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

A severe case of hyperinfection by Strongyloides stercoralis in a pet dog from Romania

Strongyloides stercoralis is a zoonotic soil-transmitted nematode affecting mainly humans and dogs but identified also in non-human primates, cats and wild carnivores. It has a cosmopolitan distribution being endemic in tropical and subtropical areas. In Romania, the infection was reported on several occasions in dogs with low prevalence (3.5% -3.8%), assessed by coproscopy and it was confirmed in human patients with no travel history. A 2-year-old male Boston Terrier dog presented to a private clinic due to severe digestive problems, in July 2022. The animal had a long history of health problems. The dog was in a very bad clinical condition with severe abdominal pain, bloody diarrhea, and weight loss. Coproparasitological examinations using the saline flotation method and the modified Baermann's technique were done, both being negative. In addition, an intestinal biopsy was performed during the second endoscopy. Nematodes were collected and identified morphologically and molecularly confirmed. Histology revealed severe inflammation of the duodenal mucosa with areas of edema, necrosis, and hemorrhage, and in the intestinal glands, there were numerous nematodes suggesting a parasitic infection by Strongyloides spp. PCR followed by sequencing confirmed the infection with S. stercoralis. The dog was treated with a combination of oral fenbendazole and milbemycin oxime for 5 months. No relapse was observed 3 months after negativity was attained. This case describes a severe clinical infection by Strongyloides stercoralis in a domestic dog from Romania and the recovery after long-term treatment.

Strongyloidiasis in Auckland: A ten-year retrospective study of diagnosis, treatment and outcomes of a predominantly Polynesian and Fijian migrant cohort

BACKGROUND

Strongyloides stercoralis is not endemic in Aotearoa New Zealand (AoNZ). However, approximately one third of Auckland residents are born in endemic countries. This study aimed to describe the epidemiology and management of strongyloidiasis in Auckland, with a focus on migrants from Pacific Island Countries and Territories.

METHODS

This study retrospectively reviewed clinical, laboratory and pharmacy records data for all people diagnosed with strongyloidiasis in the Auckland region between July 2012 and June 2022. People with negative Strongyloides serology were included to estimate seropositivity rate by country of birth.

FINDINGS

Over ten years, 691 people were diagnosed with strongyloidiasis. Most diagnoses were made by serology alone (622, 90%). The median age was 63 years (range 15-92), 500 (72%) were male, and the majority were born in Polynesia (350, 51%), Fiji (130, 19%) or were of Pasifika ethnicity (an additional 7%). Twelve participants (1.7%) had severe strongyloidiasis at diagnosis. The total proportion treated with ivermectin was only 70% (484/691), with no differences between immunocompromised and immunocompetent participants, nor by ethnicity. The outcome of treatment (based on a combination of serology and/or eosinophilia and/or stool microscopy) could only be determined in 50% of the treated cohort. One participant failed treatment with ivermectin, experiencing recurrent strongyloidiasis, and another participant died in association with severe strongyloidiasis. The rate of 'positive' Strongyloides serology was highest among participants born in Samoa (48%), Fiji (39%), and Southeast Asian countries (34%).

INTERPRETATION

Strongyloidiasis was common and under-treated in Auckland during the study period. Clinicians should have a low threshold for considering strongyloidiasis in migrants from endemic countries, including Polynesia and Fiji.

Examination of Diagnostic Performance of New IgG4 Rapid Test Compared with IgG- and IgG4-ELISAs to Investigate Epidemiology of Strongyloidiasis in Northeast Thailand

Strongyloidiasis, caused by Strongyloides stercoralis, is a neglected tropical disease with a global distribution. The infection can be fatal in immunocompromised individuals, and accurate diagnosis leading to timely treatment can save lives. Serodiagnosis is a sensitive method for diagnosis and is recommended for screening high-risk individuals. A point-of-care rapid test will facilitate the screening activities, especially in low-resource settings. This study aims to apply a new IgG4 immunochromatographic test using S. stercoralis recombinant antigen (SsRapid® cassette test) and to compare it with in-house IgG and IgG4 enzyme-linked immunosorbent assays (IgG- and IgG4-ELISAs) using native Strongyloides ratti antigen to investigate the epidemiology of strongyloidiasis in northeast Thailand. A total of 300 people participated, with 136 males and 164 females of a similar mean age. The reference tests were fecal examinations using the formalin-ethyl acetate concentration technique and an agar plate culture technique. The prevalence of S. stercoralis determined by SsRapid (81.7%) was significantly higher than that by fecal examinations (43.3%) or by antibody detection by IgG-ELISA (53.0%) or IgG4-ELISA (44.0%). The diagnostic sensitivities of SsRapid, IgG-ELISA, and IgG4-ELISA were found to be 93.9%, 77.7%, and 63.1%, respectively. The rate of positive tests by the SsRapid was significantly correlated to the levels of Strongyloides-specific IgG4 and IgG antibodies. By all diagnostic methods, male participants had a significantly higher prevalence of strongyloidiasis than females. Age was significantly associated with the concentration of specific serum IgG but not with the SsRapid grading score. In conclusion, SsRapid was shown to be a sensitive and valuable diagnostic test for the epidemiology study of strongyloidiasis.

Strongyloidiasis

Strongyloidiasis is a neglected tropical disease caused primarily by the roundworm Strongyloides stercoralis. Strongyloidiasis is most prevalent in Southeast Asia and the Western Pacific. Although cases have been documented worldwide, global prevalence is largely unknown due to limited surveillance. Infection of the definitive human host occurs via direct skin penetration of the infective filariform larvae. Parasitic females reside in the small intestine and reproduce via parthenogenesis, where eggs hatch inside the host before rhabditiform larvae are excreted in faeces to begin the single generation free-living life cycle. Rhabditiform larvae can also develop directly into infectious filariform larvae in the gut and cause autoinfection. Although many are asymptomatic, infected individuals may report a range of non-specific gastrointestinal, respiratory or skin symptoms. Autoinfection may cause hyperinfection and disseminated strongyloidiasis in immunocompromised individuals, which is often fatal. Diagnosis requires direct examination of larvae in clinical specimens, positive serology or nucleic acid detection. However, there is a lack of standardization of techniques for all diagnostic types. Ivermectin is the treatment of choice. Control and elimination of strongyloidiasis will require a multifaceted, integrated approach, including highly sensitive and standardized diagnostics, active surveillance, health information, education and communication strategies, improved water, sanitation and hygiene, access to efficacious treatment, vaccine development and better integration and acknowledgement in current helminth control programmes.

Modifications to the parasitological technique of Rugai increase the diagnostic sensitivity for strongyloidiasis

Strongyloidiasis is a neglected tropical disease caused mainly by Strongyloides stercoralis, a nematode that can persist for decades in the human host with a very low parasitic burden and without specific symptoms. Hence, it is difficult to diagnose and control. Larval concentration and culture methods with fecal samples show higher sensitivity for the diagnosis of Strongyloides-infected individuals; however, these techniques are not routinely used, primarily due to the challenges associated with processing a substantial volume of fecal samples. In the current study, we comparatively evaluated the sensitivity and applicability of modifications made to the Rugai parasitological method for the diagnosis of strongyloidiasis in fecal samples of experimentally infected rats and in 68 individuals from an urban community close to Maceió, Brazil. The presence and quantity of parasite larvae in the feces were comparatively evaluated using different parasitological techniques. In the experimental model, we demonstrated that the modified Rugai technique (RMOD) allowed for significantly higher recovery of larvae than the original Rugai technique (RO). Moreover, the sediment was cleaner and easier to evaluate using optical microscopy. Compared to other parasitological techniques, such as agar-plate culture (A-PC) and spontaneous sedimentation (SS), the RMOD technique showed higher sensitivity in the detection of larvae in all infected groups and presented comparatively better performance, especially in rats with a low parasite burden. In the human population, among the 68 stool samples evaluated, Strongyloides larvae were detected in the feces of six individuals with an estimated prevalence of 8.82%. However, the performance of each parasitological method was remarkably different. SS identified Strongyloides larvae in only two individuals and A-PC in three, whereas RMOD was able to identify six infected individuals, resulting in sensitivities of 33.3%, 50%, and 100%, respectively. In conclusion, the modifications introduced to the Rugai technique resulted in improved sensitivity for the detection of Strongyloides spp. infections, especially in stool samples with a low parasite burden, in comparison with other routinely used parasitological techniques.

Gastrointestinal parasite infections in Nepalese Gurkha recruits arriving in the United Kingdom from 2012-2020

BACKGROUND

Gastrointestinal parasite (GIP) infections are a major cause of global morbidity, infecting hundreds of millions of people each year and potentially leading to lifelong infection and serious complications. Few data exist on screening for GIP infections in migrants entering the UK or on the current performance of different traditional diagnostic approaches. This study aimed to describe the prevalence of GIP infections in Nepalese Gurkha recruits screened on arrival in the UK.

METHODOLOGY/PRINCIPAL FINDINGS

We present a retrospective analysis of data from screening male adults (18-21 years) who arrived in the UK from Nepal between 2012 and 2020. Three separate faecal samples were obtained from participants at weekly intervals and processed for formalin-ethyl acetate (FEA) concentration/light microscopy and charcoal culture. Serum samples were analysed for IgG antibodies to Strongyloides stercoralis by ELISA. Results were available from 2,263 participants, of whom 463 (20.5%, 95% CI 18.8%-22.2%) had a positive diagnostic test for at least one GIP infection. A total of 525 potential infections were identified. Giardia duodenalis was most common (231/2263, 10.2%), followed by S. stercoralis (102/2263, 4.5%), and hookworm species (86/2263, 3.8%). Analysis (microscopy and culture) of the initial stool sample diagnosed only 244/427 (57.1%) faecally identified pathogens, including 41/86 (47.7%) hookworm infections. The proportion of participants infected with any GIP showed a downward trend over the study period. Log-binomial regression showed risk of infection decreasing by 6.1% year-on-year (95% CI 3.2% - 9.0%). This was driven predominantly by a fall in hookworm, S. stercoralis and Trichuris trichiura prevalence.

