Generation of IgG antibodies against Strongyloides stercoralis in mice via immunization with recombinant antigens A133 and Ss-IR.

Strongyloidiasis, caused by the nematode Strongyloides stercoralis, remains a threat to global public health, and a vaccine would be useful to control the disease, especially in developing countries. This study aimed to evaluate the efficacy of recombinant proteins, A133 and Ss-IR, as potential vaccine candidates against strongyloidiasis by investigating the humoral and cellular immune responses in immunized mice. Respective antigens were adjuvanted with Complete Freund's Adjuvant (prime) and Incomplete Freund's Adjuvant (boost) and administered intraperitoneally (prime) and subcutaneously (boost) to female BALB/c mice. For antigen-only doses, only antigens were injected without adjuvants. Altogether, 1 prime dose, 4 booster doses, and 2 antigen-only doses were administered successively. ELISAs were conducted to assess the antibody responses, along with flow cytometry and cytokine ELISA to elucidate the cellular immune responses. Results showed that A133 and Ss-IR induced the production of IgG1 and IgG2a, with A133 generating more robust IgG2a responses than Ss-IR. Flow cytometry findings indicated that effector CD8+T-cells and memory B-cells activity were upregulated significantly for A133 only, whereas cytokine ELISA demonstrated that a Th1/Th2/Th17 mixed cell responses were triggered upon vaccination with either antigen. This preliminary study illustrated the good potential of recombinant A133 and Ss-IR as vaccine candidates against S. stercoralis. It provided information on the probable immune mechanism involved in host defence and the elicitation of protection against S. stercoralis.

Progress towards the implementation of control programmes for strongyloidiasis in endemic areas: estimation of number of adults in need of ivermectin for strongyloidiasis.

The World Health Organization has started a process to issue guidelines for the control of strongyloidiasis. The guidelines might recommend to implement preventive chemotherapy (PC) at community level (i.e. to all individuals above 5 years of age), over a defined prevalence threshold. We previously estimated the number of school-age children (SAC) who would need PC. Here we estimate the number of people above 15 years of age who might be included in PC for strongyloidiasis. Based on previous Strongyloides prevalence estimates and on countries' age distribution, we retrieved the number of adults in need of PC. We then subtracted the number of people already involved in ivermectin mass distribution for the elimination of onchocerciasis and lymphatic filariasis and people living in countries where Loa loa is endemic. The number of adults to be involved in PC was estimated at 905.4 (95% confidence interval (CI): 520.6-1177.2), 660.2 (95% CI: 512.7-1214.9), and 512.1 (95% CI: 276-719.4) million people, when the strongyloidiasis prevalence threshold for implementing PC was set to 10%, 15% and 20%, respectively. Estimates at country level are also provided.These estimates might help endemic countries wishing to implement PC for strongyloidiasis to allocate resources to include adults in addition to SAC in control programmes. This article is part of the Theo Murphy meeting issue 'Strongyloides: omics to worm-free populations'.

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.

Impact of preventive chemotherapy on Strongyloides stercoralis: A systematic review and meta-analysis.

BACKGROUND: Strongyloides stercoralis is a neglected soil-transmitted helminth (STH) that leads to significant morbidity in endemic populations. Infection with this helminth has recently been recognised by the World Health Organization (WHO) as a major global health problem to be addressed with ivermectin preventive chemotherapy, and therefore, there is now, the need to develop guidelines for strongyloidiasis control that can be implemented by endemic countries. This study aimed to evaluate the impact of ivermectin preventive chemotherapy (PC) on S. stercoralis prevalence in endemic areas to generate evidence that can inform global health policy. METHODOLOGY/PRINCIPAL FINDINGS: This study was a systematic review and meta-analysis. We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and LILACS for literature published between 1990 and 2022 and reporting prevalence of S. stercoralis before and after PC with ivermectin, administered either at school or at community level. The search strategy identified 933 records, eight of which were included in the meta-analysis. Data extraction and quality assessment were carried out by two authors. Meta-analysis of studies based on fecal testing demonstrated a significant reduction of S. stercoralis prevalence after PC: prevalence Risk Ratio (RR) 0.18 (95% CI 0.14-0.23), I2 = 0. A similar trend was observed in studies that used serology for diagnosis: RR 0.35 (95% CI 0.26-0.48), I2 = 4.25%. A sensitivity analysis was carried out for fecal tests where low quality studies were removed, confirming a post-intervention reduction in prevalence. The impact of PC could not be evaluated at different time points or comparing annual vs biannual administration due to insufficient data. CONCLUSIONS/SIGNIFICANCE: Our findings demonstrate a significant decrease of S. stercoralis prevalence in areas where ivermectin PC has taken place, supporting the use of ivermectin PC in endemic areas.

