Treatment of cryptosporidiosis in immunocompromised individuals: systematic review and meta-analysis

Cryptosporidium lysyl-tRNA synthetase inhibitors define the interplay between solubility and permeability required to achieve efficacy

Cryptosporidiosis is a diarrheal disease caused by infection with Cryptosporidium spp. parasites and is a leading cause of death in malnourished children worldwide. The only approved treatment, nitazoxanide, has limited efficacy in this at-risk patient population. Additional safe therapeutics are urgently required to tackle this unmet medical need. However, the development of anti-cryptosporidial drugs is hindered by a lack of understanding of the optimal compound properties required to treat this gastrointestinal infection. To address this knowledge gap, a diverse set of potent lysyl-tRNA synthetase inhibitors was profiled to identify optimal physicochemical and pharmacokinetic properties required for efficacy in a chronic mouse model of infection. The results from this comprehensive study illustrated the importance of balancing solubility and permeability to achieve efficacy in vivo. Our results establish in vitro criteria for solubility and permeability that are predictive of compound efficacy in vivo to guide the optimization of anti-cryptosporidial drugs. Two compounds from chemically distinct series (DDD489 and DDD508) were identified as demonstrating superior efficacy and prioritized for further evaluation. Both compounds achieved marked parasite reduction in immunocompromised mouse models and a disease-relevant calf model of infection. On the basis of these promising data, these compounds have been selected for progression to preclinical safety studies, expanding the portfolio of potential treatments for this neglected infectious disease.

Exploring the anti-protozoal mechanisms of Syzygium aromaticum phytochemicals targeting Cryptosporidium parvum lactate dehydrogenase through molecular dynamics simulations

Cryptosporidium parvum (C. parvum), a protozoan parasite, is known to induce significant gastrointestinal disease in humans. Lactate dehydrogenase (LDH), a protein of C. parvum, has been identified as a potential therapeutic target for developing effective drugs against infection. This study utilized a computational drug discovery approach to identify potential drug molecules against the LDH protein of C. parvum. In the present investigation, we conducted a structure-based virtual screening of 55 phytochemicals from the Syzygium aromaticum (S. aromaticum). This process identified four phytochemicals, including Gallotannin 23, Eugeniin, Strictinin, and Ellagitannin, that demonstrated significant binding affinity and dynamic stability with LDH protein. Interestingly, these four compounds have been documented to possess antibacterial, antiviral, anti-inflammatory, and antioxidant properties. The docked complexes were simulated for 100 ns using Desmond to check the dynamic stability. Finally, the free binding energy was computed from the last 10ns MD trajectories. Gallotannin 23 and Ellagitannin exhibited considerable binding affinity and stability with the target protein among all four phytochemicals. These findings suggest that these predicted phytochemicals from S. aromaticum could be further explored as potential hit candidates for developing effective drugs against C. parvum infection. The in vitro and in vivo experimental validation is still required to confirm their efficacy and safety as LDH inhibitors.

E-pharmacophore and deep learning based high throughput virtual screening for identification of CDPK1 inhibitors of Cryptosporidium parvum

Cryptosporidiosis, a prevalent gastrointestinal illness worldwide, is caused by the protozoan parasite Cryptosporidium parvum. Calcium-dependent protein kinase 1 (CpCDPK1), crucial for the parasite's life cycle, serves as a promising drug target due to its role in regulating invasion and egress from host cells. While potent Pyrazolopyrimidine analogs have been identified as candidate hit molecules, they exhibit limitations in inhibiting Cryptosporidium growth in cell culture, prompting exploration of alternative scaffolds. Leveraging the most potent compound, RM-1-95, co-crystallized with CpCDPK1, an E-pharmacophore model was generated and validated alongside a deep learning model trained on known CpCDPK1 compounds. These models facilitated screening Enamine's 2 million HTS compound library for novel CpCDPK1 inhibitors. Subsequent hierarchical docking prioritized hits, with final selections subjected to Quantum polarized docking for accurate ranking. Results from docking studies and MD simulations highlighted similarities in interactions between the cocrystallized ligand RM-1-95 and identified hit molecules, indicating comparable inhibitory potential against CpCDPK1. Furthermore, assessing metabolic stability through Cytochrome 450 site of metabolism prediction offered crucial insights for drug design, optimization, and regulatory approval processes.

Prodrug nanotherapy demonstrates in vivo anticryptosporidial efficacy in a mouse model of chronic Cryptosporidium infection

The gastrointestinal disease cryptosporidiosis, caused by the genus Cryptosporidium, is a common cause of diarrheal diseases in children, particularly in developing countries and frequently fatal in immunocompromised individuals. Cryptosporidium hominis (Ch)-specific bifunctional dihydrofolate reductase-thymidylate synthase (DHFR-TS) has been a molecular target for inhibitor design. (Note that this bifunctional enzyme has also been referred to as TS-DHFR in previous literature since the functional biochemical reaction first involves the conversion of methylene tetrahydrofolate to dihydrofolate at the TS site.) While nanomolar inhibitors of Ch DHFR-TS have been identified at the biochemical level, effective delivery of these compounds to achieve anticryptosporidial activity in cell culture and in vivo models of parasite infection remains a major challenge in developing new therapies. Previous studies, using a nanotherapy approach, have shown a promising Ch DHFR-TS inhibitor, 906, that can successfully target Cryptosporidium parasites in cell culture with nanomolar anticryptosporidial activity. This formulation utilized poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with 906 (NP-906) and conjugated with a Cryptosporidium monoclonal antibody (MAb) on the nanoparticle surface to specifically target the glycoprotein GP25-200 in excysting oocysts. However, a limitation for in vivo use is antibody susceptibility to gastric acidity. To address this gap, a prodrug diethyl ester form of 906 (MAb-NP-Prodrug) was synthesized that allowed higher compound loading in the MAb-coated PLGA nanoparticles. An oral formulation was prepared by loading lyophilized MAb-NP-Prodrug into gelatin capsules with an enteric coating for gastric stability. Proof-of-concept studies with this oral formulation demonstrated antiparasitic activity in a chronic mouse model of Cryptosporidium infection. Efficacy was observed after a low daily dose of 2 × 8 mg kg-1 for 5 days, when examined 6 and 20 days postinfection, offering a new avenue of drug delivery to be further explored.

Eugenol: effective complementary treatment for cryptosporidiosis in experimentally infected mice

Cryptosporidiosis is an opportunistic, globally distributed parasitic disease. Whereas Cryptosporidium causes asymptomatic infection and diarrhea in healthy people, it may lead to severe illness in immunocompromised individuals. Limited, effective therapeutic alternatives are available against cryptosporidiosis in those categories of patients. So, we are in urgent need of better drugs for the treatment of cryptosporidiosis. Fifty male Swiss albino mice were used. Mice were grouped into five groups of ten mice each. Group I was left uninfected, and four groups were infected with 1000 oocysts of cryptosporidium. The first infected group was left untreated. The remaining three-infected groups received nitazoxanide (NTZ), eugenol, and eugenol + NTZ, respectively, on the 6th day post infection (dpi) for five days. Mice were sacrificed on the 30th dpi. The efficacy of treatment was evaluated using parasitological, biochemical, and histopathological parameters. Combination therapy of eugenol with NTZ caused a significant reduction of the number of oocysts secreted in stool and improved cryptosporidiosis-induced liver injury manifested by the restoration of normal levels of liver enzymes (ALT and AST). Treatment with eugenol-NTZ combination maintained a well-balanced antioxidant status, as evidenced by a reduced level of nitric oxide (NO) and increased antioxidant Superoxide dismutase (SOD) enzyme activity. Moreover, the combination of eugenol with NTZ resulted in the restoration of the normal morphology of intestinal villi, crypts, and muscularis mucosa. Based on the findings extracted from the present work, we can conclude that eugenol is a complementary therapeutic when used with NTZ in the treatment of cryptosporidiosis. The addition of eugenol to NTZ in the treatment of cryptosporidiosis synergized the effect of NTZ, causing a greater reduction of the number of shedded oocysts, improving liver enzyme levels, and restoring normal intestinal pathology. Therefore, we presume that eugenol's antioxidant capacity accounts for the protective effect seen in the current study. We suggest eugenol as a supplemental chemotherapeutic agent with good therapeutic potential and high levels of safety in the treatment of cryptosporidiosis based on the findings of the current study.

