Strongyloides stercoralis hyperinfection associated with human T cell lymphotropic virus type-1 infection in Peru

Strongyloides stercoralis Infection in Humans: A Narrative Review of the Most Neglected Parasitic Disease

Strongyloidiasis is a helminth infection affecting 613.9 million people annually, mainly in the tropics and subtropics. The reported seroprevalence in the United States is 4% with most of the cases reported in immigrants. Human T-lympho-tropic virus 1 (HTLV-1) infections, hypogammaglobulinemia, immunosuppressant use - particularly steroid use, alcoholism, and malnutrition have been associated with an increased risk of strongyloidiasis. Recently, cases of strongyloidiasis hyperinfection syndrome have been described in coronavirus disease 2019 (COVID-19) patients treated with steroids as well. This brief review discusses the epidemiology, clinical features, management, and prevention of strongyloidiasis including some facts about the infection in pregnancy, transplant recipients, and COVID-19 patients. We conducted an online search using the PubMed, Scopus, and Google Scholar databases. Strongyloidiasis can be asymptomatic or present with mild symptoms. Strongyloides stercoralis is known to cause autoinfection. In immunocompromised individuals, it can present with severe symptoms, hyperinfection, or disseminated disease. Reported mortality in cases of disseminated Strongyloidiasis is 87.1%. Serology and detection of larvae in stool by direct microscopy are the most commonly used methods to diagnose strongyloidiasis. The drug of choice for the treatment is ivermectin. However, the use of ivermectin in human pregnancy is not well studied, and its teratogenic risks are unknown. Proactive screening of strongyloidiasis is necessary in immunocompromised individuals to prevent severe disease.

Current pharmacotherapeutic strategies for Strongyloidiasis and the complications in its treatment

INTRODUCTION

Strongyloidiasis, an infection caused by the soil-transmitted helminth Strongyloides stercoralis, can lead immunocompromised people to a life-threatening syndrome. We highlight here current and emerging pharmacotherapeutic strategies for strongyloidiasis and discuss treatment protocols according to patient cohort. We searched PubMed and Embase for papers published on this topic between 1990 and May 2022.

AREAS COVERED

Ivermectin is the first-line drug, with an estimated efficacy of about 86% and excellent tolerability. Albendazole has a lower efficacy, with usage advised when ivermectin is not available or not recommended. Moxidectin might be a valid alternative to ivermectin, with the advantage of being a dose-independent formulation.

EXPERT OPINION

The standard dose of ivermectin is 200 µg/kg single dose orally, but multiple doses might be needed in immunosuppressed patients. In the case of hyperinfection, repeated doses are recommended up to 2 weeks after clearance of larvae from biological fluids, with close monitoring and further dosing based on review. Subcutaneous ivermectin is used where there is impaired intestinal absorption/paralytic ileus. In pregnant or lactating women, studies have not identified increased risk with ivermectin use. However, with limited available data, a risk-benefit assessment should be considered for each case.

Interplay between innate immunity and the viral oncoproteins Tax and HBZ in the pathogenesis and therapeutic response of HTLV-1 associated adult T cell leukemia

The Human T-cell Leukemia virus type 1 (HTLV-1) causes an array of pathologies, the most aggressive of which is adult T-cell leukemia (ATL), a fatal blood malignancy with dismal prognosis. The progression of these diseases is partly ascribed to the failure of the immune system in controlling the spread of virally infected cells. HTLV-1 infected subjects, whether asymptomatic carriers or symptomatic patients are prone to opportunistic infections. An increasing body of literature emphasizes the interplay between HTLV-1, its associated pathologies, and the pivotal role of the host innate and adoptive immune system, in shaping the progression of HTLV-1 associated diseases and their response to therapy. In this review, we will describe the modalities adopted by the malignant ATL cells to subvert the host innate immune response with emphasis on the role of the two viral oncoproteins Tax and HBZ in this process. We will also provide a comprehensive overview on the function of innate immunity in the therapeutic response to chemotherapy, anti-viral or targeted therapies in the pre-clinical and clinical settings.

Impact of Human T Cell Lymphotropic Virus Type 1 and 2 Infection on Survival Following Stem Cell Transplantation

Human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) are delta retroviruses. HTLV-1 may lead to complications, including adult T cell leukemia-lymphoma (ATLL) and HTLV-1-associated myelopathy. Immunosuppression may result in progression from an asymptomatic carrier state to ATLL. Data on the safety of stem cell transplantation (SCT) in patients with HTLV-1/2 infection are lacking. The Center for International Blood and Marrow Transplant Research database was queried for patients who tested positive for HTLV infection in the pretransplantation workup and underwent either autologous SCT (autoSCT) or allogeneic SCT (alloSCT). Patients were excluded if they underwent SCT for ATLL. The primary outcome was overall survival (OS) at 3 years and 4 years post-SCT. In those who underwent autoSCT, 54 patients were HTLV-positive and 9836 were HTLV-negative. In those who underwent alloSCT, 105 patients were HTLV-positive and 18,077 were HTLV-negative. No difference in OS was noted between the HTLV-positive and HTLV-negative patients at 3 years post-autoSCT (76% versus 77%; P = .916). Inferior OS (32% versus 46%; P = .017) and nonrelapse mortality (35% versus 27%; P = .030) were observed in HTLV-positive patients at 4 years post-alloSCT. Future work should examine the mechanism by which HTLV-1/2 impact survival in alloSCT recipients.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Human T-Cell Lymphotropic Virus Type 1 and Strongyloides stercoralis Co-infection: A Systematic Review and Meta-Analysis

Background

The distribution of human T cell lymphotropic virus type 1 (HTLV-1) overlaps with that of Strongyloides stercoralis. Strongyloides stercoralis infection has been reported to be impacted by co-infection with HTLV-1. Disseminated strongyloidiasis and hyperinfection syndrome, which are commonly fatal, are observed in HTLV-1 co-infected patients. Reduced efficacy of anti-strongyloidiasis treatment in HTLV-1 carriers has been reported. The aim of this meta-analysis and systematic review is to better understand the association between HTLV-1 and S. stercoralis infection.

Methods

PubMed, Embase, MEDLINE, Global Health, Healthcare Management Information Consortium databases were searched. Studies regarding the prevalence of S. stercoralis, those evaluating the frequency of mild or severe strongyloidiasis, and treatment response in people living with and without HTLV-1 infection were included. Data were extracted and odds ratios were calculated. Random-effect meta-analysis was used to assess the pooled OR and 95% confidence intervals.

Results

Fourteen studies were included after full-text reviewing of which seven described the prevalence of S. stercoralis and HTLV-1. The odds of S. stercoralis infection were higher in HTLV-1 carriers when compared with HTLV-1 seronegative subjects (OR 3.2 95%CI 1.7–6.2). A strong association was found between severe strongyloidiasis and HTLV-1 infection (OR 59.9, 95%CI 18.1–198). Co-infection with HTLV-1 was associated with a higher rate of strongyloidiasis treatment failure (OR 5.05, 95%CI 2.5–10.1).

Conclusion

Strongyloides stercoralis infection is more prevalent in people living with HTLV-1. Co-infected patients are more likely to develop severe presentation and to fail treatment. Screening for HTLV-1 and Strongyloides sp. should be routine when either is diagnosed.

