Parasitologia

Endosymbiosis is a necessary process in eukaryotic evolution, yet the steps leading to full integration remain poorly understood. Trypanosomatids provide a comparative framework to study this transition through two independent systems representing distinct levels of integration. Strigomonadinae comprises a subfamily derived from a single ancestral acquisition, which maintains a single cytosolic bacterium closely synchronized with the host cell cycle. In contrast, Novymonas esmeraldas harbors multiple bacteria within symbiontophorous vacuoles, presenting a more limited coordination of division. The generation of aposymbiotic strains enables direct functional assessment of endosymbiont contributions to host biology. Comparative analyses reveal strong metabolic interdependence, with the endosymbiont supplying essential amino acids, heme, vitamins, and purines, while relying on the host for key metabolic resources including non-essential amino acids, cofactors, energy metabolism, and lipid biosynthesis. Beyond metabolism, the endosymbiont impacts protein homeostasis and cellular regulation, modulating proteolytic pathways such as GP63, cysteine peptidases, and the ubiquitin–proteasome system, as well as host networks involving kinetoplast-associated proteins (KAPs). Host-encoded endosymbiont-targeted proteins (ETPs) further mediate endosymbiont positioning, organization, and coordinated maintenance and division. Here, we critically synthesize current knowledge on mEHTs using a comparative framework based on interconnected dimensions of host–endosymbiont integration. Full article

Trichostrongylid nematodes are globally distributed gastrointestinal parasites of major veterinary and, in some cases, zoonotic importance. Accurate identification often requires an integrative approach because morphology alone may be compromised by specimen damage, cryptic diversity, and dimorphic species complexes. In the Philippines previous work has been largely limited to coproscopy, with no published DNA-based studies on adult trichostrongylids or scanning electron microscopy (SEM) documentation. Here, we provide an integrative characterization of Haemonchus contortus and Trichostrongylus axei recovered from a single goat in Mindanao, Philippines, in 2023. Identification was based on light microscopy, SEM, morphometry, and sequence data from the cox1 and ITS regions. Phylogenetic analyses and a haplotype network for H. contortus placed the Philippine material within a widely distributed lineage complex with weak geographic structuring. Because the study is based on parasites from a single host, the findings should be interpreted as a taxonomic and faunistic record rather than evidence for broader epidemiological or population-level patterns. This study provides the first molecular record of trichostrongylid nematodes from the Philippines and the first SEM-based documentation of H. contortus in the country. Broader sampling is needed to assess parasite diversity, distribution, genetic variation, and potential veterinary and public health relevance nationwide. Full article

Corticosteroid-induced immunosuppression creates a permissive environment for opportunistic intestinal parasitic infections (OIPIs), especially in endemic regions where latent or subclinical parasitic carriage is common. Yet, the interplay between corticosteroid exposure, parasitic ecology, and clinical outcomes remains insufficiently characterized. This study aimed to investigate the epidemiological and clinical characteristics of OIPIs in corticosteroid-treated patients by integrating findings from an original Egyptian case series with a systematic review of published global cases. A dual analytical approach was undertaken, combining newly characterized Egyptian corticosteroid-treated cases (ECS; n = 53) with a systematic review of global corticosteroid-associated parasitic cases (LRCS; 94 cases, 1975–2024). Clinical profiles, corticosteroid regimens, comorbidities, parasitic spectra, and outcomes were analyzed to elucidate risk patterns and pathophysiological mechanisms. Six opportunistic intestinal parasite genera were detected among ECS. The most notable species were Giardia duodenalis, Cyclospora cayetanensis, and Cryptosporidium spp., while seven were identified globally, with Strongyloides stercoralis and Cryptosporidium spp. predominating in LRCS. Remarkably, 70% of ECS patients exhibited polyparasitism, harbouring up to five different concurrent species, including both opportunistic and non-opportunistic parasites. Over half of the Egyptian patients were asymptomatic, while nearly one-third displayed extraintestinal manifestations, predominantly respiratory, which may reflect altered clinical presentation under corticosteroid-induced immune modulation. Prolonged corticosteroid therapy (≥1 month) was significantly associated with higher complication rates (p = 0.002) in ECS, and tissue invasion, organ dysfunction, hospitalization, and mortality in LRCS. The compiled LRCS mortality and hospitalization data (34 fatalities, 87 hospitalisations) reflect rare quantitative insight into global OIPI lethality under steroid exposure. This study provides the first integrated clinical and epidemiological synthesis linking corticosteroid exposure to complex parasitic dynamics across endemic and non-endemic settings. It advances the hypothesis that corticosteroids act less as mere infection triggers and more as amplifiers of pre-existing parasitic ecosystems, reshaping host–parasite interactions and facilitating subclinical dissemination. The findings underscore the importance of routine parasitic screening, risk stratification, and longitudinal monitoring before and during corticosteroid therapy, particularly in endemic regions, to ensure long-term patient care and prevent and manage OIPIs. Full article

