Diagnosis of Strongyloides stercoralis infection

Schistosoma and Strongyloides screening in migrants initiating HIV Care in Canada: a cross sectional study

BACKGROUND

Following migration from Schistosoma and Strongyloides endemic to non-endemic regions, people remain at high risk for adverse sequelae from these chronic infections. HIV co-infected persons are particularly vulnerable to the serious and potentially fatal consequences of untreated helminth infection. While general screening guidelines exist for parasitic infection screening in immigrant populations, they remain silent on HIV positive populations. This study assessed the seroprevalence, epidemiology and laboratory characteristics of these two parasitic infections in a non-endemic setting in an immigrant/refugee HIV positive community.

METHODS

Between February 2015 and 2018 individuals born outside of Canada receiving care at the centralized HIV clinic serving southern Alberta, Canada were screened by serology and direct stool analysis for schistosomiasis and strongyloidiasis. Canadian born persons with travel-based exposure risk factors were also screened. Epidemiologic and laboratory values were analyzed using bivariate logistic regression. We assessed the screening utility of serology, direct stool analysis, eosinophilia and hematuria.

RESULTS

253 HIV positive participants were screened. The prevalence of positive serology for Schistosoma and Strongyloides was 19.9 and 4.4%, respectively. Age between 40 and 50 years (OR 2.50, 95% CI 1.13-5.50), refugee status (3.55, 1.72-7.33), country of origin within Africa (6.15, 2.44-18.60), eosinophilia (3.56, 1.25-10.16) and CD4 count < 200 cells/mm3 (2.46, 1.02-5.92) were associated with positive Schistosoma serology. Eosinophilia (11.31, 2.03-58.94) was associated with positive Strongyloides serology. No Schistosoma or Strongyloides parasites were identified by direct stool microscopy. Eosinophilia had poor sensitivity for identification of positive serology. Hematuria was not associated with positive Schistosoma serology.

CONCLUSION

Positive Schistosoma and Strongyloides serology was common in this migrant HIV positive population receiving HIV care in Southern Alberta. This supports the value of routine parasitic screening as part of standard HIV care in non-endemic areas. Given the high morbidity and mortality in this relatively immunosuppressed population, especially for Strongyloides infection, screening should include both serologic and direct parasitological tests. Eosinophilia and hematuria should not be used for Schistosoma and Strongyloides serologic screening in HIV positive migrants in non-endemic settings.

The effect of maternal Strongyloides venezuelensis infection on mice offspring susceptibility and immune response

Species of Strongyloides infect a wide range of hosts worldwide. Due to their complex life cycle, it is hard to control the transmission of these parasites. Several species show evidence of vertical transmission; however, the impact of this transmission route on the susceptibility of the offspring has been poorly investigated. Herein, we used Strongyloides venezuelensis infected mice to evaluate transplacental and transmammary parasite transmission and their effect on the susceptibility of offspring. Swiss female mice were infected at the end of the gestation or during the breastfeeding period, and their offspring were examined for the presence of the parasite one week after infection of the mother. Our data showed that female mice infected with S. venezuelensis during gestation did not transmit the parasite to their offspring. On the other hand, all newborn mice breastfeeding in S. venezuelensis infected females got infected. To evaluate the effect of early exposure to the parasite on susceptibility and immune response of the hosts, the offspring of each experimental group (non-infected, gestation-infected, and breastfeeding-infected mothers) received anti-helminth treatment after parasite evaluation and were subcutaneously infected with S. venezuelensis upon reaching adulthood. Mice from the group of breastfeeding-infected mothers showed lower susceptibility to S. venezuelensis in adulthood in comparison with mice from non-infected mothers. The low parasite burden was accompanied by earlier eosinophil and neutrophil activation in the gut and higher serum levels of IgE. In contrast, S. venezuelensis infection in adult mice born from gestation-infected mothers presented with more worms in the intestine and lower levels of parasite-reactive IgM in serum in comparison with mice born from non-infected mothers, thus suggesting that early exposure to parasite antigens may modulate the protective immune response. Altogether, our data confirmed transmammary, but not transplacental, transmission of S. venezuelensis in mice and demonstrated that early exposure to the parasite and/or their antigens has an important effect on host susceptibility to a later infection.

Severe Strongyloides stercoralis infection in kidney transplant recipients: A multicenter case-control study

BACKGROUND

Severe Strongyloides stercoralis infection in kidney transplant recipients is associated with considerable morbidity and mortality, although little is known about the risk factors for such infection.

METHODOLOGY/PRINCIPAL FINDINGS

This was a retrospective, multicenter, case-control study in which we assessed the risk factors for and clinical outcomes of severe S. stercoralis infections in kidney transplant recipients in Brazil. We included 138 kidney transplant recipients: 46 cases and 92 controls. Among the cases, the median number of days from transplantation to diagnosis was 117 (interquartile range [IQR], 73.5-965) and the most common clinical findings were gastrointestinal symptoms (in 78.3%) and respiratory symptoms (in 39.1%), whereas fever and eosinophilia were seen in only 32.6% and 43.5%, respectively. The 30-day all-cause mortality among the cases was 28.3% overall and was significantly higher among the cases of infection occurring within the first three months after transplantation (47% vs. 17.2%, P = 0.04). The independent risk factors were receiving a transplant from a deceased donor (odds ratio [OR] = 6.16, 95% confidence interval [CI] = 2.05-18.5), a history of bacterial infection (OR = 3.04, 95% CI = 1.2-7.5), and a cumulative corticosteroid dose (OR = 1.005, 95% CI = 1.001-1.009). The independent predictors of mortality were respiratory failure (OR = 98.33, 95% CI = 4.46-2169.77) and concomitant bacteremia (OR = 413.00, 95% CI = 4.83-35316.61).