CONCLUSIONS/SIGNIFICANCE

The level of potentially pathogenic GIP infection in young Nepalese men migrating to the UK is high (20.5%) and requires a combined diagnostic approach including serology and analysis of multiple stool samples incorporating specialised parasitological methods. Advances in molecular approaches may optimise and simplify the intensive screening strategy required.

Evaluation of the accuracy of a multi-infection screening test based on a multiplex immunoassay targeting imported diseases common in migrant populations

BACKGROUND

We aimed to evaluate the performance of a novel multiplex serological assay, able to simultaneously detect IgG of six infections, as a screening tool for imported diseases in migrants.

METHODS

Six panels of 40 (n = 240) anonymized serum samples with confirmed infections were used as positive controls to assess the multiplex assay's sensitivity. One panel of 40 sera from non-infected subjects was used to estimate the seropositivity cutoffs, and 32 non-infected sera were used as negative controls to estimate each serology's sensitivity and specificity. The multi-infection screening test was validated in a prospective cohort of 48 migrants from endemic areas. The sensitivity of the Luminex assay was calculated as the proportion of positive results over all positive samples identified by reference tests. The specificity was calculated using 32 negative samples. Uncertainty was quantified with 95 % confidence intervals using receiver operating characteristic analyses.

RESULTS

The sensitivity/specificity were 100 %/100 % for HIV (gp41 antigen), 97.5 %/100 % for Hepatitis B virus (HBV-core antigen), 100 %/100 % for Hepatitis C virus (HCV-core antigen), 92.5 %/90.6 % for strongyloidiasis [31-kDa recombinant antigen (NIE)], 97.5 %/100 % for schistosomiasis (combined serpin Schistosoma mansoni and S.haematobium antigens) and 95 %/90.6 % for Chagas disease [combined Trypanosoma cruzi kinetoplastid membrane protein-11 (KMP11) and paraflagellar rod proteins 2 (PFR2) antigens]. In the migrant cohort, antibody response to the combination of the T.cruzi antigens correctly identified 100 % individuals, whereas HBV-core antigen correctly identified 91.7 % and Strongyloides-NIE antigen 86.4 %.

CONCLUSIONS

We developed a new, robust and accurate 8-plex Luminex assay that could facilitate the implementation of screening programmes targeting migrant populations.

Frequency of strongyloidiasis and associated factors: Analysis of 13 years of laboratory results in a tertiary referral hospital in Honduras, 2010-2022

INTRODUCTION

The frequency of detected strongyloidiasis is affected by the selected laboratory method in the studied population. Considering that Honduras has few community-based studies, the analysis of the laboratory record data can provide information helping to understand this parasitosis.

OBJECTIVE

To estimate the frequency and to identify the factors associated with strongyloidiasis, analyzing the laboratory records of the Servicio de Parasitología at Hospital Escuela in Tegucigalpa (Honduras) between 2010 and 2022.

MATERIALS AND METHODS

We carried out a descriptive, cross-sectional, analytical study. The laboratory diagnosis consisted of stool samples' examination by direct smear and modified Baermann technique. We estimated frequencies and percentages. The statistical association was calculated with prevalence ratios and a 95% confidence interval. Software R, version 4.2.0, and epiR package, version 2.0.46, were used to perform the analysis.

RESULTS

The frequency of strongyloidiasis was 0.29% (112/38,085). It was higher with the modified Baermann technique (0.87%; 40/4,575) among male patients (0.44%; 70/15,758). Regarding the age, strongyloidiasis was higher in the 20-40 years old group (0.41%; 28/6,886) with direct smear and 41-61 years old (1.14%; 14/1,232) group with the modified Baermann technique. Among the factors associated with strongyloidiasis were age between 20 and 61 years old (PR=2.26, CI 95%=1.53-3.31), male patients (PR=2.34, CI 95%=1.60‑3.44), mucus (PR=1.86, CI 95%=1.22-2.83) and Charcot-Leyden crystals in stool (PR=8.47, CI 95%=5.14-13.96); watery stool (PR=2.39, CI 95%=1.55-3.68), and other helminthiases (PR=6.73, CI 95%=3.98-11.38). Associated factors to cases detected with the modified Baermann technique were outpatient consultation (PR=4.21, CI 95%=1.91-9.28) and formed stools (PR=3.99, CI 95%=1.94-8.19).

CONCLUSIONS

The modified Baermann technique increased the detection of strongyloidiasis almost four times. Most cases were distributed among male adults. The cases diagnosed exclusively with the modified Baermann technique have differences from those with observed larvae in the direct smear. It is necessary to develop community-based population studies.

Prevalence of gastrointestinal parasites in captive mammals at Khon Kaen Zoo, Thailand

Background and Aim

Captive animals are susceptible to parasitic diseases due to the stress and confinement they experience. In addition, they can serve as reservoirs of zoonotic parasites that have the potential to infect humans. To investigate this possibility, we estimated the prevalence of gastrointestinal (GI) parasites in captive mammals at Khon Kaen Zoo, Thailand.

Materials and Methods

One hundred and forty-seven individual mammals (37 primates, 43 carnivores, 62 herbivores, and 5 rodents) were examined for parasitic infections by fecal examination daily for 3 consecutive days using the formalin-ethyl acetate concentration technique (FECT) and the agar plate culture method.

Results

According to FECT, the overall prevalence of GI parasites was 62.6% (92/147). Within animal groups, the numbers were as follows: 67.6% (25/37) in primates, 23.3% (10/43) in carnivores, 85.5% (53/62) in herbivores, and 80.0% (4/5) in rodents. Using the agar plate culture method, 21.43% (27/126) were positive for Strongyloides spp. and hookworm infections. The GI parasites identified belonged to three categories: protozoa (including Entamoeba histolytica species complex, Entamoeba coli, Giardia spp., coccidia, and ciliated protozoa), trematodes (minute intestinal flukes and rumen flukes), and nematodes (strongyle/hookworm, Strongyloides spp., Ascarididae, and Trichuris spp.).

Conclusion

The findings of this study indicate the prevalence of several GI parasites in zoo animals with the potential for transmission to humans, given the animals' close proximity to both visitors and animal caretakers.

Strongyloides infection screening in transplant candidates: What is the best strategy?

BACKGROUND

The potential that Strongyloides stercoralis infection has to cause major morbidity and high mortality when the disseminated form occurs in transplant patients is of particular concern.

METHODS

In this study, the objective was to observe S. stercoralis infection in patients who are candidates for transplantation by using parasitological, serological, and molecular techniques and to propose an algorithm for the detection of that infection in transplant candidates.

RESULTS

By parasitological techniques, 10% of fecal samples were positive. Anti-Strongyloides antibodies immunoglobulin G were detected in 19.3% and 20.7% of patients by immunofluorescence assay and enzyme-linked immunosorbent assay, respectively. S. stercoralis DNA was observed in 17.3% of samples by conventional polymerase chain reaction and 32.7% of samples by quantitative polymerase chain reaction (qPCR).

CONCLUSION

The set of results allows us to reinforce that a positive result by parasitological techniques and/or qPCR indicates that the specific treatment should be applied. However, the improvement of diagnostic techniques may suggest changes in the screening for strongyloidiasis in these patients.

Clinical presentation and diagnosis of imported strongyloidiasis at a tertiary hospital, Stockholm, Sweden

BACKGROUND

Since Strongyloides can persist in its host for decades, and cause life threatening infections data on prevalence, the burden and risk factors for infection is crucial in migrant populations.

METHODS

In this observational retrospective cohort study, we describe the epidemiological, clinical, and microbiological characteristics of imported strongyloidiasis diagnosed at the Karolinska University Hospital, Stockholm, Sweden, during 2010-2021.

RESULTS

We identified 98 individuals with strongyloidiasis, 89 (90.8%) born in endemic and 9 (9.2%) in non-endemic countries. Sub-Saharan Africa was the most common origin among the group born in endemic countries (62, 69.7%), (p < 0.005). There were 22 individuals with an underlying immunosuppressive condition. Gastrointestinal symptoms (53/98, 54.1%) were the symptoms most frequently described, and were more frequent in adults (57.0%) vs children (0%) (p = 0.013). Eosinophilia was detected in 74 (75.5%), being more frequent in the endemic-borne group (79.8% vs 33.3%, p = 0.002). Eight persons developed complications of strongyloidiasis because of either hyperinfection or disseminated disease. No people living with HIV with CD4 <500/mm3 (n = 6) developed severe strongyloidiasis.

CONCLUSION

A limited number of strongyloidiasis cases was identified, with few complicated cases in immunosuppressed patients. Further studies focusing on identifying and exploring the risk of complicated strongyloidiasis in immunosuppressed patients are needed.

First field study using Strong-LAMP for diagnosis of strongyloidiasis in Cubal, Angola

BACKGROUND

Strongyloides stercoralis infection is a common neglected tropical disease distributed worldwide, mainly in tropical and subtropical climates. The impact of S. stercoralis infections on human health ranges from mild asymptomatic infections to chronic strongyloidiasis unnoticeable until the host is immunosuppressed. In severe strongyloidiasis, a syndrome of hyperinfection and larval dissemination to various organs can occur with high mortality rates. The diagnosis of strongyloidiasis is challenging because of the absence of a single standard reference test with high sensitivity and specificity, which also makes it difficult to estimate the accuracy of other diagnostic tests. This study aimed to evaluate, for the first time, the use of an easy-to-perform loop-mediated isothermal amplification (LAMP) colorimetric assay (named Strong-LAMP) for the molecular screening of strongyloidiasis in stool samples from patients in a low-resource endemic area in Cubal, Angola. To compare different LAMP application scenarios, the performance of the Strong-LAMP under field conditions in Angola was reassessed in a well-equipped reference laboratory in Spain and compared with a quantitative polymerase chain reaction (qPCR) method.