(1) Background: Giardia duodenalis is a common protozoan parasite infecting various mammalian hosts, yet data on its prevalence in Cypriot ruminants, including the endemic and protected mouflon (Ovis gmelini ophion), remain absent. This study aimed to evaluate the prevalence and molecular characteristics of Giardia species (sp.) in domestic and wild ruminants in Cyprus to assess potential risks to wildlife. (2) Methods: We analysed 146 faecal samples—comprising 32 domestic sheep, 10 domestic and 34 free-ranging goats, and 70 wild mouflons—using nested polymerase chain reaction (PCR) and multi-locus sequence typing of the ssrRNA, tpi, bg, and gdh genes. (3) Results: Giardia was detected in only 1 of the 42 domestic ruminant samples (1/32 sheep; 3.1%), which was characterized as G. duodenalis assemblage E. No Giardia DNA was detected in the the domestic goats (0/10), wild mouflons (0/70) or the free-ranging goats (0/34) co-inhabiting the forest environment. (4) Conclusions: This study provides the first molecular report of Giardia sp. in domestic sheep in the Republic of Cyprus. While the parasite is present in domestic ruminants, the findings suggest a low positivity rate and no immediate evidence of transmission to the endangered mouflon. Further research with a larger sample size is recommended to confirm these observations and guide future conservation strategies. Full article

Nematophagous fungi are important biological control agents that naturally reduce nematode populations through specialized predatory mechanisms. This study evaluated the viability and predatory capacity of the nematophagous fungus Duddingtonia flagrans (AC001) after fourteen years of refrigerated storage in sodium alginate pellets. Fungal viability was assessed by reactivating the pellets on Corn Meal Agar and Potato Dextrose Agar, with subsequent monitoring of mycelial growth and morphological confirmation by light microscopy. The predatory capacity was determined by means of in vitro assays using Panagrellus redivivus as a model organism. Plates previously colonized by the fungus received approximately 400 nematodes and were compared with fungus-free controls. Predatory activity was evaluated daily for five days by counting live nematodes in random microscopic fields. Final recovery of viable nematodes was performed using a modified Baermann technique. The data were analyzed using Student’s t-test (p < 0.05). Isolate AC001 exhibited successful reactivation, preserved morphological characteristics, and sustained high predatory activity, resulting in reductions in nematode populations ranging from 91% on the first day to 95% on subsequent days, with a final reduction of 67% in nematode recovery. These findings demonstrate that sodium alginate encapsulation combined with refrigeration enables the exceptionally long-term preservation of functional and predatory attributes of nematophagous fungi, supporting its applicability in biological control strategies. Full article

Wild animals play an important role in the epidemiological cycle of Trypanosoma cruzi transmission. The order Chiroptera is ecologically significant as a reservoir host for parasite variants, including TcI, TcII, TcIV, and TcBat. This study aimed to detect T. cruzi in multiple organs of Desmodus rotundus from two regions of San Luis Potosí, Mexico. A total of 63 D. rotundus samples were obtained, of which 22.2% (14/63) tested positive for T. cruzi infection. The highest infection rate was observed in the Media region, with 47.3% (9/19) of samples being infected, whereas in the Huasteca region 11.3% (5/44) of samples were infected. Infection prevalence did not differ significantly by sex or age. Of the five organs tested, only the intestine and the kidney were positive. Phylogenetic and genetic distance analyses revealed sequence identity values >98% with TcI/Tbat trypanosomes. These findings add to the growing body of evidence that bats, particularly hematophagous species such as D. rotundus, play a significant role in maintaining T. cruzi in sylvatic environments and potentially facilitating transmission at the wildlife–domestic interface. Continuous surveillance integrating bat populations, vectors, humans, and domestic animals is essential for understanding and mitigating the risk of Chagas disease in regions where sylvatic and domestic transmission cycles overlap. Full article