CONCLUSIONS/SIGNIFICANCE

Severe S. stercoralis infections are associated with considerable morbidity and mortality after kidney transplantation. In endemic areas, such infection may occur late after transplantation, although it seems to be more severe when it occurs earlier after transplantation. Specific risk factors and clinical manifestations can identify patients at risk, who should receive prophylaxis or early treatment.

A bibliometric analysis of human strongyloidiasis research (1968 to 2017)

Background

Strongyloidiasis is a neglected tropical disease (NTD). It is commonly associated with poverty and poor hygiene. Strongyloidiasis poses an unseen global public health problem. The aim of this study was to assess and analyze peer-reviewed literature on human strongyloidiasis to shed light on the evolution, volume, important topics, and key players in the field of human strongyloidiasis.

Methods

A validated bibliometric method was implemented using Scopus database for the study period from 1968 to 2017. The search strategy was developed based on keywords related to strongyloidiasis. Bibliometric indicators and visualization maps were presented.

Results

In total, 1947 documents were found. Retrieved documents received 32,382 citations, an average of approximately 16.6 per document, and an h-index of 76. The most frequently encountered keywords in the retrieved literature focused on hyperinfection, diagnosis, prevalence, and ivermectin. The USA led with 540 (27.7%) documents followed by Brazil (139; 7.1%) and Japan (137; 7.0%). When research output was standardized by income and population size, India ranked first (12.4 documents per GDP/capita) followed by the USA (9.1 documents per GDP/capita). The most active journal involved in publishing articles was the American Journal of Tropical Medicine and Hygiene (95; 4.8%). In terms of institutions, the University of Ryukyus (Japan) was the most active with 62 (3.2%) publications, followed by the University of Pennsylvania with 54 (2.8%) publications.

Conclusion

The volume, growth, and international research collaboration in human strongyloidiasis were inadequate given the long history of the disease, the large number of affected people, and the results obtained for other NTDs. Research in human strongyloidiasis needs to be strengthened and encouraged in endemic regions in Southeast Asia and Latin America. International research networking needs to be established to achieve the goals of Sustainable Development Goals in fighting and eradicating NTDs by 2030.

Parasitic Infections of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient, Including Toxoplasmosis and Strongyloidiasis

Hematopoietic stem cell transplantation (HSCT) recipients may infrequently develop parasitic infections at the time of the procedure via contamination from allograft tissue or blood products, and in the post-transplantation period through the traditional route of infection or as a reactivation caused by immunosuppression related to the transplant. To reduce risk, efforts should be directed at performing a comprehensive history, maintaining a high index of suspicion, and adhering to preventive measures. Additional strategies for the prevention, screening and careful follow-up, identification, and pre-emptive treatment of parasitic infections are required to reduce morbidity and mortality in HSCT patients.

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.

Development of immunochromatographic device as a point-of-care tool for serodiagnosis of human strongyloidiasis cases

Human strongyloidiasis is an important gastrointestinal disease with an estimated 30 to 100 million people infected. Prevalence is generally underestimated since many infections are asymptomatic, and traditional diagnostic tests based on parasitological examination of stool samples are not adequately sensitive. Serological tests are useful and supportive but are still only available in a reference research setting. We made an immunochromatographic test (ICT) kit for rapid serodiagnosis of human strongyloidiasis. The antigen used in the ICT kit was extracted from larvae of Strongyloides stercoralis. Diagnostic efficacy of the kit was evaluated using human serum samples from strongyloidiasis patients, healthy persons, and those with other parasitoses. When using a cutoff level of 0.5 or above, the diagnostic sensitivity, specificity, and positive and negative predictive values at the prevalence of infection of 34.4%, were 93.3%, 83.7%, 76.7%, and 95.6%, respectively. This ICT kit is easy to use at the point-of-care and a result can be obtained in 15 min. Sophisticated instruments and highly trained staff are not required. It can be used in several diagnostic and public-health settings, e.g., prevalence surveys in endemic areas, confirmation and monitoring of cure post-treatment, diagnosis and screening of infected but asymptomatic individuals, and populations “at risk” for hyperinfection syndrome or disseminated strongyloidiasis if they are given immunosuppressive treatment for other conditions.

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.

Comparative study of two commercial tests for Strongyloides stercoralis serologic diagnosis

Background

Serological diagnosis of Strongyloides stercoralis is often limited by its low specificity due to cross-reactivity with other parasitic nematodes. Novel serological tests assumed to be more specific have been recently developed. The aim of our study was to compare two commercial tests based on different antigens for S. stercoralis diagnosis in humans from a non-endemic area.

Methods

A retrospective laboratory-based study was conducted in the Hospital Universitario 12 de Octubre, Madrid, Spain. Samples from patients with a requested S. stercoralis serology from January 2013 to October 2016 were tested with two commercial enzyme-linked immunosorbent assay (ELISA) tests (crude larval suspension ELISA [CrAg-ELISA] and recombinant antigen ELISA [NIE-ELISA]). Sensitivity, specificity and predictive values were calculated using primary and composite gold standards. The κ index was calculated.