METHODS

A total of 192 stool samples were collected from adult population in Cubal, Angola, and examined by parasitological methods (direct saline microscopy and Baermann's technique). DNA was extracted from each stool sample using a commercial kit and tested by the colorimetric Strong-LAMP assay for the detection of Strongyloides spp. under field conditions. Furthermore, all samples were shipped to a well-equipped laboratory in Spain, reanalysed by the same procedure and compared with a qPCR method. The overall results after testing were compared.

RESULTS

Strongyloides stercoralis larvae were identified by direct saline microscopy and Baermann in a total of 10/192 (5.2%) and 18/192 (9.4%) stool samples, respectively. Other helminth and protozoan species were also identified. The Strong-LAMP-positive results were visually detected in 69/192 (35.9%) stool samples. The comparison of Strong-LAMP results in field conditions and at a reference laboratory matched in a total of 146/192 (76.0%) samples. A total of 24/192 (12.5%) stool samples tested positive by qPCR.

CONCLUSIONS

This is the first study in which colorimetric Strong-LAMP has been clinically evaluated in a resource-poor strongyloidiasis endemic area. Strong-LAMP has been shown to be more effective in screening for strongyloidiasis than parasitological methods under field conditions and qPCR in the laboratory. Our Strong-LAMP has proven to be a field-friendly and highly accurate molecular test for the diagnosis of strongyloidiasis.

Prevalence of Strongyloides in Southeast Asia: a systematic review and meta-analysis with implications for public health and sustainable control strategies

BACKGROUND

Strongyloidiasis, caused by the nematodes Strongyloides stercoralis and Strongyloides fuelleborni, is estimated to affect over 600 million individuals worldwide. The disease is endemic in Southeast Asia, where a warm-humid climate and socio-economic conditions maintain the parasite's life cycle and transmission. However, the current diagnostic methods may not be sufficiently sensitive, suggesting that the true prevalence of strongyloidiasis could be seriously underestimated in this. This study aims to determine the prevalence of strongyloidiasis in Southeast Asia through a systematic review and meta-analysis and to discuss the implications of the estimated prevalence on diagnostic approaches and control strategies.

METHODS

Following PRISMA guidelines, we conducted a systematic literature search in PubMed and Google Scholar databases to identify studies reporting Strongyloides prevalence data in the 11 Southeast Asian countries up to December 2022. A random effects model was employed to estimate the pooled prevalence of S. stercoralis at both regional and country levels.

RESULTS

Out of 3722 articles identified, 224 met our inclusion criteria. For S. stercoralis specifically, we found 187 articles, of which 52.4% were from Thailand. All Southeast Asian countries, except Brunei, had at least one study on Strongyloides prevalence. The estimated pooled prevalence of S. stercoralis regionally was 12.7% (95% CI 10.70-14.80%), ranging from 0.4 to 24.9% at the country level. Cambodia had the highest pooled prevalence (24.9%, 95% CI 15.65-35.38%), followed by Lao PDR (16.5%, 95% CI 9.50-24.95%). Moreover, we obtained a pooled prevalence of 10% (95% CI 7.06-13.52%) in a group comprising immigrants, workers, and veterans from Southeast Asian countries. S. stercoralis infects various host types, including nonhuman primates, domestic dogs and cats, rodents, and transport carriers such as cockroaches and vegetables.

CONCLUSIONS

A high prevalence of strongyloidiasis in Southeast Asia was revealed, highlighting the importance of the region's ongoing research, surveillance, and control efforts. Factors contributing to the strongyloidiasis transmission include the role of animal hosts, the impact of global connectivity, and the significance of the co-endemicity of other Strongyloides species. Based on these findings, a multi-pronged One-Health approach is essential for sustainable intervention and control.

Multiple Stool Sampling and Specific Parasitological Technique are Crucial to Diagnose Strongyloidiasis in Alcoholic Patients

PURPOSE

Chronic alcoholism is a well-known risk factor for strongyloidiasis, in these patients the disease is potentially more severe, probably due to the breakdown of local protective barriers and immunosuppression caused by alcohol, which can lead to autoinfection and dissemination. The aim of this study was to evaluate multiple stool sampling and a specific parasitological assay agar plate culture (APC) for the diagnosis of Strongyloides stercoralis in alcoholics.

METHODS

APC was compared to sedimentation technique (HPJ; Hoffman, Pons and Janer), as parasitological methods to detect S. stercoralis infection in alcoholic individuals. Three stool samples from 60 alcoholic and 60 non-alcoholic individuals were analyzed.

RESULTS

S. stercoralis larvae were observed in 11 (18.3%) alcoholic individuals and 1 (1.7%) nonalcoholic individual (P = 0.0042). In view of the combined results, sensitivity for the APC method was 63.6% (CI 31.6-87.6%) with the first sample reaching 100% (CI 67.8-100%) after analyzing three fecal samples. The HPJ sensitivity was 36.4% (CI 12.4-68.4) in the first sample, reaching 72.7% (CI 39.3-92.7) after three samples analyzed.

CONCLUSION

The present results suggest that in alcoholic patients, it is important to repeat stool sampling with specific techniques, especially using the APC method, to avoid misdiagnosis in cases that could evolve to disseminated strongyloidiasis.

Prevalence of asymptomatic strongyloidiasis co-infection in COVID-19 patients residing in endemic areas

BACKGROUND

Fatal forms of strongyloidiasis, hyperinfection syndrome (HS) and disseminated strongyloidiasis (DS), are caused by exaggerated autoinfection of the intestinal nematode, Strongyloides stercoralis (S. stercoralis). Corticosteroids, frequently administered to patients with severe COVID-19, can transform chronic asymptomatic strongyloidiasis into the above-mentioned fatal diseases. This study aimed to investigate the prevalence of strongyloidiasis in COVID-19 patients receiving corticosteroids in a hypoendemic region.

METHODS

The present cross-sectional study enrolled 308 COVID-19 patients admitted to two hospitals in Ahvaz and Abadan in the southwest of Iran between 2020 and 2022. A real-time reverse transcription polymerase chain reaction (RT-PCR) test and chest computed tomography (CT) scan were employed to detect and monitor the disease's severity in the patients, respectively. All patients were evaluated for IgG/IgM against S. stercoralis using Enzyme-linked immunosorbent assay (ELISA) test. Subsequently, individuals with a positive ELISA test were confirmed using parasitological methods, including direct smear and agar plate culture (APC).

RESULTS

The patients were between 15 and 94 years old, with a mean age of 57.99 ± 17.4 years. Of the 308 patients, 12 (3.9%) had a positive ELISA test, while 296 (96.1%) had negative results. Three of the 12 patients with a positive ELISA result died, and three failed to provide a stool sample. To this end, only six cases were examined parasitologically, in which S. stercoralis larvae were observed in five patients. Significant differences were found between S. stercoralis infection with sex (p = 0.037) and age (p = 0.027). Binary regression analysis revealed that strongyloidiasis was positively associated with sex (odds ratio [OR]: 5.137; 95% confidence interval [CI]: 1.107-23.847), age (OR: 5.647; 95% CI 1.216-26.218), and location (OR: 3.254; 95% CI: 0.864-12.257).

CONCLUSIONS

Our findings suggest that screening for latent strongyloidiasis in COVID-19 patients in endemic areas using high-sensitivity diagnostic methods, particularly ELISA, before receiving suppressive drugs should be given more consideration.

Challenges in the diagnosis and management of IBD: a sub-Saharan African perspective

With the exception of South Africa, inflammatory bowel disease (IBD) has long been considered uncommon in sub-Saharan Africa (SSA) with a dearth of peer-reviewed publications from the subcontinent. This most likely reflects underreporting as some cases may be missed due to the high burden of infectious diseases which may closely mimic IBD. In addition, many countries in SSA have limited endoscopic capacity, inadequate access to diagnostic imaging and a notable scarcity of histopathologists, radiologists and gastroenterologists. Beyond these obstacles, which significantly impact patient care, there are many other challenges in SSA, particularly the unavailability of key IBD therapies. In this review, we discuss barriers in diagnosing and managing IBD in SSA, as well as some of the initiatives currently in place to address these short comings.

Gastroduodenal strongyloidiasis infection causing protein-losing enteropathy: A case report and review of the literature

Strongyloides stercoralis is an intestinal nematode in which adult worms in the host small intestine can cause strongyloidiasis. Symptoms in immunocompromised patients might range from diarrhea and bleeding to sepsis and even death. A 56-year-old patient presented with a 2-month history of weight loss, vomiting, and diarrhea. The patient had type 2 diabetes mellitus (T2DM) and was on long-term prednisone for chronic kidney disease. The results of the gastric emptying test and head magnetic resonance (MRI) were normal. A blood test revealed increased IgE levels, eosinophilia, and hypoalbuminemia. Parasitic larvae were not discovered during stool analysis. Gastroscopy revealed chronic nonatrophic gastritis with erosions and dilation of lymphatic vessels of the duodenum. Small-bowel capsule endoscopy suggested dilation of lymphatic vessels of the small intestine. Colonoscopy revealed no abnormalities. Finally, a histopathology examination identified S. stercoralis pervasion in the gastric antrum and duodenum. The patient was treated with albendazole and discharged successfully. In conclusion, we discovered S. stercoralis as a cause of protein-losing enteropathy in a patient with a long-term oral corticosteroid therapy and T2DM. The diagnosis was made through histopathology, once parasitological examination was negative. Therefore, health professionals should stay alert to S. stercoralis infection in immunocompromised patients with vague gastrointestinal symptoms. More sensitive methods should be applied in the diagnosis.