Digenean of the superfamily Echinostomatoidea exhibit complex life cycles that involve up to three host species. Several echinostomatoid species have been reported in snails of the family Littorinidae. In the zebra snail Echinolittorina peruviana from central Chile, two cercarial species resembling Echinostomatoidea were recognized based in their morphological characteristics. Molecular characterization was carried out to identify the species. Key aspects of their infection dynamics were quantified and compared between the two cercarial morphologies, with particular emphasis on transmission to secondary intermediate hosts. We evaluated: (i) swimming activity, (ii) the success of cercarial settlement in a mussel host across different body sizes, and (iii) host selection among three potential secondary intermediate hosts (a mussel, a snail, and a crab). Molecular analyses, based on the 28S gene, indicated that the examined cercariae corresponded to two distinct species from the superfamily Echinostomatoidea. However, species-level identification could not be confirmed, and they were therefore designated as species 1 and species 2. Species 1 exhibited a significantly faster decline in swimming activity compared to species 2, whose active period was approximately twice as long. Mussels were successfully infested in all trials, with no significant differences among shell-size groups. In host preference experiments, all host types were selected. However, only the cercaria species 2 showed a significant preference for the crab, suggesting that this may be an alternative secondary intermediate host. Despite their similar body size, the two cercarial species displayed distinct infection dynamics and host-use strategies, indicating divergent biological traits and transmission pathways within a limited time window. Full article

Sarcocystis felis, originally named for sarcocysts in the bobcat (Lynx rufus), has been reported in domestic cats (Felis catus) and several other wild felids in the Americas. However, ultrastructural confirmation of the sarcocyst wall, an important criterion for taxonomy of Sarcocystis species, is lacking in many reports. Here, we report ultrastructural confirmation of S. felis in the limb musculature of the Florida panther (Puma concolor coryi) in Florida. Sarcocysts in the Florida panther were thin-walled and had a “type 9c” cyst wall. Molecularly, 100% identity of the ITS1 region from the panther isolates with other felid isolates supported the ultrastructural findings. Full article

Clonorchiasis is a parasitic infection caused by the trematode Clonorchis sinensis, which is endemic to East Asia but increasingly observed in non-endemic regions due to global migration. Chronic infection can lead to recurrent pyogenic cholangitis (RPC) and other hepatobiliary complications including cholangiocarcinoma. We herein review clonorchiasis and opisthorchiasis as potential contributory drivers of RPC in migrants from Southeast Asia through framing with a case of a Filipino woman residing in Canada who presented with a two-year history of intermittent right upper quadrant pain, liver enzyme derangement, and imaging features consistent with RPC. Despite negative stool ova and parasite (O&P) testing, empirical treatment with praziquantel (1800 mg three times daily for two days) led to clinical and biochemical improvement. Hepatobiliary trematodiasis, including clonorchiasis and opisthorchiasis, can be challenging to diagnose, and clonorchiasis and opisthorchiasis cannot be distinguished on clinical or radiographic grounds alone. Clonorchiasis can be challenging to diagnose in non-endemic areas due to low parasitologic test sensitivity and non-specific clinical features. Imaging findings and epidemiologic context are critical for raising clinical suspicion and guiding management. Healthcare providers in non-endemic regions should include clonorchiasis and opisthorchiasis in the differential diagnosis of unexplained cholestasis, particularly in migrants from areas endemic for clonorchiasis and opisthorchiasis. Negative stool tests do not exclude infection, and early empirical treatment may prevent irreversible hepatobiliary damage and reduce long-term malignancy risk. Full article