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.

Ivermectin and albendazole coadministration: opportunities for strongyloidiasis control.

In 2020, WHO recognised the importance of strongyloidiasis alongside soil-transmitted helminths (STH) in their 2021-30 roadmap, which aspires to target Strongyloides stercoralis with preventive chemotherapy by use of ivermectin. Combination treatment with both albendazole, the primary drug used to treat STH, and ivermectin, would improve the efficiency of mass drug administration targeting both STH and S stercoralis. In this Personal View, we discuss the challenges and opportunities towards the development of an efficient control programme for strongyloidiasis, particularly if it is to run concurrently with STH control. We argue the need to define the prevalence threshold to implement preventive chemotherapy for S stercoralis, the target populations and optimal dosing schedules, and discuss the added benefits of a fixed-dose coformulation of ivermectin and albendazole. Implementation of an efficient control programme will require improvements to current diagnostics, and validation of new diagnostics, to target and monitor S stercoralis infections, and consideration of the challenges of multispecies diagnostics for S stercoralis and STH control. Finally, the evolution of ivermectin resistance represents a credible risk to control S stercoralis; we argue that genome-wide approaches, together with improved genome resources, are needed to characterise and prevent the emergence of resistance. Overcoming these challenges will help to reduce strongyloidiasis burden and enhance the feasibility of controlling it worldwide.

Poor outcome and high prevalence of invasive fungal infections in patients with adult T-cell leukemia/lymphoma exposed to zidovudine and interferon alfa.

Patients treated for adult T-Cell leukemia/lymphoma (ATL) have a poor prognosis and are prone to infectious complications which are poorly described. As the French reference center for ATL, we retrospectively analyzed 47 consecutive ATL (acute, n = 23; lymphoma, n = 14; chronic, n = 8; smoldering, n = 2) patients between 2006 and 2016 (median age 51 years, 96% Afro-Caribbean origin). The 3-year overall survival (OS) was 15.8%, 11.3%, and 85.7% for acute, lymphoma, and indolent (chronic and smoldering) forms respectively. Among aggressive subtypes, 20 patients received, as frontline therapy, high dose of zidovudine and interferon alfa (AZT-IFN⍺) resulting in an overall response rate (ORR) of 39% (complete response [CR] 33%) and 17 chemotherapy resulting of an ORR of 59% (CR 50%). Ninety-five infections occurred in 38 patients, most of whom had an acute subtype (n = 73/95; 77%). During their follow-up, patients receiving frontline chemotherapy or frontline AZT-IFNα developed infections in 74% (n = 14/19) and 89% (n = 24/27) of the cases respectively. Sixty-four (67%) of infections were microbiologically documented. Among them, invasive fungal infections (IFI, n = 11) included 2 Pneumocystis jirovecii pneumonia, 5 invasive aspergillosis, and 4 yeast fungemia. IFI exclusively occurred in patients with acute subtype mostly exposed to AZT-IFNα (n = 10/11) and experiencing prolonged (> 10 days) grade 4 neutropenia. Patients with aggressive subtype experiencing IFI had a lower OS than those who did not (median OS 5.4 months versus 18.4 months, p = 0.0048). ATL patients have a poor prognosis even in the modern era. Moreover, the high rate of infections impacts their management especially those exposed to AZT-IFNα.

Control programs for strongyloidiasis in areas of high endemicity: an economic analysis of different approaches.

