Search Results (104)

Background and Clinical Significance: Giardia lamblia is a protozoan parasite that causes giardiasis, a gastrointestinal disease. The disease commonly manifests with abdominal pain, diarrhea, and emesis. Many giardia infections, however, are asymptomatic and can be easily spread to others. Bupropion, a norepinephrine and dopamine reuptake inhibitor, can have side effects of nausea and abdominal pain, which can mimic or overlap with symptoms of a Giardia lamblia infection. Case Presentation: We present a 39-year-old man who has sex with men (MSM) who presented with abdominal pain with nausea and vomiting. His symptoms began 3 months after returning from a trip to Peru and 1 month after starting bupropion. Bupropion was discontinued upon admission due to suspicion of medication-induced adverse effects. CT imaging revealed thickening of the transverse colon, suggestive of an infectious or inflammatory etiology. The patient’s GI-PCR returned positive for Giardia lamblia, and the patient was treated with metronidazole. While the temporal relationship suggests an association, it remains unclear whether the clinical presentation was primarily driven by bupropion, the Giardia infection, or a synergistic effect of both. A norovirus result was indeterminate, and the patient improved after bupropion discontinuation but before metronidazole initiation, leaving open the possibility of a self-limited viral gastroenteritis. Conclusions: This case highlights a possible association between bupropion initiation and the temporal association between bupropion initiation and the detection of symptomatic giardiasis in an MSM patient. Clinicians may consider stool testing for Giardia before attributing gastrointestinal symptoms solely to medication effects. Giardia lamblia should be considered in the differential diagnosis of gastrointestinal symptoms for MSM patients, particularly when compatible exposure history, travel history, or enteric infection risk factors are present. Full article

The emergence of clinical resistance to conventional antigiardials underscores the need for compounds with novel mechanisms of action. This study demonstrates that indirubin exerts antigiardial activity by targeting important metabolic enzymes in Giardia lamblia. Indirubin induced a concentration-dependent decrease in trophozoite proliferation and viability, correlating with reduced activity of native triosephosphate isomerase and aldose reductase. Using recombinant enzymes, indirubin directly inhibited triosephosphate isomerase and aldose reductase, with the parasite enzymes showing greater susceptibility than their human orthologs. Structural and computational analyses suggest preferential binding of indirubin at the dimer interface of triosephosphate isomerase and within the NADP(H)-binding pocket of aldose reductase. The dual enzymatic inhibition was concordant with methylglyoxal accumulation, extensive protein carbonylation, and the formation of advanced glycation end products. These effects culminated in apoptotic-like death and severe ultrastructural damage, including alteration of the adhesive disc and microtubule networks. By targeting vulnerabilities in the metabolic and redox pathways of G. lamblia through a multifactorial mechanism distinct from current therapies, our findings support indirubin as a promising candidate for the treatment of giardiasis. Full article

Objectives: This study aimed to investigated the role of Giardia extracellular vesicles (EVs) in intercellular communication and to evaluated their potential as vaccine candidates. Methods: The immunomodulatory effects of Giardia EVs were assessed in mouse macrophages and human monocyte-derived dendritic cells (Mo-DCs), with a particular focus on key inflammatory signaling pathways. In vivo immunogenicity was evaluated following EV administration, and the antigenic composition of EV cargo was characterized by proteomic analysis. Results: Giardia EVs activated pro-inflammatory signaling pathways in mouse macrphages, including SAPK/JNK, ERK1/2, and NF-κB. This activation was associated with IκB-α degradation and nuclear translocation of p65. Furthermore, EV stimulation significantly upregulated the expression of pro-inflammatory genes, including Il1β, Il6, Il4, Ptgs2, Nos2, and Tnf, with log₂ fold changes ranging from 3.9 to 15.8. Consistently, EVs increased iNOS protein expression (28–45%) and nitrite production (9.6–12.3-fold). In human Mo-DCs, Giardia EVs promoted cellular maturation, as evidenced by increased expression of MHC-II, CD80, and CD86, and enhanced T-cell proliferation with a Th1-skewed profile. In vivo immunization induced antigen-specific antibody responses, with IgG subclass distribution indicative of a balanced Th1/Th2 response. Proteomic analysis identified immunoreactive EV-associated proteins, including elongation factor 1-alpha, α-7.3 giardin, tubulin, and variant surface proteins (VSPs), which are well-established antigens in Giardia infection, with prominent bands observed at approximately 22 kDa and 50 kDa. Conclusions: Collectively, these findings demonstrate that Giardia EVs modulate innate immune responses in vitro, elicit antigen-specific humoral immunity in vivo, and contain conserved immunogenic proteins. These properties support their potential as a promising cell-free vaccine platform against giardiasis. Full article