In silico and in vivo evaluation of the anti-cryptosporidial activity of eugenol

Background

Cryptosporidiosis is an opportunistic parasitic disease widely distributed worldwide. Although Cryptosporidium sp. causes asymptomatic infection in healthy people, it may lead to severe illness in immunocompromised individuals. Limited effective therapeutic alternatives are available against cryptosporidiosis in this category of patients. So, there is an urgent need for therapeutic alternatives for cryptosporidiosis. Recently, the potential uses of Eugenol (EUG) have been considered a promising novel treatment for bacterial and parasitic infections. Consequently, it is suggested to investigate the effect of EUG as an option for the treatment of cryptosporidiosis.

Materials and methods

The in silico bioinformatics analysis was used to predict and determine the binding affinities and intermolecular interactions of EUG and Nitazoxanide (NTZ) toward several Cryptosporidium parvum (C. parvum) lowa II target proteins. For animal study, five groups of immunosuppressed Swiss albino mice (10 mice each) were used. Group I was left uninfected (control), and four groups were infected with 1,000 oocysts of Cryptosporidium sp. The first infected group was left untreated. The remaining three infected groups received NTZ, EUG, and EUG + NTZ, respectively, on the 6th day post-infection (dpi). All mice were sacrificed 30 dpi. The efficacy of the used formulas was assessed by counting the number of C. parvum oocysts excreted in stool of infected mice, histopathological examination of the ileum and liver tissues and determination of the expression of iNOS in the ileum of mice in different animal groups.

Results

treatment with EUG resulted in a significant reduction in the number of oocysts secreted in stool when compared to infected untreated mice. In addition, oocyst excretion was significantly reduced in mice received a combination therapy of EUG and NTZ when compared with those received NTZ alone. EUG succeeded in reverting the histopathological alterations induced by Cryptosporidium infection either alone or in combination with NTZ. Moreover, mice received EUG showed marked reduction of the expression of iNOS in ileal tissues.

Conclusion

Based on the results, the present study signified a basis for utilizing EUG as an affordable, safe, and alternative therapy combined with NTZ in the management of cryptosporidiosis.

Clofazimine pharmacokinetics in HIV-infected adults with diarrhea: Implications of diarrheal disease on absorption of orally administered therapeutics

Oral drug absorption kinetics are usually established in populations with a properly functioning gastrointestinal tract. However, many diseases and therapeutics can alter gastrointestinal physiology and cause diarrhea. The extent of diarrhea-associated impact on drug pharmacokinetics has not been quantitatively described. To address this knowledge gap, we used a population pharmacokinetic modeling approach with data collected in a phase IIa study of matched human immunodeficiency virus (HIV)-infected adults with/without cryptosporidiosis and diarrhea to examine diarrhea-associated impact on oral clofazimine pharmacokinetics. A population pharmacokinetic model was developed with 428 plasma samples from 23 HIV-infected adults with/without Cryptosporidium infection using nonlinear mixed-effects modeling. Covariates describing cryptosporidiosis-associated diarrhea severity (e.g., number of diarrhea episodes, diarrhea grade) or HIV infection (e.g., viral load, CD4+ T cell count) were evaluated. A two-compartment model with lag time and first-order absorption and elimination best fit the data. Maximum diarrhea grade over the study duration was found to be associated with a more than sixfold reduction in clofazimine bioavailability. Apparent clofazimine clearance, intercompartmental clearance, central volume of distribution, and peripheral volume of distribution were 3.71 L/h, 18.2 L/h (interindividual variability [IIV] 45.0%), 473 L (IIV 3.46%), and 3434 L, respectively. The absorption rate constant was 0.625 h-1 (IIV 149%) and absorption lag time was 1.83 h. In conclusion, the maximum diarrhea grade observed for the duration of oral clofazimine administration was associated with a significant reduction in clofazimine bioavailability. Our results highlight the importance of studying disease impacts on oral therapeutic pharmacokinetics to inform dose optimization and maximize the chance of treatment success.

Identification of the glycopeptide epitope recognized by a protective Cryptosporidium monoclonal antibody

Cryptosporidium species are a leading cause of pediatric diarrheal disease and death in low- and middle-income countries and pose a particular threat to immunocompromised individuals. As a zoonotic pathogen, Cryptosporidium can have devastating effects on the health of neonatal calves. Despite its impact on human and animal health, consistently effective drug treatments for cryptosporidiosis are lacking and no vaccine is available. We previously showed that C. parvum mucin-like glycoproteins, gp40, and gp900 express an epitope identified by a monoclonal antibody 4E9. 4E9 neutralized C. parvum infection in vitro as did glycan-binding proteins specific for the Tn antigen (GalNAc-α1-S/T). Here, we show that 4E9 ameliorates disease in vivo in a calf challenge model. The 4E9 epitope is present on C. hominis in addition to C. parvum gp40 and gp900 and localizes to the plasma membrane and dense granules of invasive and intracellular stages. To characterize the epitope recognized by 4E9, we probed a glycan array containing over 500 defined glycans together with a custom-made glycopeptide microarray containing glycopeptides from native mucins or C. parvum gp40 and gp15. 4E9 exhibited no binding to the glycan array but bound strongly to glycopeptides from native mucins or gp40 on the glycopeptide array, suggesting that the antibody epitope contains both peptide and glycan moieties. 4E9 only recognized glycopeptides with adjacent S or T residues in the motif S*/T*-X-S*/T* where X = 0 or 1. These data define the 4E9 epitope and have implications for the inclusion of the epitope in the development of vaccines or other immune-based therapies.

Respiratory cryptosporidiosis detected by commercial multiplex-PCR in immunosuppressed pediatric patients

We report the off-label use of a commercial gastrointestinal protozoa multiplex-PCR panel for bronchoalveolar lavage samples, detecting respiratory cryptosporidiosis in 2 immunocompromised pediatric patients. We suggest that implying this readily available assay in cases in which systemic cryptosporidiosis is suspected, may widen our understanding regarding this rarely reported syndrome.

Biosensors as early warning detection systems for waterborne Cryptosporidium

Waterborne disease is a global health threat contributing to a high burden of diarrhoeal disease, and growing evidence indicates a prospective increase in incidence coinciding with the profound effects of climate change. A major causative agent of gastrointestinal disease is Cryptosporidium, a protozoan waterborne parasite identified in over 70 countries. Cryptosporidium is a cause of high disease morbidity in children and the immunocompromised with limited treatment options for patients at risk of severe illness. The hardy nature of the organism leads to its persistence in various water sources, with certain water treatment procedures proving inefficient for its complete removal. While diagnostic methods for Cryptosporidium are well-defined in the clinical sphere, detection of Cryptosporidium in water sources remains suboptimal due to low dispersion of organisms in large sample volumes, lengthy processing times and high costs of equipment and reagents. A need for improvement exists to identify the organism as an emerging threat in domestic water systems, and the technological advantages that biosensors offer over current analytical methods may provide a preventative approach to outbreaks of Cryptosporidium. Biosensors are innovative, versatile and adaptable analytical tools that could provide highly sensitive, rapid, on-site analysis needed for Cryptosporidium detection in low-resource settings.

Structure-Activity Relationship Studies of the Aryl Acetamide Triazolopyridazines against Cryptosporidium Reveals Remarkable Role of Fluorine

Our previous work identified compound 1 (SLU-2633) as a potent lead compound toward the identification of a novel treatment for cryptosporidiosis, caused by the parasite Cryptosporidium (EC50 = 0.17 μM). While this compound is potent and orally efficacious, the mechanism of action and biological target(s) of this series are currently unknown. In this study, we synthesized 70 compounds to develop phenotypic structure-activity relationships around the aryl "tail" group. In this process, we found that 2-substituted compounds are inactive, confirmed that electron withdrawing groups are preferred over electron donating groups, and that fluorine plays a remarkable role in the potency of these compounds. The most potent compound resulting from this work is SLU-10482 (52, EC50 = 0.07 μΜ), which was found to be orally efficacious with an ED90 < 5 mg/kg BID in a Cryptosporidium-infection mouse model, superior to SLU-2633.

