https://orcid.org/0000-0002-7801-5072
Figures
Abstract
Introduction
Strongyloidiasis is an important but underdiagnosed soil-transmitted helminthiasis, particularly in tropical areas and some vulnerable groups.
Objectives
To assess the parasitological prevalence, seroprevalence and sociodemographic factors of Strongyloides stercoralis infection in patients living with human immunodeficiency virus (PLWH) in an endemic area.
Materials and methods
We performed a cross-sectional study of strongyloidiasis in 537 PLWH in two hospitals in Iquitos, Peru, from 20 Oct 2023 to 20 May 2024. We tested patient sera using Strongyloides IgG enzyme-linked immunosorbent assay (ELISA) and stool via the modified Baermann technique and/or charcoal fecal culture as highly sensitive parasitological techniques. We used multivariable logistic regression to identify factors associated with S. stercoralis infection.
Results
Among the 339 PLWH whose stool samples were collected, 82 were positive for S. stercoralis (prevalence 24.2%; 95% confidence interval [CI] 20.0-29.1%). Among the 534 PLWH whose serum samples were collected, 227 were positive (seroprevalence: 42.5%; 95% CI 38.1-47.5%). The kappa value for charcoal culture and Baermann technique was 0.69. ELISA showed a sensitivity of 92.6% and a negative predictive value of 96.9%. Significant risk factors for stool positivity included living in a rural (unpaved) area (adjusted OR: 1.86), whereas significant risk factors for both stool and seropositivity included living in a poor house (made of wood/leaves) (adjusted odds ratio (ORs): 2.18 and 2.48, respectively), in the Loreto Regional Hospital catchment area (adjusted ORs: 5.66 and 5.37, respectively), or being infected by hookworms in stool (adjusted ORs: 23.88 and 9.78, respectively). Having a low level of studies was associated with seropositivity (adjusted OR 2.42).
Conclusion
The prevalence of S. stercoralis is high among PLWH in Iquitos, especially among those living in conditions of socioeconomic vulnerability or co-infected with hookworms. The negative predictive value of the S. stercoralis ELISA was high, although this result should be taken with caution in severe immunosuppression.
Author summary
Intestinal parasitic infections are especially common in warm climates, particularly where sanitation facilities are poor. Immunocompromised individuals, such as people living with human immunodeficiency virus (HIV) patients, are more susceptible to parasitic infections. Strongyloides stercoralis is a common parasite in Iquitos, the capital of the Peruvian Amazon, although its current infection rate among HIV patients is unknown. In this study, our objective was to detect the prevalence of the parasite in the stool of 339 patients from two different hospitals using three microbiological techniques, as none of them is completely reliable by itself. The prevalence of antibodies in the blood of 537 patients was also assessed, since it is useful for knowing the burden of disease in the community as a contact marker. In addition to the diagnostic procedure, we conducted an interview on sociodemographic and clinical characteristics to identify risk factors for infection that can be corrected. This information will help improve prevention, diagnosis, and clinical management in this population.
Citation: Otero-Rodriguez S, Casapia-Morales M, Pinedo-Cancino V, Mego-Campos S, Villacorta-Pezo V-Y, Parráguez-de-la-Cruz J, et al. (2025) High prevalence of Strongyloides stercoralis in people living with HIV: A critical health challenge in the Peruvian Amazon Basin. PLoS Negl Trop Dis 19(7): e0013231. https://doi.org/10.1371/journal.pntd.0013231
Editor: Dora Buonfrate, Centre for Tropical Diseases, ITALY
Received: February 13, 2025; Accepted: June 10, 2025; Published: July 15, 2025
This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Data Availability: The dataset used and/or analysed during the current study are available in Zenodo Repository, under the ORCID: 10.5281/zenodo.14864472. The laboratory protocol is available in protocols.io, under the doi: https://dx.doi.org/10.17504/protocols.io.ewov1mpqpvr2/v1
Funding: This work was supported by Miguel Hernandez University (UMH) (under Grant 11-134-4-2023-0133 to J.-M.R), Alicante Health and Biomedical Research Institute (ISABIAL) (under Grant 2024-0181 to S.O.-R) and Instituto de Salud Carlos III (ISCIII) (under Grant CM23/00050 to S.O.-R). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: Miguel Hernandez University has granted the research of J.M.-R in the field. Alicante Health and Biomedical Research Institute (ISABIAL) and Instituto de Salud Carlos III (ISCIII) have granted the research of S.O.-R in the field. None of the institutions had a role in study design, data collection, analysis, decision to publish, or preparation of the manuscript. The other authors declare that no competing interests exist.
