The laboratory diagnosis and follow up of strongyloidiasis: a systematic review

A Cross-Sectional Study of Seroprevalence of Strongyloidiasis in Pregnant Women (Peruvian Amazon Basin)

Strongyloidiasis is a soil-transmitted helminthiasis with a high global prevalence. Objectives: We aimed to evaluate the prevalence of Strongyloides stercoralis infection and assess strongyloidiasis serology as a screening technique in the Peruvian Amazon. Material and Methods: We performed a cross-sectional study of strongyloidiasis in 300 pregnant women in Iquitos (Peru) from 1 May 2019 to 15 June 2019. Women were tested using serology (Strongyloides IgG IVD-ELISA kit) as an index test and the modified Baermann technique and/or charcoal fecal culture as the parasitological reference standard. Results: The reference tests showed S. stercoralis in the stool of 30 women (prevalence: 10%; 95% confidence interval [CI] 7.1% to 13.9%), while 101 women tested positive on the blood test (prevalence: 33.7%; 95% CI 28.6% to 39.4%). Fourteen of the 15 women (93.3%) with positive results according to the modified Baermann technique, and 14 of the 23 women (56.5%) with positive charcoal cultures also had positive serological results. Serology showed a sensitivity of 63.3% and a negative predictive value of 94.4%. Conclusion: In Iquitos, pregnant women have a high prevalence of S stercoralis. S. stercoralis ELISA could be an excellent tool for population-based screening, as it has a high negative predictive value that can help to rule out the presence of active infection.

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.

Prevalence and risk factors of strongyloidiasis in patients with systemic lupus erythematosus in Southern Thailand

Background

Strongyloidiasis can be fatal in systemic lupus erythematosus (SLE) patients, but few epidemiological studies have investigated the burden of this tropical disease among the SLE population. This study aimed to assess the prevalence and associated factors of strongyloidiasis among SLE patients in Southern Thailand.

Methods

A cross-sectional study was conducted on 180 SLE patients attending the Rheumatology Clinic at Songklanagarind Hospital. Stool specimens were collected and examined using the direct smear technique and agar plate culture technique. Serum anti-Strongyloides stercoralis IgG was measured by IgG-ELISA.

Results

The overall prevalence of strongyloidiasis by combined parasitologyl and/or serology was 15.6%. The prevalence of strongyloidiasis by parasitological methods was 2.2%. Positive parasitology and/or serology was associated with male sex and a SLE disease duration of less than two years.

Conclusion

Strongyloidiasis is highly prevalent among the SLE population. A combination of serological and parasitological methods increases the rate of diagnosis of strongyloidiasis in SLE patients.

Lateral Flow Dipstick Test for Serodiagnosis of Strongyloidiasis

The conventional method of detecting Strongyloides stercoralis in fecal samples has poor diagnostic sensitivity. Detection of Strongyloides-specific antibodies increases the sensitivity; however, most tests are ELISAs that use parasite extract which may cross-react with the sera of other helminth infections. To improve the serological diagnosis of strongyloidiasis, this study aimed at developing a sensitive and specific lateral flow rapid dipstick test. Two recombinant proteins, recombinant NIE (rNIE) and recombinant Ss1a (rSs1a), were used in preparing the dipstick, with gold-conjugated antihuman IgG4 as detector reagent. In parallel, the corresponding ELISA was performed. Both assays demonstrated diagnostic sensitivity of 91.3% (21/23) when tested with serum samples of patients with Strongyloides infection, and 100% specificity with 82 sera of asymptomatic (healthy) and those with other parasitic infections. The ELISA and dipstick test results were positively correlated to each other (r = 0.6114, P = 0.0019). The developed lateral flow dipstick test may improve the serodiagnosis of strongyloidiasis and merit further validation studies.

[Recommendations for the screening for infectious diseases, mental health, and female genital mutilation in immigrant patients seen in Primary Care]

Immigrant health status may be improved if certain health conditions are identified early through the implementation of a screening program. This document presents the recommendations resulting from the Screening in immigrant population project (CRIBMI) aimed at implementing a screening program for infectious diseases (HIV, HBV, HCV, tuberculosis, strongyloidiasis, schistosomiasis and Chagas disease), as well as female genital mutilation and mental health (MH) in migrant population at Primary Care level. Screening recommendations were based on: coming from an endemic country for strongyloidiasis, schistosomiasis, and Chagas diseases; on a threshold level of prevalence for HIV (> 1%), HBV (> 2%), and HCV (> 2%), and on incidence (> 50 cases/100,000-inhabitants) for active tuberculosis in immigrants with < 5 years in Europe. Exploring the risk of FGM is recommended in women from countries where this practice is prevalent. Evaluation of MH status is recommended for people from areas of conflict and violence.

Strongyloidiasis screening in migrants living in Spain: systematic review and meta-analysis

OBJECTIVES

To provide information regarding the prevalence of strongyloidiasis among migrants coming from Strongyloides stercoralis-endemic areas who reside in Spain.

METHODS

Systematic review of the literature and meta-analysis of studies showing prevalence of S. stercoralis infection among migrants from Latin America, Africa, Eastern Europe, Asia and Oceania who reside in Spain. We included articles published until 30 April 2019 without language restriction. The keywords used for the search included 'Strongyloides stercoralis', 'strongyloidiasis', 'Spain', 'screening' and 'migrants'.

RESULTS

Twenty-four studies were included in the review and meta-analysis, comprising 12 386 screened people. Eleven studies (7020 patients) evaluated the presence of S. stercoralis infection only through investigation of larvae in faeces, showing an overall prevalence of 1% (95%CI 1-1%). Thirteen studies (5366 patients) used a serological test, showing an overall prevalence of 14% (95%CI 11-17%). Strongyloidiasis seroprevalence was 20% (95%CI 15-24%) among migrants from sub-Saharan Africa, 14% (95%CI 10-18%) among those from Latin America and 8% (95%CI 5-11%) among migrants from North Africa.

CONCLUSIONS

Migrants coming from strongyloidiasis-endemic areas living in Spain had a high S. stercoralis infection prevalence, particularly those from sub-Saharan Africa and Latin America. This population should be screened using serology as the most sensitive test for S. stercoralis infection. This could be easily implemented at primary care level.

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.