The potential therapeutic effect of Nigella sativa and Zingiber officinale extracts versus Nitazoxanide drug against experimentally induced cryptosporidiosis in laboratory mice

In this study, the potential anti-cryptosporidial effect of Nigella sativa (black seeds) and Zingiber officinale (ginger) alcoholic extracts versus Nitazoxanide (NTZ) medication was investigated in immunosuppressed (IS) laboratory mice. Parasitological, histopathological studies were used to assess their therapeutic efficacy. Serum level and tissue expression percentage of IFN-γ was also used. Nigella extract succeeded to reduce the mean oocyst counts in the feces of immunosuppressed mice followed by NTZ. Ginger-treated ones showed the lowest reduction percentage. Nigella sativa showed the best results in terms of restoring the normal architecture of ileal epithelium in histopathological sections stained with H&E. NTZ treatment sub-groups showed mild improvement, followed by ginger-treated mice, which showed a slight improvement in small intestine microenvironment. A significant substantial rise in serum and intestinal tissue IFN-γ cytokine levels were recorded in Nigella subgroups compared to those of NTZ and ginger respectively. According to our findings Nigella sativa outperformed Nitazoxanide in terms of anti-cryptosporidial effectiveness and regeneration characteristics revealing a promising medication. When compared to the commonly used Nitazoxanide medication or Nigella extracts, the outcomes of ginger extract were suboptimal.

Intestinal Coccidian Infections in Cancer Patients: A Case Series

Introduction Coccidian protozoa and microsporidian fungi are opportunistic pathogens increasingly implicated in infections in immunosuppressed individuals. These parasites typically infect the intestinal epithelium, resulting in secretory diarrhea and malabsorption. The disease burden and timeline are both greater and longer among immunosuppressed patients. Therapeutic options for immunocompromised individuals are limited. As a result, we wanted to better characterize the disease course and treatment efficacy of these parasitic gastrointestinal infections. Methods We performed a single-center, retrospective MedMined (BD Healthsight Analytics, Birmingham, AL, USA) chart review of patients between January 2012 and June 2022 diagnosed with coccidian or microsporidian infections. Relevant data were collected from Cerner's PowerChart (Oracle Cerner, Austin, TX, USA). Descriptive analysis was performed with IBM SPSS Statistics (IBM Corp., Armonk, NY, USA), and Microsoft Excel (Microsoft, Redmond, WA, USA) was used to generate graphs and tables. Results In these 10 years, there were 17 patients with Cryptosporidium infections, four with Cyclospora infections, and no positive cultures for Cystoisospora belli or microsporidian infections. In both infections, the majority of patients experienced diarrhea, fatigue, and nausea, with vomiting, abdominal pain, appetite loss, weight loss, and fever occurring to a lesser degree. Nitazoxanide was the most common treatment for Cryptosporidium, while trimethoprim-sulfamethoxazole or ciprofloxacin were the treatments of choice for Cyclospora. Of the Cryptosporidium infections, three received combination therapy with azithromycin, immunoreconstitution, or IV immunoglobulins. Among the four Cyclospora-infected patients, one received combination therapy of ciprofloxacin and trimethoprim-sulfamethoxazole. Treatment lasted around two weeks, and 88% of Cryptosporidium patients and 75% of Cyclospora patients had a resolution of symptoms. Conclusion The most detected coccidian infection was Cryptosporidium, followed by Cyclospora, with the lack of Cystoisospora or microsporidian infections likely due to diagnostic limitations and prevalence. Cryptosporidium and Cyclospora likely caused their associated symptoms in most cases, with other possible etiologies, including graft-versus-host disease, medications, and feeding tubes. The small number of patients receiving combination therapy prohibited a comparison with monotherapy. In our patient population, though, there was a clinical response to treatment despite immunosuppression. While promising, additional randomized control experiments are required to fully understand the efficacy of parasitic treatments.

Structural Analyses of a Dominant Cryptosporidium parvum Epitope Presented by H-2Kb Offer New Options To Combat Cryptosporidiosis

Cryptosporidium parvum has gained much attention as a major cause of diarrhea in the world, particularly in those with compromised immune systems. The data currently available on how the immune system recognizes C. parvum are growing rapidly, but we lack data on the interactions among host major histocompatibility complex (MHC) diversity and parasitic T-cell epitopes. To identify antigenic epitopes in a murine model, we performed systematic profiling of H-2K^b-restricted peptides by screening the dominant Cryptosporidium antigens. The results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant response in C. parvum-recovered C57BL/6 mice, and injection of the cytotoxic-T-lymphocyte (CTL) peptide with the adjuvant activated peptide-specific CD8⁺ T cells. Notably, the SVF9 epitope was highly conserved across Cryptosporidium hominis, C. parvum, and many other Cryptosporidium species. SVF9 also formed stable peptide-MHC class I (MHC I) complexes with HLA-A*0201, suggesting cross-reactivity between H-2K^b and human MHC I specificities. Crystal structure analyses revealed that the interactions of peptide-MHC surface residues of H-2K^b and HLA-A*0201 are highly conserved. The hydrogen bonds of H-2K^b-SVF9 are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by a public human T-cell receptor (TCR). Notably, we found double conformations in position 4 (P4), 5 (P5) of the SVF9 peptide, which showed high flexibility, and multiple peptide conformations generated more molecular surfaces that can potentially be recognized by TCRs. Our findings demonstrate that an immunodominant C. parvum epitope and its homologs from different Cryptosporidium species and subtypes can benefit vaccine development to combat cryptosporidiosis. IMPORTANCE Adaptive immune responses and T lymphocytes have been implicated as important mechanisms of parasite-induced protection. However, the role of CD8⁺ T lymphocytes in the resolution of C. parvum infection is largely unresolved. Our results revealed that the glycoprotein-derived epitope Gp40/15-SVF9 induced an immunodominant CD8⁺ T-cell response in C57BL/6 mice. Crystal structure analyses revealed that the interactions of the H-2K^b-SVF9 peptide are similar to those of a dominant epitope presented by HLA-A*0201, which can be recognized by human TCRs. In addition, we found double conformations of the SVF9 peptide, which showed high flexibility and multiple peptide conformations that can potentially be recognized by TCRs.

Early immune and host cell responses to Cryptosporidium infection

Cryptosporidium spp. are opportunistic protozoan parasites that infect epithelial cells of the small intestine and cause diarrheal illness in both immunocompetent and immunodeficient individuals. These infections may be more severe in immunocompromised individuals and young children, especially in children under 2 in developing countries. The parasite has a global distribution and is an important cause of childhood diarrhea where it may result in cognitive impairment and growth deficits. Current therapies are limited with nitazoxanide being the only FDA-approved drug. However, it is not efficacious in immunocompromised patients. Additionally, there are no vaccines for cryptosporidiosis available. While acquired immunity is needed to clear Cryptosporidium parasites completely, innate immunity and early responses to infection are important in keeping the infection in check so that adaptive responses have time to develop. Infection is localized to the epithelial cells of the gut. Therefore, host cell defenses are important in the early response to infection and may be triggered through toll receptors or inflammasomes which induce a number of signal pathways, interferons, cytokines, and other immune mediators. Chemokines and chemokine receptors are upregulated which recruit immune cells such neutrophils, NK cells, and macrophages to the infection site to help in host cell defense as well as dendritic cells that are an important bridge between innate and adaptive responses. This review will focus on the host cell responses and the immune responses that are important in the early stages of infection.

The Marine Compound Tartrolon E Targets the Asexual and Early Sexual Stages of Cryptosporidium parvum

New therapeutic agents for cryptosporidiosis are a critical medical need. The marine organic compound, tartrolon E (trtE), is highly effective against multiple apicomplexan parasites, including Cryptosporidium. Understanding the mechanism of action of trtE is required to advance in the drug development pipeline. Here, we validate using Nluc C. parvum parasites for the study of trtE and pinpoint the life stage targeted by trtE. Results show that trtE kills Nluc and wild type C. parvum with equal efficiency, confirming the use of the Nluc C. parvum to study this compound. Results revealed that trtE kills the parasite within an hour of treatment and while the compound has no effect on viability of sporozoites, trtE does inhibit establishment of infection. Targeting treatment at particular life cycle stages demonstrated that trtE is effective against asexual of the parasite but has reduced efficacy against mature sexual stages. Gene expression analysis shows that trtE inhibits the early sexual stage of the parasite. Results from these studies will aid the development of trtE as a therapeutic for cryptosporidiosis.