1. Introduction
Strongyloidiasis is a soil-transmitted helminthiasis caused by the parasitic nematode Strongyloides stercoralis (distributed worldwide) or Strongyloides fuelleborni (only present in some regions of Africa and Oceania) [1]. This infection is particularly prevalent in tropical and subtropical areas, where sanitary conditions are poor, and t is acquired through skin contact with contaminated soil [2]. The global prevalence of S. stercoralis is estimated to affect approximately 600 million people [3,4], although this figure may be underestimated due to the low sensitivity of the available diagnostic techniques. Strongyloidiasis is important because it is one of the few nematodes able to perpetuate a chronic infection in the host (“autoinfection”). Without treatment, the infection can persist for life and immunosuppressed patients are at risk for Strongyloides hyperinfection syndrome and disseminated strongyloidiasis, conditions that carry high morbidity and can even be fatal [5]. The World Health Organization (WHO) includes Strongyloides among the soil transmitted helminthiases targeted for improved control by 2030; for this purpose, specific guidelines have been published recently. However, the organization denounces the need for more evidence to optimize public health programs for strongyloidiasis [6].
Iquitos is a city located in the Loreto region, which has the second-highest prevalence of people living with HIV in Peru, with more than 200 new cases diagnosed in the first half of 2024 [7]. However, the prevalence of S. stercoralis infection in PLWH in Peru is understudied, as their predisposition to infection, the impact of HIV related immunosuppression, and the associated risk of hyperinfection syndrome. Despite this, we do know that this is a vulnerable population with a higher risk for high-dose corticosteroid use (a known risk factor for hyperinfection [8]), and in which treating the parasite would reduce morbimortality.
Population studies of S. stercoralis infection in Peru show widely varying prevalences depending on the geographical area, the type of diagnostic test used, or the clinical presentation. A study conducted by the Peruvian Ministry of Health, from 1981 to 2010, found a heterogenous prevalence ranging from 0.3 to 39%, with a national average of 6.25% [9]. A recent systematic review estimated an even higher prevalence of 7.34% [10]. In the Peruvian Amazon, where climatic conditions favor the endemicity of the parasite, the prevalence of S. stercoralis consistently exceeds 10% [11–13]. To the best of our knowledge, no published parasitological or sero-epidemiological studies exist on S. stercoralis infection in PLWH in the Peruvian Amazon.
The parasitological diagnosis of S. stercoralis infection is challenging. Stool processing techniques including the Baermann method and charcoal culture are diagnostic tools that yield higher sensitivity than direct stool smear, but still miss a large proportion of infections [5]. Molecular methods like PCR allow the diagnosis of a higher number of cases; however, this procedure is not available in most patient care settings. While serologic tests are the most sensitive diagnostic tools (especially in non-endemic areas), false positive results can occur due to cross-reactions with other helminth infections and the long-term persistence of Strongyloides antibodies even after treatment [14]. Overall, only a combination of techniques can be accepted as highly sensitive for the diagnosis of strongyloidiasis [4].
This study assessed the parasitological prevalence, seroprevalence, and risk factors for S. stercoralis infection in PLWH in an endemic area. Our results highlight the urgent need for improved diagnostic tools and expanded public health policies to improve strongyloidiasis diagnosis and treatment strategies for this vulnerable population.
2. Methods
2.1. Ethics statement
The Ethics Committee of Loreto Regional Hospital in Iquitos (Peru) (EXP: ID-018-CIEI-2013) approved this study. After being informed about the study, individuals who volunteered to participate provided written consent to be included. We maintained all the results in strict confidentiality, and those who tested positive for intestinal parasites received free treatment and follow-up by their HIV healthcare provider.
2.2. Study population and inclusion/exclusion criteria
This was an observational, cross-sectional study of PLWH receiving care at one of two hospitals in Iquitos, Peru: (1) the Regional Hospital of Loreto “Felipe Santiago Arriola Iglesias” (which follows patients from the districts of Punchana and Iquitos, but also from the rest of the Loreto Health Department), and (2) the Hospital of Iquitos "César Garayar García" (which follows patients from the districts of Belen and San Juan), from 20 Oct 2023 to 20 May 2024.
We included patients over 18 years with known HIV infection, attending the Regional Hospital of Loreto (located in Iquitos’ Punchana district) or the Hospital of Iquitos (located in Iquitos’ San Juan district) (Fig 1), who were able to provide stool and/or blood specimens. We offered enrollment to both eligible outpatients and inpatients.