Spectrum of Helminth Infections in Migrants from Sub-Saharan Africa to Europe: A Literature Review

Sub-Saharan Africa (SSA) is endemic to numerous neglected tropical diseases, including many helminth diseases. With the migration of people from this part of the world to Europe, as has been happening on a large scale since 2015, these diseases are becoming more relevant to European physicians. This work aims to summarize the recent literature on this topic and to raise awareness of helminth diseases afflicting SSA migrants. The databases PubMed, Embase, and MEDLINE were screened for literature published in English and German between January 1, 2015 and December 31, 2020. In total, 74 articles were included in this review. The spectrum of helminth infections in migrants from SSA found in the literature review is broad; current research, however, is particularly focused on infections with Schistosoma spp. and Strongyloides stercoralis. Both diseases are often characterized by a long course, with few or no symptoms, with the risk of long-term organ damage. Successful and reliable screening for schistosomiasis and strongyloidiasis is strongly recommended. However, the current diagnostic methods lack sensitivity and specificity, rendering the diagnosis challenging and reliable assessment of disease prevalence difficult. Novel diagnostic methods and a greater awareness of these diseases are urgently needed.

Efficacy of Oral Ivermectin as Empirical Prophylaxis for Strongyloidiasis in Patients Treated with High-Dose Corticosteroids: A Retrospective Cohort Study

People living in areas endemic for strongyloidiasis are at risk of latent Strongyloides stercoralis infection. Corticosteroid therapy is a well-established risk factor for life-threatening hyperinfection syndrome and disseminated disease owing to suppression of the immune system. There are limited data available on the efficacy and cost of providing oral ivermectin prophylaxis to all patients receiving high-dose corticosteroids for strongyloidiasis in endemic areas. We thus conducted this retrospective cohort study at Khon Kaen University's Srinagarind Hospital from 2015 to 2019. Inclusion criteria were as follows: age ≥ 18 years, having received ≥ 0.5 mg/kg/day of prednisolone or equivalent for at least 14 days, and hospitalization during the study period. A total of 250 patients were included in the study: 125 in the empirical prophylaxis group (prescribed ivermectin even if fecal examination results were negative or nonexistent) and the remaining patients in the definite therapy group (prescribed ivermectin only if S. stercoralis was detected by fecal examination). The prevalence of strongyloidiasis at enrollment estimated by fecal examination was 5.5%. Ivermectin was given to 125 patients (100%) in the prophylaxis group compared with 12 (9.6%) in the definite therapy group (P value < 0.001). During the 12-month follow-up period, S. stercoralis was detected in three patients, two in the prophylaxis group and one in the definite therapy group (P value = 1.000). No cases of hyperinfection syndrome or disseminated disease were found. The empirical prophylaxis strategy had a significantly higher cost than the definite therapy strategy (563 versus 254, P value < 0.001) and did not demonstrate superior efficacy in strongyloidiasis prevention.

A Rare Case of Strongyloides stercoralis Hyperinfection in a Diabetic Patient from Romania—Case Report and Review of the Literature

Severe cases of strongyloidiasis are most often associated with multiple causes of immune suppression, such as corticoid treatment and HTLV (human T-lymphotropic virus) coinfection. Diabetes is not traditionally considered a risk factor for the development of severe strongyloidiasis. We report a rare case of autochthonous severe strongyloidiasis in Romania, a European country with a temperate climate. A 71-year-old patient with no prior travel history was admitted with multiple gastrointestinal complaints and recent weight loss. CT (computed tomography) scans indicated duodenal wall thickening, and duodenal endoscopy evidenced mucosal inflammation, ulcerations and partial duodenal obstruction at D4. Microscopic examination of stool samples and biopsy specimens from the gastric and duodenal mucosa revealed an increased larval burden characteristic of Strongyloides stercoralis hyperinfection. Sequential treatment with albendazole and ivermectin achieved parasitological cure and complete recovery. The novelty of our case stems from the scarcity of severe strongyloidiasis cases reported in Europe and especially in Romania, the absence of other risk factors in our patient aside from diabetes, the involvement of the gastric mucosa and the rare presentation as partial duodenal obstruction. This case highlights the importance of considering strongyloidiasis as a differential diagnosis, even in temperate climates where cases are sporadic, in cases in which immune suppression is not evident and in the absence of eosinophilia. The case is presented in the context of the first literature review examining the relationship between severe strongyloidiasis and diabetes, emphasizing diabetes as a possible risk factor for severe strongyloidiasis.

Seroprevalence of Strongyloides stercolaris in Patients about to Receive Immunosuppressive Treatment in Gran Canaria (Spain)

Strongyloides stercoralis infection is generally asymptomatic or mildly symptomatic, but in the immunosuppressed host, it is associated with more severe and complicated forms with a worse prognosis. S. stercoralis seroprevalence was studied in 256 patients before receiving immunosuppressive treatment (before kidney transplantation or starting biological treatments). As a control group, serum bank data of 642 individuals representative of the population of the Canary Islands were retrospectively analyzed. To avoid false positives due to cross-reactivity with other similar helminth antigens present in the study area, IgG antibodies to Toxocara spp. and Echinococcus spp. were evaluated in cases positive for Strongyloides. The data show this is a prevalent infection: 1.1% of the Canarian population, 2.38% of Canarian individuals awaiting organ transplants and 4.8% of individuals about to start biological agents. On the other hand, strongyloidiasis can remain asymptomatic (as observed in our study population). There are no indirect data, such as country of origin or eosinophilia, to help raise suspicion of the disease. In summary, our study suggests that screening for S. stercoralis infection should be performed in patients who receive immunosuppressive treatment for solid organ transplantation or biological agents, in line with previous publications.

Seroepidemiology of Strongyloides spp. Infection in Balimo, Western Province, Papua New Guinea

Strongyloidiasis in Papua New Guinea (PNG) is poorly understood. There have been limited surveys describing the levels of endemicity in some regions of PNG, but in the Western Province, its occurrence and level of burden are unknown. This study aimed to determine the seroepidemiology of Strongyloides spp. seropositivity within a community located in the Balimo region of the Western Province. Plasma samples were collected from 120 adult participants and were subjected to anti-IgG Strongyloides spp. serological testing. Logistical regression analyses were performed to identify relationships between strongyloidiasis and attributes of sociodemography. In this cross-sectional cohort study, 22.5% (27/120; 95% CI: 15.9-30.8%) of participants were seropositive for strongyloidiasis. Participants with higher body mass indices were less likely to be seropositive for Strongyloides spp. infection (odds ratio [OR] = 0.85, P value = 0.008), and in the multivariable analysis, increasing units of age (adjusted OR [aOR] = 0.93, P value = 0.048) and participants ≤ 40 years old were associated with a decreased likelihood of Strongyloides spp. seropositivity (aOR = 0.07, P value = 0.034). The results from this study indicate that the occurrence of strongyloidiasis is high in the Western Province, PNG, and age is a determining factor of seroreactivity. This study provides evidence of endemic strongyloidiasis in this community and raises questions as to the impact of this neglected disease and other intestinal parasites on disease burden and comorbidities.

Larva Currens: Report of Seven Cases and Literature Review

Strongyloidiasis is a frequent and often unrecognized parasitic disease because of the frequently asymptomatic nature and lack of sensitivity of diagnostic tests. Under conditions of immunosuppression (particularly systemic corticosteroid treatment), potentially fatal dissemination may occur. Thus, prevention and early diagnosis are important. Larva currens is a rare and pathognomonic cutaneous sign of strongyloidiasis, but is poorly described because of its unpredictable and fleeting occurrence. We report seven imported cases of larva currens seen in Paris between 1990 and 2020. We illustrate the clinical and biological features of this specific but uncommon sign of strongyloidiasis with clinical pictures. There were three males and four females, aged between 29 and 58 years. There were five migrants from endemic countries, one tourist and one expatriate. Digestive disorders were the main extracutaneous signs. All patients had eosinophilia above 0.5 G/L. All cases were confirmed by stool tests. All were cured with ivermectin. The rapidity and the short duration of the creeping eruption distinguish it from other parasitoses. Ivermectin is a treatment of choice. The key point is to think about preventing disseminated strongyloidiasis before giving corticosteroids not only among migrants but also among expatriates and tourists in endemic countries.

Seroprevalence and microscopy detection rates of strongyloidiasis in Croatian patients with eosinophilia

Infection with the parasitic nematode Strongyloides stercoralis is characteristic for tropical and subtropical regions of the world, but autochthonous cases have been reported in European countries as well. Here we present the first nation-wide survey of S. stercoralis seroprevalence in Croatian individuals presenting with eosinophilia, and evaluate the fraction of positive microscopy rates in stool specimens of seropositive individuals. In our sample of 1407 patients tested between 2018 and 2021, the overall prevalence of strongyloidiasis was 9.31%, with significantly higher rates in those older than 60 years of age (P = 0.005). Of those, one-quarter (25.95%) were also positive following microscopy examination of faeces after using the merthiolate-iodine-formaldehyde concentration method. Our findings reinforce the notion of endemic strongyloidiasis transmission in Croatia, particularly in older individuals, and highlight the need to consider the presence of S. stercoralis in patients with eosinophilia.

