Introduction
Strongyloidiasis is a neglected parasitic disease caused by the geohelminth Strongyloides stercoralis, which remains a global public health issue. Despite its varied clinical manifestations, asymptomatic cases and low-sensitivity diagnostic methods contribute to high levels of underreporting (Czeresnia and Weiss Reference Czeresnia and Weiss2022; Luvira et al. Reference Luvira, Siripoon, Phiboonbanakit, Somsri, Watthanakulpanich and Dekumyoy2022).
Strongyloidiasis has a high prevalence worldwide, with an estimated 600 million infected individuals, especially those in tropical and subtropical areas exposed to poor sanitary conditions (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020; Yang et al. Reference Yang, Xu, Zhang, Liao, Liu, Deng and Wang2024). In addition to its high prevalence, the infection by S. stercoralis raises concerns as it can persist for long periods within the host and potentially progress to death, particularly in cases of immunosuppression (Czeresnia and Weiss Reference Czeresnia and Weiss2022; Yang et al. Reference Yang, Xu, Zhang, Liao, Liu, Deng and Wang2024).
S. stercoralis has a complex life cycle. It has both free-living and parasitic phases (Page et al. Reference Page, Judd and Bradbury2018; Yeh et al. Reference Yeh, Aggarwal, Carrig, Azeem, Nguyen, Devries, Destache, Nguyen and Velagapudi2023). Infection occurs primarily through the cutaneous route, where the filariform larvae, present in the soil, penetrate the human skin and migrate through the circulation to the lungs (Czeresnia and Weiss Reference Czeresnia and Weiss2022). Moreover, infection can also occur through the ingestion of filariform larvae-contaminated food and water or through anal-oral contact, enabling an autoinfection cycle that can persist for decades (Czeresnia and Weiss Reference Czeresnia and Weiss2022; Luvira et al. Reference Luvira, Siripoon, Phiboonbanakit, Somsri, Watthanakulpanich and Dekumyoy2022; Yang et al. Reference Yang, Xu, Zhang, Liao, Liu, Deng and Wang2024).
Once the S. stercoralis infection is established in humans, varied clinical manifestations may occur. Factors such as parasitic load and host immunity are linked to severity. The infection can be classified as acute, chronic, hyperinfection syndrome or as disseminated infection (Luvira et al. Reference Luvira, Siripoon, Phiboonbanakit, Somsri, Watthanakulpanich and Dekumyoy2022). Larvae migration can transport microorganisms from the gastrointestinal tract to other tissues, resulting in concomitant bacterial infections (Yeh et al. Reference Yeh, Aggarwal, Carrig, Azeem, Nguyen, Devries, Destache, Nguyen and Velagapudi2023). The disseminated form of infection is associated with intravascular coagulation, aseptic meningitis, and renal and respiratory failure. Thus, a high mortality rate of 87.1% is reported, highlighting the need for strongyloidiasis control programs (Yeh et al. Reference Yeh, Aggarwal, Carrig, Azeem, Nguyen, Devries, Destache, Nguyen and Velagapudi2023).
Strongyloidiasis diagnosis consists of observing larvae in fecal samples; however, larvae elimination is intermittent and limited, especially in the chronic phase of the disease. This contributes to the low sensitivity of the fecal examination, necessitating the analysis of up to 7 fecal samples (Costa et al. Reference Costa, Bosqui, Corral, Costa-Cruz, Gryschek and de Paula2021; Page, Judd and Bradbury Reference Page, Judd and Bradbury2018). Even so, due to its low cost, this technique remains the predominant method utilized in endemic areas, while serological and molecular methods of greater specificity and sensitivity are rarely implemented in these regions (Bosqui et al. Reference Bosqui, Corral, Levy, Bydlowski, Gryschek, Custódio, Pavanelli, Conchon-Costa, Costa-Cruz, de Paula and Costa2020; Bosqui et al. Reference Bosqui, da, Gonzaga, Gonçalves, Custodio, Pavanelli, Conchon-Costa, Costa-Cruz and Costa2021; Costa et al. Reference Costa, Bosqui, Corral, Costa-Cruz, Gryschek and de Paula2021). Thus, the ability of the infection to remain clinically asymptomatic and chronically unnoticed, along with diagnosis failure, allows the accelerated reproduction of larvae, leading to their dissemination (Schär et al. Reference Schär, Trostdorf, Giardina, Khieu, Muth, Marti, Vounatsou, Odermatt and Steinmann2013).