Giardiasis, caused by Giardia duodenalis, is a common gastrointestinal infection. This study aimed to evaluate the effects of Hedera helix leaf extract (HLE) and HLE-loaded chitosan nanoparticles (HLE-CsNPs) against Giardia duodenalis isolates from individuals with gastrointestinal issues, using an experimental rat model. Stool samples from 147 participants were analyzed for Giardia duodenalis, with positive samples further characterized by nested PCR-RFLP, revealing a 4.8% prevalence, all belonging to assemblage B. Ten groups of male albino rats were used to evaluate the antigiardial activity of various treatments. This included five non-infected groups [one untreated and four treated with HLE, HLE-CsNPs, CsNPs, and metronidazole (MTZ)] and five infected groups [one untreated and four similarly treated]. Treatment efficacy was assessed using parasite counts, intestinal histopathology, CD117 immunohistochemistry, and markers of liver and kidney function. HLE-CsNPs markedly reduced Giardia cysts by 88.8%, approaching the 99.2% reduction achieved by MTZ, while also improving intestinal architecture and reducing inflammation. Importantly, HLE and HLE-CsNPs provided superior protection for the liver and kidneys compared to MTZ. In conclusion, HLE-CsNPs exhibited significant antigiardial activity and organ protection in rats, suggesting a potential alternative treatment for Giardia duodenalis isolated from individuals with gastrointestinal issues. Full article

Giardiasis, caused by the protozoan parasite Giardia lamblia, remains a prevalent intestinal infection worldwide and a growing concern due to increasing resistance to nitroimidazole drugs. This study proposes an alternative therapeutic strategy by targeting fructose-1,6-bisphosphate aldolase (FBPA), a key glycolytic enzyme of the parasite, through structure-based virtual screening. A curated library of microbiome-derived metabolites was computationally evaluated and compared with clinically used antigiardial drugs. Several indole-based compounds exhibited favorable binding affinities and stable interactions within the catalytic pocket of FBPA. These findings suggest that microbiome metabolites could serve as promising scaffolds for the rational design of new antiparasitic agents. Overall, the study highlights the potential of integrating metabolic and computational approaches to identify next-generation therapeutics against giardiasis. Full article

Protozoa use iron to grow, feed, and cause harm through elaborate mechanisms to obtain it from the host. In addition, expression of virulence genes is affected by iron. In Entamoeba histolytica, the parasite that causes amoebic dysentery and complications in human organs, our group have previously reported the presence of an IRE/IRP-like (Iron Responsive Element/Iron Regulatory Protein) mechanism. Giardia duodenalis is another parasite of medical interest that causes giardiasis, including nutrient malabsorption syndrome and dysbiosis, among other complications, such as anemia in children with giardiasis. Moreover, expression of many putative giardial virulence factors by free-iron levels has been reported. Recently, we have reported stem-loop structures in some mRNAs coding virulence proteins from both parasites. However, much remains to be studied about the role of iron in pathogenesis. In this review, we summarize several aspects of gene expression regulation by iron in these protozoa as well as an iron regulatory mechanism in E. histolytica and discuss the possibility of an iron regulatory IRE/IRP-like mechanism in G. duodenalis. Full article