Palmo-plantar hyperkeratosis associated with HTLV-1 infection: a case report

Background

Palmoplantar hyperkeratosis is a cutaneous manifestation that had not been clearly associated with infection by the human T-cell lymphotropic virus, which is a retrovirus that in most cases does not develop clinical pathologies and its symptoms may be undetected. The skin is one of the most affected organs, however until now only seborrheic dermatitis, xerosis/ichthyosis and infective dermatitis associated with HTLV-1 have been described as cutaneous clinical manifestations of this disease.

Case presentation

We present the case of a 36-year-old male patient with serologically documented HTLV-1 infection, who presented symptoms of diarrhea, malabsorption due to Strongyloides stercoralis, and in whom a physical examination revealed an association with generalized xerosis and palmoplantar keratoderma confirmed by skin biopsy. Other infectious etiologies and malignancy were ruled out. This clinical manifestation was managed with dermal hydration, and skin care which improved the thickened skin and make it less noticeable.

Conclusions

According to our experience, this is the first reported case of palmoplantar keratoderma associated with a human lymphotropic virus infection. This is a skin manifestation that has not been confirmed in conjunction with HTLV-I before. This implies that palmoplantar keratoderma is a new clinical manifestation of this infection, that should be considered in the initial approach of patients in endemic areas with these dermatological characteristics.

Screening for Human T-Cell Lymphotropic Virus (HTLV) in Pregnant Women in the Peruvian Amazon and Systematic Review with Meta-Analysis of HTLV Infection in Peru

Background. Human T-cell lymphotropic virus type 1 (HTLV-1) is responsible for tropical spastic paraparesis and HTLV-1-associated leukemia/lymphoma. The infection is endemic in some areas of Peru, but its prevalence in the Peruvian Amazon is not well established. We aimed to assess the seroprevalence of HTLV-1 infection in pregnant women in the Peruvian Amazon. Moreover, we performed a systematic literature review and meta-analysis of the seroprevalence of HTLV infection in Peru. (2) Methods. This is a prospective cross-sectional study involving pregnant women attending health centers in the city of Iquitos, Peru, in May and June 2019. The presence of antibodies against HTLV-1 was assessed using ELISA (HTLV I + II ELISA recombinant v.4.0, Wiener lab, Rosario, Argentina). Positive cases were confirmed by Western Blot and HTLV-1 proviral load. (3) Results. The study included 300 pregnant women with a mean age of 26 years (standard deviation [SD] 6.4). Five patients were diagnosed with HTLV-1 infection (prevalence 1.7%, 95% confidence interval (CI) 0.7% to 3.8%). Pregnant women with HTLV-1 infection were discretely younger (mean age 22.6 [SD 22.6] vs 26.8 [SD 6.3]; p = 0.128). None of the five women had been transfused, and all were asymptomatic. Two (40%) also had a positive serology for Strongyloides, but larvae were not detected in any of the parasitological stool studies. The systematic review component identified 40 studies, which showed that the prevalence of HTLV infection in the general population was 2.9% (95% CI 1.2% to 5.3%) and in women of childbearing age, 2.5% (95% CI 1.2% to 4.0%). (4) Conclusion. The prevalence of HTLV-1 in the Peruvian Amazon basin is about 1.7%, indicating an endemic presence. Screening for HTLV-1 in prenatal care is warranted.

Human T-cell leukaemia virus type 1 associated pulmonary disease: clinical and pathological features of an under-recognised complication of HTLV-1 infection

The lung is one of several organs that can be affected by HTLV-1 mediated inflammation. Pulmonary inflammation associated with HTLV-1 infection involves the interstitium, airways and alveoli, resulting in several clinical entities including interstitial pneumonias, bronchiolitis and alveolitis, depending on which structures are most affected. Augmentation of the inflammatory effects of HTLV-1 infected lymphocytes by recruitment of other inflammatory cells in a positive feedback loop is likely to underlie the pathogenesis of HTLV-1 associated pulmonary disease, as has been proposed for HTLV-1 associated myelopathy. In contrast to the conclusions of early case series, HTLV-1 associated pulmonary disease can be associated with significant parenchymal damage, which may progress to bronchiectasis where this involves the airways. Based on our current understanding of HTLV-1 associated pulmonary disease, diagnostic criteria are proposed.

HTLV-I and Strongyloides in Australia: The worm lurking beneath

Strongyloidiasis and HTLV-I (human T-lymphotropic virus-1) are important infections that are endemic in many countries around the world with an estimated 370 million infected with Strongyloides stercoralis alone, and 5-10 million with HTVL-I. Co-infections with these pathogens are associated with significant morbidity and can be fatal. HTLV-I infects T-cells thus causing dysregulation of the immune system which has been linked to dissemination and hyperinfection of S. stercoralis leading to bacterial sepsis which can result in death. Both of these pathogens are endemic in Australia primarily in remote communities in Queensland, the Northern Territory, and Western Australia. Other cases in Australia have occurred in immigrants and refugees, returned travellers, and Australian Defence Force personnel. HTLV-I infection is lifelong with no known cure. Strongyloidiasis is a long-term chronic disease that can remain latent for decades, as shown by infections diagnosed in prisoners of war from World War II and the Vietnam War testing positive decades after they returned from these conflicts. This review aims to shed light on concomitant infections of HTLV-I with S. stercoralis primarily in Australia but in the global context as well.

Human T-cell Leukemia Virus Type 1 and Strongyloides stercoralis: Partners in Pathogenesis

Infection with human T-cell leukemia/lymphoma virus type 1 (HTLV-1) has been associated with various clinical syndromes including co-infection with Strongyloides stercoralis, which is an intestinal parasitic nematode and the leading cause of strongyloidiasis in humans. Interestingly, HTLV-1 endemic areas coincide with regions citing high prevalence of S. stercoralis infection, making these communities optimal for elucidating the pathogenesis of co-infection and its clinical significance. HTLV-1 co-infection with S. stercoralis has been observed for decades in a number of published patient cases and case series; however, the implications of this co-infection remain elusive. Thus far, data suggest that S. stercoralis increases proviral load in patients co-infected with HTLV-1 compared to HTLV-1 infection alone. Furthermore, co-infection with HTLV-1 has been associated with shifting the immune response from Th2 to Th1, affecting the ability of the immune system to address the helminth infection. Thus, despite this well-known association, further research is required to fully elucidate the impact of each pathogen on disease manifestations in co-infected patients. This review provides an analytical view of studies that have evaluated the variation within HTLV-1 patients in susceptibility to S. stercoralis infection, as well as the effects of strongyloidiasis on HTLV-1 pathogenesis. Further, it provides a compilation of available clinical reports on the epidemiology and pathology of HTLV-1 with parasitic co-infection as well as data from mechanistic studies suggesting possible immunopathogenic mechanisms. Furthermore, specific areas of potential future research have been highlighted to facilitate advancing understanding of the complex interactions between these two pathogens.

