International Survey on Screening and Management of Strongyloidiasis in Solid Organ Transplant Patients

ABSTRACT

Background

Strongyloides stercoralis infection can be associated with high mortality in solid organ transplant (SOT) recipients, yet global practices regarding screening and management remain poorly characterized. We conducted an international survey to evaluate knowledge, screening, and management practices among healthcare workers (HCWs) involved in SOT care.

Methods

We performed a cross‐sectional, web‐based survey of HCWs caring for SOT candidates and recipients. The survey assessed provider characteristics, knowledge of strongyloidiasis, as well as screening and management practices. Descriptive statistics were used to summarize responses.

Results

A total of 101 HCWs responded, including 65 (64%) infectious diseases (ID) providers and 36 (36%) non‐ID providers. Knowledge gaps were identified regarding transmission and mortality, particularly among non‐ID providers. Overall, 85% of respondents reported screening SOT candidates for S. stercoralis; among those who screen, serology is the most commonly used method. Screening strategies varied by geographic region, with universal screening more common in endemic areas and targeted screening in non‐endemic regions. Management practices, including approaches to indeterminate or negative test results, showed substantial heterogeneity.

Conclusions

This international survey demonstrates considerable variability in knowledge, screening, and management of strongyloidiasis among HCWs involved in SOT care. These findings highlight opportunities for improved education, clearer guidance, and greater standardization of practices related to Strongyloides infection to avoid unnecessary morbidity.

This international cross‐sectional survey of healthcare workers caring for solid organ transplant patients identified knowledge gaps regarding Strongyloides transmission and mortality, particularly among non‐infectious disease providers. Screening strategies varied geographically, with universal screening more common in endemic areas and targeted screening in non‐endemic regions. Substantial heterogeneity in the management of Strongyloides stercolaris infection was also observed.

Abbreviations

APPs

advanced practice providers

AST

American Society of Transplantation

HCWs

healthcare workers

ID

infectious diseases

SOT

solid organ transplant

TTS

The Transplantation Society

1. Introduction

Strongyloidiasis is a parasitic infection widely distributed in tropical and subtropical regions, affecting over 350 million people worldwide [1]. This infection is endemic in Africa, Latin America, Asia, and Oceania, but has become increasingly recognized in non‐endemic countries due to its high prevalence among migrant populations [2]. Asundi et al. reported a pooled seroprevalence of 12.2% among migrants born in endemic countries [3].

Strongyloidiasis represents a significant threat to solid organ transplant (SOT) recipients, given the risk of developing life‐threatening hyperinfection syndrome or disseminated strongyloidiasis in the context of immunosuppression [4, 5]. Mortality rates approach 50% in hyperinfection syndrome and 70% in disseminated infection [6].

Screening for Strongyloides stercoralis is recommended for SOT candidates with epidemiologic risk factors [6, 7]. However, in high‐prevalence, resource‐limited settings, universal empiric treatment rather than screening has been suggested [6]. Serologic testing is the most common screening method among SOT candidates, although false‐positive and false‐negative results may occur [6]. Nevertheless, serology outperforms stool microscopy in sensitivity and negative predictive value [8]. Ivermectin is the treatment of choice [6]; however, albendazole remains more widely available in many low‐income countries [9].

Despite existing recommendations, it remains unclear how screening and management of Strongyloides infection are performed worldwide. This survey aims to describe current practices among healthcare workers (HCWs) involved in the care of SOT patients.

2. Methods

2.1. Study Design and Population

We conducted an international, cross‐sectional, web‐based survey targeting HCWs involved in the care of SOT candidates and recipients. The survey aimed to evaluate HCW knowledge, screening, and management practices related to S. stercoralis infection.

Eligible participants included transplant physicians, surgeons, coordinators, pharmacists, advanced practice providers (APPs), infectious diseases (ID) physicians, and other professionals involved in SOT care. Participation was voluntary, anonymous, and uncompensated. No written consent was obtained from the participants, as no identifying personal or institutional data were collected. The study was deemed exempt from formal review by our institutional review board (IRB).