Treatment reduces morbidity and mortality, as well as interrupts the parasite cycle, preventing autoinfection and hetero-infection. Mass drug administration of ivermectin as a control strategy is being investigated by the World Health Organization (WHO) in endemic locations (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020; Collyer and Anderson Reference Collyer and Anderson2024; WHO 2020a). The implementation of control measures is a determining factor strongly associated with Strongyloidiasis prevalence in different populations and regions (Gordon et al. Reference Gordon, Utzinger, Muhi, Becker, Keiser, Khieu and Gray2024; Page, Judd and Bradbury Reference Page, Judd and Bradbury2018).
It is known that the global prevalence of the disease, however, is often underestimated due to low diagnostic sensitivity, contributing to its underreporting (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020; Luvira et al. Reference Luvira, Siripoon, Phiboonbanakit, Somsri, Watthanakulpanich and Dekumyoy2022; Requena-Méndez et al. Reference Requena-Méndez, Chiodini, Bisoffi, Buonfrate, Gotuzzo and Muñoz2013). Globally, it is estimated that approximately 614 million people are infected annually by S. stercoralis and 2.6 billion are at risk of infection (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020; Fleitas et al. Reference Fleitas, Travacio, Echazú, Gil, Goyeneche, Cajal, Krolewiecki and Mena2022). In tropical and subtropical regions, where humidity and high temperatures allow higher chances of survival and successful development of larval forms, between 10% and 40% of the population are affected (Vasquez-Rios et al. Reference Vasquez-Rios, Paredes, Guevara-Silva, Briceño-Mayorga, Soto-Fernández and Ticona2019).
Foci of infection occur mainly in places of poor sanitation, facilitating its transmission through fecal contamination (Schär et al. Reference Schär, Trostdorf, Giardina, Khieu, Muth, Marti, Vounatsou, Odermatt and Steinmann2013). Due to the significant size of the affected and at-risk population and its relation to poverty and lack of adequate water and sanitation conditions, strongyloidiasis is classified as a neglected tropical disease (NTD) (WHO 2017). Despite its significant impact on public health, there are no control strategies implemented at the global level or in endemic regions. However, this scenario is expected to change with the recent inclusion of strongyloidiasis by WHO in the 2021–2030 strategic road map for the control of neglected tropical diseases (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020; WHO 2020a; WHO 2023).
Several regions of Brazil offer ideal environmental and sanitary conditions for the development and persistence of S. stercoralis larvae (Carmo et al. Reference Carmo, Perez, Gerolomo, Silva and RMS2005; Schär et al. Reference Schär, Trostdorf, Giardina, Khieu, Muth, Marti, Vounatsou, Odermatt and Steinmann2013). Thus, according to a meta-analysis on the global prevalence of S. stercoralis, Brazil and Thailand emerge as the main foci of strongyloidiasis with prevalence rates ranging from 10.8% to 17% and 23.7% to 34.7%, respectively (Schär et al. Reference Schär, Trostdorf, Giardina, Khieu, Muth, Marti, Vounatsou, Odermatt and Steinmann2013).