Results

A total of 249 samples from 233 patients were tested (κ=0.735). The CrAg-ELISA yielded sensitivities from 89.2% (95% confidence interval [CI] 80.7 to 94.2) to 94.7% (95% CI 75.4 to 99.0) and the NIE-ELISA from 72.3% (95% CI 58.2 to 83.1) to 78.9% (95% CI 56.7 to 91.5). Specificity ranged from 72.3% (95% CI 58.2 to 83.1) to 89.3% (95% CI 83.1 to 93.4) for the CrAg-ELISA and from 85.1% (95% CI 72.3 to 92.6) to 93.6% (95% CI 88.2 to 96.6) for the NIE-ELISA.

Conclusions

The NIE-ELISA is more specific than the CrAg-ELISA, but its low sensitivity limits its use in S. stercoralis screening. New diagnostic tests are needed for the diagnosis of S. stercoralis.

Multiple-dose versus single-dose ivermectin for Strongyloides stercoralis infection (Strong Treat 1 to 4): a multicentre, open-label, phase 3, randomised controlled superiority trial

BACKGROUND

Strongyloides stercoralis infection is a neglected condition that places people who are immunocompromised at risk of hyperinfection and death. Ivermectin is the drug of choice for the treatment of S stercoralis infection, but there is no definitive evidence on the optimal dose. This trial aimed to assess whether multiple doses of ivermectin were superior to a single dose for the treatment of non-disseminated strongyloidiasis.

METHODS

Our study was designed as a multicentre, open-label, phase 3, randomised controlled superiority trial. Participants were enrolled in four centres in Italy, three in Spain, and two in the UK, and recruiting sites were predominantly hospitals. Eligible patients were older than 5 years, weighed more than 15 kg, were residents in an area not endemic for S stercoralis, and either were positive for S stercoralis in faecal tests and on serology (any titre) or had a positive serological test with high titres, irrespective of the result of faecal tests. Patients were randomly assigned (1:1) using a computer-generated, blinded allocation sequence (with randomly mixed block sizes of six, eight, and ten participants) to receive either one dose of ivermectin 200 μg/kg or four doses of ivermectin 200 μg/kg (given on days 1, 2, 15, and 16). The primary endpoint was the proportion of participants with clearance of S stercoralis infection at 12 months, which was assessed in all randomly assigned participants who were not lost to follow-up (modified full-analysis set) and in participants in the modified full-analysis set who did not deviate from the assigned treatment regimen (per-protocol set). All participants were included in the safety analysis. The trial was registered with ClinicalTrials.gov, NCT01570504, and is now closed for recruitment.

FINDINGS

Of the 351 patients assessed for eligibility, 309 recruited between March 26, 2013, and May 3, 2017, were randomly assigned to one dose (n=155) or four doses (n=154) of ivermectin. At 12 months in the modified full-analysis set, 86% (95% CI 79 to 91; 102 of 118 participants) had responded to treatment in the single-dose group compared with 85% (77 to 90; 96 of 113 participants) in the four-dose group (risk difference 1·48%, 95% CI -7·55 to 10·52; p=0·75); similar results were observed in the per-protocol set. Adverse events were generally of mild intensity and more frequent in the multiple-dose than in the single-dose group. The trial was terminated early due to futility.

INTERPRETATION

Multiple doses of ivermectin did not show higher efficacy and was tolerated less than a single dose. A single dose should therefore be preferred for the treatment of non-disseminated strongyloidiasis.

FUNDING

There was no funding source for this study.

Advances in the Molecular and Cellular Biology of Strongyloides spp

Purpose of Review

This paper constitutes an update of recent studies on the general biology, molecular genetics, and cellular biology of Strongyloides spp. and related parasitic nematodes.

Recent Findings

Increasingly, human strongyloidiasis is considered the most neglected of neglected tropical diseases. Despite this, the last 5 years has seen remarkable advances in the molecular biology of Strongyloides spp. Genome sequences for S. stercoralis, S. ratti, S. venezuelensis, S. papillosus, and the related parasite Parastrongyloides trichosuri were created, annotated, and analyzed. These genomic resources, along with a practical transgenesis platform for Strongyloides spp., aided a major achievement, the advent of targeted mutagenesis via CRISPR/Cas9 in S. stercoralis and S. ratti. The genome sequences have also enabled significant molecular epidemiologic and phylogenetic findings on human strongyloidiasis, including the first genetic evidence of zoonotic transmission of S. stercoralis between dogs and humans. Studies of molecular signaling pathways identified the nuclear receptor Ss-DAF-12 as one that can be manipulated in the parasite by exogenous application of its steroid ligands. The chemotherapeutic implications of this were unscored by a study in which a Ss-DAF-12 ligand suppressed autoinfection by S. stercoralis in a new murine model of human strongyloidiasis.

Summary

Seminal advances in genomics of Strongyloides spp. have transformed research into strongyloidiasis, facilitating fundamental phylogenetic and epidemiologic studies and aiding the deployment of CRISPR/Cas9 gene disruption and editing as functional genomic tools in Strongyloides spp. Studies of Ss-DAF-12 signaling in S. stercoralis demonstrated the potential of this pathway as a novel chemotherapeutic target in parasitic 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.