Strongyloides stercoralis colitis in a patient positive for human T-cell leukaemia virus with rheumatoid arthritis during an anti-rheumatic therapy: a case report

An elderly woman with rheumatoid arthritis (RA) presented with a chief complaint of abdominal pain and diarrhoea while undergoing treatment with low-dose corticosteroids and abatacept. Endoscopic and histopathological findings revealed manifestations of ulcerative colitis (UC). An intermediate dose of corticosteroids and 5-aminosalicylic acid were administered. Abatacept was discontinued; the anti-TNF biologic, golimumab, was administered for treatment of both RA and UC. However, colitis worsened in response to this therapeutic regimen. Colonoscopy revealed severe mucosal lesions; larvae were detected in samples taken from multiple shallow mucosal ulcers. The patient was diagnosed with Strongyloides stercoralis colitis based on the results of an anti-parasite antibody test and examination of the larval DNA. Furthermore, serology revealed a positive test for antibodies against human T-cell leukaemia virus type 1 (HTLV-1). Immunosuppressive treatment was terminated; ivermectin was administered, which resulted in improvements in colitis symptoms within a few weeks. There are several published reports describing S. stercoralis colitis as a lethal mimic of UC. Corticosteroid and anti-TNF therapies have been reported as among the major risk factors associated with strongyloidiasis in patients with HTLV-1 infection. Therefore, HTLV-1 and Strongyloides infections may be considered in cases of new-onset gastrointestinal symptoms during immunosuppressive therapy, particularly in HTLV-1-endemic regions.

Utility of PCR in Patients with Strongyloides stercoralis and HTLV-1 Coinfection in French Guiana

Strongyloides stercoralis and human T-lymphotropic virus 1 (HTLV-1) coinfections have been extensively reported in the literature, but the diagnosis and treatment of strongyloidiasis remains a challenge, particularly in HTLV-1 carriers. Our objectives were to evaluate the efficacy of a new PCR method for the detection of S. stercoralis in HTLV-1-positive patients. Stools were collected over a 1-year period across the endemic region of French Guiana, including remote forest areas. Two systems of real-time PCR were then used comparatively, with small subunit and specific repeat as respective targets, and compared with the results of microscopic examinations. One-hundred and twelve stool samples were included. Twenty-seven patients (24.1%) presented a positive HTLV-1 serology. The overall prevalence of strongyloidiasis among the 112 patients was 30% with small-subunit PCR and 11.6% with microscopic examinations. In the seropositive population, all tested stools were negative, whereas 51.2% were positive using small-subunit PCR. Thus, PCR allowed a much-improved sensitivity, particularly in HTLV-1 carriers. Among the two systems investigated, small subunit yielded better results than specific repeat PCR, with prevalence rates in HTLV-1 carriers of 51.2% and 22.2%, respectively. Therefore, PCR should be considered as a useful tool for the diagnosis of strongyloidiasis, particularly in HTLV-1 carriers who often present a light parasitic load due to erratic administration of anthelmintic drugs.

Clinical Characteristics of Disseminated Strongyloidiasis, Japan, 1975-2017

Clinical characteristics of disseminated strongyloidiasis, the severest form of strongyloidiasis, are not well described. We conducted a retrospective, consecutive chart review of patients with disseminated strongyloidiasis admitted to Okinawa Chubu Hospital in Okinawa, Japan, during January 1975-December 2017. The 70 patients were classified into 3 clinical phenotypes: dissemination (32 patients [45.7%]), occult dissemination with meningitis caused by enteric organisms (12 patients [17.1%]), and occult dissemination with culture-negative suppurative meningitis (26 patients [37.1%]). Associated mortality rates were 56.3%, 16.7%, and 11.5%, respectively, and sepsis occurred in 40.6%, 58.3%, and 11.5% of cases, respectively. Common symptoms included fever (52.9% of patients), headache (32.9%), and altered mental status (24.3%). Patients were treated with thiabendazole (before 2003) or ivermectin (after 2003). Our findings show that disseminated strongyloidiasis has clinical phenotypes in terms of severity and that identification of occult dissemination, a mild form with prominent neurologic manifestations, is lifesaving.

Noninvasive Detection of Antibodies to Human T-Cell Lymphotropic Virus Types 1 and 2 by Use of Oral Fluid

Human T-lymphotropic viruses type 1 and 2 (HTLV-1/2) are prevalent in endemic clusters globally, and HTLV-1 infects at least 5 to 10 million individuals. Infection can lead to inflammation in the spinal cord, resulting in HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), or adult T cell leukemia/lymphoma (ATL). Obtaining venous blood for serological screening, typically performed using enzyme immunoassays (EIAs), is invasive, sometimes socially unacceptable, and has restricted large-scale seroprevalence studies. Collecting oral fluid (OF) is a noninvasive alternative to venesection. In this study, an IgG antibody capture EIA was developed and validated to detect anti-HTLV-1/2 IgG in OF. OF and plasma specimens were obtained from seropositive HTLV-1/2-infected patients attending the National Centre for Human Retrovirology (n = 131) and from HTLV-1/2-uninfected individuals (n = 64). The assay showed good reproducibility and high diagnostic sensitivity (100%) and specificity (100%) using both OF and plasma. The Murex HTLV I+II commercial assay was evaluated and did not detect anti-HTLV-1/2 IgG in 14% (5/36) of OF specimens from seropositive donors. The reactivities of OF and plasma in the IgG capture correlated strongly (r = 0.9290) and were not significantly affected by delayed extraction when held between 3°C and 45°C for up to 7 days to simulate field testing. The use of OF serological screening for HTLV-1/2 infection could facilitate large-scale seroprevalence studies, enabling active surveillance of infection on a population level.

Association between HTLV-1 infection and adverse health outcomes: a systematic review and meta-analysis of epidemiological studies

BACKGROUND

Human T-cell lymphotropic virus type 1 (HTLV-1) is a human retrovirus that causes a lifelong infection. Several diseases, including an aggressive form of leukaemia, have been designated as associated with HTLV-1, whereby having HTLV-1 is a necessary condition for diagnosis. Beyond these diseases, there is uncertainty about other health effects of HTLV-1. We aimed to synthesise evidence from epidemiological studies on associations between health outcomes and HTLV-1.

METHODS

For this systematic review and meta-analysis, we searched Embase, MEDLINE, MEDLINE In-Process, and Global Health for publications from their inception to July, 2018. We included cohort, case-control, and controlled cross-sectional studies that compared mortality or morbidity between people with and without HTLV-1. We excluded studies of psychiatric conditions, of symptoms or clinical findings only, of people who had undergone blood transfusion or organ transplant, and of population groups defined by a behavioural characteristic putting them at increased risk of co-infection with another virus. We extracted the risk estimates (relative risks [RRs] or odds ratios [ORs]) that reflected the greatest degree of control for potential confounders. We did a random-effects meta-analysis for groups of effect estimates where case ascertainment methods, age groups, and confounders were similar, presenting pooled estimates with 95% CIs and prediction intervals.