Controlled Human Infection Models To Accelerate Vaccine Development

The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.

Nitazoxanide, Ivermectin, and Artemether effects against cryptosporidiosis in diabetic mice: parasitological, histopathological, and chemical studies

Human cryptosporidiosis is one of the most significant causes of water borne epidemics of diarrhea worldwide. It is extremely important in immunocompromised hosts and malnourished children as it could cause severe life-threatening diarrhea. Despite the global burden of the disease, there are only few available therapies against cryptosporidiosis. Diabetes mellitus is a common metabolic disorder that impair both the innate and adaptive immune responses of the patient. This study aimed to test the effect of Nitazoxanide, Ivermectin, and Artemether against cryptosporidiosis in diabetic mice. Sixty white albino mice were categorized into 6 groups; 10 mice each: GI: normal non-infected non-treated (healthy- control), GII-GVI (diabetic groups), GII: non-infected non treated (diabetic control), GIII: infected non treated (infected control), GIV: infected and treated with Nitazoxanide (NTZ), GV: infected and treated with Ivermectin (IVC), GVI: infected and treated with Artemether (ART). Parasitological, histopathological, and chemical examinations were done to evaluate the effect of NTZ, IVC, and ART against cryptosporidiosis in diabetic mice. Parasitological examination revealed maximum reduction of oocyst shedding in GVI, while histopathological examination showed the least pathologic changes in GV with mild vascular wall fibrosis and moderate lymphocytic infiltration of islets of Langerhans. Measurement of blood glucose level showed the best results with GIV. Nitazoxanide is effective against cryptosporidiosis in diabetic patients with minimal hyperglycemia, Artemether is especially effective in reducing the oocyst shedding in stool, whereas Ivermectin is associated with the least pathological changes in pancreatic islets of Langerhans.

Disseminated Cryptosporidiosis in an Infant with Non-HIV Pediatric Immunodeficiency: First Case Report from Oman

Cryptosporidium is a rare but important pathogen, especially in children with immunodeficiency. Intestinal cryptosporidiosis is well described in immunocompetent and immunocompromised children, but respiratory and disseminated cryptosporidiosis in immunodeficient children is not often reported. We describe an Omani infant with disseminated cryptosporidiosis and failing pharmacological therapy in the context of severe combined immunodeficiency. Chronic diarrhea can be an initial symptom of immunodeficiency in the pediatric population. Awareness of cryptosporidiosis is critical to early detection and management for such patients. As antiparasitic agents are often ineffective, amelioration of immunosuppression in immunodeficient children should be a priority.

Interventions promoting uptake of water, sanitation and hygiene (WASH) technologies in low- and middle-income countries: An evidence and gap map of effectiveness studies

Background

Lack of access to and use of water, sanitation and hygiene (WASH) cause 1.6 million deaths every year, of which 1.2 million are due to gastrointestinal illnesses like diarrhoea and acute respiratory infections like pneumonia. Poor WASH access and use also diminish nutrition and educational attainment, and cause danger and stress for vulnerable populations, especially for women and girls. The hardest hit regions are sub-Saharan Africa and South Asia. Sustainable Development Goal (SDG) 6 calls for the end of open defecation, and universal access to safely managed water and sanitation facilities, and basic hand hygiene, by 2030. WASH access and use also underpin progress in other areas such as SDG1 poverty targets, SDG3 health and SDG4 education targets. Meeting the SDG equity agenda to "leave none behind" will require WASH providers prioritise the hardest to reach including those living remotely and people who are disadvantaged.

Objectives

Decision makers need access to high-quality evidence on what works in WASH promotion in different contexts, and for different groups of people, to reach the most disadvantaged populations and thereby achieve universal targets. The WASH evidence map is envisioned as a tool for commissioners and researchers to identify existing studies to fill synthesis gaps, as well as helping to prioritise new studies where there are gaps in knowledge. It also supports policymakers and practitioners to navigate the evidence base, including presenting critically appraised findings from existing systematic reviews.

Methods

This evidence map presents impact evaluations and systematic reviews from the WASH sector, organised according to the types of intervention mechanisms, WASH technologies promoted, and outcomes measured. It is based on a framework of intervention mechanisms (e.g., behaviour change triggering or microloans) and outcomes along the causal pathway, specifically behavioural outcomes (e.g., handwashing and food hygiene practices), ill-health outcomes (e.g., diarrhoeal morbidity and mortality), nutrition and socioeconomic outcomes (e.g., school absenteeism and household income). The map also provides filters to examine the evidence for a particular WASH technology (e.g., latrines), place of use (e.g., home, school or health facility), location (e.g., global region, country, rural and urban) and group (e.g., people living with disability). Systematic searches for published and unpublished literature and trial registries were conducted of studies in low- and middle-income countries (LMICs). Searches were conducted in March 2018, and searches for completed trials were done in May 2020. Coding of information for the map was done by two authors working independently. Impact evaluations were critically appraised according to methods of conduct and reporting. Systematic reviews were critically appraised using a new approach to assess theory-based, mixed-methods evidence synthesis.

Results

There has been an enormous growth in impact evaluations and systematic reviews of WASH interventions since the International Year of Sanitation, 2008. There are now at least 367 completed or ongoing rigorous impact evaluations in LMICs, nearly three-quarters of which have been conducted since 2008, plus 43 systematic reviews. Studies have been done in 83 LMICs, with a high concentration in Bangladesh, India, and Kenya. WASH sector programming has increasingly shifted in focus from what technology to supply (e.g., a handwashing station or child's potty), to the best way in which to do so to promote demand. Research also covers a broader set of intervention mechanisms. For example, there has been increased interest in behaviour change communication using psychosocial "triggering", such as social marketing and community-led total sanitation. These studies report primarily on behavioural outcomes. With the advent of large-scale funding, in particular by the Bill & Melinda Gates Foundation, there has been a substantial increase in the number of studies on sanitation technologies, particularly latrines. Sustaining behaviour is fundamental for sustaining health and other quality of life improvements. However, few studies have been done of intervention mechanisms for, or measuring outcomes on sustained adoption of latrines to stop open defaecation. There has also been some increase in the number of studies looking at outcomes and interventions that disproportionately affect women and girls, who quite literally carry most of the burden of poor water and sanitation access. However, most studies do not report sex disaggregated outcomes, let alone integrate gender analysis into their framework. Other vulnerable populations are even less addressed; no studies eligible for inclusion in the map were done of interventions targeting, or reporting on outcomes for, people living with disabilities. We were only able to find a single controlled evaluation of WASH interventions in a health care facility, in spite of the importance of WASH in health facilities in global policy debates. The quality of impact evaluations has improved, such as the use of controlled designs as standard, attention to addressing reporting biases, and adequate cluster sample size. However, there remain important concerns about quality of reporting. The quality and usefulness of systematic reviews for policy is also improving, which draw clearer distinctions between intervention mechanisms and synthesise the evidence on outcomes along the causal pathway. Adopting mixed-methods approaches also provides information for programmes on barriers and enablers affecting implementation.

Conclusion

Ensuring everyone has access to appropriate water, sanitation, and hygiene facilities is one of the most fundamental of challenges for poverty elimination. Researchers and funders need to consider carefully where there is the need for new primary evidence, and new syntheses of that evidence. This study suggests the following priority areas:Impact evaluations incorporating understudied outcomes, such as sustainability and slippage, of WASH provision in understudied places of use, such as health care facilities, and of interventions targeting, or presenting disaggregated data for, vulnerable populations, particularly over the life-course and for people living with a disability;Improved reporting in impact evaluations, including presentation of participant flow diagrams; andSynthesis studies and updates in areas with sufficient existing and planned impact evaluations, such as for diarrhoea mortality, ARIs, WASH in schools and decentralisation. These studies will preferably be conducted as mixed-methods systematic reviews that are able to answer questions about programme targeting, implementation, effectiveness and cost-effectiveness, and compare alternative intervention mechanisms to achieve and sustain outcomes in particular contexts, preferably using network meta-analysis.