From north to south: Punchana district, Iquitos district, San Juan Bautista district and Belen district. The red crosses symbolized the two hospitals included in the study (from north to south: Loreto Regional Hospital and Iquitos Hospital). *Map created with uMap project (version 3.0.6), using data from OpenStreetMap and OpenStreetMap Foundation, licensed under ODbL. https://www.openstreetmap.org/#map=12/-3.7432/-73.2342. Custom data and layers included in this map are licensed under Creative Commons BY-SA 4.0. https://www.openstreetmap.org/copyright/. https://creativecommons.org/licenses/by-sa/4.0/.
2.3. Enrollment procedures
After providing informed consent, study participants provided a stool specimen for S. stercoralis larvae copro-parasitological examination (given the complexity of collecting it at home, only one sample per patient was required), and a blood specimen for S. stercoralis serology. We collected epidemiological demographic and risk factor variables using an oral semi-structured interview and clinical history of the patient, if available.
2.4. Stool examination for S. stercoralis
Each fecal specimen was analyzed using three techniques: direct examination with Lugol’s iodine, modified Baermann technique, and charcoal fecal culture. A specimen was considered positive when S. stercoralis larvae were identified by any of these techniques.
- Modified Baermann technique [15]. Briefly, five grams of fresh feces were placed in the center of a cotton-wool gauze sieve, positioned in a funnel partially submerged in a sedimentation flask filled with water at 37 °C. After one hour at room temperature (25-37ºC), larvae migrated from the fecal suspension into the heated water. The supernatant was discarded, and 1 mL of sediment from the funnel bottom was microscopically examined for the presence of larvae.
- Charcoal culture (Dancescu culture) [16]: Briefly, four grams of fresh feces were mixed with equal parts of distilled water and granulated charcoal. The mixture was placed in a Petri dish, sealed with vinyl tape, and incubated at 30 °C in darkness. The culture was examined with a compound microscope for S. stercoralis adult worm (free-living or filariform) on the second, fourth, and seventh days before discarding the culture.
2.5. S. stercoralis serology
Blood samples were centrifuged at 2058 relative centrifugal force for 10 minutes to separate plasma from erythrocytes. The plasma was stored at -80°C until analysis. For serological testing, we employed a commercially available Strongyloides crude antigen IgG enzyme-linked immunosorbent assay (ELISA), specifically the Strongyloides IgG IVD-ELISA kit (DRG Instruments GmbH, Marburg, 278 Germany, approved by the European Commission). This kit utilizes microtiter wells coated with a soluble fraction of the S. stercoralis L3 filariform larval antigen. All assays were performed following the manufacturer’s protocol. Considering the anticipated high seroprevalence and potential false positives near the manufacturer’s recommended cut-off value (0.200), we conducted duplicate ELISA testing for the initial 100 participants. Based on these preliminary results, we established an optimized cut-off value of 0.220 for determining test positivity.
2.6. Data analysis
Statistical analyses were performed via IBM SPSS Statistics version SPSS 22.0 (IBM, Armonk, EEUU). For descriptive statistics, categorical variables were expressed as frequencies and percentages, while continuous variables were presented as medians with interquartile range (IQR). The 95% confidence intervals were calculated using the Newcombe method [17]. Categorical variables were compared using Chi-square tests, while continuous variables were analyzed using the U-Man Whitney test. Agreement between modified Baermann and charcoal culture results was assessed using Cohen’s Kappa coefficient.
Risk factors for S. stercoralis infection were initially evaluated through bivariate analysis, with associations quantified using ORs. Subsequently, multivariable logistic regression models were constructed to identify independent risk factors for both parasitological S. stercoralis infection and seropositivity to S. stercoralis. These models included age and sex, and variables that showed statistical significance (p ≤ 0.05) in the univariate analyses. The models’ goodness of fit was assessed using CoxSnell R2 and Nagelkerke R2 statistics to determine the strength of association between dependent variables (parasitological infection S. stercoralis infection and seropositivity to S. stercoralis) and independent variables.
We calculated the sensitivity, specificity, positive predictive value and negative predictive value for the ELISA results, along with their respective 95% CIs, using the parasitologic results (i.e., outcomes from the modified Baermann technique and/or charcoal culture) as the reference standard. Same analysis was realized also including other helminths infections, in other to rule out cross-reactions.