Nematocidal effect of Piper retrofractum Vahl on morphology and ultrastructure of Strongyloides stercoralis third-stage infective larvae

In a previous research work aimed at discovering natural helminthicides as alternatives to conventional synthetic drugs, Piper retrofractum fruit hexane extract (PHE) has been shown to possess promising nematocidal activity against the third-stage infective larvae of Strongyloides stercoralis. Thus, this study was designed to evaluate the chemical composition and the impact of PHE on symptom and structural alterations of S. stercoralis. Chemical analysis of PHE by gas chromatography-mass spectrometry demonstrated 26 different compounds, constituting 100% of the total composition. The main components were 4-acetylphenyl (4-benzoylphenoxy) acetate (14.86%) and octyl methoxycinnamate (12.72%). Nematocidal bioassays revealed promising potential of PHE against S. stercoralis larvae, with an LC50 value of 0.059 mg/ml, while the reference drug ivermectin exerted higher efficacy, with an LC50 value of 0.020 µg/ml. Behavioural observations under light microscopy revealed that PHE-treated S. stercoralis larvae moved slowly, became paralysed and eventually died during 24 h of incubation. The dead larvae appeared under light microscope as straight worms with unknown vacuoles of different sizes inside their internal bodies. Morphological alterations of the PHE-treated S. stercoralis larvae, such as straight bodies with swollen cuticle, faded transverse annulations and faded longitudinal striations, as well as shallow and smooth lateral longitudinal grooves, were seen clearly under scanning electron microscopy. Ultrastructural changes in the treated larvae, such as protruded lateral longitudinal grooves, loose muscle with vacuolation, dissociation between the hypodermis and cuticle and marked intracellular disorganization with vacuolation, were detected under transmission electron microscopy. The results of this study provide evidence that PHE is toxic against S. stercoralis and also a potential new alternative for anti-Strongyloides chemotherapy.

High Prevalence of Strongyloidiasis in Spain: A Hospital-Based Study

Introduction: Strongyloidiasis is a prevailing helminth infection ubiquitous in tropical and subtropical areas, however, seroprevalence data are scarce in migrant populations, particularly for those coming for Asia. Methods: This study aims at evaluating the prevalence of S. stercoralis at the hospital level in migrant populations or long term travellers being attended in out-patient and in-patient units as part of a systematic screening implemented in six Spanish hospitals. A cross-sectional study was conducted and systematic screening for S. stercoralis infection using serological tests was offered to all eligible participants. Results: The overall seroprevalence of S. stercoralis was 9.04% (95%CI 7.76-10.31). The seroprevalence of people with a risk of infection acquired in Africa and Latin America was 9.35% (95%CI 7.01-11.69), 9.22% (7.5-10.93), respectively. The number of individuals coming from Asian countries was significantly smaller and the overall prevalence in these countries was 2.9% (95%CI -0.3-6.2). The seroprevalence in units attending potentially immunosuppressed patients was significantly lower (5.64%) compared with other units of the hospital (10.20%) or Tropical diseases units (13.33%) (p < 0.001). Conclusions: We report a hospital-based strongyloidiasis seroprevalence of almost 10% in a mobile population coming from endemic areas suggesting the need of implementing strongyloidiasis screening in hospitalized patients coming from endemic areas, particularly if they are at risk of immunosuppression.

Morbidity Associated with Chronic Strongyloides stercoralis Infection: A Systematic Review and Meta-Analysis

Strongyloides stercoralis, a worldwide-distributed soil-transmitted helminth, causes chronic infection which may be life threatening. Limitations of diagnostic tests and nonspecificity of symptoms have hampered the estimation of the global morbidity due to strongyloidiasis. This work aimed at assessing S. stercoralis-associated morbidity through a systematic review and meta-analysis of the available literature. MEDLINE, Embase, CENTRAL, LILACS, and trial registries (WHO portal) were searched. The study quality was assessed using the Newcastle-Ottawa scale. Odds ratios (ORs) of the association between symptoms and infection status and frequency of infection-associated symptoms were calculated. Six articles from five countries, including 6,014 individuals, were included in the meta-analysis-three were of low quality, one of high quality, and two of very high quality. Abdominal pain (OR 1.74 [CI 1.07-2.94]), diarrhea (OR 1.66 [CI 1.09-2.55]), and urticaria (OR 1.73 [CI 1.22-2.44]) were associated with infection. In 17 eligible studies, these symptoms were reported by a large proportion of the individuals with strongyloidiasis-abdominal pain by 53.1% individuals, diarrhea by 41.6%, and urticaria by 27.8%. After removing the low-quality studies, urticaria remained the only symptom significantly associated with S. stercoralis infection (OR 1.42 [CI 1.24-1.61]). Limitations of evidence included the low number and quality of studies. Our findings especially highlight the appalling knowledge gap about clinical manifestations of this common yet neglected soil-transmitted helminthiasis. Further studies focusing on morbidity and risk factors for dissemination and mortality due to strongyloidiasis are absolutely needed to quantify the burden of S. stercoralis infection and inform public health policies.

Overcoming challenges in the diagnosis and treatment of parasitic infectious diseases in migrants

Introduction: Recent increases in population movements have created novel health challenges in many areas of the World, and health policies have been adapted accordingly in several countries. However, screening guidelines for infectious diseases are not standardized and generally do not include comprehensive screening for parasitic infections.Areas covered: Malaria, Chagas disease, leishmaniasis, amebiasis, filariases, strongyloidiasis, and schistosomiasis are reviewed, focusing on the challenges posed for their diagnosis and management in vulnerable populations such as migrants. The methodology included literature searches in public databases such as PubMed.gov and Google Scholar and search of the US National Library of Medicine online database of privately and publicly funded clinical studies (ClinicalTrials.gov) until November 2019.Expert opinion: Parasitic infections which may remain asymptomatic for prolonged periods, leading to chronic infection and complications, and/or may be transmitted in non-endemic areas are ideal candidates for screening. Proposed strategies to improve diagnosis in vulnerable groups such as migrants include facilitating access to healthcare in a multi-dimensional manner considering location, individual characteristics, and timing. Limitations and availability of specific diagnostic techniques should be addressed and focus on drug and vaccine development for these neglected infections should be prioritized through collaborative initiatives with public disclosure of results.