Antiparasitic and immunomodulating effects of nitazoxanide, ivermectin and selenium on Cryptosporidium infection in diabetic mice

The present work aims to investigate the antiparasitic and the immunomodulating effects of nitazoxanide (NTZ) and ivermectin (IVC) alone or combined together or combined with selenium (Se), on Cryptosporidium infection in diabetic mice. The results revealed that the combined NTZ and IVC therapy achieved the highest reduction of fecal oocysts (92%), whereas single NTZ showed the lowest reduction (63%). Also, adding Se to either NTZ or IVC resulted in elevation of oocyst reduction from 63% to 71% and from 82% to 84% respectively. All treatment regimens, with the exception of NTZ monotherapy, showed a significant improvement in the intestinal histopathology, the highest score was in combined NTZ and IVC therapy. The unique results of immunohistochemistry in this study showed reversal of the normal CD4/CD8 T cell ratio in the infected untreated mice, however, following therapy it reverts back to a normal balanced ratio. The combined (NTZ+ IVC) treatment demonstrated the highest level of CD4 T cell expression. Taken together, NTZ and IVC combined therapy showed remarkable anti-parasitic and immunostimulatory effects, specifically towards the CD4 population that seem to be promising in controlling cryptosporidiosis in diabetic individuals. Further research is required to explore other effective treatment strategies for those comorbid patients.

Review on Emerging Waterborne Pathogens in Africa: The Case of Cryptosporidium

Water-related diseases, particularly waterborne diseases, remain significant sources of morbidity and mortality worldwide but especially in developing countries. Emerging waterborne pathogens represent a major health risk. Cryptosporidium is one such pathogen which is globally recognized as a major cause of diarrhea in children and adults. The objective of this paper is not only to review published studies on the impact of these emerging waterborne pathogens but also to identify the various risk factors that favor their transmission. A number of envisaged and needed actions to tackle the challenge of these pathogens in Africa have also been discussed. We have searched the web of ScienceDirect, PubMed, Scopus. ISI Web of Science, SpringerLink, and Google Scholar. The first database search yielded 3099 articles. As a result, 141 studies were submitted for abstract review. A total of 68 articles were selected for full text analysis. After evaluating a considerable number of articles on this topic, the following results were obtained. A number of pathogens are likely to present public health risks, including Cryptosporidium. The contaminating potential of these pathogens is associated with a multitude of factors, such as the effects of climate change, social and behavioral aspects of local populations, water issues, geographical locations that may cause isolation, and inequalities due to lack of transparency of governments in the distribution of financial resources. We stress the need to maintain and strengthen real-time surveillance and rapid epidemiological responses to outbreaks and the emergence of new waterborne pathogens in all countries. African governments, for their part, should be aware of future risks of waterborne protozoan diseases. They must provide immediate and effective responses by establishing technical and financial mechanisms to ensure sufficient quantities of safe drinking water, sewage disposal, and hygiene for all.

In vitro and in vivo anti-Cryptosporidium and anti-inflammatory effects of Aloe vera gel in dexamethasone immunosuppressed mice

Cryptosporidiosis has been considered as a serious diarrheal disease, especially in immunodeficient patients, where they failed to clear the infection leading to several consequences of infection (i.e death). The role of cell mediated immunity in clearing the infection was demonstrated by the increased susceptibility of HIV/AIDS patients to infection. To date, no specific treatment has been proven for cryptosporidiosis in immunodeficient patients. The study aimed to evaluate the efficacy of Aloe vera gel for the treatment of cryptosporidiosis in immunocompetent and dexamethasone immunosuppressed mice in comparison to that of nitazoxanide. Mice were orally administrated with Aloe vera gel, in a daily dose of 250 mg/L in drinking water, for 14 consecutive days post infection. Parasitological, molecular and immunological measurements were recorded on the 7th, 14th, 21st and 32nd days post infection. Our in vitro results showed that 250 mg/L of prepared gel achieved the highest parasitic reduction. The body weights of Aloe vera treated mice on the 21st and 32nd day post infection, either in immunocompetent or immunosuppressed groups, were nearly the same as those of their corresponding control groups. Aloe vera gel succeeded in clearing cryptosporidiosis with a percent reduction of 100% in immunocompetent mice and 99.67% in immunosuppressed mice. The anti-inflammatory effect of Aloe vera reduced the levels of IFN-γ, IL-4, -6 and -17. The success of Aloe vera gel, in clearing cryptosporidiosis in immunosuppressed mice, was obvious either from the reduction of Cryptosporidium DNA or the oocysts in stool samples; and from the improvement of histopathological sections.

Optimization of the Urea Linker of Triazolopyridazine MMV665917 Results in a New Anticryptosporidial Lead with Improved Potency and Predicted hERG Safety Margin

Cryptosporidiosis is caused by infection of the small intestine by Cryptosporidium parasites, resulting in severe diarrhea, dehydration, malabsorption, and potentially death. The only FDA-approved therapeutic is only partially effective in young children and ineffective for immunocompromised patients. Triazolopyridazine MMV665917 is a previously reported anti-Cryptosporidium screening hit with in vivo efficacy but suffers from modest inhibition of the hERG ion channel, which could portend cardiotoxicity. Herein, we describe our initial development of structure-activity relationships of this novel lead series with a particular focus on optimization of the piperazine-urea linker. We have discovered that piperazine-acetamide is a superior linker resulting in identification of SLU-2633, which has an EC₅₀ of 0.17 μM, an improved projected margin versus hERG, prolonged pharmacokinetic exposure in small intestine, and oral efficacy in vivo with minimal systemic exposure. SLU-2633 represents a significant advancement toward the identification of a new effective and safe treatment for cryptosporidiosis.

Infectious Gastroenteritis in Transplant Patients

Infectious gastroenteritis is common after transplantation and can lead to increased morbidity and mortality. A wide range of organisms can lead to gastroenteritis in this patient population. Clostridioides difficile, cytomegalovirus, and norovirus are the most common pathogens. Newer diagnostic methods, especially multiplex polymerase chain reaction, have increased the diagnostic yield of infectious etiologies. In this review, we describe the epidemiology and risk factors for common infectious pathogens leading to gastroenteritis.

Mucosal Papillary Hyperplasia in Gallbladder: A Clue for Infectious Etiology in HIV Patients

Gallbladder specimens are ditzel in surgical pathology and opportunistic diseases like cryptosporidiosis where they are easy to miss. We describe three cases of gallbladders with mucosal papillary hyperplasia with acute and chronic inflammation, all of which revealed cryptosporidiosis on complete histological evaluation. The patients were found to be HIV positive on further chart review. In the absence of clinical history, which is often the case with gallbladder specimens, the finding of mucosal papillary hyperplasia can be a reactive response to an infectious cause and can serve as a helpful clue to look for organisms with patience at higher magnification.

PREVALENCE OF ZOONOTIC CRYPTOSPORIDIUM SPP. ISOLATES IN NJORO SUB-COUNTY, NAKURU COUNTY, KENYA

BACKGROUND

There is no information on human and animal Cryptosporidium spp. in Njoro sub- county. The risk posed to humans and animals within the sub-county is therefore unknown.

MATERIALS AND METHODS

A total of 1476 animal and 378 human fecal samples were evaluated. Multivariate logistic regression was used to evaluate association between infection status and the predisposing factors. Results were expressed as odds ratio (OR) with a 95% confidence interval. Chi-square and Maentel-Haenszel tests were used to quantify relationships among variables.

RESULTS

Prevalence of Cryptosporidium spp. was 9.8% in humans, 10.8% in cows, 19.6% in sheep and 4.5% in goats. Prevalence in humans was significantly higher in females 12/37. Infection was highest in the elderly (27.27%), and significantly lower in adolescents and adults at 8.66% and 9.59%, respectively. Goats had lowest overall parasitization at all levels, while sheep had the highest parasitization at levels (+1 and +2). Relatively, humans had the highest parasite counts +3 cases (1.5%).