Psychodid flies are non-parasitic insects commonly found in humid domestic environments, where larvae develop in organic matter within drains. Human pseudomyiasis caused by these flies is a rare and often neglected condition, typically involving urogenital or intestinal tracts. Most cases are reported in Southeast Asia and the Middle East, while occurrences in Europe and Africa remain uncommon. This study reports the first documented pediatric cutaneous pseudomyiasis case associated with a psychodid larva in Italy. A 4-year-old girl presented with a small (0.5 cm) subcutaneous swelling on the right arm, showing dark discoloration and a protruding structure. No pruritus or systemic symptoms were observed. A partially removed larval specimen was analyzed using morphological and molecular approaches. Morphological analysis confirmed that the specimen was a dipteran larva; however, its degraded condition precluded reliable determination of the larval instar. Molecular characterization targeting the mitochondrial cytochrome c oxidase subunit I (COI) gene assigned the specimen to the genus Psychoda (family Psychodidae). These findings are consistent with an incidental recovery of a psychodid larva and support an interpretation of pseudomyiasis rather than true myiasis. This case highlights the role of interdisciplinary collaboration between pediatricians and entomologists and a One Health approach in diagnosing unusual parasitological conditions. Full article

Lepeophtheirus salmonis (Krøyer, 1837) represents a major biological challenge in Atlantic salmon aquaculture. Despite extensive research on salmon lice biology, host interaction, and immunomodulation, the mechanisms underlying early host recognition and attachment remain poorly understood. Microscopic examination of the infective stage revealed a previously undescribed spike-like structure in the anterior rostral region of the copepodids. The structure appeared flexible, moved synchronously with body movements, and was present prior to exposure to host tissues or detectable host contact. Behavioral observations further revealed that copepodids actively probe salmon skin explants and fins with their anterior appendages before initial attachment, often followed by prolonged immobility. Scanning electron microscopy suggested that the structure may exist in both protruded and retracted forms and revealed a crevice- or pore-like feature at its proximal end. It is hypothesized that this structure may contribute to early host interrogation through localized sensing and the initial attachment process. These findings highlight a component of early host–parasite interactions and may contribute to future strategies to disrupt host recognition mechanisms in salmon lice. Full article

In Mexico, since June 2025, human cases of myiasis caused by Cochliomyia hominivorax (the screwworm) have been identified, prompting health authorities to issue a surveillance alert for potential infections by this fly. Here we report the identification and interdisciplinary management of a case of nasal myiasis caused by Lucilia sericata. In September 2025, a 40-year-old Hispanic man was admitted to the emergency room due to an altered mental status; after a 17-day hospital stay, nasal larvae were detected. The larvae were submitted for morphological identification by microscopy and molecular identification by polymerase chain reaction, using ITS-2 and 16S loci as nuclear and mitochondrial markers, respectively; the amplicons were purified and sequenced, and a Bayesian phylogenetic analysis was performed. Morphological analysis showed that they were L. sericata larvae at different developmental stages (1st to 3rd instars). Molecular analysis confirmed the morphological result, as phylogenetic inferences showed a clear grouping of the sequences within the L. sericata cluster. While remaining vigilant for possible human cases of myiasis caused by C. hominivorax, here, we confirmed by morphological and molecular analysis the identification of an unexpected case of nasal myiasis caused by L. sericata, demonstrating the importance of care in all aspects of thorough epidemiological surveillance and the interdisciplinary management to address these alerts and any related cases. Full article

Acute diarrheal disease (ADD) caused by parasites and Tuberculosis (TB) remain major public health concerns in vulnerable indigenous communities with limited access to sanitation, safe water, and healthcare, and where humans, animals and the environment interact closely. Using a One Health framework, this study investigated TB and Intestinal parasites in human, animal and environmental samples from 15 Wayuu indigenous communities in Manaure, La Guajira. A total of 190 samples, including human sputum and feces, animal milk and feces, soil and drinking water, were analyzed according to sample type, preservation suitability, and availability using parasitological concentration techniques, qPCR for helminth detection, metatranscriptomic sequencing, Xpert ^® MTB/RIF assay, and mycobacterial culture. Mycobacterium tuberculosis was detected in 8.3% of human sputum samples, with no evidence of rifampicin resistance, whereas Mycobacterium bovis was not detected in animal milk. Human fecal samples analyzed by microscopy showed Blastocystis sp. and the Entamoeba histolytica/Entamoeba dispar complex (38.8% each), followed by Giardia (19.4%), Hymenolepis nana and Trichuris trichiura (5.1% each) and Hymenolepis diminuta (1%). Commensal parasites were also identified, with Entamoeba coli (46.9%) being the most frequent species, indicating inadequate sanitary conditions and poor hygiene practices. Co-infections were common in humans (60.2%). In animal fecal samples, strongylids (66.7%), amoebas (16.7%) and Giardia (8.3%) were observed. Giardia sp. was detected in 2.38% of soil samples by microscopy, supporting environmental circulation, whereas no parasites were detected in water sediments. Multiplex qPCR detected Trichuris trichiura DNA in human feces and Trichuris spp. DNA in soil and sheep fecal samples. Metatranscriptomic analysis of 22 human fecal samples revealed a high diversity and frequency of parasitic protozoa (90.9%), with Blastocystis spp. being the most frequent (81.8%). Additionally, reads of free-living amoebae, including Acanthamoeba spp. (10%) and Naegleria spp. (5%) were detected in community drinking water sources. These findings suggest active transmission of TB and parasitic-associated ADD in Wayuu communities and highlight the need for integrated surveillance and culturally appropriate interventions focused on sanitation, hygiene, veterinary services and community health education to improve the living and health conditions of these vulnerable populations. Full article