Accurate characterization of strongyloidiasis epidemiology is the first step toward implementing disease control programs, according to WHO (2020b). However, the epidemiology of strongyloidiasis is poorly documented or completely unknown in several countries (WHO 2020b; WHO 2023). This lack of comprehensive epidemiological data results in a limited knowledge of the real public health impact of the disease, since most deaths caused by the parasite go undetected (Buonfrate et al. Reference Buonfrate, Bisanzio, Giorli, Odermatt, Fürst, Greenaway, French, Reithinger, Gobbi, Montresor and Bisoffi2020). Therefore, this literature review aims to summarize reports of the prevalence and factors associated with strongyloidiasis in Brazil, a place considered a hotspot for the disease, in order to contribute to the formulation of prevention and control strategies for this parasitosis (Luvira et al. Reference Luvira, Siripoon, Phiboonbanakit, Somsri, Watthanakulpanich and Dekumyoy2022).
Methods
Articles published between 2005 and 2025 were obtained by using the following keywords: Strongyloidiasis; Brazil; Strongyloides stercoralis; and Epidemiology. These terms were searched in the title and abstract fields. The databases used were PubMed, Science Direct, Scielo and LiLacs. A total of 88 scientific articles were obtained with this search, of which only 33 were retained for this study. Exclusion criteria included review articles, editorials, or other publications without primary research data, duplicated papers, and experimental studies lacking data on S. stercoralis (Figure 1).
Figure 1. Flowchart of the selection process of the studies included in this review. The flowchart illustrates the stages of literature search, of screening, and of inclusion of articles, including the number of records identified in each database, the applied exclusion criteria, and the final number of studies retained.
Results and discussion
An examination of the included articles revealed that most of the published works were concentrated in the Southeast region of the country, predominantly in the state of Minas Gerais (21.6%), which also had the highest number of publications in the country, followed by São Paulo (18.9%), Rio de Janeiro (10.8%) and Espírito Santo (2.7%). The Northeast region had the second-highest number of publications, with the state of Ceará having the largest number of published works in this region (8.1%), followed by Bahia (5.4%). In the South region, the state of Paraná had the largest number of studies (5.4%). The North and Central-West regions had the smallest number of published works, with a very similar distribution between them, both registering only 2.7% of all articles included in this review (Figure 2).
Figure 2. Geographic distribution of the number of published studies on the epidemiology of strongyloidiasis in Brazil, divided by state. The map highlights the regions with the highest number of studies according to scale on the right, represented as percentages (%). Gray areas indicate states with no studies found.
Table 1 presents the geographical regions of the retained articles, listed in decreasing order by the number of articles. The table also provides information on the positivity rate for S. stercoralis, the population analyzed, associated comorbidities, and the type of analysis used to obtain the results in each study.
Table 1. Summary of the studies found regarding the epidemiology of strongyloidiasis in Brazil. The data include the region and state where the study was conducted, positivity rate, population group and associated comorbidities, diagnostic method, and reference
The publications examined in this review demonstrate a wide distribution of strongyloidiasis and report considerably variable prevalence rates. However, these estimates should be interpreted with caution, as many studies are based on small sample sizes, which may compromise the reliability of the reported data. Robust prevalence estimates are still scarce in most regions due to the limited number of investigations and the use of small sample sizes. The observed variation may also be influenced by the diagnostic methods employed, the population profiles investigated, and the methodological approaches used. In Brazil, this disease is neglected and is not subject to mandatory reporting, which limits the accurate identification of at-risk populations. Additionally, the available studies usually investigate parasitic infections in general, with no specific focus or direct association with strongyloidiasis (Governo do Brasil (GOV) 2025; WHO 2023).