scFv against HSP60 of Strongyloides sp. and Its Application in the Evaluation of Parasite Frequency in the Elderly

The present study is aimed at evaluating serological method using scFv anti-Strongyloides sp. and reporting the frequencies of the results with conventional parasitological technique (faeces) in elderly individuals. Among 112 elderly individuals (≥60 years of age), 14.28% were positive for at least one enteroparasite, with one individual positive for S. stercoralis. Sera were evaluated for the presence of anti-Strongyloides sp. antibodies using total or detergent fraction extracts of Strongyloides venezuelensis, which presented positivity rates of 19.64% and 10.71%, respectively. An anti-HSP60 single-chain variable fragment from Strongyloides sp. was used to detect parasite antigens, with 5.36% (6 individuals) of ELISA-positive individuals returning a positive result. While the serological test indicates previous or recent infection and may be limited by antigen purification, the anti-HSP60 method reflects the presence of Strongyloides sp. immune complexes and exhibits greater sensitivity and specificity. Our results demonstrate the variable occurrence of enteroparasites in elderly individuals residing in long-term nursing homes and validate a novel epidemiological tool to describe infection cases by Strongyloides sp.

Zoonotic transmission of intestinal helminths in southeast Asia: Implications for control and elimination

Intestinal helminths are extremely widespread and highly prevalent infections of humans, particularly in rural and poor urban areas of low and middle-income countries. These parasites have chronic and often insidious effects on human health and child development including abdominal problems, anaemia, stunting and wasting. Certain animals play a fundamental role in the transmission of many intestinal helminths to humans. However, the contribution of zoonotic transmission to the overall burden of human intestinal helminth infection and the relative importance of different animal reservoirs remains incomplete. Moreover, control programmes and transmission models for intestinal helminths often do not consider the role of zoonotic reservoirs of infection. Such reservoirs will become increasingly important as control is scaled up and there is a move towards interruption and even elimination of parasite transmission. With a focus on southeast Asia, and the Philippines in particular, this review summarises the major zoonotic intestinal helminths, risk factors for infection and highlights knowledge gaps related to their epidemiology and transmission. Various methodologies are discussed, including parasite genomics, mathematical modelling and socio-economic analysis, that could be employed to improve understanding of intestinal helminth spread, reservoir attribution and the burden associated with infection, as well as assess effectiveness of interventions. For sustainable control and ultimately elimination of intestinal helminths, there is a need to move beyond scheduled mass deworming and to consider animal and environmental reservoirs. A One Health approach to control of intestinal helminths is proposed, integrating interventions targeting humans, animals and the environment, including improved access to water, hygiene and sanitation. This will require coordination and collaboration across different sectors to achieve best health outcomes for all.

Frequency and distribution of neglected tropical diseases in Mozambique: a systematic review

BACKGROUND

Neglected tropical diseases (NTDs) affect more than one billion people living in vulnerable conditions. In spite of initiatives recently contributing to fill NTDs gaps on national and local prevalence and distribution, more epidemiological data are still needed for effective control and elimination interventions.

MAIN TEXT

Mozambique is considered one of the countries with highest NTDs burden although available data is scarce. This study aims to conduct a systematic review on published available data about the burden and distribution of the different NTDs across Mozambique since January 1950 until December 2018. We identified manuscripts from electronic databases (Pubmed, EmBase and Global Health) and paper publications and grey literature from Mozambique Ministry of Health. Manuscripts fulfilling inclusion criteria were: cross-sectional studies, ecological studies, cohorts, reports, systematic reviews, and narrative reviews capturing epidemiological information of endemic NTDs in Mozambique. Case-control studies, letters to editor, case reports and case series of imported cases were excluded. A total of 466 manuscripts were initially identified and 98 were finally included after the revision following PRISMA guidelines. Eleven NTDs were reported in Mozambique during the study span. Northern provinces (Nampula, Cabo Delgado, Niassa, Tete and Zambezia) and Maputo province had the higher number of NTDs detected. Every disease had their own report profile: while schistosomiasis have been continuously reported since 1952 until nowadays, onchocerciasis and cysticercosis last available data is from 2007 and Echinococcosis have never been evaluated in the country. Thus, both space and time gaps on NTDs epidemiology have been identified.

CONCLUSIONS

This review assembles NTDs burden and distribution in Mozambique. Thus, contributes to the understanding of NTDs epidemiology in Mozambique and highlights knowledge gaps. Hence, the study provides key elements to progress towards the control and interruption of transmission of these diseases in the country.

Strongyloides, HTLV-1 and small bowel obstruction

An 81-year-old Jamaican man who has been resident in the UK for many years presented with one week history of generalised abdominal pain, postprandial vomiting, anorexia, weight loss and abdominal distension. He was managed conservatively for acute small bowel obstruction. Investigations revealed a duodenal stricture. Live Strongyloides stercoralis larvae were observed in stool samples and duodenal biopsy confirmed the presence of the parasite at multiple life cycle stages within the lamina propria. He was diagnosed with Strongyloides hyperinfection with underlying human T-cell lymphotropic virus type 1 and treated with a prolonged course of ivermectin with ongoing monitoring for relapse. This case demonstrates a rare but potentially fatal cause of small bowel obstruction.

A case of fatal disseminated strongyloidiasis accompanied with intestinal obstruction

Strongyloides stercoralis is an endemic parasite in some regions including the tropical and subtropical areas with high humidity. Most infections are asymptomatic with nonspecific signs and symptoms, making the final diagnosis complicated. Here, we report a patient referred to our hospital with signs consistent with sepsis, intestine obstruction, which finally died with the diagnosis of strongyloidiasis. The patient was from northern parts of Iran which are considered as endemic areas for S. stercoralis. In conclusion, there is an important message in this history, i.e. physicians should be aware of specific and non-specific signs of strongyloidiasis especially in people living in endemic areas to make an accurate final diagnosis by proper clinical and paraclinical examinations.

Strongyloidiasis: A Neglected Tropical Disease

Most of the 30 to 100 million people infected with Strongyloides stercoralis have subclinical (or asymptomatic) infections. These infections are commonly chronic and longstanding. A change in immune status can increase parasite numbers, leading to hyperinfection syndrome, dissemination, and death if unrecognized. The use of corticosteroids and HTLV-1 infection are most commonly associated with the hyperinfection syndrome. Strongyloides adult parasites reside in the small intestine and induce immune responses that are like other nematodes. Definitive diagnosis of S stercoralis infection is based on stool examinations for larvae. S stercoralis remains largely neglected.