Vector-borne pathogens (VBPs) can affect equine health, welfare, and productivity, with potential implications for animal management and trade. However, data on their occurrence in North Africa remain limited. The present study aimed to estimate the molecular occurrence of selected equine VBPs in clinically healthy horses from Algeria. Specifically, a cross-sectional molecular survey was conducted between May and November 2024 on 241 clinically healthy horses selected using convenience sampling from three ecologically distinct regions of Algeria (Tiaret, Laghouat, and Tlemcen). Demographic and management data were collected at sampling, and blood samples were spotted onto filter paper for DNA preservation. Genomic DNA was extracted using a modified Chelex/InstaGene Matrix protocol, followed by conventional and nested PCR assays targeting piroplasms, Anaplasmataceae, filarioid helminths, Rickettsia spp., Trypanosomatidae, haemotropic Mycoplasma spp., and Bartonella spp. Positive amplicons were subjected to sequence and phylogenetic analysis. Theileria equi (T. equi) DNA was detected in 4.98% (12/241) of examined horses, and one animal (0.41%; 1/241) tested positive for Theileria capreoli (T. capreoli). T. equi genotypes A and B were identified via molecular characterisation, but no amplification was obtained for Anaplasmataceae, Babesia caballi, Rickettsia spp., haemotropic Mycoplasma spp., Bartonella spp., Trypanosomatidae, or filarioid helminths. These findings should be interpreted cautiously, given the convenience sampling design, the clinically healthy status of the sampled animals, and the known limitations of PCR-based detection in low-parasitaemia infections. Nevertheless, this study provides preliminary molecular data on equine VBPs in Algeria and supports the need for broader epidemiological investigations using complementary molecular and serological approaches. Full article

Monieziosis presents a considerable challenge to livestock farming, mainly due to the parasite’s resistance to common anthelmintics, prompting the need for alternative control strategies. This study examined the in vitro effect of two enzymatic sources (plant and fungal) on the structural integrity of Moniezia expansa eggs, aiming to find new environmental management solutions. The plant enzyme papain was tested at various concentrations and time points, while the fungal enzyme was produced through solid-state fermentation using Duddingtonia flagrans (AC001), resulting in an active crude enzymatic extract (ACEE). Papain at 10% w/v showed nonlinear degradation (R² = 0.998), achieving 95% egg reduction after 48 h. The fungal extract ACEE (71.2 U mL⁻¹) caused a 60% reduction after 72 h. Morphological studies indicated significant eggshell damage following both treatments. A compatibility assay showed an antagonistic interaction, with enzyme activity decreasing by 83.83% within 48 h, likely due to cross-proteolysis. Although each agent is effective individually, combining them is not feasible. This is the first study documenting the activity of ACEE and papain against M. expansa eggs, and it recommends using them separately or sequentially for effective parasite control. Full article