In regard to gender, some publications suggest a possible association between S. stercoralis infection and males (Bachur et al. Reference Bachur, Vale, Coêlho, Queiroz and Chaves2008; Barreto et al. Reference Barreto, Farias, Oliveira, Araujo, Grassi, de Souza, Jacobina, Teixeira, Galvao-Castro and Soares2022; Bueno et al. Reference Bueno, Reis, Corrêa, Schiavon and Narciso-Schiavon2015; Cabral et al. Reference Cabral, Iniguez, Brown, Buoy and Carvalho-Costa2015; Faria et al. Reference Faria, Zanini, Dias, da Silva, de Freitas, Almendra, Santana and Sousa2017; Naves and Costa-Cruz, Reference Naves and Costa-Cruz2013; Santarém et al. Reference Santarém, Doline, dos Santos, Ferreira, Gomes, Meisel, Biondo, Lescano, Gryschek, Giuffrida, Dos Santos, Kmetiuk, de Paula and Biondo2023; Valverde et al. Reference Valverde, Gomes-Silva, De Carvalho Moreira, Leles De Souza, Jaeger, Martins, Meneses, Bóia and Carvalho-Costa2011). According to these authors, adult males may be more exposed to the infective forms due to occupational or behavioral factors. In Florianópolis (SC), the infection rate was 1.1% among men and 0.3% among women (Bueno et al. Reference Bueno, Reis, Corrêa, Schiavon and Narciso-Schiavon2015). However, such differences should be interpreted with caution, especially in studies with small sample sizes, since the statistical significance of these variations is not always clear (Bueno et al. Reference Bueno, Reis, Corrêa, Schiavon and Narciso-Schiavon2015). Furthermore, the prevalence of S. stercoralis infection tends to increase with age, being more frequent among adults and the elderly. In Uberlândia (MG), a study conducted with institutionalized elderly demonstrated a prevalence rate of 5% (Naves and Costa-Cruz Reference Naves and Costa-Cruz2013). However, children, even in areas with high endemicity, had a lower infection rate (1.3%) (Machado et al. Reference Machado, Santos and Costa-Cruz2008). This may indicate lower environmental exposure, although this difference should also be analyzed with caution. The hypothesis of increased susceptibility with age has been proposed by some authors and may be related to cumulative exposure and immunological changes (Monteiro et al. Reference Monteiro, Soares, de O Ramalho, Cavalcante, Silva, Vianna, Freitas, de and CMB de L2018; Moura et al. Reference Moura, Ramos, Colombo, Aidar, Hernández, Silva and Oliveira2017).
In Indigenous communities from different regions, varying S. stercoralis infection rates have been reported. In the South and Southeast region, particularly in the states of Paraná and São Paulo, a high seroprevalence of 37.6% was observed among the Guarani, Terena, and Kaingang ethnic groups. This high rate is possibly attributed to the lifestyle of these populations and poor sanitation conditions (Santarém et al. Reference Santarém, Doline, dos Santos, Ferreira, Gomes, Meisel, Biondo, Lescano, Gryschek, Giuffrida, Dos Santos, Kmetiuk, de Paula and Biondo2023). However, in Minas Gerais state, the infection was identified in a smaller proportion of the Maxakali Indigenous group (5.4%) (Assis et al. Reference Assis, Oliveira, Moreira, Pena, Rodrigues and Machado-Coelho2013), and the prevalence of strongyloidiasis was 0.97% among Indigenous people in the state of Mato Grosso do Sul (Barbosa et al. Reference Barbosa, Barreto, Andrade, Sodré, d’Avila-Levy, Peralta, Igreja, de Macedo and Santos2018). Such differences may be attributed to variations in diagnostic methods, environmental and socioeconomic factors, or study sampling. In this context, associated risk factors may include environmental habits linked to hunting and fishing, lack of water treatment and septic tanks, and vulnerable socioeconomic conditions (Valverde et al. Reference Valverde, Gomes-Silva, De Carvalho Moreira, Leles De Souza, Jaeger, Martins, Meneses, Bóia and Carvalho-Costa2011).
Additionally, healthcare professionals working in these regions had an even higher seroprevalence (52.4%), suggesting a potential occupational risk linked to their professional activities, as they were 1.83 times more likely to be infected than the Indigenous individuals themselves (Santarém et al. Reference Santarém, Doline, dos Santos, Ferreira, Gomes, Meisel, Biondo, Lescano, Gryschek, Giuffrida, Dos Santos, Kmetiuk, de Paula and Biondo2023).