FINDINGS

Of the 3318 identified studies, 39 met the inclusion criteria, examining 42 clinical conditions between them. The adjusted risk of death due to any cause was higher in people with HTLV-1 when compared with HTLV-1-negative counterparts (RR 1·57, 95% CI 1·37-1·80). From meta-analysis, HTLV-1 was associated with increased odds of seborrheic dermatitis (OR 3·95, 95% CI 1·99-7·81), Sjogren's syndrome (3·25, 1·85-5·70), and, inversely, with lower relative risk of gastric cancer (RR 0·45, 0·28-0·71). There were a further 14 diseases with significant associations or substantially elevated risk with HTLV-1 from single studies (eczema [children]; bronchiectasis, bronchitis and bronchiolitis [analysed together]; asthma [males]; fibromyalgia; rheumatoid arthritis; arthritis; tuberculosis; kidney and bladder infections; dermatophytosis; community acquired pneumonia; strongyloides hyperinfection syndrome; liver cancer; lymphoma other than adult T-cell leukaemia-lymphoma; and cervical cancer).

INTERPRETATION

There is a broad range of diseases studied in association with HTLV-1. However, the elevated risk for death among people with HTLV-1 is not explained by available studies of morbidity. Many of the diseases shown to be associated with HTLV-1 are not fatal, and those that are (eg, leukaemia) occur too rarely to account for the observed mortality effect. There are substantial research gaps in relation to HTLV-1 and cardiovascular, cerebrovascular, and metabolic disease. The burden of disease associated with the virus might be broader than generally recognised.

FUNDING

Commonwealth Department of Health, Australia.

Intestinal parasites including Cryptosporidium, Cyclospora, Giardia, and Microsporidia, Entamoeba histolytica, Strongyloides, Schistosomiasis, and Echinococcus: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of intestinal parasites in the pre- and post-transplant period. Intestinal parasites are prevalent in the developing regions of the world. With increasing travel to and from endemic regions, changing immigration patterns, and the expansion of transplant medicine in developing countries, they are increasingly recognized as a source of morbidity and mortality in solid-organ transplant recipients. Parasitic infections may be acquired from the donor allograft, from reactivation, or from de novo acquisition post-transplantation. Gastrointestinal multiplex assays have been developed; some of the panels include testing for Cryptosporidium, Cyclospora, Entamoeba histolytica, and Giardia, and the performance is comparable to conventional methods. A polymerase chain reaction test, not yet widely available, has also been developed to detect Strongyloides in stool samples. New recommendations have been developed to minimize the risk of Strongyloides donor-derived events. Deceased donors with epidemiological risk factors should be screened for Strongyloides and recipients treated if positive as soon as the results are available. New therapeutic agents and studies addressing the optimal treatment regimen for solid-organ transplant recipients are unmet needs.

Implementation and evaluation of a quality and safety tool for ambulatory strongyloidiasis patients at high risk of adverse outcome

Background

Strongyloidiasis is a common infection in Canadian migrants that can cause life-threatening hyperinfection in immunosuppressed hosts. We designed and implemented a safety tool to guide management of patients with Strongyloides in order to prevent adverse outcomes. Methods: Patients treated at our centre for strongyloidiasis from January 1, 2013 to December 31, 2015 were identified through our ivermectin access log. Patients were categorized into pre-implementation and post-implementation groups. A retrospective chart review for predefined variables was conducted.

Results

Of 37 patients with strongyloidiasis, 26 were in the pre-implementation group and 11 were in the post-implementation group. Documented seroreversion (positive to negative) occurred in 42.1% of patients pre-implementation and 62.5% of patients post-implementation (p = 0.420). Documented stool clearance occurred in 80.0% of patients pre-implementation and 100.0% of patients post-implementation (p = 1.000). More patients were screened for HTLV-1 coinfection post-implementation (80.0%) versus pre-implementation (30.8%) (p = 0.011). Loss to follow-up after treatment occurred in 23.1% of patients pre-implementation and 20.0% of patients post-implementation (p = 1.000).

Conclusions

The safety tool may be useful in the treatment of patients with strongyloidiasis to improve documentation of patient outcomes and standardize care. Future research should include a powered prospective study.

Electronic supplementary material

The online version of this article (10.1186/s40794-019-0080-1) contains supplementary material, which is available to authorized users.

Is Strongyloides seropositivity associated with diabetes mellitus? A retrospective case-control study in an East London NHS Trust

BACKGROUND

The association between diabetes and Strongyloides stercoralis remains controversial. We conducted a case-control study examining the association between diabetes and Strongyloides seropositivity in a large UK centre.

METHODS

Between January 2013 and October 2016, cases and controls were identified by positive and negative Strongyloides serology, respectively. Demographic, clinical and microbiological data were retrospectively collected. Multivariate logistic regression analysis was performed.

RESULTS

Over the study period, 532 samples were serologically tested for Strongyloides. After exclusion of duplicates and cases with missing data, 100 (22.3%; 95% CI 18.5-26.4%) out of 449 tested positive. Of seropositive cases, the mean age was 57 years (SD 16), 71 (71%) were male, 94 (94%) were migrants and 92 (92%) had eosinophilia.Univariate logistic regression analysis demonstrated a significant association between Strongyloides seropositivity and age (OR 1.04, 95% CI 1.02-1.05), male sex (OR 2.22, 95% CI 1.37-3.59), migration (OR 5.36, 95% CI 2.27-12.67), eosinophilia (OR 4.36, 95% CI 2.04-9.33) and diabetes (OR 3.52, 95% CI 2.19-5.66). In multivariate analysis, there remained a significant association between diabetes and Strongyloides seropositivity (OR 1.81, 95% CI 1.04-3.16).

CONCLUSIONS

We demonstrated a high rate of Strongyloides seropositivity in our East London cohort and a significant association with diabetes.

Strongyloides stercoralis larvae in the urine of a patient with transitional cell carcinoma of the bladder: a case report

Disseminated infection with Strongyloides stercoralis refers to the massive migration of infective larvae from the gastrointestinal tract to other organs that are not involved in the normal life cycle of the parasite. We describe the case of a Nigerian male with transitional cell carcinoma of the bladder in whom larvae of S. stercoralis was identified in the urine. This report involves a 60-year old male Nigerian presenting to the Urology clinic of the Jos University teaching hospital, Nigeria with disseminated S. stercoralis. The index patient presented with a 5 month history of total haematuria, urinary frequency, urgency, nocturia, straining to pass urine, feeling of incomplete voiding and terminal dribbling. He also had episodes of suprapubic pain. Physical examination revealed a cachexic patient who had mild suprapubic tenderness. Urinary examination showed numerous red blood cells and rhabditiform larvae of S. stercoralis. Abdominal ultrasound revealed a heterogeneous mass in the urinary bladder measuring 4.0 × 3.3 cm. Abdominal computed tomography also showed an irregular mass measuring 4.2 × 3.8 cm with HU of 41 projecting into the bladder from the posterior wall towards the dome. Histology of the biopsy specimen revealed transitional cell carcinoma. The patient was treated with a single dose of oral ivermectin but died 1 week later. Physicians working in areas that are endemic for S. stercoralis should consider investigating immunocompromised patients for S. stercoralis infection given the poor prognosis of disseminated infection in this group of patients.