CONCLUSION

Cryptosporidium spp. is prevalent in Njoro sub-county and domestic animals are important reservoirs and a potential source of zoonosis in humans. Children, elderly and females are at increased risk of infection, especially during rainy season. The study recommends maintenance of proper sanitation when handling domestic animals, treatment of drinking water and use of alternative safer sources of water in order to reduce infection.

Use-case scenarios for an anti-Cryptosporidium therapeutic

Cryptosporidium is a widely distributed enteric parasite that has an increasingly appreciated pathogenic role, particularly in pediatric diarrhea. While cryptosporidiosis has likely affected humanity for millennia, its recent "emergence" is largely the result of discoveries made through major epidemiologic studies in the past decade. There is no vaccine, and the only approved medicine, nitazoxanide, has been shown to have efficacy limitations in several patient groups known to be at elevated risk of disease. In order to help frontline health workers, policymakers, and other stakeholders translate our current understanding of cryptosporidiosis into actionable guidance to address the disease, we sought to assess salient issues relating to clinical management of cryptosporidiosis drawing from a review of the literature and our own field-based practice. This exercise is meant to help inform health system strategies for improving access to current treatments, to highlight recent achievements and outstanding knowledge and clinical practice gaps, and to help guide research activities for new anti-Cryptosporidium therapies.

PROTOCOL: Water, sanitation and hygiene for reducing childhood mortality in low- and middle-income countries

Respiratory tract infections and diarrhoea are the two biggest killers of children in low income contexts. They are closely related to access to, and use of improved water, sanitation and hygiene (WASH). However, there is no high quality systematic review that quantifies the effect of WASH improvements on childhood mortality. Existing systematic reviews of WASH improvements measure effects on morbidity, under the (often implicit) assumption that morbidity is closely correlated with mortality. This is at least partly because the impact evaluations on which they are based are only designed to detect changes in morbidity with statistical precision, whereas mortality is a relatively rare outcome. The proposed review will address this evidence synthesis gap, using the greater statistical power of meta-analysis to pool findings across studies.

The immunomodulatory activity of secnidazole-nitazoxanide in a murine cryptosporidiosis model

Introduction. Cryptosporidium parvum causes intestinal parasitic infections affecting both immunosuppressed and immunocompetent individuals.Gap statement. Given the absence of effective treatments for cryptosporidiosis, especially in immunodeficient patients, the present study was designed to assess the therapeutic efficacy of secnidazole (SEC) and its combination with nitazoxanide (NTZ) in comparison to single NTZ treatment in relation to the immune status of a murine model of C. parvum infection.Methodology. The infected groups were administered NTZ, SEC or NTZ-SEC for three or five successive doses. At days 10 and 12 post-infection (p.i.), the mice were sacrificed, and the efficacy of the applied drugs was evaluated by comparing the histopathological alterations in ileum and measuring the T helper Th1 (interferon gamma; IFN-γ), Th2 [interleukin (IL)-4 and IL-10] and Th17 (IL-17) cytokine profiles in serum.Results. The NTZ-SEC combination recorded the maximal reduction of C. parvum oocyst shedding, endogenous stages count and intestinal histopathology, regardless of the immune status of the infected mice. The efficacy of NTZ-SEC was dependent on the period of administration, as the 5 day-based treatment protocol was also more effective than the 3 day-based one in terms of immunocompetence and immunosuppression. The present treatment schedule induced an immunomodulatory effect from SEC that developed a protective immune response against C. parvum infection with reduced production of serum IL-17, IFN-γ, IL-4 and IL-10.Conclusions. Application of NTZ-SEC combined therapy may be useful in treatment of C. parvum, especially in cases involving immunosuppression.

Characterization of Three Calcium-Dependent Protein Kinases of Cryptosporidium parvum

In Cryptosporidium spp., calcium-dependent protein kinases (CDPKs) are considered promising targets for the development of pharmaceutical interventions. Whole-genome sequencing has revealed the presence of 11 CDPKs in Cryptosporidium parvum (CpCDPKs). In this study, we expressed recombinant CpCDPK4, CpCDPK5, and CpCDPK6 in Escherichia coli. The biological characteristics and functions of these CpCDPKs were examined by using quantitative reverse transcription PCR (qRT-PCR), immunofluorescence microscopy, and an in vitro neutralization assay. The expression of the CpCDPK4 gene peaked at 12 h post-infection, the CpCDPK5 gene peaked at 12 and 48 h, and the CpCDPK6 gene peaked at 2–6 h. CpCDPK4 protein was located in the anterior and mid-anterior regions of sporozoites, and CpCDPK5 protein was located over the entire sporozoites, while CpCDPK6 protein was expressed in a spotty pattern. Immune sera of CpCDPK4 and CpCDPK6 exhibited significant inhibitory effects on host cell invasion, while the immune sera of CpCDPK5 had no effects. These differences in protein localization, gene expressions, and neutralizing capacities indicated that the CpCDPK proteins may have different roles during the lifecycle of Cryptosporidium spp.

Novel acyl carbamates and acyl / diacyl ureas show in vitro efficacy against Toxoplasma gondii and Cryptosporidium parvum

Toxoplasma gondii and Cryptosporidium parvum are protozoan parasites that are highly prevalent and opportunistically infect humans worldwide, but for which completely effective and safe medications are lacking. Herein, we synthesized a series of novel small molecules bearing the diacyl urea scaffold and related structures, and screened them for in vitro cytotoxicity and antiparasitic activity against T. gondii and C. parvum. We identified one compound (GMG-1-09), and four compounds (JS-1-09, JS-2-20, JS-2-35 and JS-2-49) with efficacy against C. parvum and T. gondii, respectively, at low micromolar concentrations and showed appreciable selectivity in human host cells. Among the four compounds with efficacy against T. gondii, JS-1-09 representing the diacyl urea scaffold was the most effective, with an anti-Toxoplasma IC50 concentration (1.21 μM) that was nearly 53-fold lower than its cytotoxicity IC50 concentration, indicating that this compound has a good selectivity index. The other three compounds (JS-2-20, JS-2-35 and JS-2-49) were structurally more divergent from JS-1-09 as they represent the acyl urea and acyl carbamate scaffold. This appeared to correlate with their anti-Toxoplasma activity, suggesting that these compounds' potency can likely be enhanced by selective structural modifications. One compound, GMG-1-09 representing acyl carbamate scaffold, depicted in vitro efficacy against C. parvum with an IC50 concentration (32.24 μM) that was 14-fold lower than its cytotoxicity IC50 concentration in a human intestinal cell line. Together, our studies unveil a series of novel synthetic acyl/diacyl urea and acyl carbamate scaffold-based small molecule compounds with micromolar activity against T. gondii and C. parvum that can be explored further for the development of the much-needed novel anti-protozoal drugs.

A Single Cysteine Residue in the Translocation Pathway of the Mitosomal ADP/ATP Carrier from Cryptosporidium parvum Confers a Broad Nucleotide Specificity

Cryptosporidiumparvum is a clinically important eukaryotic parasite that causes the disease cryptosporidiosis, which manifests with gastroenteritis-like symptoms. The protist has mitosomes, which are organelles of mitochondrial origin that have only been partially characterized. The genome encodes a highly reduced set of transport proteins of the SLC25 mitochondrial carrier family of unknown function. Here, we have studied the transport properties of one member of the C. parvum carrier family, demonstrating that it resembles the mitochondrial ADP/ATP carrier of eukaryotes. However, this carrier has a broader substrate specificity for nucleotides, transporting adenosine, thymidine, and uridine di- and triphosphates in contrast to its mitochondrial orthologues, which have a strict substrate specificity for ADP and ATP. Inspection of the putative translocation pathway highlights a cysteine residue, which is a serine in mitochondrial ADP/ATP carriers. When the serine residue is replaced by cysteine or larger hydrophobic residues in the yeast mitochondrial ADP/ATP carrier, the substrate specificity becomes broad, showing that this residue is important for nucleotide base selectivity in ADP/ATP carriers.