BACKGROUND: Implementation of control programmes for Strongyloides stercoralis infection is among the targets of the World Health Organization Roadmap to 2030. Aim of this work was to evaluate the possible impact in terms of economic resources and health status of two different strategies of preventive chemotherapy (PC) compared to the current situation (strategy A, no PC): administration of ivermectin to school-age children (SAC) and adults (strategy B) versus ivermectin to SAC only (strategy C). METHODS: The study was conducted at the IRCCS Sacro Cuore Don Calabria hospital, Negrar di Valpolicella, Verona, Italy, at the University of Florence, Italy, and at the WHO, Geneva, Switzerland, from May 2020 to April 2021. Data for the model were extracted from literature. A mathematical model was developed in Microsoft Excel to assess the impact of strategies B and C in a standard population of 1 million subjects living in a strongyloidiasis endemic area. In a case base scenario, 15% prevalence of strongyloidiasis was considered; the 3 strategies were then evaluated at different thresholds of prevalence, ranging from 5 to 20%. The results were reported as number of infected subjects, deaths, costs, and Incremental-Effectiveness Ratio (ICER). A 1-year and a 10-year horizons were considered. RESULTS: In the case base scenario, cases of infections would reduce dramatically in the first year of implementation of PC with both strategy B and C: from 172 500 cases to 77 040 following strategy B and 146 700 following strategy C. The additional cost per recovered person was United States Dollar (USD) 2.83 and USD 1.13 in strategy B and C, respectively, compared to no treatment in the first year. For both strategies, there was a downtrend in costs per recovered person with increasing prevalence. The number of adverted deaths was larger for strategy B than C, but cost to advert one death was lower for strategy C than B. CONCLUSIONS: This analysis permits to estimate the impact of two PC strategies for the control of strongyloidiasis in terms of costs and adverted infections/deaths. This could represent a basis on which each endemic country can evaluate which strategy can be implemented, based on available funds and national health priorities.

Preventive chemotherapy for the control of strongyloidiasis in school-age children: Estimating the ivermectin need.

BACKGROUND: Strongyloides stercoralis is a soil-transmitted helminth (STH) that affects approximately 600 million people worldwide. Interventions targeting S. stercoralis have not been implemented yet. Specific treatment (ivermectin) could be included in already ongoing preventive chemotherapy (PC) campaigns targeting other STHs. The aim of this study was to estimate the quantity of ivermectin needed for an integrated STH/S. stercoralis control program. METHODODOLOGY/PRINCIPAL FINDINGS: Our study estimates the number of school- age children (SAC) (the main focus of STH deworming campaigns) in need of PC with ivermectin. The normal approximation of the binomial distribution was adopted to calculate the hypothetical prevalence distribution in each endemic country. Considering prevalence thresholds for PC equal to 10%, 15%, and 20%, we estimated the number of SAC in need of treatment. We adjusted the estimates accounting for ivermectin distributed in lymphatic filariasis and onchocerciasis elimination programs and excluded from our calculation areas where Loa loa is endemic. The global number of SAC that should be targeted in PC campaigns was estimated at 283.9 M (95% CI: 163.4-368.8), 207.2 M (95% CI: 160.9-380.7), and 160.7 M (95% CI: 86.6-225.7) when the threshold for intervention was set to 10%, 15%, and 20%, respectively. India, China, Indonesia, Bangladesh, and Nigeria accounted for about 50% of the global SAC would have to be covered by PC intervention. CONCLUSIONS/SIGNIFICANCE: Our analysis may support endemic countries to evaluate the ivermectin quantity needed for integrating strongyloidiasis in the existing STH programs. These estimates might also show to generic drug manufacturers the size of the potential market for ivermectin and encourage its production.

Tratamento farmacológico da estrongiloidíase em pacientes transplantados / Pharmacological treatment of strongilloidiasis in transplanted patients

O objetivo deste artigo foi comparar o uso da ivermectina e do albendazol em pacientes transplantados e relatar os respectivos sucessos terapêuticos nessa população. Foram analisados artigos que abordassem relatos de casos publicados nos últimos 4 anos no PubMed® relacionando os descritores "transplante de órgãos", "estrongiloidíase" e "tratamento". Foram encontrados e analisados dez relatos de caso que abordaram a estrongiloidíase em situa- ção pós-transplante contemplando 13 indivíduos. Desses, cinco (38,5%) utilizaram ambos os medicamentos, dos quais quatro (80%) se curaram, tendo recebido albendazol e ivermectina por via subcutânea (50%) ou albendazol e ivermectina por vias oral/ subcutânea (50%). O paciente que morreu recebeu albendazol e ivermectina por via subcutânea. Sete (53,8%) indivíduos utiliza- ram apenas ivermectina, dos quais três (42,8%) se curaram tendo recebido o medicamento oral (dois pacientes) ou subcutâneo (um paciente); dois (28,6%) morreram recebendo o medicamento via oral, dois (28,6%) usaram profilaticamente via oral e apenas um não manifestou sintomas. Apenas um (7,7%) indivíduo utilizou somente albendazol via oral tendo sobrevivido à infecção. A uti- lização combinada dos medicamentos ivermectina e albendazol parece ter efeito positivo no tratamento da estrongiloidíase. A administração da ivermectina por via subcutânea apresentou resultados promissores, contudo estudos controlados de siner- gia medicamentosa e vias de administração devem ser realizados para efetiva avaliação.