Infectious Disease Transmission in Solid Organ Transplantation: Donor Evaluation, Recipient Risk, and Outcomes of Transmission

In 2016, the Transplantation Society of Australia and New Zealand, with the support of the Australian Government Organ and Tissue authority, commissioned a literature review on the topic of infectious disease transmission from deceased donors to recipients of solid organ transplants. The purpose of this review was to synthesize evidence on transmission risks, diagnostic test characteristics, and recipient management to inform best-practice clinical guidelines. The final review, presented as a special supplement in Transplantation Direct, collates case reports of transmission events and other peer-reviewed literature, and summarizes current (as of June 2017) international guidelines on donor screening and recipient management. Of particular interest at the time of writing was how to maximize utilization of donors at increased risk for transmission of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus, given the recent developments, including the availability of direct-acting antivirals for hepatitis C virus and improvements in donor screening technologies. The review also covers emerging risks associated with recent epidemics (eg, Zika virus) and the risk of transmission of nonendemic pathogens related to donor travel history or country of origin. Lastly, the implications for recipient consent of expanded utilization of donors at increased risk of blood-borne viral disease transmission are considered.

Strongyloides stercoralis hyperinfection in an unconscious diabetic patient with dermatomyositis

A case of Strongyloides stercoralis hyperinfection in a patient with dermatomyositis and diabetes mellitus is herein reported. The case was a 60-year-old female admitted due to watery diarrhea and unconsciousness. She had a 10-year history of chronic immunosuppressive therapy including methotrexate and prednisolone for dermatomyositis. Stool parasitological examination revealed numerous rhabditiform larvae of threadworm "S. stercoralis." Larva in stool sample was characterized by sequencing of mitochondrial DNA. After treatment with ivermectin, the patient recovered without evidence of S. stercoralis in follow-up stool samples. In endemic areas, stool examination for detection of S. stercoralis should be performed on a regular basis for all patients receiving immunosuppressive therapy, as early detection and treatment are necessary to minimize complications of severe strongyloidiasis.

Clinical and haematological characteristics of human trichostrongyliasis

Trichostrongylus spp. are primarily parasites of ruminants, but humans can become infected as accidental hosts. Information about the clinical aspects of human trichostrongyliasis is limited. This study investigated the clinical and haematological characteristics of a large number of trichostrongyliasis patients. In the Fouman district of Guilan Province in northern Iran, during 2015-2016, 60 patients were identified as positive for Trichostrongylus spp., using stool examination methods. The clinical manifestations and demographic data of all patients were recorded and further analysed. Twenty-three patients (38.3%) were male and 37 (61.7%) were female. Among the individuals infected only with Trichostrongylus, only nine patients (16.4%) were asymptomatic. Forty-six patients (83.6%) presented with gastrointestinal (76.3%), pulmonary (30.9%) and cutaneous (12.7%) symptoms. No statistically significant relationship was found between clinical manifestations and sex or age groups. Ten patients (18.1%) revealed eosinophilia and five (9.1%) presented with hypochromic microcytic anaemia. The relationship between eosinophilia and age group, sex and clinical manifestations showed no statistical significance. Our study indicated that trichostrongyliasis may be a major parasitic aetiology for gastrointestinal symptoms and eosinophilia in rural residents of endemic areas.

Importance of a Rapid and Accurate Diagnosis in Strongyloides Stercoralis and Human T-Lymphotropic Virus 1 Co-infection: A Case Report and Review of the Literature

Strongyloides (S.) stercoralis and Human T-Lymphotropic Virus 1 (HTLV-1) share some endemic regions such as Japan, Jamaica, and South America and are mostly diagnosed elsewhere in immigrants from endemic areas. This co-infection has not been documented in Argentina although both pathogens are endemic in the Northwest. We present a case of S. stercoralis and HTLV-1 co-infection with an initial presentation due to gastrointestinal symptoms which presented neither eosinophilia nor the presence of larvae in stool samples in a non-endemic area for these infections. A young Peruvian woman living in Buenos Aires attended several emergency rooms and finally ended up admitted in a gastroenterology ward due to incoercible vomiting, diarrhea, abdominal pain, fever, and weight loss. Gastrointestinal symptoms started 3 months before she returned to Argentina from a trip to Peru. She presented malnutrition and abdominal distension parameters. HIV-1 and other immunodeficiencies were discarded. The serial coproparasitological test was negative. Computed tomography showed diffuse thickening of duodenal and jejunal walls. At the beginning, vasculitis was suspected and corticosteroid therapy was initiated. The patient worsened rapidly. Skin, new enteral biopsies, and a new set of coproparasitological samples revealed S. stercoralis. Then, HTLV-1 was suspected and infection was confirmed. Ivermectin and albendazole were administrated, until the stool sample remained negative for 2 weeks. Larvae were not observed in fresh stool, Ritchie method, and agar culture 1 week post-treatment. Although she required initial support with parenteral nutrition due to oral intolerance she slowly progressed favorably. It has been highly recommended to include a rapid and sensitive PCR strategy in the algorithm to confirm Strongyloides infection, which has demonstrated to improve early diagnosis in patients at-risk of disseminated strongyloidiasis.

Human T Cell Leukemia Virus Type 1: Persistence and Pathogenesis

Human T cell leukemia virus type 1 (HTLV-1), also known as human T lymphotropic virus type 1, was the first exogenous human retrovirus discovered. Unlike the distantly related lentivirus HIV-1, HTLV-1 causes disease in only 5-10% of infected people, depending on their ethnic origin. But whereas HIV-1 infection and the consequent diseases can be efficiently contained in most cases by antiretroviral drug treatment, there is no satisfactory treatment for the malignant or inflammatory diseases caused by HTLV-1. The purpose of the present article is to review recent advances in the understanding of the mechanisms by which the virus persists in vivo and causes disabling or fatal diseases.

Association of Tuberculosis Status with Neurologic Disease and Immune Response in HTLV-1 Infection

The human T cell lymphotropic virus type 1 (HTLV-1) is the etiologic agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-1 infected individuals have increased susceptibility to Mycobacterium tuberculosis infection but the influence of tuberculosis (TB) on the course of HTLV-1 infection is unknown. The aim of this study was to evaluate the influence of TB on immunological, virologic, and neurologic features of HTLV-1 infection. This is a retrospective analysis of individuals enrolled in a cohort study from an HTLV-1 clinic who were evaluated for past or latent tuberculosis (LTB) and classified clinically as HTLV-1 carriers, probable HAM/TSP and definite HAM/TSP. Spontaneous cytokine production (interferon-gamma [IFN-γ], tumor necrosis factor [TNF], and interleukin[IL]-10), serum chemokines (CXCL9 and CXCL10) and HTLV-1 proviral load were evaluated. Of 172 participants, 64 did not have histories of TB (TB- group), 81 had LTB and 27 had TB in the past (TB+ group). In the TB+ group, there was a higher frequency of HAM/TSP patients (35%) than in HTLV-1 carriers (10%) (OR = 3.8, p = .0001). HAM/TSP patients with histories of TB had higher IFN-γ/IL-10 and TNF/IL-10 ratios when compared with HAM/TSP patients without histories of TB. There were no differences in serum chemokine production and proviral load across TB groups stratified on HTLV-1 clinical status. In conclusion, TB may influence the development of HAM/TSP, and patients with these two diseases have an impairment in the modulation of immune response.