Influence of weather and climate on cryptosporidiosis-A review

Studies have shown that climatic factors can significantly influence transmission of many waterborne diseases. However, knowledge of the impact of climate variability on cryptosporidiosis is much less certain. Associations between the incidence of cryptosporidiosis and climatic variables have been reported in several countries. Given that the identified relationships were not consistently reported across studies, it is not known whether these were country-specific observations or can be considered more globally. Variation in the disease risk in both low- and middle-income countries and high-income countries presents new challenges and opportunities to enact responsive changes in research and public health policies. Available epidemiological evidence of the influence of weather and climate on cryptosporidiosis is reviewed. Fourteen studies met the inclusion criteria, and most studies showed that the incidence of cryptosporidiosis is highly sensitive to climatic conditions, especially temperature, rainfall and relative humidity. The identified associations varied across studies, with different conditions of importance and lag times across different locations. Therefore, there is a need for countries at risk to assess Cryptosporidium transmission routes based on the spatiotemporal patterns of the disease and what role climate and other socio-ecological changes play in the transmission. Information gathering will then allow us to provide information for evidence-based control strategies and mitigation of transmission. This review offers new perspectives on the role of climate variability on Cryptosporidium transmission. It highlights different epidemiological approaches adopted and provides the potential for future research and surveillance to reduce the disease burden. By evaluating the epidemiological transmission of this organism in high-income countries, all mitigation strategies, for example filtration and water catchment management, can be used as exemplars of preventing infection in low- to middle-income countries.

Biofilm Sampling for Detection of Cryptosporidium Oocysts in a Southeastern Pennsylvania Watershed

This study investigated the use of biofilms to monitor Cryptosporidium in water. Benthic rock and submersible slide biofilms were sampled upstream and downstream of point sources in a suburban watershed in southeastern Pennsylvania. More oocysts were detected in biofilms scraped from rocks downstream than upstream of a wastewater treatment plant (WWTP) (19 versus 5, respectively; n = 1). Although not statistically significant, Cryptosporidium oocysts were detected more frequently, and in greater numbers, in biofilms grown on slides downstream than upstream of this same WWTP (83.3% positive samples [n = 12] versus 45.5% positive samples [n = 11], respectively; P = 0.0567). Similarly, Cryptosporidium oocysts were detected more frequently, and in greater numbers, in rock biofilms collected downstream than upstream of a stormwater outfall impacted by defective sewer laterals (50% positive samples downstream and 17% positive samples upstream; n = 6; P = 0.2207). While oocyst detection data obtained by slide biofilms versus filters did not necessarily agree on a given day, there was no seasonal difference in the frequency of oocyst detection (P > 0.05) or numbers of oocysts detected (P > 0.05) whether the water was monitored by filtration or slide biofilm sampling. Within any given season, there was no difference in the frequency of oocyst detection (P > 0.05) or the numbers of oocysts detected (P > 0.05) whether the water was monitored by filtration or slide biofilm sampling. These data show that oocyst detection in biofilms is comparable to oocyst detection in filtered water samples. Biofilm sampling offers significant cost savings compared to the filtration-based EPA Method 1623.1 and could be used to identify watershed locations at potential risk for increased oocyst loads.IMPORTANCE Monitoring Cryptosporidium occurrence in watersheds that provide drinking water is necessary to determine where limited resources should most effectively be directed to protect consumers from waterborne exposure to pathogenic oocysts. Biofilms are a useful tool to monitor complex watersheds and identify point sources of Cryptosporidium oocyst contamination that need to be managed to protect public health. Compared to EPA Method 1623.1, the cost benefit of using biofilms to monitor for Cryptosporidium contamination will enable utilities to sample water supplies more frequently, and at more locations, than is currently possible given limited operating budgets. Biofilm sampling could be used to identify high-risk regions within a large, complex watershed and the associated water treatment plants at potential risk for increased oocyst loads in the water supply; this information could then be used to select the locations within the watershed where the more expensive EPA Method 1623.1 is warranted.

Epidemiology of Cryptosporidiosis in France from 2017 to 2019

Cryptosporidiosis is currently recognized worldwide as a leading cause of moderate to severe diarrhea. In Europe, large water- and foodborne outbreaks have been reported, highlighting the widespread distribution of the parasite and its important health impact. Surveillance networks have been progressively set up and the aim of this study was to present recent epidemiological data obtained in France from 2017 to 2019 by the National Reference Center-Expert Laboratory of cryptosporidiosis (Centre National de Référence-Laboratoire Expert cryptosporidioses CNR-LE). Data were obtained from online reports of volunteer network participants and stools were sent to the CNR-LE for species identification and GP60 genotyping. During this period, data from 750 online reports were available. Cryptosporidiosis occurred predominantly in young children (<5 years old) and in young adults, especially during late summer. Most patients were immunocompetent (60%), and deaths were reported only in immunocompromised patients. Cryptosporidium parvum was largely predominant (72% of cases) over C. hominis (24%) and some other uncommon species. C. parvum GP60 subtypes IIa and IId were the most represented, which suggests frequent zoonotic transmission. For C. hominis, subtypes IbA10G2 and IaA22R2 were predominant.

Potential therapeutic and prophylactic effects of Asafoetida in murine cryptosporidiosis

Cryptosporidium parvum is an important coccidian parasite that could infect the intestine, respiratory and biliary tracts of man and animals. This study aims to test the potential therapeutic and prophylactic effects of a natural herbal agent (Asafoetida) versus the nowadays drug of choice (Nitazoxanide). Fifty bred female, white Albino mice of CDI strain were divided into 5 groups; group I (GI): immunosuppressed, infected with C. parvum and treated with Asafoetida, group II (GII): immunosuppressed, prophylactically treated with Asafoetida for 7 days prior to infection, group III (GIII): immunosuppressed, infected and treated with Nitazoxanide, group IV (GIV): immunosuppressed and infected (Positive control), group V (GV): immunosuppressed and non infected (Negative control). Parasitological and histopatholgical examinations of the stool, ileocaecal and liver specimens were performed for the study groups. GI showed reduction of the mean oocyst count in stool with improvement of the pathological changes at the ileocaecal region with preservation of hepatic architecture. Results of GI were better than GII and GIV but not as good as GIII. GII showed the least improvement among the test groups. GIII showed the best response between the test groups. GIV show no statistical significant difference between the mean oocyst count in the mice stool at the time of infection and 7 days after infection. It was therefore concluded that Asafoetida is a promising natural therapeutic and prophylactic agent against cryptosporidiosis while, Nitazoxanide is the best chemotherapeutic agent against cryptosporidiosis.

Characterization of Calcium-Dependent Protein Kinases 3, a Protein Involved in Growth of Cryptosporidium parvum

Calcium-dependent protein kinases (CDPKs) are considered promising targets for pharmaceutical intervention of cryptosporidiosis. Whole-genome sequencing has revealed the presence of several CDPKs (CpCDPKs) in Cryptosporidium parvum. In this study, we expressed recombinant CpCDPK3 encoded by the cgd5_820 gene in Escherichia coli. The biologic characteristics and functions of CpCDPK3 were examined using qRT-PCR, immunofluorescence microscopy, and in vitro neutralization assay. The expression of the cgd5_820 gene peaked in merozoites during in vitro culture while the CpCDPK3 protein was expressed in both sporozoites and merozoites. Polyclonal antibodies against CpCDPK3 showed no significant inhibitory effects on host invasion by the parasites. We assessed the inhibitory effects of 46 candidate compounds from molecular docking of CpCDPK3 on both C. parvum development and CpCDPK3 enzyme activities. One compound was identified to be effective. Results of these analyses suggest that CpCDPK3 might play an important role in the growth of C. parvum.

Piperazine-Derivative MMV665917: An Effective Drug in the Diarrheic Piglet Model of Cryptosporidium hominis

BACKGROUND

Cryptosporidiosis, an enteric protozoon, causes substantial morbidity and mortality associated with diarrhea in children <2 years old in low- to middle-income countries. There is no vaccine and treatments are inadequate. A piperazine-based compound, MMV665917, has in vitro and in vivo efficacy against Cryptosporidium parvum. In this study, we evaluated the efficacy of MMV665917 in gnotobiotic piglets experimentally infected with Cryptosporidium hominis, the species responsible for >75% of diarrhea reported in these children.