Fatty acid and retinol-binding protein: A novel antigen for immunodiagnosis of human strongyloidiasis

The tenacious human parasitic helminth Strongyloides stercoralis is a significant health problem worldwide. The current lack of a definitive diagnostic laboratory test to rule out this infection necessitates designing more specific diagnostic methods. Fatty acid and retinol-binding protein (FAR) plays a crucial role in the development and reproduction of nematodes. We generated a recombinant form of this protein and determined its applicability for immunodiagnosis of S. stercoralis. The L3 form of S. stercoralis was harvested and used for RNA extraction and cDNA synthesis. The coding sequence of S. stercoralis FAR (SsFAR) was cloned into pET28a(+) vector, expressed in E. coli BL21 and purified. ELISA and immunoblotting were employed to determine the specificity and sensitivity of rSsFAR using a set of defined sera. In addition, we analyzed the phylogenetic relationship of SsFAR with different FAR sequences from other nematodes. The cloned SsFAR had an open reading frame of 447 bp encoding 147 amino acids, with a deduced molecular mass of 19 kD. The SsFAR amino acid sequence was 93% identical to FAR of S. ratti. For differential immunodiagnosis of strongyloidiasis, rSsFAR exhibited 100% sensitivity and 97% specificity. However, cross-reactivity with FAR proteins of other parasites, namely Toxocara canis and Echinococcus granulosus, was noted. Our results provide a novel approach for immunodiagnosis of S. stercoralis infections using rSsFAR with reliable sensitivity and specificity.

Strongyloides stercoralis Hyperinfection and Concomitant Cytomegalovirus Gastroenteritis in an Immunocompromised Host

Strongyloides stercoralis infection typically presents with nonspecific gastrointestinal symptoms and no definitive or pathognomonic endoscopic findings. Disease burden can vary depending on a patient's immune status. Immunocompromised patients with strongyloidiasis can develop tremendous disease burden, extraintestinal dissemination, and are at risk for coinfection with other organisms. We present the case of an immunocompromised patient presenting with multiple gastrointestinal complaints found to have S. stercoralis hyperinfection and concomitant cytomegalovirus gastroenteritis.

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.

Strongyloidiasis in Ethiopia: systematic review on risk factors, diagnosis, prevalence and clinical outcomes

BACKGROUND

Strongyloidiasis is a gastrointestinal infection caused by the parasitic nematode Strongyloides stercoralis. It is estimated to infect up to 370 million people globally and is predominately found in tropical and subtropical areas of socioeconomic disadvantage.

MAIN BODY

This systematic literature review identified studies published in the last ten years on the risk factors, diagnosis, prevalence and/or clinical outcomes of strongyloidiasis in Ethiopia. The prevalence of S. stercoralis ranged from 0.2 to 11.1% in adults, 0.3% to 20.7% in children, 1.5% to 17.3% in HIV positive adults and 5% in HIV positive children. The identified studies primarily used microscopy based techniques that potentially underestimated the prevalence four fold compared with serology and PCR. Strongyloidiasis in children presents a particularly significant issue in Ethiopia as children often presented with anemia, which is associated with impaired mental and cognitive development. The most significant risk factor for strongyloidiasis was HIV status and although other risk factors were identified for helminth infections, none were statistically significant for S. stercoralis specifically. Several studies detected S. stercoralis in dogs and non-biting cyclorrhaphan flies. However, future research is needed to explore the role of these reservoirs in disease transmission.

CONCLUSIONS

This review demonstrated that strongyloidiasis is an overlooked and neglected disease in Ethiopia. There is a need for a systematic approach using a combination of molecular and serology based diagnostic methods to ascertain the true incidence and burden of strongyloidiasis in Ethiopia. Further research is also needed to break the cycle of transmission by identifying environmental reservoirs, risk factors and exploring the potential for zoonotic transfer.

Strongyloidiasis and Culture-Negative Suppurative Meningitis, Japan, 1993-2015

Community-acquired Enterobacteriaceae infection and culture-negative meningitis are rare and atypical subtypes of meningitis in adults. Of 37 patients who had atypical suppurative meningitis during 1993–2015 in Okinawa, Japan, 54.5% had strongyloidiasis, of which 9.1% cases were hyperinfections and 3.0% dissemination. Strongyloidiasis should be considered an underlying cause of atypical suppurative meningitis.

Molecular and Immnune Diagnosis: Further Testing for Human Strongyloidiasis

INTRODUCTION

Detection of Strongyloides stercoralis larvae is particularly challenging because only a small number of larvae are released into the feces, regardless of infection stage.

OBJECTIVE

Our objective was to apply conventional polymerase chain reaction (PCR) to the detection of S. stercoralis DNA in feces samples to evaluate its performance in samples of patients with strongyloidiasis and compare results with those of immunodiagnosis.

METHODS

Stool, serum, and saliva samples were collected from each individual (n = 48) at the clinic hospital of the State University of Londrina, Brazil, for parasitological, immunological, and molecular tests. Stool samples were processed via parasitological methods. Serum samples were used for immunoglobulin G (IgG) detection and saliva samples for IgA detection by ELISA.

RESULTS

For amplification by conventional PCR, two different primers were used: species specific (101 bp) and genus specific (392 bp). The results showed that 34 (97.1%) of the 35 copro-positive individuals for S. stercoralis were positive for serum IgG and 19 (54.3%) were positive for salivary IgA. Regarding molecular analysis, both primers (species and genus specific) demonstrated positivity in 100% of the samples, which was confirmed by sequencing the positive samples.

CONCLUSION

Complementary examinations of the parasitological method demonstrated excellent results in the context of the diagnosis of strongyloidiasis, especially in asymptomatic patients with irregular larval release in the feces.