The survey instrument was developed by a panel of transplant ID physicians with expertise in parasitic infections. The questionnaire was designed to assess four major domains:

1. Respondent and transplant center characteristics, including participants’ clinical role, institution type, transplant program type and volume, geographic region, and whether they work in a Strongyloides‐endemic area.

2. Knowledge of S. stercoralis, including understanding of modes of transmission, perceived mortality in SOT recipients, and endemicity.

3. Screening practices, including whether transplant candidates are screened, whether screening is applied universally or limited to those with endemic exposure, the screening modalities used, and barriers to implementation.

4. Management practices, including use of universal treatment before and/or after SOT, treatment regimens for screened‐positive cases, and approaches to indeterminate and negative test results.

Multiple‐response options were permitted where applicable. The survey underwent expert review by the leadership of the Transplant ID Section of The Transplantation Society (TTS) for content validity, clarity, and relevance, but was not formally psychometrically validated. The complete questionnaire is provided in the Supporting Information.

2.2. Survey Distribution

The survey was created using Google Forms and distributed between February and July 2025 to HCWs caring for SOT patients. The survey was first disseminated electronically to the Transplant ID Section members of the TTS on February 27, 2025, with subsequent reminders sent on March 26 and April 4. In parallel, it was featured in the TTS Pulse Weekly Newsletter from April 4 to April 25, 2025. To optimize the response rate, the survey was subsequently circulated to the Brazilian Association of Organ Transplantation, the Non‐HIV Immunocompromised Hosts Committee of the Brazilian Society of Infectious Diseases, the ID Community of Practice of the American Society of Transplantation (AST), and to the International Society for Heart and Lung Transplantation Hispanic WhatsApp group.

2.3. Statistical Analysis

Descriptive statistics were used to summarize survey responses. Categorical variables were presented as frequencies and percentages. Fisher's exact test and chi‐square were used to evaluate associations between categorical variables. A p‐value of < 0.05 was considered statistically significant.

3. Results

3.1. Transplant Center Data

A total of 101 HCWs responded to our survey. Of these, 65 (64%) were ID providers (transplant ID physicians [63], and general ID physicians and ID APP [1 each]), and 36 (36%) were non‐ID providers (transplant physicians [28], transplant coordinators [3], transplant surgeons [2], and transplant pharmacists, microbiologists, and transplant APPs [1 each]).

Respondents were primarily employed by universities/medical schools (49), hospitals (48), and private practices (4). Seventy‐three (72%) reported involvement in multiple transplant programs. Program representation included kidney 78 (77%), heart 64 (63%), liver 60 (59%), kidney/pancreas 53 (52%), lung 45 (45%), and intestinal/multivisceral 19 (19%). Over half worked at centers performing > 100 transplants per year (Figure S1, Supporting Information). Transplant ID services were available at 88 institutions (87%).

Most respondents were based in the United States, followed by South America (Figure S2, Supporting Information). Twenty‐eight (28%) self‐reported working in Strongyloides‐endemic regions, five (5%) were unsure, and 68 (67%) reported not working in endemic areas. Among these 68, the majority (82%) reported caring for patients from endemic regions. Notably, eight HCWs stated neither working in nor caring for patients from endemic areas.

3.2. Knowledge About Strongyloidiasis Among Providers

Most respondents selected skin penetration from contaminated soil (89) as a mode of transmission, followed by organ transplant (64), fecal‐oral (48), and person‐to‐person (31). The “skin penetration from contaminated soil” option was more likely to be chosen by ID providers compared to non‐ID providers (65 [100%] vs. 24 [67%], p < 0.001).

Fifty‐six HCWs indicated that mortality from disseminated strongyloidiasis in SOT recipients can reach 70%. Mortality estimates of up to 50%, 20% and “I don't know” were selected by 20, 10, and 15 participants, respectively. A significantly higher proportion of ID providers selected the option that mortality could reach 70% compared to non‐ID providers (43 [66%] vs. 13 [36%], p = 0.004).

