clinical manifestations, and risk factors associated to this condition. A comprehensive review of the literature was conducted in PubMed, LILACS, EBSCO and SciELO by using the keywords: "hyperinfection syndrome"; "Strongyloides stercoralis"; "disseminated strongyloidiasis"; "systemic strongyloidiasis", "pathogenesis" and "pathophysiology". Relevant articles on this topic were evaluated and included by consensus. Also, a secondary search of the literature was performed. Articles in English and Spanish language were included. SHS has been described in tropical and sub-tropical regions. However, there is growing evidence of cases detected in developed countries favored by increasing migration and the advance in immunosuppressive therapies for oncologic and inflammatory diseases. SHS is characterized by massive multiplication of larvae, typically in immunocompromised hosts. Clinical manifestations vary according to the organ involved and include diarrhea, intestinal bleeding, alveolar hemorrhages, heart failure, jaundice, bacteremia among others. Despite advances in the understanding of this condition, fatality rates are near 90%. Clinicians should consider SHS in the differential diagnosis of acutely ill patients with multiple organ damage and epidemiological risk factors. Adverse outcomes are common, especially with delayed anti-parasitic treatment.

Lethal strongyloidiasis - Diagnostic and forensic issues

Strongyloidiasis is an infectious disease affecting approximately 30-100 million people globally. The main human pathogen is Strongyloides stercoralis which may cause a brief period of acute symptoms and signs after the initial infection, and then lapse into a chronic asymptomatic carrier state for decades due to the nematode's unique ability to autoinfect hosts. Immunosuppression from steroid therapy, T-lymphocytic viral (HTLV-1) infections, or a variety of underlying medical conditions may then result in dissemination and the highly lethal and infectious hyperinfection syndrome. Clinical suspicions for the condition are often not high in non-endemic areas, the diagnosis is difficult, and the incidence is increasing, particularly given recent mass population movements. Indications of infection at autopsy include gastrointestinal ulceration and haemorrhage, with pulmonary oedema, congestion, haemorrhage and diffuse alveolar damage.

Fatal Strongyloides hyperinfection syndrome in an immunocompetent adult with review of the literature

Strongyloides hyperinfection syndrome is rarely described in immunocompetent individuals. We present a case of fatal Strongyloides hyperinfection syndrome, and a literature review identifying nine other cases occurring in immunocompetent individuals, highlighting the challenges of diagnosis and treatment in this setting. While overall mortality is lower compared to immunocompromised patients, fatal outcomes still occur. A high index of suspicion is required for early diagnosis and treatment.

Strongyloidiasis with emphasis on human infections and its different clinical forms

Strongyloidiasis (caused by Strongyloides stercoralis, and to a lesser extent by Strongyloides fuelleborni) is one of the most neglected tropical diseases with endemic areas and affecting more than 100 million people worldwide. Chronic infections in endemic areas can be maintained for decades through the autoinfective cycle with the L3 filariform larvae. In these endemic areas, misdiagnosis, inadequate treatment and the facilitation of the hyperinfection syndrome by immunosuppression are frequent and contribute to a high mortality rate. Despite the serious health impact of strongyloidiasis, it is a neglected disease and very little is known about this parasite and the disease when compared to other helminth infections. Control of the disease is difficult because of the many gaps in our knowledge of strongyloidiasis. We examine the recent literature on different aspects of strongyloidiasis with emphasis in those aspects that need further research.

Dexamethasone effects in the Strongyloides venezuelensis infection in a murine model

The aim of this study was to investigate the immunomodulatory effects of glucocorticoids on the immune response to Strongyloides venezuelensis in mice. Balb/c mice were infected with S. venezuelensis and treated with Dexamethasone (Dexa) or vehicle. Dexa treatment increased circulating blood neutrophil numbers and inhibited eosinophil and mononuclear cell accumulation in the blood, bronchoalveolar, and peritoneal fluid compared with control animals. Moreover, Dexa decreased tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-3 (IL-3), IL-4, IL-5, IL-10, and IL-12 production in the lungs and circulating immunoglobulin G1 (IgG1), IgG2a, and IgE antibody levels while increasing the overall parasite burden in the feces and intestine. Dexa treatment enhanced the fertility of female nematodes relative to untreated and infected mice. In summary, the alterations in the immune response induced by Dexa resulted in a blunted, aberrant immune response associated with increased parasite burden. This phenomenon is similar to that observed in S. stercoralis-infected humans who are taking immunosuppressive or antiinflammatory drugs, including corticosteroids.