S. stercoralis infection has also been investigated in transplant patients in several centers in the Southeast and Northeast regions of Brazil. Positivity among these patients varied, with studies reporting a rate of 2.4% in São Paulo, Uberlândia, and Belo Horizonte, while only 53 cases tested positive out of more than 15,000 patients analyzed in centers from Rio de Janeiro, São Paulo, and Ceará (Batista et al. Reference Batista, Pierrotti, Abdala, Clemente, Girão, Rosa, Ianhez, Bonazzi, Lima, Fernandes, Pádua-Neto, Bacchella, Oliveira, Viana, Ferreira and Shikanai-Yasuda2011; Miglioli-Galvão et al. Reference Miglioli-Galvão, Pestana, Santoro-Lopes, Torres Gonçalves, Requião Moura, Pacheco Silva, Camera Pierrotti, David Neto, Santana Girão, Costa de Oliveira, Saad Abboud, Dias França, Devite Bittante, Corrêa and Aranha Camargo2020). Other rates of S. stercoralis infection ranging from 0.11% to 10% have also been reported (Paula et al. Reference Paula, Malta, Marques, Melo, Corral, Gottardi, Pinho, Gonçalves, Castilho, Pierrotti, Abdala, Costa, Chieffi and Gryschek2018; Miglioli-Galvão et al. Reference Miglioli-Galvão, Pestana, Santoro-Lopes, Torres Gonçalves, Requião Moura, Pacheco Silva, Camera Pierrotti, David Neto, Santana Girão, Costa de Oliveira, Saad Abboud, Dias França, Devite Bittante, Corrêa and Aranha Camargo2020). Although the overall incidence is low, transplant patients are more susceptible to severe forms of the disease, with high mortality rates, especially when the infection occurs in the first months after transplantation. Factors such as receiving a graft from a deceased donor, cumulative corticosteroid use, and previous bacterial infection were identified as risk factors for the severity of strongyloidiasis in this population (Miglioli-Galvão et al. Reference Miglioli-Galvão, Pestana, Santoro-Lopes, Torres Gonçalves, Requião Moura, Pacheco Silva, Camera Pierrotti, David Neto, Santana Girão, Costa de Oliveira, Saad Abboud, Dias França, Devite Bittante, Corrêa and Aranha Camargo2020; Gryschek et al. Reference Gryschek, Corral, Sitta, Gottardi, Pierrotti, Costa, Abdala, Chieffi and de Paula2023; Corral et al. Reference Corral, Meisel, Gouvêa, Pessoa, Abdala, Terrabuio, da Costa, de Paula and Gryschek2024).
Across urban and rural areas of different states, the prevalence rate of S. stercoralis varied. In Bahia, a prevalence of 4.7% was recorded among residents of rural areas, while the rural region of Sumidouro (RJ) had a high rate of general intestinal parasitism (64.3%), but low prevalence of strongyloidiasis (0.97%). In contrast, the metropolitan region of Rio de Janeiro had positivity rates of 4.3% (Faria et al. Reference Faria, Zanini, Dias, da Silva, de Freitas, Almendra, Santana and Sousa2017; Barbosa et al. Reference Barbosa, Barreto, Andrade, Sodré, d’Avila-Levy, Peralta, Igreja, de Macedo and Santos2018; Farias et al. Reference Farias, Barreto, Araújo, Oliveira, Gonçalves, Campagnollo, Teixeira, Galvão-Castro, Soares and Souza2023). Located in the non-metropolitan area of São Paulo state, the city of Araraquara had a positivity rate of 6.7%, higher than that of Marília (1.16%) which is also in the inland region of São Paulo (Miné et al. Reference Miné and da Rosa2008; Martins et al. Reference Martins, Castanho, Chagas and Martins2019). In Alfenas (MG), serological diagnostic methods revealed a high positivity of 53.9%, with higher occurrence in peripheral neighborhoods (Nunes et al. Reference Nunes, Emídio, Marques, Caldas, Souza, Kanamura and Costa-Cruz2018). Several authors have linked these infection rates to inadequate sanitation conditions and direct soil contact (Barbosa et al. Reference Barbosa, Barreto, Andrade, Sodré, d’Avila-Levy, Peralta, Igreja, de Macedo and Santos2018; Neres-Norberg et al. Reference Neres-Norberg, Guerra-Sanches, Blanco Moreira-Norberg, Madeira-Oliveira, Santa-Helena and Serra-Freire2014).