Detailed breakdowns of transmission and mortality responses, stratified by clinical role, are presented in Figures 1 and 2, respectively.

FIGURE 1.

Knowledge about Strongyloides transmission by clinical role. Multiple choices allowed.

FIGURE 2.

Knowledge about disseminated strongyloidiasis mortality by clinical role.

Seventy‐eight respondents self‐reported that strongyloidiasis is endemic in their country. Among them, 63 (81%) indicated that it is confined to certain areas, 7 (9%) stated that it is present throughout the entire country, and 8 (10%) providers (three ID and five non‐ID) were unsure of its national distribution. Four HCWs (one ID and three non‐ID) were unaware whether strongyloidiasis was endemic in their country. United States respondents were more likely to report that strongyloidiasis was confined to certain areas in their country compared to non‐United States respondents (47 [75%] vs. 16 [42%], p = 0.001).

3.3. Screening Practices of Strongyloidiasis

Of 101 respondents, 86 (85%) reported performing some level of screening for S. stercolaris among SOT candidates. These respondents included 60 transplant ID physicians, 19 transplant physicians, 2 transplant surgeons, 2 APPs, and 1 each of a transplant coordinator, transplant pharmacist, and microbiologist. In contrast, 15 (15%) respondents reported no screening at all. Reasons for not screening included universal treatment after SOT (8 respondents [5 from Brazil, 2 from Colombia, and 1 from an unspecified state of the United States]), universal treatment before SOT, either alone (1 from Brazil and 1 from India) or with limited resources (1 from Brazil), and unspecified (4 respondents).

Among those who screen, 39 (45%) screen all candidates, while 44 (51%) screen only individuals with exposure to endemic areas. Two respondents screen on a case‐by‐case basis, and screening details were missing for one. Universal screening was more likely to be performed in endemic regions (16/20 [80%] vs. 20/62 [32%], p < 0.001). Four HCWs were excluded from this analysis because they were unsure whether they worked in endemic areas.

Serology was the most common method used: 70/86 (81%) respondents, followed by stool microscopy: 15 (17%), stool PCR: 3 (3%), and immunochromatography: 1 (1%). Two were unsure of the method used. Three respondents selected more than one screening test. Challenges in implementing screening were reported by 33 (38%) respondents. These challenges included a lack of awareness of strongyloidiasis (28) and a lack of resources for screening, including access to diagnostic testing (5 responses).

3.4. Management Practices of Strongyloidiasis

3.4.1. Universal Treatment

Among 101 respondents, 5 (5%) provide universal treatment before transplantation (2 HCWs each from India and Brazil and 1 from Ohio/United States), 12 (12%) after transplantation (7 from Brazil, 2 from Colombia, and 1 each from Argentina, Florida/United States, and Connecticut/United States), and 9 (9%) both before and after transplantation (2 each from Brazil and Colombia, and 1 each from India, Illinois/United States, Florida/United States, South Carolina/United States, and Indiana/United States). The proportion of HCWs providing universal treatment by continent was as follows: South America 16 (80%), Asia 2 (29%), North America 7 (11%), and none from Africa and Asia.

3.4.2. Empiric Treatment During Rejection

Out of 101 respondents, 33 (33%) provide empiric treatment during high‐dose steroid therapy (Always [17; 12 from endemic regions] and Sometimes [16; 5 from endemic regions]); of these, two use ivermectin 0.2 mg/Kg daily for 2 days, and treatment was not specified by the other 31 HCWs.

Among the remaining respondents, 62 (61%) provided no empiric treatment, and 6 (6%) were unsure.

3.4.3. Positive Screening Test

Among the 86 Strongyloides‐screeners, 75 [61 ID and 14 non‐ID HCWs; 87%] treat strongyloidiasis independently, including 6 who would do so after consulting ID (2 transplant physicians, 1 transplant surgeon, and 1 transplant pharmacist) or pharmacy (2 transplant ID). ID providers were more likely to treat strongyloidiasis independently compared to transplant physicians (61 [100%] vs. 9/19 [47%], p < 0.001).