[Acute renal failure and rare severe complication of systemic steroid treatment in a 73-year-old woman]

This article reports about a 73-year-old woman of Bosnian descent who presented with acute renal failure. A renal biopsy was diagnostic for a postinfect necrotizing and extracapillary proliferative glomerulonephritis. The patient reported a febrile infection fever 2 weeks previously. The diagnostics did not reveal any indications of an ongoing infection. The glomerulonephritis responded to treatment with systemic steroids. The patient was readmitted to hospital 6 weeeks later in a severely ill condition. A gastric biopsy revealed a Strongyloides stercoralis infestation. Due to the systemic steroid therapy the patient had developed a so-called hyperinfection syndrome and died despite treatment on the intensive care unit. This case illustrates the need for awareness of this rare parasitosis, particularly in patients from endemic areas. A likely causal relationship with the glomerulonephritis is discussed and an overview of the diagnostics, course of the disease and treatment of this parasitosis is given.

Molecular characterization of human isolates of Strongyloides stercoralis and Rhabditis spp. based on mitochondrial cytochrome c oxidase subunit 1 (cox1)

Background

Due to the similarity of Strongyloides stercoralis with free-living nematodes of Rhabditis species they might be miss-diagnosed with each other in microscopical examination of stool samples. The aim of this study was molecular characterization and differentiation of human derived isolates of S. stercoralis and Rhabditis species based on the mitochondrial gene of cytochrome c oxidase subunit 1 (cox1) amplification.

Methods

Using parasitological methods, ten isolates of S. stercoralis and three isolates of Rhabditis spp. were obtained from fresh stool samples of patients and the genomic DNA of the samples were extracted. PCR amplification of cox1 gene was carried out for all the isolates and the products were sequenced.

Results

The phylogenetic analysis illustrated that S. stercoralis and Rhabditis spp. isolates were placed in two distinguishable separate clades. Inter-species genetic variation between isolates of S. stercoralis and Rhabditis spp. were ranged from 13.5 to 14.5%.

Conclusions

Cox1 gene was a suitable marker for discrimination of S. stercoralis from Rhabditis spp. retrieved from human in the current study. The availability of gene sequence information will be helpful in the future development and validation of discriminatory PCR-based assays of these nematodes.

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.

Clinical and Diagnostic Features of 413 Patients Treated for Imported Strongyloidiasis at the Hospital for Tropical Diseases, London

This study describes the clinical features of a cohort of imported cases of strongyloidiasis and the performance of standard diagnostic techniques for this condition. A total of 413 cases were identified, of whom 86 had microscopically proven infection. In proven cases, 23% had normal eosinophil counts, 19% had negative Strongyloides-specific serology, and 9.3% had normal blood counts and were seronegative. Serological testing was less sensitive for returning travelers (46.2%) than for migrants (89.7%). Immunosuppression, including human T-cell lymphotropic virus 1, was significantly associated with proven infection after controlling for age, presence of symptoms, duration of infection, and eosinophilia (OR 5.60, 95% CI 1.54-20.4). Patients with proven infection had lower serology values than those diagnosed with strongyloidiasis on the basis of positive serology and eosinophilia alone (P = 0.016). Symptomatic patients were significantly younger, had a shorter presumed duration of infection, and lower serology values. These data suggest a correlation between immunologic control of strongyloidiasis and the amplitude of the humoral response.

Prevalence and risk factors of Strongyloides stercoralis infection among Orang Asli schoolchildren: new insights into the epidemiology, transmission and diagnosis of strongyloidiasis in Malaysia

This cross-sectional study aimed to determine the prevalence and risk factors of S. stercoralis infection among 1142 Orang Asli primary schoolchildren in six different states of Peninsular Malaysia. Fecal samples were examined using direct smear, formalin-ether sedimentation (FES), agar plate culture (APC) and PCR techniques. Overall, 15.8% of the children were found to be infected with S. stercoralis. The prevalence was 0.2, 1.3, 15.2 and 13.7% by direct smear, FES, APC and PCR, respectively. Multivariate analysis showed that an age of >10 years, being male, belonging to a Proto-Malay tribe, belonging to the Senoi tribe, indiscriminate defecation, using an unimproved water source for drinking water and not wearing shoes when outside were the significant risk factors of infection among these children. In conclusion, we provide new evidence on the occurrence of S. stercoralis in Malaysia to show that there is a relatively high prevalence of infection among Orang Asli schoolchildren. Therefore, the use of specific methods for detecting S. stercoralis should be considered when screening these children for intestinal parasites. Moreover, prevention and control measures specific to S. stercoralis should be integrated into the intestinal parasitic infections control programme in Malaysia.

Strongyloides stercoralis: Spatial distribution of a highly prevalent and ubiquitous soil-transmitted helminth in Cambodia

Background

Strongyloides stercoralis is a neglected soil-transmitted helminth that occurs worldwide, though it is particularly endemic in tropical and subtropical areas. It can cause long-lasting and potentially fatal infections due to its ability to replicate within its host. S. stercoralis causes gastrointestinal and dermatological morbidity. The objective of this study was to assess the S. stercoralis infection risk and, using geostatistical models, to predict its geographical distribution in Cambodia.

Methodology / Principal findings

A nation-wide, community-based parasitological survey was conducted among the Cambodian population, aged 6 years and older. S. stercoralis was diagnosed using a serological diagnostic test that detects IgG antibodies in urine. Data on demography, hygiene and knowledge about helminth infection were collected. S. stercoralis prevalence among 7,246 participants with a complete data record was 30.5%, ranging from 10.9% to 48.2% across provinces. The parasite was ubiquitous in Cambodia; only five south-eastern provinces had prevalence rates below 20%. Infection risk increased with age for both men and women, although girls under the age of 13 and women aged 50 years and over had lower odds of infection than their male counterparts. Open defecation was associated with higher odds of infection, while having some knowledge of the health problems caused by worms was a protective factor. Infection risk was positively associated with nighttime maximum temperature, minimum rainfall, and distance to water; it was negatively associated with land occupied by rice fields.