Evaluation of larval surface antigens from infective larvae of Strongyloides venezuelensis for the serodiagnosis of human strongyloidiasis

Serodiagnosis of strongyloidiasis is usually performed by ELISA for the detection of IgG antibodies due to its high sensitivity and practicality, but its main limitation is a constant source of S. stercoralis antigens. The use of S. venezuelensis as a heterologous source of antigens has facilitated several published studies on the serodiagnosis and epidemiology of human strongyloidiasis. The main objective of this study was to evaluate the diagnostic accuracy of surface cuticle antigens of infective larvae of S. venezuelensis extracted with CTAB detergent (L3-CTAB) in comparison with soluble somatic extracts (L3-SSE) using a panel of sera from immunocompetent and immunocompromised individuals, at three different cut-offs. ROC curve analysis showed that L3-CTAB had an AUC of 0.9926. At the first cut-off value (OD 450 nm = 0.214), sensitivity and specificity were 100% and 90.11%, respectively, with a diagnostic accuracy of 0.93. At a second cut-off value (OD 450 nm = 0.286), sensitivity and specificity were 70% and 100%, respectively, with a diagnostic accuracy of 0.91. However, at an alternative third cut-off value (OD 450 nm = 0.589), sensitivity and specificity were 95% and 97.8%, respectively, with a diagnostic accuracy of 0.97. Using L3-CTAB as an antigenic source, the seropositivity rate in immunocompromised patients was 28.13% (9/32) whereas a seropositivity rate of 34.38% (11/32) was found when L3-SSE was used in ELISA. Therefore, the L3-CTAB is simple and practical to obtain and was found to be highly sensitive and specific.

Strongyloidiasis infection in a borderline lepromatous leprosy patient with adrenocorticoid insufficiency undergoing corticosteroid treatment: a case report

BACKGROUND

Strongyloidiasis is a soil-transmitted helminthiasis mainly caused by Strongyloides stercoralis. It is endemic to the tropics and subtropics. Sri Lanka has a 0-1.6% prevalence rate. S. stercoralis infection was identified in a 33-year-old Sri Lankan male patient treated with corticosteroids for borderline lepromatous leprosy with adrenocortical dysfunction.

CASE PRESENTATION

In March 2020, a 33-year-old Sri Lankan (Sinhalese) male patient presented with watery diarrhea, lower abdominal pain, and post-prandial abdominal fullness. Previously, he was diagnosed with borderline lepromatous leprosy and was treated with rifampicin, clofazimine, and prednisolone 60 mg daily since July 2019. After developing gastrointestinal symptoms, he had defaulted leprosy treatment including the prednisolone for 3 months. Duodenal biopsy revealed numerous intraepithelial nematodes within the lumina of glands in the duodenum whose appearance favored Strongyloides. Fecal wet smear revealed numerous Strongyloidis stercoralis L1 rhabditiform larvae. Larval tracks were seen in the agar plate culture. L3 filariform larvae of Strongyloidis stercoralis were seen in the Harada-Mori culture. In addition, the short synacthen test revealed adrenocortical insufficiency, and oral hydrocortisone and fludrocortisone were started with albendazole treatment against strongyloidiasis. Fecal wet smear and culture repeated after treatment with albendazole were negative for Strongyloidis stercoralis. The patient was discharged in July 2020 on oral hydrocortisone. One month later his condition was reviewed and the repeated fecal wet smear and agar plate culture was normal. He is being followed up every 3 months.

CONCLUSION

This is the first case of strongyloidiasis diagnosed in a patient with borderline lepromatous leprosy from Sri Lanka. The patient manifested symptoms of strongyloidiasis while on high-dose steroid therapy for his lepromatous reaction. Subsequently, the patient not only discontinued his steroid therapy, but also developed adrenocortical insufficiency as a complication of leprosy. Therefore, although diagnosis of strongyloidiasis was delayed, his subsequent low steroid levels probably protected him from disseminated disease. This is an interesting case where symptomatic strongyloidiasis was diagnosed in a patient who was initially treated with high-dose steroids but subsequently developed adrenocortical insufficiency. We emphasize the need to screen all patients prior to the commencement of immunosuppressive therapy.

A simple parasitological technique to increase detection of Strongyloides stercoralis in Bolivian primary health care system

BACKGROUND

Strongyloides stercoralis is widespread; however, there is limited information on its prevalence owing to laboratory underestimation and low clinical manifestations. The Baermann method and agar culture stand out among the parasitological techniques. Strongyloides stercoralis is present in Bolivia, but its prevalence in children remains unknown. The objective of this study was to estimate the applicability of simple parasitological techniques to increase the detection of this parasite in children living in the tropics.

METHODS

This cross-sectional study was conducted in a tropical village in Cochabamba, Bolivia. Participants were 304 children aged 5 - 12 years who provided stool samples for different parasitological analyses (direct examination, Ritchie, Baermann, and Dancescu techniques), and their parents provided informed consent.

RESULTS

Up to 64.8% of pathogenic parasites were detected using the modified Ritchie method. The Baermann technique identified 17.8% of Strongyloides stercoralis cases, and a high sensitivity with respect to the Baermann technique was only for the Dancescu technique (75.9%) that is also specific for Strongyloides stercoralis, followed by 66.7% for the modified Ritchie technique, which is used in second-line care.

DISCUSSION

The Baermann technique is the best parasitological option for improving Strongyloides stercoralis diagnosis in the first-line care of the Primary Health Care System. A particular cycle of reinfection, combined with the environment and some other risk factors are related with persistence. Control is difficult without a proper diagnosis, and the Baermann technique is an approach to the solution. We conclude that with a high suspicion of the presence of Strongyloides stercoralis, the use of the Baermann technique is strongly recommended as support for direct examination in primary health care systems especially in tropical areas.

Improving the detection of infectious diseases in at-risk migrants with an innovative integrated multi-infection screening digital decision support tool (IS-MiHealth) in primary care: a pilot cluster-randomized-controlled trial

BACKGROUND

There are major shortfalls in the identification and screening of at-risk migrant groups. This study aims to evaluate the effectiveness of a new digital tool (IS-MiHealth) integrated into the electronic patient record system of primary care centres in detecting prevalent migrant infections. IS-MiHealth provides targeted recommendations to health professionals for screening multiple infections, including human immunodeficiency virus (HIV), hepatitis B and C, active tuberculosis (TB), Chagas disease, strongyloidiasis and schistosomiasis, based on patient characteristics (including variables of country of origin, age and sex).

METHODS

A pragmatic pilot cluster-randomized-controlled trial was deployed from March to December 2018. Eight primary care centres in Catalonia, Spain, were randomly allocated 1:1 to use of the digital tool for screening, or to routine care. The primary outcome was the monthly diagnostic yield of all aggregated infections. Intervention and control sites were compared before and after implementation with respect to their monthly diagnostic yield using regression models. This study is registered on international standard randomised controlled trial number (ISRCTN) (ISRCTN14795012).

RESULTS

A total of 15 780 migrants registered across the eight centres had at least one visit during the intervention period (March-December 2018), of which 14 598 (92.51%) fulfilled the criteria to be screened for at least one infection. There were 210 (2.57%) individuals from the intervention group with new diagnoses compared with 113 (1.49%) from the control group [odds ratio: 2.08, 95% confidence interval (CI) 1.63-2.64, P < 0.001]. The intervention centres raised their overall monthly diagnosis rate to 5.80 (95% CI 1.23-10.38, P = 0.013) extra diagnoses compared with the control centres. This monthly increase in diagnosis in intervention centres was also observed if we consider all cases together of HIV, hepatitis B and C, and active TB cases [2.72 (95% CI 0.43-5.00); P = 0.02] and was observed as well for the parasitic infections' group (Chagas disease, strongyloidiasis and schistosomiasis) 2.58 (95% CI 1.60-3.57; P < 0.001).

CONCLUSIONS

The IS-MiHealth increased screening rate and diagnostic yield for key infections in migrants in a population-based primary care setting. Further testing and development of this new tool is warranted in larger trials and in other countries.

Health and Vaccination Status of Unaccompanied Minors After Arrival in a European Border Country: A Cross-sectional Study (2017-2020)

BACKGROUND

Unaccompanied and separated children (UASC) are a high-risk group for infectious diseases and information on their vaccination status is scarce. Different approaches are used to screen newly arrived minors in Europe. The aim of this study was to describe the health status and serological protection against different vaccine-preventable diseases among UASC to inform public health decision-making.

METHODS

Retrospective study of all UASC seen at an international health reference center in Barcelona (Spain) between January 2017 and February 2020. Screening results were analyzed using binary logistic regression with adjustment for symptoms, geographic origin, and time since arrival.

RESULTS

We studied 289 UASC (88.9% males; median age, 17 years). At least one infection was diagnosed in 136 minors (47.1%). There was a high prevalence of intestinal parasites (22.8%), latent tuberculosis infection (22.5%), and hepatitis B (5.2%), even in asymptomatic individuals, and especially among UASC from sub-Saharan Africa (odds ratio, 2.5; 95% confidence interval, 1.5-4.0, P &lt; 0.001). We did not observe a significant association between clinical symptoms and the presence of infection or differences in the prevalence of different infections according to number of months since arrival. Protection against hepatitis B virus (36%), measles (80%), and varicella (83%) was suboptimal.

CONCLUSIONS

Our results highlight the importance of screening and vaccination programs for UASC arriving in Europe, especially border countries. Protocols should be adjusted according to geographic origin. Absence of symptoms does not necessarily rule out infection, highlighting the importance of screening in asymptomatic minors. These programs are a public health priority and should not be neglected during the current COVID-19 pandemic.

Building an integrated serosurveillance platform to inform public health interventions: Insights from an experts' meeting on serum biomarkers

The use of biomarkers to measure immune responses in serum is crucial for understanding population-level exposure and susceptibility to human pathogens. Advances in sample collection, multiplex testing, and computational modeling are transforming serosurveillance into a powerful tool for public health program design and response to infectious threats. In July 2018, 70 scientists from 16 countries met to perform a landscape analysis of approaches that support an integrated serosurveillance platform, including the consideration of issues for successful implementation. Here, we summarize the group's insights and proposed roadmap for implementation, including objectives, technical requirements, ethical issues, logistical considerations, and monitoring and evaluation.