The objective of this article was to compare the use of ivermec- tin and albendazole in transplanted patients and to report the respective therapeutic successes in this population.Articles ad- dressing case reports published in the last 4 years in the PubMed relating the descriptors "organ transplantation", "strongyloidia- sis", and "treatment" were analyzed. Ten case reports addres- sing strongyloidiasis in a post-transplant situation, covering 13 individuals, were found and analyzed. Of these, five (38.5%) used both drugs of which 4 (80%) were cured having received subcu- taneous albendazole and ivermectin (50%) or oral/subcutaneous albendazole and ivermectin (50%). The patient who died received subcutaneous albenzadole and ivermectin. Seven (53.8%) indi- viduals used only ivermectin, of which three (42.8%) were cured having received the oral (2/3) or subcutaneous (1/3) medication, two (28.6%) died receiving the oral medication, and two (28.6%) used oral medication prophylactically, and only one did not show symptoms. Only one (7.7%) individual used only oral albenzadole and survived the infection. The combined use of the drugs iver- mectin and albendazole seems to have a positive effect on the treatment of strongyloidiasis. The administration of subcuta- neous Ivermectin has shown promising results; however, con- trolled studies of drug synergy and administration routes shall be performed for effective evaluation.

Practical approach to monitoring and prevention of infectious complications associated with systemic corticosteroids, antimetabolites, cyclosporine, and cyclophosphamide in nonmalignant hematologic diseases.

Corticosteroids constitute a first-line therapy for adults and children suffering from nonmalignant immune-mediated hematologic diseases. However, high disease relapse rates during the tapering period or upon drug discontinuation result in long-term corticosteroid use that increases the risk of infection. This same concept applies to other immunosuppressive agents, such as antimetabolites, calcineurin inhibitors, and cyclophosphamide. Corticosteroids are associated with a length-of-treatment and dose-dependent risk for infection. Screening and antimicrobial prophylaxis against tuberculosis, hepatitis B, Strongyloides stercoralis, and Pneumocystis jirovecii pneumonia (PJP) might be indicated in patients who are scheduled to be on high-dose corticosteroids for >4 weeks (>30 mg of prednisone-equivalent dose [PEQ]) or in patients chronically treated (≥8 weeks of continuous or intermittent corticosteroid use) with moderate doses (≥15 to <30 mg PEQ). Antimetabolites (azathioprine, mycophenolate) increase the risk of progressive multifocal leukoencephalopathy (PML); however, other opportunistic infections and viral reactivation have also been reported. In case of new onset of neurological symptoms, PML needs to be considered, and an urgent neurology consultation should be obtained. Cyclophosphamide-induced myelosuppression can lead to serious infections related to neutropenia. PJP prophylaxis should be considered with combination therapy of cyclophosphamide and corticosteroids until a PEQ dose ≤ 5 mg/d is reached. Data on infectious risk when cyclosporine is used in patients with nonmalignant hematologic diseases are lacking. Discontinuation of any immunosuppressive agent during an episode of infection is recommended. In all patients, adherence to an age-based immunization schedule is appropriate.

Integrating testing for chronic strongyloidiasis within the Indigenous adult preventive health assessment system in endemic communities in the Northern Territory, Australia: An intervention study.