The most common treatment (56%) is ivermectin 0.2 mg/Kg daily for 2 days, repeated in 2 weeks. Other regimens are summarized in Table 1. Regarding timing relative to transplantation, 48 (64%) HCWs treat before, 5 (7%) after, and 22 (29%) before and after transplantation.

TABLE 1.

Treatment regimens used for solid organ transplant candidates who screened positive for Strongyloides.

Type of treatment	Respondents N = 75 (%)
Ivermectin 0.2 mg/kg for 1 day	2 (3)
Ivermectin 0.2 mg/kg daily for 2 days	23 (31)
Ivermectin 0.2 mg/kg daily for 2 days, and repeat treatment in 2 weeks	42 (56)
Albendazole 400 mg every 12 h for 7 days	3 (4)
Albendazole 400 mg every 12 h with ivermectin 0.2 mg/day for 2 days	1 (1)
Albendazole 400 mg every 12 h with ivermectin 0.2 mg/day for 2 days, and repeat treatment in 2 weeks	3 (4)
No response	1 (1)

Note that, 52 (69%) provide counseling, including avoiding walking barefoot in soil or sand (50), gardening without gloves (25), or avoiding gardening entirely (3 respondents).

In addition, 53 (71%) check for eosinophilia when treating strongyloidiasis prior to transplantation. Among these, 37 (70%) repeat a complete blood count after treatment to evaluate for improvement, with 27 doing so consistently and 10 intermittently.

Among 14 non‐ID HCWs who treat strongyloidiasis, seven subsequently refer patients to ID specialists (five at diagnosis, one at transplantation, and one after transplantation).

3.4.4. Indeterminate Serology

Overall, 70 respondents using serology were included (52 ID vs. 18 non‐ID providers). Among ID providers, 30 (58%) treat as positive, 14 (27%) repeat serology, 4 (8%) assess risk factors to determine whether to repeat testing or treat empirically, and 4 (8%) take no action. Among non‐ID providers, 7 (39%) treat, 5 (28%) refer to ID, 3 (17%) repeat serology, 1 (6%) takes no action, and 2 (11%) did not respond.

3.4.5. Negative Screening Test

3.4.5.1. With Unexplained Eosinophilia

The majority of respondents investigate alternative parasitic causes (40%) or initiate empiric treatment for strongyloidiasis (24%), while smaller proportions repeat or obtain alternative S. stercoralis testing, assess risk factors, or refer to subspecialists (Figure 3). Among those evaluating for other parasitic infections, 8 check for Schistosoma (6 from the United States), 5 each for Toxocara and Trichinella (4 from the United States for both), 4 each for roundworm (none from the United States) and hookworm (2 from the United States), and 1 each for Filaria (from the United States) and unspecified helminths (not from United States). Twenty provided no response.

FIGURE 3.

Challenging scenarios of negative S. stercoralis testing among solid organ transplant candidates. Respondents were limited to a single choice for each of the scenarios. “Other” responses included: empiric treatment and testing for other parasitic infections causing eosinophilia (4 respondents), assessment for risk factors (2), referral to hematology, referral to infectious diseases, evaluation for other etiologies of eosinophilia, or no response (1 each).

3.4.5.2. With High Exposure Risk (e.g., Gardening)

Responses were split between no further intervention and empiric treatment for strongyloidiasis (40% vs. 37%), with fewer repeating or obtaining alternative S. stercoralis testing (Figure 3).

3.4.5.3. With Immunosuppression (e.g., SOT Recipients Being Evaluated for Retransplantation)

Approximately half of the participants (48%) undertake no further intervention, while others treat empirically or repeat/obtain additional S. stercoralis testing (Figure 3).