Conclusions / Significance

S. stercoralis infection is rampant in Cambodia. Control programs delivering ivermectin are needed to manage the parasite. However, the high cost of this drug in Cambodia currently precludes the implementation of control initiatives. Donations, subsidies or affordable generics are needed so that S. stercoralis, which infects almost a third of the Cambodian population, can be addressed through an adequate control program.

The threadworm, Strongyloides stercoralis, is a highly neglected worm infection, transmitted through infective larvae in the soil. Threadworms occur worldwide, particularly in tropical climates. It may cause long-lasting and potentially fatal infections due to the parasite’s ability to replicate within its host. This study aimed to assess the risk of threadworm infection at national level in Cambodia. We conducted a nation-wide, community-based parasitological survey of the Cambodian population, aged 6 years and over. The threadworm was diagnosed using a serological diagnostic test that detects antibodies in urine. Data on demography, hygiene and knowledge about helminth infection were collected. The purpose of this study was to predict the risk of S. stercoralis infection in unsurveyed locations, assess risk factors for infection, and map its geographical distribution in Cambodia. About one third (30.5%) of the enrolled study participants (n = 7,246) were infected with threadworms. At provincial level, the lowest and highest infection rates were 10.9% and 48.2%, respectively. Prevalence rates below 20% were found in just five south-eastern provinces. The risk of a threadworm infection increased with age for both men and women. Open defecation was associated with higher risk of infection, while having some knowledge of the health problems caused by worms was a protective factor. Infection risk was positively associated with environmental factors, such as nighttime maximum temperature, minimum rainfall, and distance to water; it was negatively associated with land occupied by rice fields. Threadworm infection is highly prevalent in Cambodia and adequate control measures, including access to treatment, are warranted to address the burden of this Neglected Tropical Disease (NTD) in Cambodia.

Strongyloides stercoralis in Patients on Corticosteroids Therapy Using Enzyme-Linked Immunosorbent Assay and Gelatin Particles Indirect Agglutination Tests: A Diagnostic Approach

INTRODUCTION

Patients on corticosteroids therapy (POCT) are more likely to flare up concealed Strongyloides infection and develop Strongyloides hyperinfection syndrome and/or dissemination. Such critical complications can lead to high mortality rates. Rapid detection methods are, therefore, necessary to detect Strongyloides infection in POCT with the advantage of being applicable in a developing country.

METHODS

Two hundred POCT have been enrolled in this study to determine the rate of infection with Strongyloides. Three different groups of POCT (Strongyloides infected, non-infected, infected with other parasites) were used to evaluate the antibodies detection capability of two serological techniques (enzyme-linked immunosorbent assay (ELISA) and gelatin particles indirect agglutination (GPIAT) against the results of the gold standard agar plate culture (APC).

RESULTS

With APC, the infection rate of Strongyloides stercoralis in POCT was 9.5% (19/200). POCT with Strongyloides infection displayed related risk factors (job, rural settlements, and soil contact) for infection combined with the subtropical nature of Ismailia Governorate. With regard to serology, ELISA detection results were poor compared to APC with sensitivity and specificity of 42.1% and 82.6%, respectively, and positive and negative predictive values of 72% and 30%. GPIAT appeared to be closely related to APC with sensitivity and specificity of 89.4% and 81.8%, respectively, and positive and negative predictive values of 80.9% and 96.7%. Statistical moderate correlation was detected between GPIAT and ELISA.

CONCLUSION

The GPIAT technique is more convenient, easier, cheaper and faster to rule out the infection of Strongyloides in POCT. It might be the test of choice for routine immunodiagnosis of human strongyloidiasis.

Imported strongyloidiasis: Data from 1245 cases registered in the +REDIVI Spanish Collaborative Network (2009-2017)

BACKGROUND

Imported strongyloidiasis is increasingly being diagnosed in non-endemic areas. The aim of this study was to describe the epidemiological, clinical and microbiological characteristics of patients with imported strongyloidiasis in Spain.

METHODOLOGY

This is an observational retrospective study that included all patients diagnosed of strongyloidiasis registered in the +REDIVI Collaborative Network from 2009 to 2017. Demographic, epidemiological and clinical information was collected from the +REDIVI database, and extra information regarding microbiological techniques, treatment and follow-up was requested to participant centers.

FINDINGS

Overall, 1245 cases were included. Most of them were immigrants (66.9%), and South America was the most frequent area of origin. Detection of larvae in stool samples was observed in 21.9% of the patients, and serological tests allowed making the diagnosis in the rest of the cases. Eosinophilia was present in 82.2% of cases. Treatment with ivermectin (compared with albendazole) was the most strongly associated factor to achieve the cure (OR 2.34).

CONCLUSIONS

Given the long latency of the infection and the risk of developing a severe presentation, screening of S. stercoralis infection should be mandatory in patients coming from or had traveling to endemic areas, especially in those with immunosuppressant conditions.

Hypereosinophilia and severe bone disease in an African child: an unexpected diagnosis

Hypereosinophilic syndromes are rare in children. Sporadic, mild-severity FIP1L1-platelet-derived growth factor receptor α (PDGFRα) rearrangement cases have been reported, mainly in boys. We present the case of a 5-year-old girl referred from her African country of birth, due to severe constitutional symptoms, multifocal bone pain, headache, gastrointestinal complaints, cardiomyopathy and unexplained hypereosinophilia. She presented multiple end-organ diseases and striking bone involvement. Although she had a positive serology for Strongyloides stercoralis, extensive evaluation detected a FIP1L1-PDGFRA fusion gene. Systemic corticosteroids and low-dose imatinib were started and the child became asymptomatic. After 9 months of treatment, FIP1L1-PDGFRA was no longer detected.

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.

Detection of helminths by loop-mediated isothermal amplification assay: a review of updated technology and future outlook

Background

Helminths are endemic in more than half of the world’s countries, raising serious public health concerns. Accurate diagnosis of helminth infection is crucial to control strategies. Traditional parasitological methods, serological tests and PCR-based assays are the major means of the diagnosis of helminth infection, but they are time-consuming and/or expensive, and sometimes provide inaccurate results. Loop mediated isothermal amplification (LAMP) assay, a sensitive, simple and rapid method was therefore developed for detection of helminths. This study aims to discuss the current status of application of LAMP on helminths detection and to make a comprehensive evaluation about this updated technology and its future outlook by comparing with several other diagnostic methods.