Highly specific and sensitive anti-Strongyloides venezuelensis IgY antibodies applied to the human strongyloidiasis immunodiagnosis

Due to the epidemiological problem of the neglected condition of human strongyloidiasis, rapid and effective diagnosis is extremely important, with the development of new diagnostic tools being essential to reduce infections and chronic cases. Avian immunoglobulin Y (IgY) technology is an alternative for antibody production that has high specificity and profitability. This study aimed to produce and fractionate IgY antibodies from the egg yolks of hens that were immunized with the total antigenic extracts of Strongyloides venezuelensis infectious filariform larvae (iL3) and parthenogenetic females (pF). IgY antibodies were then evaluated by their recognition of antigenic proteins, evolutive helminth forms, and serological diagnosis of human strongyloidiasis by the detection of immune complexes in serum samples. Egg yolks were fractionated to obtain IgY antibodies by thiophilic interaction chromatography. Immune complex detection in serum samples showed diagnostic values for anti-iL3 IgY and anti-pF IgY antibodies at 95.56% and 88.89% sensitivity and 95.56% and 91.11% specificity, respectively. Therefore, IgY technology is a promising tool for the detection of blood circulating Strongyloides antigens, with possible application as a serological diagnostic method.

Tissue and blood protozoa including toxoplasmosis, Chagas disease, leishmaniasis, Babesia, Acanthamoeba, Balamuthia, and Naegleria in solid organ transplant recipients- 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 tissue and blood protozoal infections in the pre- and post-transplant period. Significant new developments in the field have made it necessary to divide the previous single guideline published in 2013 into two sections, with the intestinal parasites separated from this guideline devoted to tissue and blood protozoa. The current update reflects the increased focus on donor screening and risk-based recipient monitoring for parasitic infections. Increased donor testing has led to new recommendations for recipient management of Toxoplasma gondii and Trypanosoma cruzi. Molecular diagnostics have impacted the field, with access to rapid diagnostic testing for malaria and polymerase chain reaction testing for Leishmania. Changes in Babesia treatment regimens in the immunocompromised host are outlined. The risk of donor transmission of free-living amebae infection is reviewed. Changing immigration patterns and the expansion of transplant medicine in developing countries has contributed to the recognition of parasitic infections as an important threat to transplant outcomes. Medications such as benznidazole and miltefosine are now available to US prescribers as access to treatment of tissue and blood protozoa is increasingly prioritized.

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.

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.

Donor-derived strongyloidiasis in a Saudi pediatric kidney transplant recipient: A case report and mini-review

S. stercoralis infection has been identified as a donor-derived infection in cases of solid organ transplant among recipients with no prior risk factor for parasitic exposure. Worldwide and regional reports from the adult kidney transplant population highlight this indirect method of infection and caution about delayed diagnosis, severe complications, and death related to donor-derived S. stercoralis infection. We report a deceased-donor-derived S. stercoralis infection in a 12-year-old Saudi girl who underwent kidney transplantation. This is the first pediatric case reported outside the United States of America. Although she presented with mild bouts of gastrointestinal symptoms, the need for additional immune suppression put her at risk of serious complications. A literature review highlights the importance of awareness about S. stercoralis infections and complications in kidney transplant recipients, pretransplant screening of donors based on risk assessment, and the challenges with treatment availability and duration in this vulnerable population.

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.

The investigation of Strongyloides stercoralis seroprevalence in immunosupressed patients in Turkey

Background/aim

In immunosuppressed patients, strongyloidiasis can be lifethreatening because of hyperinfection or dissemination. Therefore, diagnosis of S. stercoralis is important in immunosuppressed patients with chronic strongyloidiasis. In this study, our objective was to investigate the presence of S. stercoralis antibodies by an ELISA method in immunosuppressed patients.

Materials and methods

A total of 100 immunosuppressed patients’ sera were included in the study. Forty-two of the patients were receiving immunosuppressive therapies for cancer or being treated for hematopoietic malignancies, 38 of the patients were receiving immunosuppressive drugs for rheumatic diseases, 14 were receiving immunosuppressive therapies for liver transplantation. Two of the patients were being treated for HIV infection and 4 were being treated for hypogammaglobulinemia. As control group, 50 individuals without a known disease were included in the study. The presence of IgG antibodies against S. stercoralis was investigated with a commercial ELISA kit.

Results

S. stercoralis antibody test was positive in 4 of 100 (4%) sera from immunosuppressed patients. All control patients were negative for S. stercoralis.

Conclusions

Strongyloidiasis can be a lifelong chronic infection if not treated. In patients who are going to receive immunosuppressive therapy, it should be tested before treatment, as it can become a disseminated and life-threatening infectious disease.

Efficacy of ivermectin to control Strongyloides stercoralis infection in sheltered dogs

In dogs, information on treatments against S. stercoralis infection is rare and anecdotal. The aim of the present work was to evaluate the treatment outcome of S. stercoralis natural infection in sheltered dogs. Furthermore, based on the potential risk of infection, people working in the infected shelter were also tested. Seventeen sheltered dogs positive to S. stercoralis using the Baermann test were treated with ivermectin 200 μg/kg/sid/os for two consecutive days. Only two dogs showed clinical signs suggestive of strongyloidiasis (diarrhea, weigh loss) at diagnosis. All dogs showed consistently negative results for S. stercoralis at weekly monitoring after treatment using both the direct microscopy and Baermann test. Real-time PCR confirmed negative results at the last follow up 2 months after treatment. Serology performed at the first diagnosis showed that 82% and 41% of dogs were positive for S. stercoralis using an IFAT (titres ranging from 1:40 to 1:320) and ELISA, respectively. Two months after treatment, IFAT titres were strongly reduced in all animals. The results of clinical pathological laboratory tests at diagnosis in the positive dogs were within normal ranges, except for the two symptomatic dogs. Serum collected from two out of 14 shelter workers tested positive with titres 1:20 and 1:40 for S. stercoralis using an IFAT. Results of the study confirm that ivermectin was an effective treatment option to control S. stercoralis infection in dogs. Shelter workers are at risk of infection with S. stercoralis, thus the application of correct deworming protocols to reduce the environmental infective larval burden is essential to protect dogs and probably also shelter workers from the risk of infection.