A systematic review and meta-analysis of human and zoonotic dog soil-transmitted helminth infections in Australian Indigenous communities

Soil-transmitted helminths (STH) infect 1.5 billion people and countless animals worldwide. In Australian Indigenous communities, STH infections have largely remained endemic despite control efforts, suggesting reservoirs of infection may exist. Dogs fulfil various important cultural, social and occupational roles in Australian Indigenous communities and are populous in these settings. Dogs may also harbour zoonotic STHs capable of producing morbidity and mortality in dogs and humans. This review provides an overview of human and zoonotic STH infections, identifies the Australian Indigenous locations affected and the parasite species and hosts involved. The meta-analysis provides estimates of individual study and pooled true prevalence of STH infections in Australian Indigenous communities and identifies knowledge gaps for further research on zoonotic or anthroponotic potential. A systematic literature search identified 45 eligible studies documenting the presence of Strongyloides stercoralis, Trichuris trichiura, Ancylostoma caninum, Ancylostoma duodenale, Ancylostoma ceylanicum, undifferentiated hookworm, and Ascaris lumbricoides. Of these studies, 26 were also eligible for inclusion in meta-analysis to establish true prevalence in the light of imperfect diagnostic test sensitivity and specificity by Rogan-Gladen and Bayesian methods. These studies revealed pooled true prevalence estimates of 18.9% (95% CI 15.8–22.1) for human and canine S. stercoralis infections and 77.3% (95% CI 63.7–91.0) for canine A. caninum infections indicating continued endemicity, but considerably more heterogenous pooled estimates for canine A. ceylanicum infections, and A. duodenale, undifferentiated hookworm and T. trichiura in humans. This review suggests that the prevalence of STHs in Australian Indigenous communities has likely been underestimated, principally based on imperfect diagnostic tests. Potential misclassification of hookworm species in humans and dogs due to outdated methodology, also obscures this picture. High-quality contemporary studies are required to establish current true prevalence of parasite species in all relevant hosts to guide future policy development and control decisions under a culturally sound One Health framework.

Soil-transmitted helminths include hookworms, threadworms, whipworms and roundworms. These worms may infect different hosts including humans and dogs, and some species are zoonotic, meaning that they are able to transmit between animals and humans. In many Australian Indigenous communities, people remain infected with these worms at high rates compared to other parts of the country despite various control strategies. Resource and health literacy inequalities are primary drivers for these differences. However, the potential for dogs to act as reservoirs for zoonotic worm infections in humans must also be considered. For this reason, it’s important to create a clear picture of the level of infection by location and host. Given that tests used to establish prevalence can produce false positive or negative results, we performed a meta-analysis allowing comparison of true prevalence estimates by location and host, regardless of the test used. This review suggests that threadworm and dog hookworm remain endemic in Australian Indigenous communities, though a gap exists to accurately inform the prevalence of the other worms. It also highlights the need for One Health strategies in research, policy and control where humans, all animal hosts and the environment are considered in a culturally relevant way.

The diagnosis of human and companion animal Strongyloides stercoralis infection: Challenges and solutions. A scoping review

Strongyloidiasis is the infection caused by soil-transmitted nematodes of Strongyloides species, infecting humans and some animals. Strongyloides stercoralis is the species with most clinical and epidemiological relevance in humans and dogs, due to its high prevalence and its capacity of inducing a life-threatening hyperinfection. Diagnosis of strongyloidiasis is challenging, due to the absence of a single reference standard test with high sensitivity and specificity, which also hampers the estimation of the accuracy of other diagnostic tests. In this chapter, we review the deployment and performance of the parasitological, immunological, molecular tests for the diagnosis of strongyloidiasis in humans and in dogs. Further, we comment the available evidence from genotyping studies that have addressed the zoonotic potential of S. stercoralis. Finally, we discuss the use of different diagnostic methods in relation to the purpose (i.e., screening, individual diagnosis, inclusion in a clinical trial) and the setting (endemic/non-endemic areas) and report the accuracy figures reported by systematic reviews on either parasitological, serological or molecular techniques published in literature.

A Rare Presentation of Strongyloides stercoralis Infection from an Immunocompetent Individual in a Tertiary Care Center in South India

Strongyloidiasis is a neglected parasitic disease caused by the intestinal parasite, Strongyloides stercoralis. Most patients with strongyloidiasis are asymptomatic, but few present with varied clinical manifestations such as cutaneous, gastrointestinal, pulmonary, and disseminated disease. It creates a diagnostic dilemma and undue delay in the diagnosis of patients. We report the case of a 79-year-old male who presented with fever and abdominal pain due to strongyloidiasis with no history of immunosuppression. The infection resolved entirely on treatment with ivermectin.

Proteomic analysis of the excretory-secretory products from Strongyloides venezuelensis infective larvae: new insights for the immunodiagnosis of human strongyloidiasis

Serodiagnosis of human strongyloidiasis is a practical alternative to parasitological methods due to its high sensitivity. However, cross-reactivity with other helminth infections limits its utility, and this problem is due to the use of homologous or heterologous somatic extracts of the parasite as an antigen source. Excretory-secretory (E/S) products from Strongyloides infective larvae can be used to improve the serodiagnosis. The combined use of western blot and proteomics became an interesting strategy to identify immunological markers for the serodiagnosis of strongyloidiasis. The present study describes the proteomic analysis of the antigenic components from E/S products of S. venezuelensis infective larvae that were recognized by IgG antibodies from patients with strongyloidiasis. Our results showed that IgG antibodies from patients with strongyloidiasis recognized between 15 and 16 antigenic bands in the E/S products from S. venezuelensis that were incubated in PBS or in RPMI culture medium, respectively. Overall, antigenic bands of low and high molecular weight were more specific than those of intermediate molecular weight, which were cross-reactive. A 36-kDa antigenic band was 93% sensitive and 100% specific (a probably arginine kinase of 37 kDa), while other antigenic bands were highly sensitive but low specific. Proteomic analysis revealed differences between the protein profiles from E/S-RPMI and E/S-PBS since only one-third of all proteins identified were common in both types of E/S products. Bioinformatic analysis showed that more than 50% of the proteins from E/S products are secreted within extracellular vesicles and only a small percentage of them are actually released by the classical secretory pathway. Several components from the E/S products were identified as plasminogen-binding proteins, probably used as an immune evasion mechanism. The data provided here provide valuable information to increase understanding of E/S products from S. venezuelensis infective larvae. This may help us to find new targets for the immunodiagnosis of human strongyloidiasis.

Current pharmacotherapeutic strategies for Strongyloidiasis and the complications in its treatment

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Clinical Performance of Real-Time Polymerase Chain Reaction for Strongyloides stercoralis Compared with Serology in a Nonendemic Setting

Strongyloides stercoralis is a nematode endemic to subtropical and tropical regions that may cause asymptomatic carriage, peripheral eosinophilia, cutaneous, gastrointestinal, and pulmonary disease, or hyperinfection syndrome. Conventional diagnostic methods for strongyloidiasis include feces microscopy and culture, with low sensitivity in chronic infection due to the low helminth burden, and serology, which may be prone to false-negative results with immunocompromise and false-positive results with other infections and immunological disorders. We evaluated a laboratory-developed real-time polymerase chain reaction (RT-PCR), detecting the 18S SSU ribosomal RNA gene, compared with conventional diagnostic methods, using serology via ELISA as the gold-standard. The population studied included tertiary hospital inpatients and outpatients residing in a nonendemic area. Seven hundred fifty unfixed stool specimens submitted sequentially between 2014 and 2018 were tested for S. stercoralis via microscopy and RT-PCR. Agar plate culture (APC), Harada-Mori culture (HMC), and ELISA were performed in conjunction with 141, 135, and 177 of the specimens, respectively. RT-PCR yielded 13 positive and 730 negative results, with inhibition in seven specimens. ELISA yielded 53 positive, 18 equivocal, and 106 negative results. Results for direct diagnostic methods obtained after treatment with ivermectin were excluded from the performance analysis. Compared with ELISA, RT-PCR, microscopy, APC, and HMC exhibited sensitivities of 38%, 6%, 3%, and 0%, respectively, and specificities of 100%. Given the low sensitivities commensurate with testing a population with remote infection and thus low parasite burden, we recommend a combination of serological and molecular diagnostic testing to achieve the best balance of sensitivity and specificity.

Screening for strongyloidiasis in Spain in the context of the SARS-CoV-2 pandemic: Results of a survey on diagnosis and treatment

Introduction

The generalization of treatment with dexamethasone or other immunosuppressants in patients with SARS-CoV-2 infection may increase the risk of occurrence of severe forms of strongyloidiasis. A nationwide survey was conducted to better understand the diagnostic and therapeutic situation of strongyloidiasis in SARS-CoV-2 co-infected patients in Spain.

Materials and methods

A survey was designed and sent to all SEIMC members during February and March 2021. Responses were exported for computer processing to Microsoft Excel 2017 and statistically processed with the free software PSPP.

Results

189 responses were received, of which 121 (64%) were selected for further processing. Eighty-four centers (69.5%) had no specific strongyloidiasis screening protocol. Forty-two centers (34.7%) had serological techniques available in their laboratories and the rest were sent to a reference laboratory. Only 22 centers (18%) screened for strongyloidiasis in SARS-CoV-2 infected patients. A total of 227 cases of strongyloidiasis were diagnosed in patients with SARS-CoV-2 infection. In four cases patients developed a massive hyperinfestation syndrome leading to the death of one patient.

Conclusion

COVID-19 has highlighted the need to unify screening and treatment protocols for imported pathologies such as strongyloidiosis. Efforts to disseminate knowledge are needed to ensure that this potentially fatal disease is adequately treated in patients with the highest risk of complications, such as those with COVID-19.