Background and Clinical Significance: Henoch–Schönlein purpura (HSP), also known as Immunoglobulin A (IgA) vasculitis (IgAV), is a common systemic vasculitis in children characterized by palpable purpura, abdominal pain, and joint and kidney involvement. While respiratory tract viral or bacterial infections are the most common causes of HSP, parasitic infections, such as giardiasis, are occasionally reported. Giardia lamblia is the most common parasite infecting humans and a major cause of infectious diarrhea, which can lead to post-infection complications. To our knowledge, this is the first report in Greece describing a pediatric patient with HSP secondary to giardiasis. A review of pediatric HSP cases caused by parasitic infections is also included. Case presentation: An 8-year-old girl presented with a purpuric rash, joint tenderness, severe abdominal pain, and bloody diarrhea, raising suspicion of HSP. Laboratory tests revealed elevated IgA levels, and stool analysis tested positive for Giardia lamblia antigen. The diagnosis of HSP secondary to giardiasis was confirmed, and the patient was successfully treated with supportive care, metronidazole, and corticosteroids. Conclusion: This case report and literature review highlight parasitic infections as an underrecognized but important trigger of pediatric HSP. Although giardiasis is linked to various post-infectious complications, its association with HSP is rarely reported. Pediatricians should maintain a high level of suspicion for underlying infectious diarrhea, such as giardiasis, in patients with HSP, especially in children with prominent gastrointestinal symptoms. Early recognition can reduce complications and facilitate faster recovery. Further research is needed for the immunopathogenic mechanisms linking parasitic infections and HSP in children. Full article

Background/Objectives: Giardia lamblia is an intestinal protozoan responsible for giardiasis, a globally prevalent parasitic disease. Current therapeutic options, including nitroimidazoles and benzimidazoles, have increasing treatment failures due to resistance, adverse reactions, and patient non-compliance. Drug repositioning offers a cost-effective strategy for identifying new antigiardial agents. This study aimed to evaluate the in vitro antiparasitic effects and possible mechanisms of action of the tricyclic antidepressant imipramine against G. lamblia trophozoites. Methods: Trophozoites were exposed to increasing concentrations of imipramine (25–125 µM). Growth inhibition and adhesion capacity were quantified using cell counts. Apoptosis- or necrosis-like death was evaluated through Annexin V/PI staining. The expression and distribution of α-tubulin and lipid rafts were analyzed by immunofluorescence microscopy. Finally, the effect of the drug on encystment efficiency was assessed in vitro. Results: Imipramine inhibited G. lamblia trophozoite growth in a concentration-dependent manner, with an IC₅₀ of 42.31 µM at 48 h. The drug significantly reduced adhesion capacity (>90% at 125 µM) and induced apoptosis-like cell death, as evidenced by Annexin V positivity. Immunofluorescence revealed disruption of α-tubulin distribution and lipid raft organization, accompanied by morphological rounding. Moreover, encystment efficiency decreased in a concentration-dependent mode, suggesting interference in the differentiation process. Conclusions: This investigation describes, for the first time, the antigiardial potential of imipramine, which alters cytoskeletal organization, membrane microdomains, and differentiation pathways, ultimately leading to apoptosis-like cell death. These findings position this compound as a promising lead structure and support further exploration of tricyclic antidepressants as scaffolds for the development and optimization of new antiparasitic agents, as well as future studies on their molecular targets and in vivo efficacy. Full article

Background/Objectives: Carvacrol and thymol are monoterpenes present in phenolic-rich essential oils extracted from aromatic plants that exhibit antimicrobial activity. This study evaluates the antiprotozoal effect of carvacrol, thymol and their precursor, p-Cymene, against Giardia lamblia and investigates their mechanism of action and cytotoxicity profile. Methods: G. lamblia susceptibility, cell viability, swelling and adhesion abilities following application of carvacrol, thymol and p-Cymene were assessed. Ultrastructural changes were evaluated using electron microscopy. Cytotoxicity was determined in mammalian cell lines (murine macrophages RAW 264.7 and bovine aortic endothelial cells) exposed to the same IC₅₀ concentrations effective against G. lamblia. Results: Carvacrol and thymol led to significant inhibition of G. lamblia trophozoite proliferation (IC₅₀ ≅ 50 µg/mL). After 7 h of incubation, total cell number decreased by 30% (p < 0.01) with carvacrol and by 50% (p < 0.001) with thymol, accompanied by reduced motility and adhesion (<20% attached cells). At IC₅₀ concentrations, G. lamblia trophozoites exposed to carvacrol and thymol underwent considerable ultrastructural alterations (e.g., aberrant-shaped cells, mitochondrial swelling and autophagosomal structures). Reduced trophozoite motility and adhesion capacity were also observed. In mammalian cells, thymol showed no significant cytotoxicity, whereas carvacrol significantly reduced viability in both cell lines. In contrast, p-Cymene showed no antigiardial activity. Conclusions: Our data suggests that carvacrol and thymol disrupt G. lamblia trophozoite integrity, possibly through alterations in membrane permeability and osmoregulatory processes. In conclusion, these compounds reveal in vitro antigiardial activity, supporting their potential as antigiardial drugs. Full article