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.

Acute Respiratory Distress Syndrome With Alveolar Hemorrhage due to Strongyloidiasis Hyperinfection in an Older Patient

Strongyloides stercoralis is an intestinal nematode that occurs sporadically in temperate areas like Korea. People who are in the immunosuppressed state, over the age of 65 or under the corticosteroid therapy are at risk for developing Strongyloides hyperinfection syndrome. Acute respiratory distress syndrome (ARDS) with alveolar hemorrhage is a rare presentation of Strongyloides hyperinfection. A 78-year-old man had been irregularly injected corticosteroid on his knees, but did not have any immunosuppressive disease. He was initially diagnosed with ARDS and septic shock. Bronchoalveolar lavage (BAL) fluid was bloody and its cytology revealed helminthic larvae identified as S. stercoralis. Results of Cytomegalovirus polymerase chain reaction (PCR), Pneumocystis jirovecii PCR, and Aspergillus antigen testing of the BAL fluid were positive. The clinical progress quickly deteriorated with multiple organ failure, shock and arrhythmia, so he finally died. This is a rare case of ARDS in an older patient without any known immunosuppressive conditions, with alveolar hemorrhage and S. stercoralis being found via BAL.

Severe strongyloidiasis and systemic vasculitis: comorbidity, association or both? Case-based review

A possible association between strongyloidiasis and systemic vasculitis is rarely reported in the literature. We report the case of a patient with severe strongyloidiasis and an angiographic finding consistent with polyarteritis nodosa. Diagnosis of strongyloidiasis was made by finding of larvae and adult parasites in samples of the upper gastrointestinal tract mucosa and stool. The patient was treated with albendazole, ivermectin and corticosteroid withdrawal. This therapy led to the resolution of symptoms, with repeated stool samples negative for S. stercoralis. However, the clinical course was complicated with pulmonary tuberculosis. Despite tuberculostatic therapy and supportive measures, a lethal outcome occurred. The report is followed by a focused review of the available literature on the association of strongyloidiasis and systemic vasculitis.

Strongyloidiasis in humans: diagnostic efficacy of four conventional methods and real-time polymerase chain reaction

INTRODUCTION

Strongyloides stercoralis is an intestinal parasitic nematode that causes hyperinfection and/or a dissemination syndrome in hosts, which is often difficult to diagnose. This study aims to compare the diagnostic efficacy of four conventional methods used to diagnose strongyloidiasis with real-time polymerase chain reaction (qPCR) to detect S. stercoralis in fecal samples.

METHODS

We analyzed 143 fecal samples collected from Colombian regions with varying degrees of risk for intestinal infections caused by S. stercoralis to assess the validity, performance, overall efficiency, and concordance of the qPCR using a direct stool test, modified Ritchie concentration technique, agar plate culture, and Harada-Mori technique as reference tests.

RESULTS

While four fecal samples were positive for S. stercoralis using conventional methods, 32 were positive via qPCR. The diagnostic sensitivity of the qPCR was 75% [95% confidence interval (CI): 20.07-100%], whereas its specificity, negative predictive value, negative likelihood ratio, and Youden's J index were 78.42% (95% CI: 71.22-85.62%), 99.09% (95% CI: 96.86-100%), 0.32 (95% CI: 0.06-1.74), and 0.53, respectively. In addition, the estimated kappa index between the qPCR and the conventional methods was 0.12 (95% CI: -0.020-0.26).

CONCLUSIONS

The diagnostic sensitivity of qPCR to detect strongyloidiasis is analogous to that of conventional parasitology methods, with an additional advantage of being capable of identifying the parasite DNA at low sample concentrations.

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.

Late post-kidney transplant Strongyloides hyperinfection syndrome

Disseminated strongyloidiasis is a potentially life-threatening infection in organ transplant recipients that typically occurs within the first 6 months of transplantation. We discuss a patient from the Appalachia region of Virginia who appeared to acquire Strongyloides stercoralis domestically years after kidney transplantation and then develop disseminated strongyloidiasis.

A case of an incidental Strongyloides stercoralis infection in the intestine of an Indian monitor lizard (Varanus bengalensis)

The present study reports a case of an incidental Strongyloides stercoralis infection in the intestine of an Indian monitor lizard (Varanus bengalensis). Nematode larvae were embedded in the mucosa of the small intestine. The nematodes were small, whitish in colour and measures (2.16 ± 69.85) mm length and (206.75 ± 38.85) µm width. Histopathologically, the intestine showed tufting of degenerated surface epithelium. There was presence of sections of the nematodes within the mucosa of the intestinal epithelium.