3. Results
3.1. Description of the study population and epidemiologic data
For the 537 PLWH included in this study, we obtained serum from 534 and stool from 339 patients (Fig 2). More than 60% were heterosexual men with few comorbidities, and the median age was 41 years (range 32-49) (Table 1). Most patients had well-controlled HIV with an undetectable HIV viral load.
3.2. S. stercoralis stool examination (parasitologic) results
Among the 339 participants with available stool samples, only 1 was positive in the direct exam, while 82 tested positive by the modified Baermann technique and/or charcoal culture (prevalence 24.2%; 95% CI 20.0-29.1%). Five were positive via the Baermann technique alone, 30 via charcoal culture alone, and 47 via both tests. The Kappa index was 0.69 (95% CI: 0.58-0.79), indicating a good correlation between the modified Baermann method and charcoal culture (Table 2).
3.3. Other Helminths isolated in stool examination
Among the 339 patients with stool specimen, 17 (5.0%) were positive for hookworms, 10 (2.9%) for Ascaris lumbricoides, 2 (0.6%) for Hymenolepis nana and 1 (0.3%) for Trichuris trichiura.
Among the 82 patients who were positive for S. stercoralis infection in stool, 15 (18.2%) were also co-infected by hookworms, 6 (7.3%) coinfected by Ascaris lumbricoides and 1 (1%) co-infected by Trichuris trichiura.
3.4. S. stercoralis serologic results
Among the 534 participants with available serum specimens, 227 tested positive by ELISA (seroprevalence: 42.5%; 95% CI 38.1-47.5%).
3.5. Risk factors associated with parasitological S. stercoralis infection
After adjusting for sex, age, and variables with p values ≤ 0.05 in the bivariate analysis (Table 3), the characteristics most strongly associated with parasitological infection of S. stercoralis in PLWH were belonging to the Loreto Regional Hospital catchment area (adjusted OR: 5.43), living in a rural area (adjusted OR: 1.86), living in a house made of wood/leaves (adjusted OR: 2.18) and having hookworms in stools (adjusted OR: 23.88) (Fig 3a). The model’s Cox–Snell R2 value was 0.18 and the Nagelkerle R2 value was 0.27, with an AUC of 0.76 (95% CI 0.70 – 0.82, p < 0.001).
b. Independent Predictors of S. stercoralis seropositivity (defined by positive ELISA in serum) from Multivariable Logistic-Regression Analysis.
3.6. Risk factors associated with S. stercoralis seropositivity
After adjusting by sex, age, and variables with p values ≤ 0.05 in the bivariate analysis (Table 4), four variables had a significant association with S. stercoralis seropositivity: belonging to Loreto Regional Hospital catchment area (adjusted OR: 3.88), living in a house made of wood/leaves (adjusted OR: 2.82), having hookworms in stools (adjusted OR: 9.78), and having a low level of education (illiteracy or primary school) (adjusted OR 2.42) (Fig 3b). The model’s Cox–Snell R2 value was 0.17 and the Nagelkerle R2 value was 0.23, with an AUC of 0.72 (95% CI 0.67 – 0.78, p < 0.001).
3.7. Detection of S. stercoralis by serology versus stool examination
A total of 354 participants had both stool and serologic results. With the modified Baermann technique and/or charcoal culture as the parasitological reference standard, ELISA had a sensitivity of 92.6% and a negative predictive value of 96.9% (Table 5).
Only one hookworm infection was found to have a positive serology in absence of S. stercoralis stool infection.
Discussion
We detected a high prevalence of S. stercoralis infections in this population; approximately 1 in 4 PLWH had S. stercoralis larvae identified in stool and the seroprevalence was higher than 40%. These findings underscore the importance of developing public health campaigns to screen populations living in tropical regions for S. stercoralis infection. Published data describing S. stercoralis prevalence among PLWH are scarce [8,18]. Most publications suggest a higher risk of co-infection with S. stercoralis in PLWH versus the general population [19–21], although PLWH do not seem to have a higher risk of disseminated strongyloidiasis, probably due to their protective Th2 cytokine patterns [22–24]. S. stercoralis prevalence is likely highest in impoverished tropical areas such as the Peruvian Amazon basin, although no prior studies exist of S. stercoralis infection in PLWH living in this region [5].