Background: Cryptosporidium spp. cause opportunistic infections in immunosuppressed individuals, such as people living with HIV (PLWH). However, the association between giardiasis and HIV infection remains uncertain. This study assessed co-infections in Ghanaian PLWH and HIV-negative individuals, analyzing socio-economic, clinical, and immunological implications, including the Giardia duodenalis assemblage and Cryptosporidium spp. sub-family levels. Methods: Stool samples from Ghanaian PLWH were tested using several real-time PCR assays targeting G. duodenalis at the species level and assemblages A and B to optimize diagnostic accuracy. GD60 gene-based Sanger sequencing was used for Cryptosporidium spp. subtyping. Results were correlated with anonymized patient data to evaluate interactions with HIV infection. Results: In PLWH, C. hominis Ib, C. hominis Ie, and C. parvum IIc were detected at similar frequencies, followed by C. hominis Ia, C. hominis Id, and C. parvum IIe in decreasing order. Only C. parvum IIc was repeatedly observed in individuals with CD4+ T cell counts above 200/µL, while other sub-families occurred preferentially in those with lower counts. C. hominis Ia and Ib were associated with PLWH not receiving antiretroviral therapy; C. hominis Ia was linked to recently diagnosed HIV infections. No relevant associations between G. duodenalis assemblages and HIV infection were found. Conclusions: Sub-families Ia and Ib of C. hominis preferentially occur in individuals with severe immunosuppression, while C. parvum IIc is also detectable in individuals with better immune function. The prevalence of giardiasis in Ghana appears to be influenced by factors other than HIV-induced immunosuppression. Full article

Giardiasis is a globally prevalent waterborne zoonosis. Rapid enrichment and detection technologies for this disease are essential. Cyst outer wall proteins are ideal targets for the enrichment and detection of cysts in the environment, but there are few available targets with suboptimal effectiveness. In this study, Giardia duodenalis (G. duodenalis) cysts were purified, and outer wall proteins were biotinylated, followed by streptavidin magnetic bead purification and mass spectrometry. Sixty-three novel cyst wall proteins were identified, and their functions were annotated through Gene Ontology (GO) and KEGG analyses. The β-giardin and α-1 giardin were among the newly identified and predicted to be located on the outer wall of G. duodenalis cysts. For the characterization of these two targets, we applied sequence analysis, prokaryotic expression, preparation of polyclonal antibodies, and determination of subcellular localization. Finally, based on β-giardin immunomagnetic beads were prepared using the polyclonal antibodies and tested for their enrichment efficiency. Immunomagnetic beads targeting β-giardin achieved 65% cyst enrichment efficiency in fecal samples, comparable to conventional methods. Clinical evaluation across 163 multi-host fecal samples (ferrets, Siberian tigers, red-crowned cranes) demonstrated concordance with nested PCR, successfully enriching cysts from PCR-positive specimens. The immunomagnetic beads method targeting β-giardin demonstrated effective G. duodenalis cyst enrichment in multi-host fecal samples. These results provide a proteomic framework for the cyst wall proteins of G. duodenalis, expanding the detection targets for G. duodenalis cysts. It also establishes a theoretical foundation for subsequent research on the composition and function of G. duodenalis cysts. Full article