Evidence-Based Guidelines for Screening and Management of Strongyloidiasis in Non-Endemic Countries

Strongyloidiasis is an intestinal parasitic infection becoming increasingly important outside endemic areas, not only because of the high prevalence found in migrant populations, but also because immunosuppressed patients may suffer a potentially fatal disseminated disease. The aim of these guidelines is to provide evidence-based guidance for screening and treatment of strongyloidiasis in non-endemic areas. A panel of experts focused on three main clinical questions (who should be screened and how, how to treat), and reviewed pertinent literature available in international databases of medical literature and in documents released by relevant organizations/societies. A consensus of the experts' opinion was sought when specific issues were not covered by evidence. In particular, six systematic reviews were retrieved and constituted the main support for this work. The evidence and consensus gathered led to recommendations addressing various aspects of the main questions. Grading of evidence and strength of recommendation were attributed to assess the quality of supporting evidence. The screening of individuals at risk of the infection should be performed before they develop any clinical complication. Moreover, in immunosuppressed patients, the screening should be mandatory. The screening is based on a simple and widely accessible technology and there is now a universally accepted treatment with a high efficacy rate. Therefore, the screening could be implemented as part of a screening program for migrants although further cost-effectiveness studies are required to better evaluate this strategy from a public health point of view.

Multiorgan Dysfunction Syndrome from Strongyloides stercoralis Hyperinfection in a Patient with Human T-Cell Lymphotropic Virus-1 Coinfection After Initiation of Ivermectin Treatment

Strongyloides stercoralis is well known to cause hyperinfection syndrome during the period of immunosuppression; but dissemination, worsening hyperinfection, and development of multiorgan dysfunction syndrome after initiation of ivermectin has not been reported in the past. Herein, we describe the case of a 62-year-old man with chronic strongyloidiasis and human T-cell lymphotropic virus-1 coinfection, who developed significant clinical worsening after 24-48 hours of initiation of treatment with ivermectin (200 μg/kg daily). Oral albendazole (600 mg every 12 hours) was added to the regimen due to clinical deterioration. Notably, after a protracted clinical course with multiple complications, which included respiratory failure from gram-negative pneumonia and pulmonary alveolar hemorrhage, Klebsiella meningitis, Clostridium difficile colitis, and herpes labialis, the patient eventually recovered. Health-care providers should be aware that during the early days of antihelminthic treatment initiation, significant dissemination of S. stercoralis and worsening of the clinical scenario can occur.

Parasites

Parasites are an important cause of human disease worldwide. The clinical severity and outcome of parasitic disease is often dependent on the immune status of the host. Specific parasitic diseases discussed in this chapter are amebiasis, giardiasis, cryptosporidiosis, cyclosporiasis, cystoisosporiasis, microsporidosis, granulomatous amebic encephalitis, toxoplasmosis, leishmaniasis, Chagas disease, malaria, babesiosis, strongyloidiasis, and scabies.

Unsuspected Strongyloides stercoralis infection in hospital patients with comorbidity in need of proper management

BACKGROUND

Investigate the role of latent strongyloidiasis infection in patients at the University Hospital, Honduras.

METHODS

Prospective observational cohort study during 20 non consecutive months from March 2009 to February 2011. Epidemiological and clinical data obtained from patients excreting Strongyloides stercoralis larvae in stool who consulted at the hospital were recorded and analyzed.

RESULTS

Thirty five (5 %) of 712 patients had S. stercoralis larvae in one stool sample; 62.8 % came from rural areas and 91.7 % were poor; 68.5 % (24/35) were 21 years old or older. Eight patients (22.8 %) had no predisposing illness; 3 (8.6 %) received steroid treatment, 29/35 (82.8 %) presented with persistent diarrhea and 24/35 (68.5 %) presented following comorbidities: HIV/AIDS (31.4 %), alcoholism alone (11.4 %) or with other associated illness (8.6 %), malignancy (8.6 %), renal failure (5.7 %) and hyperthyroidism (2.8 %). A combination of symptoms suggestive of strongyloidiasis but indistinguishable from those potentially associated to their comorbid condition included severe epigastric pain, diarrhea of weeks duration, peripheral eosinophilia, astenia, adynamia, fever, anemia and weight loss in 85.7 % of the cases, 3 of whom described skin lesions compatible with larva currens. None of the diagnostic clinical impressions mentioned Strongyloides infection. Ten strongyloidiasis patients received partial treatment with albendazole or ivermectin. Incomplete data, underestimation of the parasitic infection and no laboratory follow-up of the patients limited our observations.

CONCLUSIONS

Strongyloides stercoralis is an unsuspected and neglected parasitic infection by health personnel in Honduras. Lack of awareness of its importance represents a strong barrier to proper treatment and follow-up, posing a threat of possible fatal complications in patients with comorbid conditions.

Relationship Among Strongyloides stercoralis Infection, Human T-Cell Lymphotropic Virus Type 1 Infection, and Cancer: A 24-Year Cohort Inpatient Study in Okinawa, Japan

This study evaluated the prevalence of Strongyloides stercoralis infection and human T-cell lymphotropic virus type 1 (HTLV-1) infection in the population. In addition, this study investigated the relationship between S. stercoralis infection or HTLV-1 infection and a patient's risk of developing related cancers. This is a retrospective cohort study of 5,209 patients. The prevalence of S. stercoralis infection was 5.2% among all patients. The prevalence among men (6.3%) was significantly higher than among women (3.6%, P < 0.001). The prevalence of HTLV-1 infection among this population was 13.6% and the prevalence among women (15.5%) was significantly higher than that of men (12.3%, P < 0.001). HTLV-1 seroprevalence was higher in patients with liver cancer (P = 0.003, odds ratio [OR]: 1.91, 95% confidence interval [CI]: 1.24, 2.95) and in those with lymphoma other than adult T-cell leukemia/lymphoma (ATLL) (P = 0.005, adjusted OR: 2.76, 95% CI: 1.36, 5.62) if compared with patients without any neoplasm. The prevalence of both S. stercoralis and HTLV-1 in the Okinawan population has been steadily decreasing over the past 24 years. HTLV-1 infection significantly increases the odds of developing liver cancer and lymphomas other than ATLL.

Human T-lymphotropic virus-1 serology in the Northern Territory: 2008-2011

A retrospective observational study of human T-lymphotropic virus-1 (HTLV-1) serology requests made to the Northern Territory Government Pathology Service (NTGPS) between 2008 and 2011, was undertaken to review aspects of HTLV-1 sero-epidemiology and performance of the assays. A total of 5686 HTLV-1 serology requests, representing 3555 individual patients, were received during the study period; 368 HTLV-1 confirmed positive serology results were identified from the 3555 individual patients included in the sample. There was a distinct difference in the performance of the two antibody assays in use during this period, with the Serodia particle agglutination having a 5.7% indeterminate positivity rate compared to 18.1% indeterminate positivity rate of the Abbott HTLV 1/2 assay. We believe this is partially a serological anomaly related to current Australian western blot positive interpretative criteria, rather than false positive screening assay results.The majority (99.7%) of positive results occurred in Indigenous patients. The HTLV-1 positive rate varied geographically from a regional high of 51.7%, and falling inversely with distance from Central Australia. Patients with positive serology had a mean age of 49.9 (±13.9) years, with positivity occurring equally in males and females.

High prevalence of bronchiectasis is linked to HTLV-1-associated inflammatory disease

Background

Human T-lymphotropic virus type 1 (HTLV-1), a retrovirus, is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) and adult T-cell leukaemia/lymphoma (ATLL). The reported association with pulmonary disease such as bronchiectasis is less certain.