Main body

This review summarizes LAMP assay applied for helminth detection and helminthiasis surveillance. The basic principle of LAMP is introduced to help better understand its characteristics and each reported assay is assessed mainly based on its detection sensitivity, specificity and limitations, in comparison with other common diagnostic tests. Moreover, we discuss the limitations of the assays so as to clarify some potential ways of improvement.

Conclusions

Here, we summarize and discuss the advantages, disadvantages and promising future of LAMP in heliminth detection, which is expected to help update current knowledge and future perspectives of LAMP in highly sensitive and specific diagnosis and surveillance of helminthiasis and other parasitic diseases, and can contribute to the elimination of the diseases from endemic areas.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0530-z) contains supplementary material, which is available to authorized users.

Implementation of a Strongyloides screening strategy in solid organ transplant donors and recipients

BACKGROUND

Strongyloides stercoralis infects 100 million people worldwide. Mortality rates in hyperinfection syndrome exceed 50%. Donor-derived Strongyloides infection has occurred after heart, kidney, kidney-pancreas and liver transplantation; yet, only 10% of the US organ procurement organizations currently screen donors for strongyloidiasis.

METHODS

We report a fatal case of donor-derived disseminated Strongyloides infection in a liver transplant recipient. Following this case, we implemented universal screening and treatment of donors and recipients. We reviewed our local epidemiology and outcomes after protocol implementation.

RESULTS

From a total of 355 deceased donors accepted at our center between January 2016, and March 2018, 14 (3.9%) had positive Strongyloides serology. Except for the index case, all other recipients of Strongyloides antibody-positive donors within that period (including 10 kidneys, 3 livers, one combined liver/kidney, and one kidney/pancreas from eight seropositive donors) received post-transplant prophylaxis with ivermectin, and to date are alive and doing well without signs of infection. Between October 2015, and September 2016, a total of 441 deceased donor solid organ transplants were performed at our center. 220 of these recipients had pretransplant Strongyloides serology available, and 23 of them were seropositive (10.5%). Within the first two years after the implementation of universal screening and treatment of donors and recipients, we had no cases of Strongyloides reactivation in our center.

CONCLUSIONS

Implementation of a Strongyloides screening and treatment protocol in our center was an effective strategy to prevent both recipient- and donor-derived strongyloidiasis. Transplant centers should consider implementation of Strongyloides preventive strategies.

Strongyloides stercoralis infection: A systematic review of endemic cases in Spain

Background

Strongyloides stercoralis infection, a neglected tropical disease, is widely distributed. Autochthonous cases have been described in Spain, probably infected long time ago. In recent years the number of diagnosed cases has increased due to the growing number of immigrants, travelers and refugees, but endemically acquired cases in Spain remains undetermined.

Methodology

We systematically searched the literature for references on endemic strongyloidiasis cases in Spain. The articles were required to describe Strongyloides stercoralis infection in at least one Spanish-born person without a history of travel to endemic areas and be published before 31st May 2018. Epidemiological data from patients was collected and described individually as well as risk factors to acquisition of the infection, diagnostic technique that lead to the diagnosis, presence of eosinophilia and clinical symptoms at diagnosis.

Findings

Thirty-six studies were included, describing a total of 1083 patients with an average age of 68.3 years diagnosed with endemic strongyloidiasis in Spain. The vast majority of the cases were described in the province of Valencia (n = 1049). Two hundred and eight of the 251 (82.9%) patients in whom gender was reported were male, and most of them had current or past dedication to agriculture. Seventy percent had some kind of comorbidity. A decreasing trend in the diagnosed cases per year is observed from the end of last decade. However, there are still nefigw diagnoses of autochthonous cases of strongyloidiasis in Spain every year.

Conclusions

With the data provided by this review it is likely that in Spain strongyloidiasis might have been underestimated. It is highly probable that the infection remains undiagnosed in many cases due to low clinical suspicion among Spanish population without recent travel history in which the contagion probably took place decades ago.

S. stercoralis is a soil transmitted helminth that is common in many subtropical and tropical countries, but is also found in other regions of the world. In this study we reviewed all published material on endemic infection of S. stercoralis acquired in Spain issued before 31st May 2018. We collected data from these articles and reported clinical and epidemiological characteristics of patients. Our systematic review of the articles showed a clear geographical pattern; nearly 97% of the cases described had been acquired in the Valencia province. Most of them (82.9%) were male, and most had current or past dedication to agriculture. Our results showed that 70.3% had at least one condition or treatment that could have made them more vulnerable to suffer a severe form of this helminthic disease. Our data suggests that S. stercoralis infection probably remains underdiagnosed in Spanish population. Due to the scarce information available about endemic strongyloidiasis in Spain until now, we believe that the present work will be relevant and the conclusions derived from it might raise awareness about underdiagnosis. Transmission risk factors described in the people diagnosed may be key for prevention and control strategies implementation.

Migration Medicine

Migration is increasing and practitioners need to be aware of the unique health needs of this population. The prevalence of infectious diseases among migrants varies and generally mirrors that of their countries of origin, but is modified by the circumstance of migration, the presence of pre-arrival screening programs and post arrival access to health care. To optimize the health of migrants practitioners; (1) should take all opportunities to screen migrants at risk for latent infections such as tuberculosis, chronic hepatitis B and C, HIV, strongyloidiasis, schistosomiasis and Chagas disease, (2) update routine vaccines in all age groups and, (3) be aware of "rare and tropical infections" related to migration and return travel.

Comparison of ELISA and PCR of the 18S rRNA gene for detection of human strongyloidiasis using serum sample

BACKGROUND

Strongyloides stercoralis infection is a neglected tropical disease with global distribution which is fatal in immunosuppressed patients. This study aimed to determine the prevalence of strongyloidiasis in immunocompromised individuals and cases with infectious diseases, as well as comparing ELISA and conventional PCR with coprological examination, in the central parts of Mazandaran province, northern Iran.

METHODS

A single serum and a fresh stool samples were obtained from 272 and 220 patients, respectively. Serum was tested by ELISA and PCR of the 18S rRNA gene, and stool samples were examined with various parasitological methods. The optimum point for ELISA reaction and cut-off points were recognized by receiver operating characteristic curves (ROC).