Strongyloides stercoralis prevalence in solid-organ and haematopoietic stem cell transplant candidates and recipients: a systematic review and meta-analysis protocol

INTRODUCTION

Strongyloides stercoralis is an intestinal helminth ubiquitous in tropical and subtropical regions worldwide. It persists in the human host for a lifetime as a result of autoinfection and if undetected and untreated, can lead to increased morbidity and high mortality in immunocompromised individuals such as the transplant population. Transplant patients, including solid-organ and haematopoietic stem cell transplants (SOT and HSCT, respectively), are at a high risk of hyperinfection and disseminated strongyloidiasis. Unfortunately screening is often not systematically performed. Prevalence estimates of Strongyloides in this high-risk population is not well studied. Through this systematic review, we aim to summarise the descriptive evidence on Strongyloides prevalence in SOT and HSCT patients, including diagnostic and screening practices alongside the cases of hyperinfection, disseminated strongyloidiasis and the mortality rate in this population.

METHODS AND ANALYSES

Through the use of various online library databases, we will conduct a systematic review including relevant literature on the prevalence of Strongyloides in SOT and HSCT patients as well as studies assessing hyperinfection and disseminated strongyloidiasis in this patient population. The Population, Intervention, Comparison, Outcome and Study Design strategy and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines will be used to determine a final subset of studies for analysis. Quality assessment for case series and case reports will be determined by a modified quality assessment tool developed by the National Heart, Lung, and Blood Institute (NIH), and the CARE guidelines, respectively. We will provide a narrative synthesis of the findings pertaining to the primary and secondary outcomes of interest (prevalence of Strongyloides and mortality rate in transplant population, respectively) alongside the associated 95% CI. Estimates from individual studies will be pooled using a random effects model.

ETHICS AND DISSEMINATION

This systematic review does not require formal ethical approval since no primary data will be collected. Findings will be disseminated through a peer-reviewed publication and relevant conferences.

PROSPERO REGISTRATION NUMBER

CRD42021269305.

Seroprevalence of Strongyloides stercoralis infection in a South Indian adult population

Background

The prevalence of Strongyloides stercoralis infection is estimated to be 30–100 million worldwide, although this an underestimate. Most cases remain undiagnosed due to the asymptomatic nature of the infection. We wanted to estimate the seroprevalence of S. stercoralis infection in a South Indian adult population.

Methods

To this end, we performed community-based screening of 2351 individuals (aged 18–65) in Kanchipuram District of Tamil Nadu between 2013 and 2020. Serological testing for S. stercoralis was performed using the NIE ELISA.

Results

Our data shows a seroprevalence of 33% (768/2351) for S. stercoralis infection which had a higher prevalence among males 36% (386/1069) than among females 29.8% (382/1282). Adults aged ≥55 (aOR = 1.65, 95% CI: 1.25–2.18) showed higher adjusted odds of association compared with other age groups. Eosinophil levels (39%) (aOR = 1.43, 95% CI: 1.19–1.74) and hemoglobin levels (24%) (aOR = 1.25, 95% CI: 1.11–1.53) were significantly associated with S. stercoralis infection. In contrast, low BMI (aOR = 1.15, 95% CI: 0.82–1.61) or the presence of diabetes mellitus (OR = 1.18, 95% CI: 0.83–1.69) was not associated with S. stercoralis seropositivity.

Conclusions

Our study provides evidence for a very high baseline prevalence of S. stercoralis infection in South Indian communities and this information could provide realistic and concrete planning of control measures.

Evaluation of antibody serology to determine current helminth and Plasmodium falciparum infections in a co-endemic area in Southern Mozambique

Background

Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure.

Methodology

We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference.

Principal findings

IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed.

Conclusions

We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens.

Parasitic worms and Plasmodium falciparum, the causal agent of malaria, are among the most relevant parasitic diseases of our time and efforts are under way for their control and, ultimately, elimination. An accurate diagnosis is relevant for case management, but also allows calculating the prevalence and evaluating the effectiveness of treatment and control measures. Unfortunately, current diagnostic methods for parasitic worms are not optimal and many infections remain undetected. As for P. falciparum, current diagnostic techniques are satisfactory but do not allow for ascertaining exposure, which is relevant for evaluating control measures. Here we investigated the utility of measuring antibodies to these parasites as a diagnostic method. Our results indicate that it is possible to detect current infection with parasitic worms and P. falciparum using antibody detection with a moderate to high accuracy. We also show that antibodies against the antigens in this study have potential as markers of exposure. Importantly, we used a platform that allows for the simultaneous detection of immunoglobulins to different parasites, which would be extremely useful as a tool to integrate control and elimination programs for several pathogens.

Ineffectiveness of TF-Test® and Coproplus® Methods in Strongyloides stercoralis Infection Diagnosis

PURPOSE

S. stercoralis diagnosis is currently performed by parasitological methods, mainly by Baermann-Moraes (BM), although Agar Plate Culture (APC) presents a higher sensitivity. New techniques, such as TF-Test® and Coproplus® have been suggested as more practical alternatives. The aim of this study was to evaluate the sensitivity of TF-Test® and Coproplus®, compared with APC, BM and Spontaneous Sedimentation (SS) methods.

METHODS

One-hundred and forty male alcoholic patients, who provided three stools samples collected on alternate days, were included in this study. The most frequently found parasite was S. stercoralis, 20% (28/140), and the most sensitive method was APC, 96.4% (27/28), followed by BM, 89.3% (25/28) and SS, 57.1% (16/28). TF-Test® and Coproplus® presented a sensitivity of 46.4 (13/28) and 39.3% (11/28), respectively. In samples with a parasitic load of 1-10 larvae/g of feces, which occurred in 39.3% (11/28) of the infected patients, both the TF-Test® and Coproplus® methods demonstrated sensitivities of 18.2% (2/11), while APC and BM methods reached a sensitivity of 100% (11/11) (p < 0.05). For other intestinal helminth infections, TF-Test® and Coproplus® sensitivities were 22.2 (4/18) and 11.1% (2/18), respectively, this being lower than the SS, 66.7% (12/18) (p < 0.05). On the other hand, for protozoa infection diagnosis, TF-Test® and Coproplus® presented the highest sensitivities, 62.2 (46/74) and 43.2% (32/74), respectively.

CONCLUSION

TF-Test® and Coproplus® methods presented the lowest sensitivities for S. stercoralis and other helminth infection diagnosis; therefore, they can be indicated for use in parasitological diagnosis, only when associated with other more effective methods of helminth identification.

Prevalence of major nematodes and human factors that affect infection in the zebra dove in a closed cage system

Background and Aim:

Roundworms cause infections in the avian population that lead to illness and poor production. The singing zebra dove is an economically important animal in the Indo-Malay region. The prevalence of these parasitic groups in zebra doves is unknown. This study estimated the prevalence and associated human risk factors of gastrointestinal nematode infections in zebra dove farming.

Materials and Methods:

A cross-sectional survey was conducted from January to April 2021. The study was conducted on 184 doves in three zebra dove farms. Fecal samples were collected from pooled zebra dove droppings. Major proportions and infection intensity of gastrointestinal nematodes were morphologically identified and morphometrically investigated. Associated human factors were assessed through the interview surveys among farmers.

Results:

Results showed that 36.96% of the zebra doves were infected. The primary nematodes were Ascaridia galli (34.78%), Heterakis gallinarum (6.52%), Trichostrongylus tenuis (2.17%), Syngamus spp. (4.35%), and Amidostomum spp. (2.17%). The primary human factors that contribute to parasitic infection were poor hygiene, food contamination with parasites, and inappropriate deworming.

Conclusion:

There was a high prevalence of gastrointestinal nematodes in the zebra dove in the close cage system. Human factors played key roles as risk factors, and improves farming management will help reduce parasitic infections. However, these nematodes may contribute to poor health status and poor productivity of zebra doves. Further extensive studies on clinical signs and pathological changes should be conducted.

Soil-Transmitted Helminths and Anaemia: A Neglected Association Outside the Tropics

Anaemia is an important cause of morbidity and mortality globally. Among infectious agents responsible for anaemia, helminthic infections are often neglected, particularly in non-endemic countries. However, they should not be neglected in this setting, as international travel and migration are on the rise. In this narrative review, we aimed to describe soil-transmitted helminths as a cause of or contributing factor to anaemia, focusing on hookworms (Necator americanus and Ancylostoma duodenale), the whipworm (Trichuris trichiura), the roundworm (Ascaris lumbricoides), and the threadworm (Strongyloides stercoralis). A general review on the epidemiology, lifecycle, and clinical spectrum of anaemia is proposed, with a special focus on helminthic infections’ association with anaemia as well as the diagnostic approach, which are both particularly important in non-endemic settings.

Prevalence of Strongyloides stercoralis infection and associated clinical symptoms among schoolchildren living in different altitudes of Amhara National Regional State, northwest Ethiopia

Background

Strongyloides stercoralis is a parasite that causes strongyloidiasis in humans. It is prevalent in the tropics and sub-tropics where poor sanitation is a common problem. The true prevalence of S. stercoralis in Ethiopia is underestimated due to the lack of a “Gold” standard diagnostic method. Moreover, its prevalence across altitudinal gradient in Amhara Region has not been studied.

Methods

A cross-sectional study was conducted among 844 schoolchildren in Amhara Region from April to December 2019. A stool sample was collected from each study participant and processed using formol ether concentration technique (FECT), spontaneous tube sedimentation technique (STST), Baermann concentration technique (BCT), agar plate culture (APC) and real-time polymerase chain reaction (RT-PCR). Data were entered using EpiData and analyzed by SPSS version 23 statistical software. Prevalence of S. stercoralis infection was determined using a single diagnostic technique and combination of techniques. Association of clinical variables with S. stercoralis infection was assessed by logistic regression and independent variables with p<0.05 were considered statistically significant.