Zoonotic gastrointestinal parasites such as Toxocara canis and Ancylostoma caninum are a public health concern, particularly in tropical and urban environments. This study evaluated Mexican veterinarians’ perceptions, knowledge, and deworming practices regarding these parasites and their zoonotic risks. A nationwide online survey obtained 717 fully completed responses from veterinarians across all Mexican states, exceeding the required sample size. Inclusion criteria required participants to be active small-animal practitioners with no missing data on core deworming questions; veterinarians working exclusively in pharmacies, feed stores, boarding facilities, dog daycares, or grooming services were excluded. Overall ESCCAP guideline compliance was 34.2%. Compliance was highest in northern states (41.8%) and lowest in southern states (23.5%). Deworming practices in lactating dogs showed uniformly low adherence, and no state reached moderate compliance for puppies aged 1–3 weeks. Compliance with the recommended puppy deworming frequency was notably higher. Compliance with the recommended adult deworming frequency was very low (9.8%), while coprological monitoring was recommended by 43.4% of respondents. Professional formation was the strongest predictor of overall guideline adherence across nearly all criteria. The 16–20-year experience group showed the highest overall compliance. Sex was not a significant predictor of overall ESCCAP compliance; the only significant sex difference was observed for coprological monitoring, where female veterinarians showed higher compliance rates. These findings suggest that academic training, years of experience, and geographic region are independently associated with guideline adherence, underscoring the value of standardized national protocols and continuing education to strengthen zoonotic risk awareness among veterinarians in Mexico. Full article

Chagas disease, caused by Trypanosoma cruzi (T. cruzi), includes clinically relevant intestinal inflammation; however, the mechanisms associated with tissue injury remain incompletely understood. ArtinM is an immunomodulatory lectin with known effects on innate and adaptive immunity, although its intestinal role during acute T. cruzi infection remains unclear. This study investigated whether ArtinM modulates the intestinal inflammatory response during acute experimental T. cruzi infection. In vivo, BALB/c mice were allocated to Saline control, T. cruzi + Saline, and T. cruzi + ArtinM groups. Intestinal inflammatory infiltrate and tissue concentrations of TNF-α, IFN-γ, IL-12p40, and IL-10 were quantified. Acute infection markedly increased TNF-α, IFN-γ, IL-12p40, and inflammatory infiltrate, whereas ArtinM significantly attenuated these responses. TNF-α, IFN-γ, and IL-12p40 remained associated with group after adjustment for infiltrate, whereas IL-10 reached statistical significance only in the adjusted model and was therefore interpreted cautiously. In parallel, an exploratory analysis of a public murine intestinal scRNA-seq dataset (GSE319934; GSM9529706 and GSM9529707), derived from a chronic infection setting, was performed to provide pathway-level context for inflammatory mediators assessed in vivo. This transcriptomic analysis indicated that related inflammatory, innate immune, chemotactic, and adhesion-associated genes were detectable in intestinal single-cell data from T. cruzi infection. However, because this dataset was not temporally matched to the acute model, it was not interpreted as a phase-matched comparator, mechanistic validation, or temporal extension of the experimental findings. Together, the results support that ArtinM treatment is associated with attenuation of acute intestinal inflammatory outcomes in experimental T. cruzi infection. Because local intestinal parasite burden was not measured, these findings should be interpreted as evidence of inflammatory modulation rather than as direct evidence of local antiparasitic activity. The public scRNA-seq analysis provides only exploratory contextual information for related inflammatory pathways. Full article

Human scabies, caused by Sarcoptes scabiei var. hominis, is a neglected tropical disease with a significant public health burden worldwide. This retrospective study analyzed the spatiotemporal epidemiology of scabies in Mexico from 2004 to 2024 using national surveillance data. A total of 1,500,348 cases were reported. Children were disproportionately affected, with the highest crude incidence rates in the 0–4 age group. Females had higher incidence than males across all age groups, except in the 0–4 and ≥65 years age groups. Temporal trends were assessed using joinpoint regression on age-standardized incidence rates. Joinpoint regression identified two joinpoints in 2012 and 2017 for both sexes. Among males, the age-standardized incidence rate decreased from 2004 to 2012 (APC = −5.75%), increased from 2012 to 2017 (APC = 19.00%), and decreased from 2017 to 2024 (APC = −20.86%), with an AAPC of −6.02% (p < 0.001). Among females, a similar pattern was observed (APC = −5.94%, 18.23%, and −20.83%, respectively), with an AAPC of −6.24% (p < 0.001). Both sexes showed a significant net decrease in scabies incidence over the study period, despite a transient increase between 2012 and 2017. Spatial analyses revealed statistically significant spatial clustering, with persistent hot spots in the southeast, the Yucatán Peninsula, the Gulf of Mexico coast, and the Pacific Coast. These findings highlight the persistent burden of scabies in Mexico and the need for targeted public health interventions in high-incidence regions and among vulnerable populations. Full article