Fatal strongyloidiasis after corticosteroid therapy for presumed chronic obstructive pulmonary disease

INTRODUCTION

Strongyloidiasis is a neglected tropical disease with global prevalence. Under some cases of immune suppression (especially with corticosteroid administration), the nematode involved disseminates, leading to an amplified, possibly lethal hyper-infection syndrome.

CASE PRESENTATION

A 56-year-old Nepalese man presenting with chief complaints of nausea, vomiting, joint pain and abdominal cramps was admitted to Sumeru Hospital. His past history revealed: chronic obstructive pulmonary disease (COPD), systemic hypertension and previously treated pulmonary tuberculosis. The patient had been treated with oral prednisolone (60 mg gl-1) for 8 days due to a presumed exacerbation of his COPD. Sequentially, he developed haemoptysis, chest tightness, frequent wheezing and worsening cough. Bronchoscopy showed severe diffuse alveolar haemorrhage; microbiological examination of broncho-alveolar lavage (BAL) was recommended. Examination of an acid fast bacilli stain preparation of BAL revealed filariform larvae of Strongyloides. Stool specimen examination revealed larvae of Strongyloides. The physical condition of the patient began to deteriorate; a few days after admission, vancomycin-sensitive Enterococcus faecium was isolated from a blood sample. He was treated with ivermectin and albendazole for strongyloides and linezolid plus vancomycin for E. faecium. However, the patient failed to recover from the illness and died.

CONCLUSION

The findings of our study suggest that corticosteroid administration in strongyloidiasis can lead to the development of fatal strongyloides hyper-infection syndrome. Hence our experience suggests the need for early diagnosis of strongyloidiasis to avoid such an outcome. A deterioration of the patient's condition after the initiation of corticosteroid therapy in endemic areas should raise the possibility of strongyloidiasis.

Evaluation of Parasitological Methods for the Detection of Strongyloides Stercoralis among Individuals in Selected Health Institutions In Addis Ababa, Ethiopia

Background

Strongyloides stercoralis causes chronic intestinal infection that may lead to disseminated disease during immunosuppression. Therefore, efficient diagnostic methods are essential to detect silent and latent infections. The present study was aimed to compare the efficacy of parasitological methods for the detection of S. stercoralis infection.

Methods

A cross-sectional study was conducted on 351 subjects (226 HIV positive and 125 HIV negative) from October 2005 to May 2006. The study participants were selected by systematic random sampling method. Fresh fecal samples were collected from each participant and processed by different parasitological methods.

Results

Among the 351 individuals involved in the study, 43(12.3%) were infected by S. stercoralis. The prevalence of S. stercoralis infection was significantly higher among HIV positive subjects (17.3%) as compared with 3.2% in HIV negative subjects (p=0.001). The odd of being infected by S. stercoralis was significantly higher among AIDS patients (OR=6.31; 95% CI, 2.2–18.1) and HIV patients with diarrhea (OR=9.3; 95% CI 4.6–18.9) as compared with respective controls. Agar plate culture showed superior sensitivity (97.7%) than other methods for detection of S. stercoralis. Similarly, agar plate culture showed strong diagnostic agreement with Baermann's method (kappa = 0.82; 95% CI 0.72 – 0.92) followed by fecal concentration (kappa= 0.67; 95% CI=0.54–0.80).

Coclusion

This study revealed that HIV patients were about 6 folds susceptible for S. stercoralis infection. Similarly, agar plate culture showed superior diagnostic efficiency for detections of S. stercoralis infection.

Intestinal Parasitosis and Their Associated Factors among People Living with HIV at University of Gondar Hospital, Northwest-Ethiopia

Background

Most HIV clients die of AIDS related intestinal parasitic infections rather than due to the HIV infection itself. Therefore, this study was aimed at determining the prevalence of intestinal parasite and their associated factors among HIV/AIDS clients at the University of Gondar Hospital, Northwest Ethiopia.

Methods

Institution based cross sectional study was conducted using systematic random sampling technique from March to May 2016. A semi-structured questionnaire was used to collect data. Stool samples were collected and processed using direct wet mount, formol-ether concentration and modified Ziehl-Neelson staining techniques. Besides, blood samples were collected for CD4+ count estimation. Both descriptive and logistic regression analyses were used in data analysis. P-values <0.05 were considered as statistically significant.

Results

A total of 223 participants were enrolled in this study, and the prevalence of intestinal parasitosis was found to be 29.1%. The most predominant intestinal parasite detected was cyst of Entamoeba histolytica (8.5%) followed by Ascaris lumbricoides (6.7%), Strongyloides sterocoralis (3.6%) and Cryptosporidium parvum (3.1%), whereas Schistosoma mansoni (0.9%) and Hymenolepis nana (0.9%) were the least detected. Absence of toilet (AOR= 19.4, CI: 6.46–58.3), improper hand washing before meal (AOR=11.23, 95% CI: 4.16–30.27 and CD4+ count < 200 cells/mm³ (AOR=33.31, 95% CI: 9.159–121.149) had significant association with prevalence of intestinal parasites.

Conclusion

The study indicated that intestinal parasites are still a problem among HIV/AIDS patients in the study area. Thus, routine examination for intestinal parasites and interventions should be carried out for better management of clients.