Methods

A retrospective case review of a HTLV-1 seropositive cohort attending a national referral centre. The cohort was categorised into HTLV-1 symptomatic patients (SPs) (ATLL, HAM/TSP, Strongyloidiasis and HTLV associated inflammatory disease (HAID)) and HTLV-1 asymptomatic carriers (ACs). The cohort was reviewed for diagnosis of bronchiectasis.

Result

34/246 ACs and 30/167 SPs had been investigated for respiratory symptoms by computer tomography (CT) with productive cough +/- recurrent chest infections the predominant indications. Bronchiectasis was diagnosed in one AC (1/246) and 13 SPs (2 HAID, 1 ATLL, 10 HAM/TSP) (13/167, RR 19.2 95 % CI 2.5-14.5, p = 0.004) with high resolution CT. In the multivariate analysis ethnicity (p = 0.02) and disease state (p < 0.001) were independent predictors for bronchiectasis. The relative risk of bronchiectasis in SPs was 19.2 (95 % CI 2.5-14.5, p = 0.004) and in HAM/TSP patients compared with all other categories 8.4 (95 % CI 2.7-26.1, p = 0.0002). Subjects not of African/Afro-Caribbean ethnicity had an increased prevalence of bronchiectasis (RR 3.45 95 % 1.2-9.7, p = 0.02).

Conclusions

Bronchiectasis was common in the cohort (3.4 %). Risk factors were a prior diagnosis of HAM/TSP and ethnicity but not HTLV-1 viral load, age and gender. The spectrum of HTLV-associated disease should now include bronchiectasis and HTLV serology should be considered in patients with unexplained bronchiectasis.

Strongyloidiasis in a diabetic patient accompanied by gastrointestinal stromal tumor: cause of eosinophilia unresponsive to steroid therapy

We report here a case of strongyloidiasis in a 72-year-old diabetic patient (woman) accompanied by gastrointestinal stromal tumor receiving imatinib therapy, first diagnosed as hypereosinophilic syndrome and treated with steroids for uncontrolled eosinophilia. She suffered from lower back pain and intermittent abdominal discomfort with nausea and diagnosed with gastrointestinal stromal tumor. After post-operative imatinib treatment eosinophilia persisted, so that steroid therapy was started under an impression of hypereosinophilic syndrome. In spite of 6 months steroid therapy, eosinophilia persisted. Stool examination was performed to rule out intestinal helminth infections. Rhabditoid larvae of Strongyloides stercoralis were detected and the patient was diagnosed as strongyloidiasis. This diagnosis was confirmed again by PCR. The patient was treated with albendazole for 14 days and her abdominal pain and diarrhea improved. This case highlights the need for thorough investigation, including molecular approaches, to test for strongyloidiasis before and during steroid therapies.

Persistent strongyloidiasis complicated by recurrent meningitis in an HTLV seropositive Peruvian migrant resettled in Italy

We describe a case of persistent strongyloidiasis complicated by recurrent meningitis, in a human T cell lymphotropic virus type 1 (HTLV-1) seropositive Peruvian migrant adult resettled in Italy. He was admitted with signs and symptoms of acute bacterial meningitis, reporting four other meningitis episodes in the past 6 years, with an etiological diagnosis of Escherichia coli and Enterococcus faecium in two cases. He had been previously treated with several antihelmintic regimens not including ivermectin, without eradication of strongyloidiasis, and he had never been tested for HTLV before. During the described episode, the patient was treated for meningitis with broad-spectrum antibiotic therapy and 200 μg/kg/dose oral ivermectin once daily on day 1, 2, 15 and 16 with full recovery and no further episodes of meningitis. The presented case underlines several critical points concerning the management of poorly known neglected diseases such as strongyloidiasis and HTLV infection in low-endemic areas. Despite several admissions for meningitis and strongyloidiasis, the parasitic infection was not adequately treated and the patient was not previously tested for HTLV. The supply of ivermectin and the choice of treatment scheme was challenging since ivermectin is not approved in Italy and there are no standardized guidelines for the treatment of severe strongyloidiasis in HTLV seropositive subjects.

Strongyloides stercoralis hyperinfection associated with impaired intestinal motility disorder

Infection by Strongyloides stercoralis is a highly prevalent helminthiasis, which is mostly distributed in the tropical and subtropical regions of the world. Although a substantial number of cases are asymptomatic or paucisymtomatic, severe and life-threatening forms of this infection still occur and not infrequently is lately diagnosed. Gram-negative bacteria septicemia, which frequently accompanies the severe helminthiasis, contributes to the high mortality rate. Severe infection is invariably triggered by any imbalance in the host's immunity, favoring the auto-infective cycle, which increases the intraluminal parasite burden enormously. Clinical presentation of severe cases is varied, and diagnosis requires a high suspicion index. Acute abdomen has been reported in association with S. stercoralis infection, but intestinal necrosis is rarely found during the surgical approach. The authors report the case of a man who sought the emergency unit with recent onset abdominal pain. Clinical and imaging features were consistent with obstructive acute abdomen. Scattered adhesions and a necrotic ileal segment with a tiny perforation represented the surgical findings. The patient outcome was unfavorable and respiratory distress required an open lung biopsy. Both surgical specimens showed S. stercoralis infection. Unfortunately the patient underwent multiple organ failure and septicemia, and subsequently died. The authors call attention to the finding of intestinal necrosis and impaired intestinal motility disorder as possibilities for the diagnosis and risk factor, respectively, for a severe infection of S. stercoralis.

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.

Strongyloidiasis--an insight into its global prevalence and management

BACKGROUND

Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.

METHODOLOGY AND RESULTS

In this review, we have discussed various conventional methods for the diagnosis and management of this disease, with an emphasis on recently developed molecular and serological methods that could be implemented to establish guidelines for precise diagnosis of infection in patients and screening in epidemiological surveys. A comprehensive analysis of various cases reported worldwide from different endemic and nonendemic foci of the disease for the last 40 years was evaluated in an effort to delineate the global prevalence of this disease. We also updated the current knowledge of the various clinical spectrum of this parasitic disease, with an emphasis on newer molecular diagnostic methods, treatment, and management of cases in immunosuppressed patients.

CONCLUSION

Strongyloidiasis is considered a neglected tropical disease and is probably an underdiagnosed parasitic disease due to its low parasitic load and uncertain clinical symptoms. Increased infectivity rates in many developed countries and nonendemic regions nearing those in the most prevalent endemic regions of this parasite and the increasing transmission potential to immigrants, travelers, and immunosuppressed populations are indications for initiating an integrated approach towards prompt diagnosis and control of this parasitic disease.

Treatment of strongyloidiasis in HTLV-1 and Strongyloides stercoralis coinfected patients is associated with increased TNFα and decreased soluble IL2 receptor levels

BACKGROUND

Human T cell lymphotropic virus type 1 (HTLV-1) infection has been associated with recurrent and disseminated strongyloidiasis and adult T cell leukemia/lymphoma (ATLL).

METHODS

We compared immunological aspects and markers for ATLL in HTLV-1 patients with or without strongyloidiasis, and evaluated the influence of Strongyloides stercoralis treatment on the immune response and clinical outcomes of HTLV-1 infection.