RESULTS

Out of 220 stool specimens, 14(6.3%) cases were positive for S. stercoralis larvae. The overall seroprevalence rate was 27.9% (76/272). The seroprevalence rate was 25.2% and 30.1% in immunocompromised group and patients with infection, respectively. Based on the ROC curve of ELISA compared with microscopy, the optimum cut-off point was 12.74 with 79% sensitivity and 76% specificity. The optimum cut-off point was 10.42 with 69% sensitivity and specificity using ROC curve of ELISA compared with PCR.

CONCLUSIONS

This study seroprevalence rate for Strongyloides infection in the studied group. It also observed that the ELISA technique and the PCR used here have 100 demonstrated a high % sensitivity and acceptable specificity compared with coprological examination. It seems that the ELISA technique is a good screening assay in ruling out strongyloidiasis in such patients.

A diagnostic study comparing conventional and real-time PCR for Strongyloides stercoralis on urine and on faecal samples

Strongyloides stercoralis is a soil-transmitted helminth with a wide distribution in tropical and subtropical areas. The diagnosis of S. stercoralisinfection can be challenging, due to the low sensitivity of microscopic examination of stool samples and coproculture. In the last decade, different in-house molecular biology techniques for S. stercoralis have been implemented. They demonstrated good accuracy, although sensitivity does not seem sufficiently high yet. Recently, a novel PCR technique has been evaluated for the detection of S. stercoralis DNA in urine. Aim of this work was to compare the sensitivity of the real-time PCR (qPCR) on feces routinely used at the Centre for Tropical Disease (CTD) of Negrar, Verona, Italy, with that of the novel based PCR on urine. As secondary objective, we evaluated a Urine Conditioning Buffer ® (Zymoresearch) with the aim of improving nucleic acid stability in urine during sample storage/transport at ambient temperatures. Patients attending the CTD and resulting positive at routine screening with serology for S. stercoralis were invited, previous written consent, to supply stool and urine samples for molecular biology. A convenience sample of 30 patients was included. The sensitivity of qPCR on feces resulted 63%, and that of based PCR on urine was 17%. In all the samples treated with the Urine Conditioning Buffer ® there was no detectable DNA. In conclusion, the sensitivity of the novel technique resulted low, and needs further implementation before being considered as a valid alternative to the validated method.

Intestinal Parasitic Infections in Mental Retardation Center of Bandar Abbas, Southern Iran

BACKGROUND

The present study aimed to evaluate the prevalence of intestinal parasitic infection among mentally retarded individuals and the staff of the center in Bandar Abbas, south of Iran.

METHODS

This cross-sectional study was conducted in central institution for mentally retarded in Bandar Abbas, Hormozgan Province, from 2016 to 2017. A triple fecal specimen was collected from each one of the 163 participants and were evaluated using wet mount and formalin-ethyl acetate methods. Trichrome and Ziehl-Neelsen staining were used to confirm suspected cases of protozoa. As well as Baermann and Harada-Mori techniques and agar plate culture were implemented to diagnosis of Strongyloides stercoralis.

RESULTS

Overall, 163 subjects were examined including 126 mentally retarded individuals and 37 personnel. Ninety (55.2%) cases of participants were infected with at least one of the intestinal parasites, 69 (54.7%) of mentally retarded and 21 (56.7%) of personnel. Twenty-six mentally retarded individuals were infected with S. stercoralis (20.6%), Blastocystis hominis 30.2%, Entamoeba coli 25.4%, Giardia lamblia 5.6%, Enterobius vermicularis 1.6%, Hymenolepis nana 0.8% and Iodamoeba butschlii 1.6%. Twelve staff (32.4%) harbored B. hominis, E. coli 27%, S. stercoralis 2.7%, G. lamblia 10.8%, H. nana 2.7% and Endolimax nana 2.7%.

CONCLUSION

High rate of intestinal parasites particularly, S. stercoralis compared to the most recent studies of general population. Therefore, regular screening and tracking the positive cases, disinfection of the living environment, training and financing of the staff, increasing the number of the workers, recruiting of professionals and trained personnel in these centers are suggested.

Diagnosis and drug resistance of human soil-transmitted helminth infections: A public health perspective

Soil-transmitted helminth (STH) infections represent a major public health problem globally, particularly among socio-economically disadvantaged populations. Detection of STH infections is often challenging, requiring a combination of diagnostic techniques to achieve acceptable sensitivity and specificity, particularly in low infection-intensity situations. The microscopy-based Kato-Katz remains the most widely used method but has low sensitivity in the detection of, for instance, Strongyloides spp. infections, among others. Antigen/antibody assays can be more sensitive but are parasite species-specific. Highly sensitive PCR methods have been developed to be multiplexed to allow multi-species detection. Novel diagnostic tests for all STH species are needed for effective monitoring, evaluation of chemotherapy programmes, and to assess the potential emergence of parasite resistance. This review discusses available diagnostic methods for the different stages of STH control programmes, which vary in sensitivity and spectrum of detection requirements, and tools to evaluate drug efficacy and resistance.

Effectiveness of Screening and Treatment Approaches for Schistosomiasis and Strongyloidiasis in Newly-Arrived Migrants from Endemic Countries in the EU/EEA: A Systematic Review

We aimed to evaluate the evidence on screening and treatment for two parasitic infections-schistosomiasis and strongyloidiasis-among migrants from endemic countries arriving in the European Union and European Economic Area (EU/EEA). We conducted a systematic search of multiple databases to identify systematic reviews and meta-analyses published between 1 January 1993 and 30 May 2016 presenting evidence on diagnostic and treatment efficacy and cost-effectiveness. We conducted additional systematic search for individual studies published between 2010 and 2017. We assessed the methodological quality of reviews and studies using the AMSTAR, Newcastle⁻Ottawa Scale and QUADAS-II tools. Study synthesis and assessment of the certainty of the evidence was performed using GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. We included 28 systematic reviews and individual studies in this review. The GRADE certainty of evidence was low for the effectiveness of screening techniques and moderate to high for treatment efficacy. Antibody-detecting serological tests are the most effective screening tests for detection of both schistosomiasis and strongyloidiasis in low-endemicity settings, because they have higher sensitivity than conventional parasitological methods. Short courses of praziquantel and ivermectin were safe and highly effective and cost-effective in treating schistosomiasis and strongyloidiasis, respectively. Economic modelling suggests presumptive single-dose treatment of strongyloidiasis with ivermectin for all migrants is likely cost-effective, but feasibility of this strategy has yet to be demonstrated in clinical studies. The evidence supports screening and treatment for schistosomiasis and strongyloidiasis in migrants from endemic countries, to reduce morbidity and mortality.