BACKGROUND: The life-threatening clinical manifestations of strongyloidiasis are preventable with early detection and effective treatment. The aim of this study was to assess if there was an increase to the number and proportion of persons tested for chronic strongyloidiasis, as a result of integrating Strongyloides stercoralis serology into the existing preventive health assessment system in four Aboriginal health services in endemic communities. METHODOLOGY: A prospective, longitudinal, before-and-after intervention study was conducted in four Aboriginal health services in remote endemically infected communities in the Northern Territory, Australia, from July 2012 to December 2016. The electronic patient information and recall systems enabled the integration of Strongyloides stercoralis serology into the adult preventive health assessment. Strongyloides reports for each health service were extracted half-yearly to examine the number and proportion of persons tested for chronic strongyloidiasis during the study and to measure the effect of the intervention. PRINCIPAL FINDINGS: The number and proportion of persons tested increased significantly during the study. From a total resident population of 3650 Indigenous adults over 15 years of age, 1686 persons (47.4%) were tested. The percentage of adults who had at least one serology test increased in all four health services to between 41% (446/1086) and 81.9% (172/210). Of the 1686 persons tested, 680 positive cases of chronic strongyloidiasis (40.3%) were identified. CONCLUSIONS/SIGNIFICANCE: This population health systems intervention increased the number and proportion of persons tested for chronic strongyloidiasis in four health services in endemically infected communities. This intervention is relevant to other health services with high-risk populations.

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

OBJECTIVES: To provide information regarding the prevalence of strongyloidiasis among migrants coming from Strongyloides stercoralis-endemic areas who reside in Spain. METHODS: Systematic review of the literature and meta-analysis of studies showing prevalence of S. stercoralis infection among migrants from Latin America, Africa, Eastern Europe, Asia and Oceania who reside in Spain. We included articles published until 30 April 2019 without language restriction. The keywords used for the search included 'Strongyloides stercoralis', 'strongyloidiasis', 'Spain', 'screening' and 'migrants'. RESULTS: Twenty-four studies were included in the review and meta-analysis, comprising 12 386 screened people. Eleven studies (7020 patients) evaluated the presence of S. stercoralis infection only through investigation of larvae in faeces, showing an overall prevalence of 1% (95%CI 1-1%). Thirteen studies (5366 patients) used a serological test, showing an overall prevalence of 14% (95%CI 11-17%). Strongyloidiasis seroprevalence was 20% (95%CI 15-24%) among migrants from sub-Saharan Africa, 14% (95%CI 10-18%) among those from Latin America and 8% (95%CI 5-11%) among migrants from North Africa. CONCLUSIONS: Migrants coming from strongyloidiasis-endemic areas living in Spain had a high S. stercoralis infection prevalence, particularly those from sub-Saharan Africa and Latin America. This population should be screened using serology as the most sensitive test for S. stercoralis infection. This could be easily implemented at primary care level.

OBJECTIFS: Fournir des informations sur la prévalence de la strongyloïdose parmi les migrants résidant en Espagne et provenant de zones endémiques pour Strongyloides stercoralis. MÉTHODES: Revue systématique de la littérature et méta-analyse des études montrant la prévalence de l'infection à S. stercoralis parmi les migrants d'Amérique latine, d'Afrique, d'Europe de l'Est, d'Asie et d'Océanie qui résident en Espagne. Nous avons inclus des articles publiés jusqu'au 30 avril e 2019 sans restriction de langue. Les mots clés utilisés pour la recherche comprenaient "Strongyloides stercoralis", "strongyloïdose", "Espagne", "dépistage" et "migrants". RÉSULTATS: Vingt-quatre études ont été incluses dans la revue et la méta-analyse, comprenant 12.386 personnes dépistées. Onze études (7.020 patients) ont évalué la présence d'une infection à S. stercoralis uniquement en examinant les larves dans les selles, montrant une prévalence globale de 1% (IC95%: 1-1%). Treize études (5.366 patients) ont utilisé un test sérologique, montrant une prévalence globale de 14% (IC95%: 11-17%). La séroprévalence de la strongyloïdose était de 20% (IC95%: 15-24%) chez les migrants d'Afrique subsaharienne, 14% (IC95%: 10-18%) chez ceux d'Amérique latine et 8% (IC95%: 5-11%) chez ceux d'Afrique du Nord. CONCLUSIONS: Les migrants en provenance de zones d'endémie pour la strongyloïdose vivant en Espagne avaient une prévalence élevée d'infection à S. stercoralis, en particulier ceux d'Afrique subsaharienne et d'Amérique latine. Cette population devrait être dépistée en utilisant la sérologie comme le test le plus sensible pour l' infection à S. stercoralis. Cela pourrait être facilement mis en œuvre au niveau des soins primaires.