4. Discussion

Strongyloidiasis is a neglected tropical disease that occurs worldwide, and while seen more in tropical and subtropical regions, it is also found in countries with temperate climates, such as the United States and Italy [2, 10, 11], and is associated with significant mortality in immunocompromised hosts [10]. Therefore, all HCWs who care for SOT patients should be knowledgeable about this potentially lethal infection. De l'Étoile‐Morel et al. demonstrated a general lack of knowledge regarding Strongyloides infection among Canadian physicians caring for immunocompromised patients [12]. Our study is the first international survey conducted exclusively among HCWs involved in SOT, and it revealed considerable variability in knowledge, screening practices, and management of S. stercoralis infection.

Most participants correctly identified skin penetration through contaminated soil as the main transmission route for S. stercoralis, but fewer recognized organ transplantation as a potential mode of transmission. This is concerning, given that donor‐derived infection, although uncommon, has been repeatedly reported and can be fatal when unrecognized [13, 14]. Assessing clinical approaches to donor screening was beyond the scope of this survey.

More than half of the respondents accurately perceived the high mortality associated with disseminated infection in SOT recipients, consistent with what has been published in the literature [6]. Nevertheless, a significant proportion of respondents underestimated its severity, underscoring the need for ongoing education even among clinicians who routinely manage transplant recipients.

Screening practices reported in this survey were generally encouraging, with the majority of providers (85%) screening SOT candidates for S. stercoralis, in contrast to a previous Canadian survey [12]. Most respondents limit testing to SOT candidates with a history of residence in endemic areas (targeted screening), consistent with the fact that the majority (72%) of HCWs in this cohort practice in non‐endemic areas. This approach aligns with the AST guidelines, which recommend targeted screening in non‐endemic areas for patients who were born or lived in tropical or subtropical regions, traveled to endemic areas, or have unexplained eosinophilia [6]. Targeted screening also includes individuals with remote exposure, as S. stercoralis can persist indefinitely through autoinfection [15]. Nearly all respondents practicing in endemic areas report performing universal screening, in line with the AST guidelines [6]. However, despite this pattern of universal screening in endemic regions and targeted screening in non‐endemic regions, some respondents still follow practices that deviate from guidelines, highlighting opportunities to improve standardization. Within a standardized framework, adopting a low threshold for screening in the presence of epidemiologic uncertainty may provide an additional margin of safety in the transplant population.

Screening for strongyloidiasis among SOT candidates is usually performed using serological methods [6] and represented the most commonly used diagnostic testing among respondents to our survey. However, serologic testing has limited sensitivity and may yield false‐negative results, particularly in immunocompromised hosts. In one study including patients with various immunocompromising conditions, such as corticosteroid use, chemotherapy, hematologic malignancies, and organ transplantation, serology demonstrated a sensitivity of only 42.9% [16]. Sensitivity may also be reduced in SOT candidates who are immunosuppressed as a result of end‐stage organ disease. To mitigate the risk of missed diagnoses, some transplant centers have adopted a universal treatment strategy [14].

The 2019 AST guidelines recommend universal treatment only for SOT candidates from high‐prevalence endemic areas with limited resources [6]. In our survey, approximately one‐quarter of respondents reported providing universal treatment, which is most frequently provided by respondents working in highly endemic areas, such as South America, but also provided, to a lesser extent, by providers practicing in non‐highly‐endemic areas, such as North America. Among HCWs adopting this approach, the majority reported administering therapy after transplantation (12%) rather than before (5%). Posttransplant treatment could also cover potential donor‐derived infection, which is especially relevant for transplant centers utilizing organs from endemic areas. Notably, a universal screening and treatment strategy was implemented at a large transplant center in Florida, United States, following a fatal case of donor‐derived disseminated strongyloidiasis in a SOT recipient, with no subsequent cases reported [14].