Sensitivity and specificity of recombinant proteins in Toxocara spp. for serodiagnosis in humans: Differences in adult and child populations

Toxocariasis is a neglected zoonosis that affects children and adults. Recombinant proteins have been widely investigated for diagnosis, achieving high sensitivity and specificity in an overall population; however, little is known about age as a factor in its application. This study aims to investigate the diagnostic potential of Toxocara canis TES-30 and TES-120 recombinant proteins in humans, differentiating between its performance in children and adults. Serum samples collected from children and adults seropositive to Toxocara spp. were tested with indirect ELISA using T. canis TES-30 and TES-120 recombinant proteins produced in Escherichia coli. While rTES-30 sensitivity was not affected by age (81.8% in children and 87% in adults), rTES-120 sensitivity severely decreased in children to only 63.6%, down from 95.7% in adults. Furthermore, the sensitivity of rTES-30 increased to 97.8% after Western blotting confirmation. High specificity (>94%) against other geohelminths was reported for both recombinant proteins. Our study favors the use of rTES-30 with total IgG as the primary antibody in an indirect ELISA assay as a tool for epidemiological human studies.

High seroprevalence of Strongyloides stercoralis among individuals from endemic areas considered for solid organ transplant donation: A retrospective serum-bank based study

Background

Strongyloides stercoralis is a worldwide disseminated parasitic disease that can be transmitted from solid organ transplant (SOT) donors to recipients. We determined the serological prevalence of S. stercoralis among deceased individuals from endemic areas considered for SOT donation, using our institution’s serum bank.

Methodology

Retrospective study including all deceased potential donors from endemic areas of strongyloidiasis considered for SOT between January 2004 and December 2014 in a tertiary care hospital. The commercial serological test IVD-Elisa was used to determine the serological prevalence of S. stercoralis.

Principal findings

Among 1025 deceased individuals during the study period, 90 were from endemic areas of strongyloidiasis. There were available serum samples for 65 patients and 6 of them tested positive for S. stercoralis (9.23%). Only one of the deceased candidates was finally a donor, without transmitting the infection.

Conclusions

Among deceased individuals from endemic areas considered for SOT donation, seroprevalence of strongyloidiasis was high. This highlights the importance of adhering to current recommendations on screening for S. stercoralis among potential SOT donors at high risk of the infection, together with the need of developing a rapid diagnostic test to fully implement these screening strategies.

Strongyloidiasis is a neglected tropical disease caused by a parasite which is endemic in most parts of the world. It can cause a life-threatening disease among immunosuppressed individuals and can be transmitted from solid organ transplant donors to recipients. We retrospectively investigated the prevalence of strongyloidiasis among deceased individuals from endemic areas who were considered for solid organ transplant donation in our center, by performing a serological assay using our institution’s serum bank. We found a high prevalence of strongyloidiasis among these deceased candidates to donation, but only one of the six who tested positive was finally a donor, without transmitting the disease to recipients. Our results should encourage physicians to adhere to current guidelines which recommend active screening of strongyloidiasis in potential solid organ transplant donors from endemic areas who may be infected. There is a clear need for a rapid diagnostic test to fully implement systematic screening among these individuals.

Strongyloides stercoralis larvae found for the first time in tap water using a novel culture method

Strongyloides stercoralis (S. stercoralis) is a soil-borne helminth but its prevalence in water samples is underestimated. The aim of the present study is to propose non-nutrient agar (NNA) as a novel culture method in the diagnosis of Strongyloides and to detect the prevalence rate of S. stercoralis larvae in tap water samples in Beni-Suef Governorate, Egypt. Eighty tap water samples were collected from Beni-Suef Governorate and each sample was filtered in three steps using three filters: one filter for microscopic examination of wet mount, while the remaining two filters were cultured on both NNA and nutrient agar plate (APC). S. stercoralis larvae, adults, and eggs were detected in two (2.5%) and four (5%) out of 80 samples after examination of wet mount preparation and cultures on both NNA and APC, respectively. NNA succeeded to maintain Strongyloides alive for up to 1 month. Our study is the first to detect Strongyloides larvae in tap water in Egypt and the first to use NNA as a novel culture media for Strongyloides.

Diagnostic comparison of Baermann funnel, Koga agar plate culture and polymerase chain reaction for detection of human Strongyloides stercoralis infection in Maluku, Indonesia

Human infection with the nematode Strongyloides stercoralis, which may have a life-threatening course, primarily occurs in tropical settings. Epidemiological data on the occurrence of strongyloidiasis are scarce, and microscopic stool-based detection methods are insensitive. Polymerase chain reaction (PCR) assays have been developed, yet conflicting results have been reported. Our goal was to determine whether there was diagnostic agreement between an in-house PCR and two microscopic techniques, the Baermann funnel (BM) and the Koga agar plate culture (KAP) for the detection of S. stercoralis in stool samples. Eighty ethanol-fixed stool samples stemming from a cross-sectional survey in Maluku, Indonesia, were purposefully selected for PCR analysis. The final sample size comprised four groups, each with 20 samples: group 1, positive for S. stercoralis on both BM and KAP; group 2, positive only by BM; group 3, positive only by KAP; and group 4, negative on both BM and KAP. A Strongyloides-specific PCR targeting the internal transcribed spacer 2 (ITS2) region was carried out in an Indonesian reference laboratory. The overall agreement between PCR and microscopy was 61% (49/80 samples), being highest in group 1 (15/20, 75%) and lowest in group 3 (9/20, 45%). PCR revealed eight additional S. stercoralis infections in group 4. Future studies should elucidate the 'true' infection status of samples that are negative by PCR, but positive upon microscopy. Taken together, there is a lack of agreement between microscopy and PCR results for the diagnosis of human S. stercoralis infection in Indonesia. ClinicalTrials.gov (identifier: NCT02105714).