Studies conducted with specific groups, such as alcoholics, have also been analyzed and have demonstrated greater vulnerability of this population to infection by S. stercoralis. A group of alcoholics in Vitória (ES) and Salvador (BA) exhibited significantly high positivity rates of 20.5% and 23.5%, respectively. This greater susceptibility in alcoholics may be related to the fact that chronic alcoholism favors infection through multifactorial mechanisms, including malnutrition, poor hygiene, and immunosuppression. Additionally, high cortisol levels were observed in a group of infected alcoholics, suggesting a possible association with high parasite load and increased risk of hyperinfection (Marques et al. Reference Marques, da Penha Zago-Gomes, Gonçalves and Pereira2010; Silva et al. Reference Silva, Inês, Souza, Dias, Guimarães, Menezes, Barbosa, Alves, Teixeira and Soares2016). These findings indicate that social and occupational factors may contribute to an increased risk of exposure to S. stercoralis infection.
The relationship between S. stercoralis and immunosuppression is another important factor that has been investigated in Human Immunodeficiency Virus (HIV) and Human T-lymphotropic Virus (HTLV) carriers. In Jataí (GO), S. stercoralis infection was identified in 3.8% of HIV-positive patients, while in Fortaleza (CE), it reached a rate of 30.1% (Bachur et al. Reference Bachur, Vale, Coêlho, Queiroz and Chaves2008; Barcelos et al. Reference Barcelos, Silva, Dias, Menezes Filho and Rodrigues2018). At the Casa da Aids reference center in São Paulo, the positivity rate was only 0.14%, possibly influenced by the use of antiretroviral therapy (HAART); in a similar manner, in Fortaleza (CE), only 11% of patients in HAART were positive, indicating that the treatment can have a protective effect against these infections (Bachur et al. Reference Bachur, Vale, Coêlho, Queiroz and Chaves2008; Werneck-Silva et al. Reference Werneck-Silva and Prado2009). Patients with HTLV also presented significant infection rates, with prevalences of 3.4% in Salvador (BA) and 9% in Belém (PA), where cases of hyperinfection were observed in patients co-infected with HTLV-1, especially among those with unfavorable socioeconomic conditions (Barreto et al. Reference Barreto, Farias, Oliveira, Araujo, Grassi, de Souza, Jacobina, Teixeira, Galvao-Castro and Soares2022; Furtado et al. Reference Furtado, Costa, Ferreira, Martins, Linhares, Ishikawa, Batista and Sousa2013).
The analysis of the selected studies also indicated that the diagnosis of S. stercoralis in Brazil is mainly based on traditional coproparasitological examinations, such as the Graham, Baermann-Moraes, Ritchie, and Hoffman techniques, often using three fecal samples. Studies that utilized serological diagnostic methods demonstrated a high prevalence of anti-S. stercoralis antibodies among different populations, although these findings should be approached with caution, considering potential methodological differences and limitations in study design (Barreto et al. Reference Barreto, Farias, Oliveira, Araujo, Grassi, de Souza, Jacobina, Teixeira, Galvao-Castro and Soares2022; Bosqui et al. Reference Bosqui, Gonçalves, Gonçalves-Pires, Custodio, de Menezes, Murad, de Paula, Pavanelli, Conchon-Costa, Costa-Cruz and Costa2015; Gonzaga et al. Reference Gonzaga, Mendonça, Gonçalves, Ferreira-Júnior, Rodrigues, Gonçalves-Pires, Feliciano, Ribeiro and Costa-Cruz2023; Nunes et al. Reference Nunes, Emídio, Marques, Caldas, Souza, Kanamura and Costa-Cruz2018; Santarem et al. 2023). In the same manner, the use of molecular techniques such as PCR and qPCR exhibited greater sensitivity in parasite detection compared to parasitological methods (Paula et al. Reference Paula, Malta, Marques, Melo, Corral, Gottardi, Pinho, Gonçalves, Castilho, Pierrotti, Abdala, Costa, Chieffi and Gryschek2018). The literature emphasizes the need for the complementary use of parasitological, immunological, and molecular methods to achieve a more accurate and reliable diagnosis, where molecular techniques play a crucial role in confirmation due to their high sensitivity and specificity.