Regarding available epidemiologic data for strongyloidiasis in Latin America, a recent systematic review estimated the global pooled prevalence of HIV and S. stercoralis co-infection to be 5%, and as high as 8% in some Caribbean and Latin American countries (including Cuba, Bazil, and Venezuela) [22]. Studies of strongyloidiasis in Brazil, a large country that shares Amazonian areas with Peru, indicate varied prevalences in PLWH, from 2-4% in the subtropical city of Sao Paulo [25,26], to 12% in the high altitude tropical city of Minas Gerais [27] and 30% in the northeastern tropical city of Fortaleza [28]. In this last study, conducted in an area similar to ours, S. stercoralis prevalence was significatively higher in PLWH than in general population: 30% vs 11%. A Colombian cohort of PLWH demonstrated 0.5% stool prevalence of S. stercoralis, but, notably, the investigators performed only one stool test specific for S. stercoralis (agar culture). Ehsan et al. [18], in one of the few meta-analyses describing geographical S. stercoralis prevalence in PLWH, reported a pooled stool prevalence of 6.9% in Peru. To the best of our knowledge, our study is the first to provide strongyloidiasis prevalence data for one of the largest cohorts of PLWH in the Peruvian Amazon.
Expanding our review of the HIV-S. stercoralis coinfection literature to outside of Latin America, several publications of Asian and African PLWH utilized specific S. stercoralis techniques to evaluate prevalence in stool specimens. One study of nearly 1,500 PLWH from eastern India found a stool prevalence of 3.76% [29]. Similar studies describe stool prevalence of 10.8% in Laos [30], 2.4-11.5% in Ethiopia [31,32], and 8.2% in Uganda [33]. Therefore, globally, most studies of stool specimens of PLWH reveal a lower prevalence of S. stercoralis than our study.
Studies of S. stercoralis in populations without HIV living in or near Iquitos report a 10% stool prevalence among pregnant women [10], 8.7% among people living along the Nanai River [11], and 10.5% among children living in Padre Cocha [13]. Several studies published prevalences closer to ours: 16% in schoolchildren in San Martin in 1999 and 19.5% in outpatients with diarrhea in Madre de Dios in 2001 [10]. Gallardo et al. [12] reported one of the highest prevalences (28.8%), while studying stools of another vulnerable population, soldiers, in 2015. Finally, a 2005 study in a rural community of the Pasco region, which is further from Iquitos but still within the Amazon, concluded a higher prevalence than ours, 38.5% [34].
Regarding seropositivity, we found a 42.5% Strongyloides seroprevalence in our cohort of PLWH. Studies of other populations living in or near Iquitos also describe high seroprevalences, including 72% in a rural community 15 km from Iquitos [11], 65% in recently published cross-sectional study in general population [35], and 33% in pregnant women [10], being the latter two studies conducted by our research group, with a median difference of prevalence between stool and serum of approximately 20% [36]. Outside Latin America, Asia is the continent best represented, from which studies report seroprevalence rates ranging between 20% and 45% and indicate that seroprevalence increases with the population’s degree of rurality or distance from health care [37–39].
In areas of high endemicity, Strongyloides crude antigen IgG ELISA is known to have a lower specificity compared to reference stool tests because (1) Strongyloides IgG antibodies persist for many years after treatment and (2) the crude antigen lysate allows for cross-reactivity with other helminths that can be co-endemics with S. stercoralis [40]. Besides, ELISA´s sensitivity may be reduced in patients with AIDS due to impaired immune responses to the parasite [41]. In our study, the specificity of the ELISA was close to 70%, similar to a study of pregnant women in Iquitos performed with the same test [10], probably due to the persistence of antibodies in an endemic area (only one patient had a positive ELISA for S. stercoralis with a discordant parasite in stool). About ELISA’s sensitivity and negative predictive value, they were greater than 90%, higher than in the previously cited study, where it only reached 70% [10]. The higher cutoff point that we chose for this study could be responsible for this improvement.
Although various immunocompromising conditions have been associated with Stronglyoides hyperinfection syndrome, HTLV-1 infection (also present in Iquitos, with an estimated prevalence in general population of 1–2% [10,35] but unknown between PLWH), and iatrogenic immunosuppression via corticosteroid use are the most consistent associations [8]. PLWH, especially those with AIDS, are a vulnerable group with a relatively high utilization of corticosteroid therapy [23]. Previous investigations in PLWH [18,25,32,42] suggest that the socioeconomic status, AIDS stage, alcoholism or male gender may contribute to risk for S. stercoralis infection in this group [8,21].