Results

Prevalence of soil-transmitted helminths (STHs) and S. mansoni infections was 38.0% and 20.4%, respectively. Among STHs, the prevalence of hookworm infection was 32.8%. Prevalence of S. stercoralis infection was 39.0%, 28.8%, 10.9%, 10.3%, 4.0% and 2.0% by the respective, combinations of the five methods, RT-PCR, APC, BCT, STST and FECT. The highest prevalence rates, 48.2%, 45.0% and 41.1% of S. stercoralis were recorded in the age group of 12–14 years, males and rural dwellers, respectively. Prevalence rates of S. stercoralis infection in highland, semi-highland and lowland areas were 40.4%, 41.8% and 25.9%, respectively. Having abdominal pain (AOR = 2.48; 95% CI:1.65–3.72), cough (AOR = 1.63;95%CI:1.09–2.42), urticaria (AOR = 2.49;95%CI:1.50–4.01) and being malnourished (AOR = 1.44;95%:1.10–2.01) were significantly associated with strongyloidiasis.

Conclusion

Prevalence of S. stercoralis infection was high and varied across different altitudes in Amhara Region. Some clinical syndromes were found to be significantly associated with S. stercoralis infection. Therefore, proper diagnosis and preventive strategies against S. stercoralis infection are highly recommended to be devised and implemented in Amhara Region.

Prevalence of S. stercoralis is under-reported in many resource-poor countries including Ethiopia. We carried out a school-based cross-sectional study among 844 schoolchildren across highlands, semi-highlands and lowland areas of Amhara Region. We used an approach made of five diagnostic methods, namely, FECT, STST, BCT, APC, and RT-PCR. The total prevalence of S. stercoralis was 39.0%. The highest S. stercoralis prevalence (41.8%) was observed in the semi-highland areas of the region. Strongyloidiasis was significantly higher among 12–14 years age groups, males, and rural dweller children. Clinical symptoms such as presence of abdominal pain, cough, skin rash and malnourishment were significantly associated with strongyloidiasis. We recommend that preventive strategies against strongyloidiasis in Amhara Region should be implemented.

Strongyloides stercoralis

Strongyloidiasis has been estimated to affect over 600 million people worldwide. It is caused by Strongyloides stercoralis, a roundworm endemic to the tropics and subtropics, especially areas where sanitation is suboptimal Autochthonous transmission has been documented in rural areas of the USA and Europe. Humans are infected when larvae penetrate the skin or are ingested. Autoinfection, in which larvae generated in the host go on to re-infect the host, leads to a state of chronic asymptomatic infection often with eosinophilia. Hyperinfection syndrome may develop when patients develop immune suppression, due to medications such as corticosteroids or following solid-organ transplantation. Hyperinfection is characterized by exponential increase in parasitic burden, leading to tissue invasion and life-threatening disease and associated bloodstream infections due to enteric organisms. Cases following use of corticosteroids for COVID-19 pneumonia have been described. Strongyloidiasis can be diagnosed by direct visualization of larvae in stool or other body fluids, or by serology. Ivermectin is highly effective in treating the disease. Patients with exposure to endemic areas and those expected to become immune suppressed should be screened and treated before starting immune suppressive agents. Empiric treatment should be considered when timely testing is not readily available.

Evaluation of five diagnostic methods for Strongyloides stercoralis infection in Amhara National Regional State, northwest Ethiopia

Background

Strongyloides stercoralis is an intestinal parasite that can cause chronic infection, hyperinfection and/or a dissemination syndrome in humans. The use of techniques targeting ova fails to detect S. stercoralis, as only larvae of the parasite are excreted in faeces. Due to the absence of “Gold” standard diagnostic method for S. stercoralis, there is a paucity of reported data worldwide.

Objective

This study aimed to evaluate the performance of diagnostic methods of S. stercoralis infection by taking the composite reference as a “Gold” standard.

Methods

A cross-sectional study was conducted among 844 schoolchildren in Amhara Region, Ethiopia, from April to December 2019. Stool samples were collected and processed with formol-ether concentration technique (FECT), spontaneous tube sedimentation technique (STST), Baermann concentration technique (BCT), agar plate culture (APC) and real-time polymerase chain reaction (RT-PCR). Sensitivity, specificity, positive predictive value, and negative predictive value of each diagnostic method were computed against the composite reference. The agreements of diagnostic methods were evaluated by Kappa value at 95% CI.

Results

The composite detection rate of S. stercoralis by the five diagnostic methods was 39.0% (329/844). The detection rate of the parasite from stool samples by FECT, STST, BCT, APC and RT-PCR was 2.0% (17/844), 4.0% (34/844), 10.2% (86/844), 10.9% (92/844) and 28.8% (243/844), respectively. The highest detection rate (37.8%; 319/844) of S. stercoralis was recorded by a combination of BCT, APC, and RT-PCR followed by a combination of STST, BCT, APC and RT-PCR (37.3%; 315/844). The sensitivity of FECT, STST, BCT, APC and RT-PCR against the composite reference was 5.2%, 10.3%, 26.4%, 28.0% and 73.9%, respectively. The diagnostic agreements of RT-PCR, APC, BCT, STST and FECT with the composite reference in detection of S. stercoralis were substantial (0.775), fair (0.321), fair (0.305), slight (0.123), and slight (0.062), respectively.

Conclusion

RT-PCR detected the highest number of S. stercoralis infections. A combination of RT-PCR with APC and/or BCT better detected S. stercoralis from stool samples compared to other combinations or single diagnostic methods. Therefore, RT-PCR and combination of RT-PCR with APC and/or BCT diagnostic methods should be advocated for detection of S. stercoralis infection.

Metabolic alterations in Strongyloidiasis stool samples unveil potential biomarkers of infection

Strongyloidiasis, a parasitosis caused by Strongyloides stercoralis in humans, is a very prevalent infection in tropical or subtropical areas. Gaps on public health strategies corroborates to the high global incidence of strongyloidiasis especially due to challenges involved on its diagnosis. Based on the lack of a gold-standard diagnostic tool, we aimed to present a metabolomic study for the assessment of stool metabolic alterations. Stool samples were collected from 25 patients segregated into positive for strongyloidiasis (n = 10) and negative control (n = 15) and prepared for direct injection high-resolution mass spectrometry analysis. Using metabolomics workflow, 18 metabolites were annotated increased or decreased in strongyloidiasis condition, from which a group of 5 biomarkers comprising caprylic acid, mannitol, glucose, lysophosphatidylinositol and hydroxy-dodecanoic acid demonstrated accuracy over 89% to be explored as potential markers. The observed metabolic alteration in stool samples indicates involvement of microbiota remodeling, parasite constitution, and host response during S. stercoralis infection.

Global prevalence of Strongyloides stercoralis in dogs: A systematic review and meta-analysis

Strongyloides stercoralis is an intestinal parasitic helminth that mainly affects humans and dogs throughout the world. Canine strongyloidosis is generally characterized by asymptomatic infection, with fatal disease in cases of immunodeficiency. This study was conducted in order to evaluate the global prevalence of S. stercoralis in dogs. Six electronic databases were searched for this purpose. The random effects model and 95% confidence intervals (CI) were applied to determine the overall and subgroup pooled prevalence. Heterogeneity was assessed by Cochran's Q test and I2 statistic. In total, 56 datasets from 50 studies from 1,202 peer-reviewed papers were included in the current meta-analysis. 20,627 dogs were assessed in 27 countries across six World Health Organization (WHO) regions. The global prevalence of S. stercoralis infection among dogs was 6% (95% CI 4–8%; 868/20,627). According to WHO regions, the estimated prevalence ranges 2% to 11% as follows: Western Pacific (11%, 0–31%); Africa (9%, 2–19%); America (6%, 3–11%); South-East Asia (5%, 1–13%)’ Europe (3%, 2–5%); and Eastern Mediterranean (2%, 0–6%). The pooled prevalence of S. stercoralis infection in dog owners was 7% (1–18%). The prevalence of S. stercoralis infection in studies based on serological assays was significantly higher than other techniques (29%, 20–39%). Younger female dogs, less than one year old, from rural areas had higher prevalence rates than their male counterparts, with no statistically significant differences. From this review, it is concluded that the low global prevalence of S. stercoralis in dogs may be strongly associated with low sensitivity diagnostic methods applied in most studies leading to the underestimation of infection rates. Therefore, the improvement of diagnostic techniques is recommended for precise evaluation of the disease.

Case Report: Challenges for the Diagnosis and Treatment of Strongyloides stercoralis in Chronic Obstructive Pulmonary Disease Patients

Strongyloidiasis, a neglected tropical disease (NTD), which is caused by Strongyloides stercoralis, can be fatal in immunocompromised patients. In most chronic cases, infections most frequently are asymptomatic, and eosinophilia might be the only clinical characteristic of this disease. The use of corticosteroids in some diseases like chronic obstructive pulmonary disease (COPD) may lead to the development of the life-threatening S. stercoralis hyperinfection syndrome. In the present research, we presented five cases of strongyloidiasis with a history of COPD and receiving corticosteroids from Abadan County, southwestern Iran. By performing the direct smear stool examinations, two cases were identified and the other three cases were diagnosed using the agar plate culture method. Despite reporting eosinophilia in previous patients' hospitalizations, the fecal examination was not performed for parasitic infections. Moreover, pulmonary symptoms were similar, but gastrointestinal symptoms were varied, including nausea, vomiting, abdominal pain, epigastric pain, constipation, and diarrhea. All the included patients were treated with albendazole, which is the second-line drug for S. stercoralis, and relapse of infection was observed in two patients by passing few months from the treatment. The increased blood eosinophil count was shown to play important roles in both the management of COPD and diagnosis of helminthic infections. In COPD patients who are receiving steroids, screening and follow-up for strongyloidiasis should be considered as priorities. In addition, ivermectin, which is the first-line drug for strongyloidiasis, should be available in the region.