Background/Objectives: Giardiasis is one of the oldest-reported infectious diseases worldwide. It affects individuals with weakened immune systems and progresses into chronic infection if untreated. Morphological analysis and visualization of cell shapes using unlabeled or fluorophore-labeled samples are commonly employed to identify the parasite. Methods: To distinguish molecular content variations between trophozoites and infectious type I cysts, the current research presents an alternative approach based on label-free Raman microscopy. Results: Constituents responsible for plasma membrane thickening and cyst wall formation during encystation, such as N-acetylgalactosamine (GalNAc) and N-acetylglucosamine (GlcNAc) were detected. Although these two coexisting compounds have similar molecular structures, their spectroscopic distinction and visual localization through Raman microscopy are achievable. While immature and non-viable cysts contain a larger amount of GlcNAc, a potential transition of this moiety to GalNAc might occur as the cysts mature and become infectious. Other Raman results revealed changes in the oxidation states of heme-binding proteins and in lipid–protein metabolism, each serving as an additional protection mechanism that the parasite employs for survival. Complementary bright field and confocal fluorescence microscopy results corroborate the Raman outcomes. Conclusions: The molecular-level findings of this work, which presents a detailed spectroscopic analysis of Giardia’s encystation and excystation stages, substantiate the need to use complementary methods for monitoring the parasite’s dynamics and efficacy in terms of self-protection. This alternative method provides accurate insights for further understanding the multifaceted factors involved in Giardia’s encystation process and its acquired resistance to external stimuli. Full article

Human milk, especially colostrum, is a biologically complex fluid with potent protective properties against gastrointestinal disturbances in infants. Among intestinal protozoa transmitted via the fecal–oral route, this review focuses on Giardia lamblia and Entamoeba histolytica, as the protective role of milk-derived factors against these parasites is the most extensively documented. Its protective effects result from a wide range of bioactive components, including mucins, lactoferrin, human milk oligosaccharides, melatonin, and secretory IgA, which support the integrity of the intestinal barrier, regulate immune responses, and inhibit the adhesion and activity of pathogens. The composition of human milk can be influenced by maternal factors such as nutritional status, stress, sleep quality, and physical activity, which may modulate its immunological potential. Dietary intake of micronutrients, fermentable fibers, and fermented foods also appears to play a role in shaping the milk’s protective properties. This review discusses the molecular mechanisms by which selected milk components contribute to the defense against protozoan infections in early life and considers how maternal health and lifestyle may affect the effectiveness of these protective mechanisms. Full article

Background: Since the current increase in antimicrobial resistance globally, parasitic infectious diseases have become a greater public health crisis than ever before and an absolute priority. The Egyptian community pharmacist, as a health care provider and advisor, has a potential role to play in deworming. Objective: To evaluate the outcomes of community pharmacist-led deworming-related counseling services. Methods: A prospective randomized controlled study was conducted in Damanhur, Behera, Egypt. The intervention group received community pharmacy counseling, and the control group received the usual care. Both groups were monitored for 12 months for recurrence evaluation. Results: A total of 173 patients were included, of whom 96 (55.5%) received patient counseling. The types of infection included Oxyuris (44.5%), Entamoeba histolytica (28.9%), Ascaris (8.7%), Entamoeba Cyst (8.7%), Giardiasis (4.6%), Schistosomiasis (2.9%), and pinworm (1.7%). A total of 119 participants (68.8%) reported a need for dose repetition. Personal hygiene practices were reported by 71 participants (41%). Recurrence of infection was observed in 101 cases (58.4%). Patient counseling was significantly associated with lower recurrence rates and higher rates of personal hygiene application (p < 0.001). Multivariate logistic regression analysis revealed that patient counseling and personal hygiene measures were the only significant predictors of infection recurrence rate. Conclusions: Community pharmacists’ deworming-related counseling had positive behavioral and clinical outcomes. Full article

Giardia lamblia is a flagellated protozoan and the etiological agent of giardiasis, a leading cause of epidemic and sporadic diarrhoea globally. The clinical and public health relevance of giardiasis underscores the need for robust methodologies to investigate and manage this pathogen. This study reviews the main methodologies described in the literature for studying the life cycle of G. lamblia, focusing on isolation, purification, axenization, excystation, and encystation. A systematic literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA 2020) statement. Searches were performed in MEDLINE, ScienceDirect, and Web of Science Core Collection databases. A total of 43 studies were included, revealing 58 methods for isolation and purification, 7 for excystation, 2 for axenization, and 5 for encystation. Isolation and purification methods exhibited significant variability, often involving two phases: an initial separation (e.g., filtration and centrifugation) followed by purification using a density gradient for faecal samples or immunomagnetic separation for water samples. Method effectiveness differed depending on the sample source and type, limiting comparability across studies. In contrast, methods used for other life cycle stages were more consistent. These findings underscore the need for standardised methodologies to enhance the reproducibility and reliability of research outcomes in this field. Full article