Studies evaluating specific risk factors are rare. In our cohort, adjusted risk of S. stercoralis stool positivity was higher among PLWH living in a house made of wood/leaves (used as a proxy for low socioeconomic status), in a rural area (defined by the presence of unpaved streets, regardless of housing material), or with a low level of education. These findings are consistent with well-established risk factors, including poor sanitation, contact with fecal contaminated soil due to lifestyle practices, limited access to healthcare, and overall socioeconomic vulnerability [5,23,43,44]. Additionally, we found that study participants attending Loreto Regional Hospital —an urban area in the confluence of two major rivers—, had a higher risk of S. stercoralis infection than those attending Iquitos Hospital. Loreto Regional Hospital is the referral hospital for people from river communities with limited access to potable water, which may explain our results. This data also could be influenced by the higher amount of patients collected in this Hospital. Hookworm infection in stool was significantly associated with both S. stercoralis infection and seropositivity. This co-occurrence has been discussed in previous literature, as the distribution of both helminths often overlaps due to similar biological and epidemiological characteristics. Consequently, hookworm has been proposed as a proxy indicator for estimating the global burden of strongyloidiasis [11,45]. Although cross-reactivity in serology remains a concern, it did not affect ELISA´s specificity in our cohort, as previously discussed.
In our study, AIDS stage was not significantly associated with either S. stercoralis stool positivity or seropositivity [33]. A viral load >2000 copies/ml was significantly associated with seropositivity in the bivariate analysis, though not in the multivariate analysis. However, the substantial amount of missing data on CD4 count and viral load limits the strength of conclusions regarding the association between poor immunovirological control and infection risk. Other previously described risk factors, including a non-heterosexual sexual orientation [25,20], low educational level, agricultural occupation [31], and male sex [18,43], were borderline-associated with S. stercoralis seropositivity in the bivariate analysis but not found to be significant risk factors in the multivariate analysis. Deworming treatment within the past six months appeared protective against S. stercoralis stool positivity in the bivariable analysis but was not significant in the multivariate analysis [33]. Although albendazole (administered twice over three days) may explain this effect, many participants could not recall the exact drug dosage, which may have influenced the results.
A key strength of this study is its comprehensive approach to evaluate S. stercoralis infection in PLWH, utilizing two complementary classes of tests: parasitological analysis of stool samples and serological testing. Additionally, the study focuses on a population from a highly endemic Amazonian region, providing valuable epidemiological insights into an area where data on this common coinfection are scarce. Our large sample size further strengthens the reliability and generalizability of the findings.
This study has several limitations. First, we collected and analyzed only a single stool sample, which may have underestimated the true prevalence of S. stercoralis [46]. Analyzing three samples could have improved the detection rate of active infection [47]. To mitigate this limitation, we used two different parasitological techniques to enhance the sensitivity of larval detection. Second, the absence of molecular techniques, (e.g., PCR), which are highly sensitive and useful for identifying low-level infections, may have limited diagnostic accuracy. Additionally, our cohort primarily included PLWH who were actively engaged in routine care, possibly underrepresenting individuals not accessing care—who may be at greater risk of infection. Finally, the large amount of missing data on CD4 and viral load hindered our ability to fully explore associations between immunovirological control and infection risk. While our findings highlight a high burden of S. stercoralis in the Amazon, they may not be generalizable to regions with different epidemiological contexts.
Conclusion
Infection with Strongyloides stercoralis is common and potentially serious among people living with PLWH in Iquitos and the surrounding areas, affecting nearly one in four individuals, primarily from impoverished backgrounds. It is essential to implement a routine screening program for S. stercoralis, especially at the time of entry into HIV care and during follow-up visits, due to the risk of reinfection. This measure could reduce Strongyloides-related morbidity and prevent severe complications, such as Strongyloides hyperinfection syndrome.
Furthermore, our findings underscore the urgent need for large-scale public health interventions, including deworming protocols targeted at vulnerable populations and improved access to effective screening and diagnostic tools tailored to low resource endemic regions. Proactively working toward the control of strongyloidiasis will not only improve the quality of life for PLWH but also reduce the broader public health burden in Amazonian areas.
Supporting information
S1 File. Graphical abstract summarizing the study protocol and its main results.
https://doi.org/10.1371/journal.pntd.0013231.s001
(TIF)
Acknowledgments
We want to thank the medical staff of the Infectious Diseases Service in Loreto Regional Hospital and Iquitos Hospital, together with the laboratory staff of LIPNAA-CIRNA and Asociación Civil Selva Amazónica for the support on the field.
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