Bethony J. Diagnostic performance of urinary IgG antibody detection: A novel approach for population screening of strongyloidiasis

The diagnosis of strongyloidiasis by coprological methods has a low sensitivity, underestimating the prevalence of Strongyloides stercoralis in endemic areas. Serodiagnostic tests for strongyloidiasis have shown robust diagnostic properties. However, these methods require a blood draw, an invasive and labor-intensive sample collection method, especially in the resource-limited settings where S. stercoralis is endemic. Our study examines a urine-based assay for strongyloidiasis and compares its diagnostic accuracy with coprological and serological methods. Receiver operating characteristic (ROC) curve analyses determined the diagnostic sensitivity (D-Sn) and specificity (D-Sp) of the urine ELISA, as well as estimates its positive predictive value and diagnostic risk. The likelihood ratios of obtaining a positive test result (LR+) or a negative test result (LR-) were calculated for each diagnostic positivity threshold. The urine ELISA assay correlated significantly with the serological ELISA assay for strongyloidiasis, with a D-Sn of 92.7% and a D-Sp of 40.7%, when compared to coprological methods. Moreover, the urine ELISA IgG test had a detection rate of 69%, which far exceeds the coprological method (28%). The likelihood of a positive diagnosis of strongyloidiasis by the urine ELISA IgG test increased significantly with increasing units of IgG detected in urine. The urine ELISA IgG assay for strongyloidiasis assay has a diagnostic accuracy comparable to serological assay, both of which are more sensitive than coprological methods. Since the collection of urine is easy and non-invasive, the urine ELISA IgG assay for strongyloidiasis could be used to screen populations at risk for strongyloidiasis in S. stercoralis endemic areas.

Chronic intestinal pseudo-obstruction due to Strongyloides stercoralis

We report a case of chronic intestinal pseudo-obstruction due to a generalized visceral autonomic neuropathy in an immune-competent patient infected with Strongyloides stercoralis. The patient had immigrated to the United States from Sierra Leone in childhood but had not returned for decades. His symptoms resolved with ivermectin treatment. Clinicians should have a high index of suspicion for strongyloidiasis in any patient with abdominal complaints and a history of travel to endemic areas, even if the travel history is remote.

Strongyloides stercoralis: detection of parasite-derived DNA in serum samples obtained from immunosuppressed patients

Strongyloidiasis is an important neglected disease, which is life threatening in immunocompromised patients. This study aimed to evaluate the frequency of Strongyloides stercoralis infection among immunosuppressed subjects living in endemic communities by conventional PCR of the 18S rRNA and Cox1 genes to detect cell-free DNA in the patients' serum samples. Fresh stool and serum samples were obtained from participants. The stool samples were examined using parasitological methods. Total DNA was extracted from the serum samples and S. stercoralis larvae isolated from patient fecal samples. Conventional PCR to amplify a 101 bp fragment of the 18S rRNA gene was carried out for all extracted DNA, and then positive samples were further evaluated for a 121 bp fragment of the Cox1 gene. The PCR products of selected samples were sequenced and BLAST analysis was performed. Out of 120 patients, 57 and 63 cases had autoimmune disorders and cancer, respectively. The 101 bp fragments of the 18S rRNA were successfully amplified in 36 out of 120 (30%) serum samples. The PCR products of five samples were sequenced and compared with reference sequences in GenBank, which showed 97% identity and 90% coverage. In conclusion, to the best of our knowledge, this is the first molecular study for the detection of S. stercoralis cell-free DNA in human serum samples. These results provide useful insights for future studies and show that serum is an alternative specimen and may be useful in molecular diagnosis of diseases, particularly in immunosuppressive patients.

Synchronous MALT lymphoma of the colon and stomach and regression after eradication of Strongyloides stercoralis and Helicobacter pylori

Mucosa-associated lymphoid tissue (MALT) is vital for host immunological surveillance against pathogens. MALT lymphoma, also known as extranodal marginal zone B cell lymphoma, is a non-Hodgkin's lymphoma subtype that predominantly arises in the gastrointestinal tract. Chronic Helicobacter pylori (H. pylori) infection is a common cause of gastric MALT lymphoma, although other infections are reported in association with extragastric MALT lymphomas. To our knowledge, here we report the first case of synchronous MALT lymphomas of the colon and stomach in the presence of Strongyloides stercoralis and H. pylori infections that resolved after eradication of both organisms.

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

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

Human Strongyloidiasis in Hawaii: A Retrospective Review of Enzyme-Linked Immunosorbent Assay Serodiagnostic Testing

Human strongyloidiasis is widely prevalent in tropical and subtropical regions worldwide but is not endemic in Hawaii. Subclinical, chronic infections may be lifelong; immunosuppressive therapy, particularly with glucocorticoids, may lead to serious or fatal disseminated disease, which is preventable. We performed a retrospective analysis of patients tested for Strongyloides immunoglobulin G antibody in an academic medical center in Honolulu, Hawaii, from 2005 to 2012. Of the 475 patients tested, 78 (16%) were seropositive. The largest proportion of seropositive cases was found among Micronesians (30%), Polynesians (26%), Filipinos (13%), and Southeast Asians (11%). Among the seropositive patients, the most likely reason for clinicians to order testing was blood eosinophilia. Stool parasite examination results were available for 58% of seropositive patients of which 11% were positive for Strongyloides stercoralis larvae. Antihelminthic therapy, usually ivermectin, was ordered for 71% of patients. After treatment, blood eosinophilia and Strongyloides serology results were reassessed for 76% and 35% of patients, respectively; both tests tended to show improvement. Travelers and immigrants from Strongyloides-endemic areas, including Micronesia and Polynesia, should have serodiagnostic testing for latent strongyloidiasis, and if positive, treated empirically with ivermectin, particularly when corticosteroids or other immunosuppressive therapies are anticipated.