RESULTS

Levels of TNFα and IFNγ were lower in patients coinfected with HTLV-1 and S. stercoralis than in patients with HTLV-1 only (p < 0.05), and there was an increase in TNFα levels after anthelmintic treatment. Levels of sIL-2R were higher in patients with HTLV-1 coinfected with S. stercoralis and anthelmintic treatment decreased sIL-2R levels (p < 0.05). The one patient who developed ATLL was coinfected with S. stercoralis.

CONCLUSION

These data show that helminthic infection has a modulatory role in HTLV-1 infection and that S. stercoralis may be a cofactor in the development of ATLL.

Higher human T-lymphotropic virus type 1 subtype C proviral loads are associated with bronchiectasis in indigenous australians: results of a case-control study

In this case-control study, HTLV-1 infection increased risk of bronchiectasis 1.84 times. HTLV-1 proviral loads for bronchiectasis patients were significantly higher than those of controls. HTLV-1 proviral loads correlated with the extent of radiologically determined pulmonary injury.

Background.

 We previously suggested that infection with the human T-lymphotropic virus type 1 (HTLV-1) subtype C is associated with bronchiectasis among Indigenous Australians. Bronchiectasis might therefore result from an HTLV-1-mediated inflammatory process that is typically associated with a high HTLV-1 proviral load (PVL). Human T-lymphotropic virus type 1 PVL have not been reported for Indigenous Australians.

Methods.

 Thirty-six Indigenous adults admitted with bronchiectasis from June 1, 2008, to December 31, 2009 were prospectively recruited and matched by age, sex, and ethno-geographic origin to 36 controls. Case notes and chest high-resolution computed tomographs were reviewed, and pulmonary injury scores were calculated. A PVL assay for the HTLV-1c subtype that infects Indigenous Australians was developed and applied to this study. Clinical, radiological, and virological parameters were compared between groups and according to HTLV-1 serostatus.

Results.

 Human T-lymphotropic virus type 1 infection was the main predictor of bronchiectasis in a multivariable model (adjusted risk ratio [aRR], 1.84; 95% confidence interval [CI], 1.19–2.84; P = .006). Moreover, the median HTLV-1c PVL (interquartile range) for cases was >100-fold that of controls (cases, 0.319 [0.007, 0.749]; controls, 0.003 [0.000, 0.051] per 100 peripheral blood lymphocytes; P = .007), and HTLV-1c PVL were closely correlated with radiologically determined pulmonary injury scores (Spearman's rho = 0.7457; P = .0000). Other predictors of bronchiectasis were positive Strongyloides serology (aRR, 1.69; 95% CI, 1.13–2.53) and childhood skin infections (aRR, 1.62; 95% CI, 1.07–2.44). Bronchiectasis was the major predictor of death (aRR, 2.71; 95% CI, 1.36–5.39; P = .004).

Conclusions.

 These data strongly support an etiological association between HTLV-1 infection and bronchiectasis in a socially disadvantaged population at risk of recurrent lower respiratory tract infections.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) in Strongyloides stercoralis Hyperinfection

Strongyloides stercoralis (S. stercoralis) is a soil transmitted intestinal roundworm that has a unique ability to multiply within the human host and reinfect the human carrier by a process of autoinfection. By this property, S. stercoralis can persist as an occult infection for many decades. In situations of immunosuppression or other permissive gastrointestinal conditions, there occurs a massive increase in parasite multiplication. The parasites penetrate through the intestinal mucosa and are carried in circulation and can cause multisystem involvement. We report a case of a 76-year-old Columbian male who presented with intractable vomiting and hyponatremia who was then diagnosed to have syndrome of inappropriate antidiuretic hormone (SIADH). The patient's symptoms improved after treatment with two doses of ivermectin and his serum sodium levels returned to normal. S. stercoralis infection should be suspected in patients from endemic regions who present with gastrointestinal symptoms and unexplained hyponatremia.

High prevalence of Strongyloides stercoralis infection among the elderly in Brazil

Little is known about the frequency of intestinal parasites in the elderly due to a lack of attention given to the occurrence of these infections among older adults. This study compares the frequency of Strongyloides stercoralis and other enteroparasites between elderly living in nursing homes (n = 100) and those noninstitutionalized (n = 100) from Uberlândia, state of Minas Gerais, southeastern Brazil, associated with data of epidemiological and socio-demographic conditions. Through coproparasitological examination of both groups, enteroparasites were detected in 15 of 200 individuals examined (7.5%; CI: 5.1- 9.9). S. stercoralis was the most frequent parasite 10/200 (5%; CI: 4.2-5.8), being significantly higher in males and in individuals with autonomy for daily living activities. There were no statistical differences in the prevalence of parasites between the two groups compared. In conclusion, S. stercoralis infection was highly prevalent in elderly patients and it does not depend on whether the individual was institutionalized or not.

Clinical associations of Human T-Lymphotropic Virus type 1 infection in an indigenous Australian population

INTRODUCTION

In resource-poor areas, infectious diseases may be important causes of morbidity among individuals infected with the Human T-Lymphotropic Virus type 1 (HTLV-1). We report the clinical associations of HTLV-1 infection among socially disadvantaged Indigenous adults in central Australia.

METHODOLOGY AND PRINCIPAL FINDINGS

HTLV-1 serological results for Indigenous adults admitted 1(st) January 2000 to 31(st) December 2010 were obtained from the Alice Springs Hospital pathology database. Infections, comorbid conditions and HTLV-1 related diseases were identified using ICD-10 AM discharge morbidity codes. Relevant pathology and imaging results were reviewed. Disease associations, admission rates and risk factors for death were compared according to HTLV-1 serostatus. HTLV-1 western blots were positive for 531 (33.3%) of 1595 Indigenous adults tested. Clinical associations of HTLV-1 infection included bronchiectasis (adjusted Risk Ratio, 1.35; 95% CI, 1.14-1.60), blood stream infections (BSI) with enteric organisms (aRR, 1.36; 95% CI, 1.05-1.77) and admission with strongyloidiasis (aRR 1.38; 95% CI, 1.16-1.64). After adjusting for covariates, HTLV-1 infection remained associated with increased numbers of BSI episodes (adjusted negative binomial regression, coefficient, 0.21; 95% CI, 0.02-0.41) and increased admission numbers with strongyloidiasis (coefficient, 0.563; 95% CI, 0.17-0.95) and respiratory conditions including asthma (coefficient, 0.99; 95% CI, 0.27-1.7), lower respiratory tract infections (coefficient, 0.19; 95% CI, 0.04-0.34) and bronchiectasis (coefficient, 0.60; 95% CI, 0.02-1.18). Two patients were admitted with adult T-cell Leukemia/Lymphoma, four with probable HTLV-1 associated myelopathy and another with infective dermatitis. Independent predictors of mortality included BSI with enteric organisms (aRR 1.78; 95% CI, 1.15-2.74) and bronchiectasis (aRR 2.07; 95% CI, 1.45-2.98).

CONCLUSION

HTLV-1 infection contributes to morbidity among socially disadvantaged Indigenous adults in central Australia. This is largely due to an increased risk of other infections and respiratory disease. The spectrum of HTLV-1 related diseases may vary according to the social circumstances of the affected population.