Regarding strongyloidiasis treatment in Brazil, regional and population-specific variations were identified. While thiabendazole was given in isolated cases in endemic areas of the Amazon (Valverde et al. Reference Valverde, Gomes-Silva, De Carvalho Moreira, Leles De Souza, Jaeger, Martins, Meneses, Bóia and Carvalho-Costa2011), the administration of ivermectin resulted in parasitological cure in all individuals diagnosed with strongyloidiasis (Farias et al. Reference Farias, Barreto, Araújo, Oliveira, Gonçalves, Campagnollo, Teixeira, Galvão-Castro, Soares and Souza2023). In immunocompromised patients, specifically those with HIV infection and Acquired Immunodeficiency Syndrome (AIDS), the use of antiretroviral therapy (HAART) has been shown to exert a protective effect, contributing to a reduction in the prevalence of enteric parasites, including strongyloidiasis (Barcelos et al. Reference Barcelos, Silva, Dias, Menezes Filho and Rodrigues2018; Werneck-Silva et al. Reference Werneck-Silva and Prado2009), whereas among patients undergoing kidney transplantation who developed severe S. stercoralis infection, the use of ivermectin, either alone or combined with albendazole, was a common practice. However, in individuals with compromised immune responses, the efficacy of anthelmintic drugs, including azoles and ivermectin, may be limited, requiring prolonged therapeutic regimens and strict monitoring. Additionally, prophylactic treatment with ivermectin is recommended for patients who initiate corticosteroid therapy and for those with positive serology or a history of exposure to strongyloidiasis (Keiser et al. Reference Keiser and Nutman2004; Miglioli-Galvão et al. Reference Miglioli-Galvão, Pestana, Santoro-Lopes, Torres Gonçalves, Requião Moura, Pacheco Silva, Camera Pierrotti, David Neto, Santana Girão, Costa de Oliveira, Saad Abboud, Dias França, Devite Bittante, Corrêa and Aranha Camargo2020).
In summary, the available data indicates that the prevalence of S. stercoralis in Brazil is heterogeneous and difficult to quantify precisely, given the variability of diagnostic methods and limited study sample of many publications. Although high rates have been reported among some Indigenous communities and vulnerable populations, especially in the Southeast and Northeast regions, these findings warrant cautious interpretation. Precarious socioeconomic conditions and lack of basic sanitation emerge as consistent risk factors in several populational groups, also emphasizing that the choice and sensitivity of diagnostic methods influence the results of studies, thus reinforcing the need for complementary approaches for a more accurate diagnosis. Therefore, interpretations regarding the distribution of S. stercoralis infection must take the reported limitations into account, avoiding extrapolations and highlighting the need for further studies with more comprehensive data.
Conclusion
The data compiled in this review suggest that the prevalence of strongyloidiasis is probably underestimated in the literature, considering the limitations of available diagnostic methods and high rates of false-negative results, especially in asymptomatic patients. Thus, the analysis of multiple samples can contribute to a more precise diagnosis. Moreover, the scarcity of studies focused exclusively on this disease also poses a challenge to an accurate estimative of its real magnitude in Brazil. It was observed that Southeast and Northeast regions concentrated the majority of publications, with particular emphasis on the Minas Gerais state for the highest number of published works. Overall, the findings of this review underscore the need of expanding scientific research on strongyloidiasis in the country, as a crucial step toward furthering the knowledge of its distribution and strengthening its recognition as a neglected disease.
Competing interests
The authors declare none.
Financial support
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