Only one‐third of respondents reported providing empiric Strongyloides treatment during rejection therapy with high‐dose corticosteroids, a proportion that appears low, given the strong association between corticosteroid exposure and reactivation of latent strongyloidiasis [10]. Interpretation of this finding is limited by ambiguity in the survey question, which did not specify whether patients who had received peri‐transplant Strongyloides treatment were included; this may have contributed to the underestimation of empiric treatment during rejection episodes. Abad et al. reported cases of strongyloidiasis following steroid treatment for acute rejection among SOT recipients [5], underscoring the clinical relevance of this scenario, which was not addressed in the 2019 AST guidelines [6].

Most respondents use ivermectin for SOT candidates, which is considered the drug of choice [6]. Among these, the majority administer a 2‐day course with repeat dosing 2 weeks later, in accordance with expert opinion [6]. Fewer use albendazole monotherapy or combined ivermectin‐albendazole, the latter being supported only for disseminated strongyloidiasis [6]. Interestingly, none used moxidectin, which was found to be non‐inferior and as safe as ivermectin in a systematic review study that did not include immunocompromised patients [17]

Empiric strongyloidiasis treatment for SOT candidates in selected clinical scenarios appears justified, given the potential for false‐negative diagnostic testing and the life‐threatening nature of post‐transplant Strongyloides reactivation. Among respondents, 24%, 37%, and 21% provide empiric treatment despite negative screening in the settings of unexplained eosinophilia, high exposure risk (e.g., gardening), and immunosuppression (e.g., SOT recipients being evaluated for retransplantation), respectively. While empiric treatment in the setting of unexplained eosinophilia is supported by AST guidelines, the latter scenarios were not explicitly addressed [6]. It is uncertain whether the heterogeneity in responses shown in Figure 3 reflects true differences in providers’ practice or is influenced by the fact that this question allowed only a response, even though multiple interventions might be considered in practice.

This study has limitations inherent to cross‐sectional survey research, including potential selection, nonresponse, and response bias, reliance on self‐reported data, and the inability to verify reported practices. A formal response rate could not be determined due to the multichannel distribution strategy. Respondents from Asia and Africa were underrepresented, with no representation from Central America and Oceania. In contrast, respondents from the United States were overrepresented relative to other countries, which may have influenced the overall findings. Future surveys could improve representation by directly engaging transplant societies in Africa, Asia, Oceania, the Caribbean, and Latin America. The relatively small number of non‐ID providers may have limited statistical power to detect differences across specialties. In addition, the cross‐sectional design captures practices at a single point in time and may not reflect evolving clinical approaches. Finally, this study did not evaluate clinical approaches to donor screening; however, future studies are encouraged to incorporate this aspect, as it is vital to the management of strongyloidiasis and its impact on SOT recipients.

Despite these limitations, the international scope and multidisciplinary nature of the respondent cohort provide valuable baseline data to guide future research and guideline development.

In conclusion, this survey provides an overview of current screening and management practices for strongyloidiasis in solid organ transplantation, highlighting opportunities to improve guidance and optimize care for transplant candidates and recipients with, or at risk for, Strongyloides infection.

Author Contributions

Jonathan Hand: writing – review and editing. Matthew B. Roberts: writing – review and editing. Alessandra Mularoni: writing – review and editing. Monica Slavin: writing – review and editing. John W. Baddley: writing – review and editing. Jacques Simkins: writing – original draft, writing – review and editing, conceptualization, methodology, formal analysis, investigation, visualization, validation. Cameron R. Wolfe: writing – review and editing. Stephanie Pouch: writing – review and editing. Maricar Malinis: writing – review and editing. Akshatha Ravindra: conceptualization, methodology, writing – review and editing. Ines Ushiro‐lumb: writing – review and editing. Ban Hock Tan: writing – review and editing. Marcelo Radisic: writing – review and editing. Wanessa T. Clemente: conceptualization, methodology, writing – review and editing, supervision, investigation. Maristela P. Freire: writing – review and editing. Siriorn Watcharananan: writing – review and editing.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Supporting File 1: tid70233‐sup‐0001‐SuppMat.docx.

Supporting File 2: tid70233‐sup‐0002‐VisualAbstact.pptx.