METHODS

Gnotobiotic piglets were orally challenged with C hominis oocysts, and oral treatment with MMV665917 was commenced 3 days after challenge. Oocyst excretion and diarrhea severity were observed daily, and mucosal colonization and lesions were recorded after necropsy.

RESULTS

MMV665917 significantly reduced fecal oocyst excretion, parasite colonization and damage to the intestinal mucosa, and peak diarrheal symptoms, compared with infected untreated controls. A dose of 20 mg/kg twice daily for 7 days was more effective than 10 mg/kg. There were no signs of organ toxicity at either dose, but 20 mg/kg was associated with slightly elevated blood cholesterol and monocytes at euthanasia.

CONCLUSIONS

These results demonstrate the effectiveness of this drug against C hominis. Piperazine-derivative MMV665917 may potentially be used to treat human cryptosporidiosis; however, further investigations are required.

Acute Infectious Diarrhea and Gastroenteritis in Children

PURPOSE OF REVIEW

We aimed to summarize the most current evidence on the main aspects of the diarrheal diseases in children. The following key elements were addressed: definitions, etiology, pathogenesis, diagnosis, dietary management, pharmacological treatments, and prevention. We covered the following questions: What are the most important clinical and laboratory features of the disease? What are the best approaches for the dietary management? What is the best way to classify the hydration status, and to prevent and treat the dehydration? What are the most effective and safe interventions for reducing the diarrhea and vomiting?

RECENT FINDINGS

Diarrheal diseases are one of the most common diseases in childhood. The most common cause is rotavirus. A key element in the approach of a child with diarrhea is determining their hydration status, which determines the fluid management. Laboratory tests are nor routinely required, as most of the cases, they do not affect the management and it should be indicated only in selected cases. Several treatments have been studied to reduce the duration of the diarrhea. Only symbiotics and zinc have shown to be effective and safe with high certainty on the evidence. Rest of the interventions although seem to be effective have low to very low quality of the evidence. The only effective and safe antiemetic for controlling vomiting is ondansetron. A list of antimicrobials indications according to the identified microorganisms is provided. We summarized the most current evidence on diagnosis, management, and prevention of diarrhea in children. More research is needed in some areas such as dehydration scales, rehydration management, antidiarrheals, and antibiotic treatments.

Nitazoxanide in the Treatment of Intestinal Parasitic Infections in Children: A Systematic Review and Meta-Analysis

OBJECTIVES

To evaluate the efficacy and safety of nitazoxanide in intestinal parasitic infections in children.

METHODS

Four databases, PubMed, EMBASE, Web of Science and Cochrane Library, have been systematically searched from the inception of each database up to March 1st, 2019. The enrolled studies were limited to randomized clinical trials in children, comparing nitazoxanide with placebo or other antiparasitic drugs. The data extraction and quality assessment of pooled studies were conducted by two reviewers independently. For meta-analysis, Stata12.0 was used and a randomized effect model or a fixed effect model was selected according to the outcomes of heterogeneity test.

RESULTS

A total of 1645 subjects in 13 randomized controlled trials (RCTs) were enrolled, including 768 cases in the trial group and 877 cases in the control group. The effect of nitazoxanide vs. placebo and other antiparasitic drugs on the excretion rate of pathogens was uncertain (OR = 2.06, 95%CI [1.01,4.20], P = 0.047; I² = 84.7%; very low quality evidence). Compared with placebo, subgroup analysis suggested that nitazoxanide could significantly improve the excretion rate of pathogens (OR = 7.01, 95%CI [1.82,26.94], P = 0.005; I² = 79.1%; moderate quality evidence), while it made little or no difference compared with antiparasitic drugs (OR = 0.72, 95%CI [0.47,1.09], P = 0.124; I² = 33.1%; low quality evidence). Meanwhile, nitazoxanide might increase the remission rate of diarrhea with OR = 5.12, 95%CI [2.00,13.08], P = 0.001; I² = 72.3%; low quality evidence). However, it might also increase the rate of adverse events (OR = 1.47, 95%CI [1.05,2.07], P = 0.026; I² = 44.7%; low quality evidence).

CONCLUSIONS

The authors are uncertain whether or not nitazoxanide could improve the excretion rate of pathogens. Based on low-certainty evidence, nitazoxanide may improve the remission rate of diarrhea in children with intestinal parasite infections, but it may be associated with an increased risk of adverse reactions. Hence, more RCTs with a low risk of bias are still needed to assess the efficacy and safety of nitazoxanide.

An immunocompetent rat model of infection with Cryptosporidium hominis and Cryptosporidium parvum

A major obstacle to developing vaccines against cryptosporidiosis, a serious diarrheal disease of children in developing countries, is the lack of rodent models essential to identify and screen protective immunogens. Rodent models commonly used for drug discovery are unsuitable for vaccine development because they either are purposefully immunodeficient or immunosuppressed. Here, we describe the development and optimization of an immunocompetent intratracheal (IT) rat model susceptible to infections with sporozoites of Cryptosporidium parvum and Cryptosporidium hominis - the primary causes of human cryptosporidiosis. A model suitable for screening of parasite immunogens is a prerequisite for immunogen screening and vaccine development.

Cryptosporidiosis And Other Intestinal Parasitic Infections And Concomitant Threats Among HIV-Infected Children In Southern Ethiopia Receiving First-Line Antiretroviral Therapy

Background

Children infected with human immunodeficiency virus (HIV) are at high risk of acquiring intestinal parasitic infections. This study aimed to determine the magnitude of Cryptosporidium and other intestinal parasitic infections and concomitant threats among HIV-infected children.

Methods

A hospital-based cross-sectional study was carried out at three antiretroviral therapy clinics in southern Ethiopia from February 2016 to June 2017 in 384 HIV positive children. Socio-demographic and clinical data were collected using structured questionnaires. Direct stool microscopic examination and modified Zeihl–Neelsen staining technique to identify parasites. Chi-square test was conducted to determine the real predictors of the infection. Significant association was considered when p-value <0.05 at 95% CI.

Results

The overall magnitude of intestinal parasitic infections among the study population was 16.9% (95% CI: 13.0–20.8%). The most predominant parasitic infections were Cryptosporidium spp. (9.6%) and the least was Taenia spp. (0.78%). Diarrheal status (χ²=7.653, df=2, p=0.022) was detected to be the only significant associated variable.

Conclusion

Cryptosporidium infection was found to be the most common intestinal parasitosis among HIV-infected children. Routine screening service for Cryptosporidium and other intestinal parasites is important in the clinical management of HIV-infected children.

Cytoplasmic RNA Sensor Pathways and Nitazoxanide Broadly Inhibit Intracellular Mycobacterium tuberculosis Growth

To establish stable infection, Mycobacterium tuberculosis (MTb) must overcome host innate immune mechanisms, including those that sense pathogen-derived nucleic acids. Here, we show that the host cytosolic RNA sensing molecules RIG-I-like receptor (RLR) signaling proteins RIG-I and MDA5, their common adaptor protein MAVS, and the RNA-dependent kinase PKR each independently inhibit MTb growth in human cells. Furthermore, we show that MTb broadly stimulates RIG-I, MDA5, MAVS, and PKR gene expression and their biological activities. We also show that the oral FDA-approved drug nitazoxanide (NTZ) significantly inhibits intracellular MTb growth and amplifies MTb-stimulated RNA sensor gene expression and activity. This study establishes prototypic cytoplasmic RNA sensors as innate restriction factors for MTb growth in human cells and it shows that targeting this pathway is a potential host-directed approach to treat tuberculosis disease.

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MTb infection induces RNA sensor (RIG-I, MDA5, PKR) mRNA levels and activities

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RIG-I, MDA5, MAVS, and PKR restrict intracellular MTb growth in human cells

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NTZ enhances MTb-driven RNA sensor mRNA levels and RLR activities

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NTZ and NTZ derivatives inhibit intracellular MTb growth in primary human cells

Discovery of Novel Anti-cryptosporidial Activities From Natural Products by in vitro High-Throughput Phenotypic Screening

Cryptosporidium parvum is a globally distributed zoonotic protozoan parasite of both medical and veterinary importance. Nitazoxanide is the only FDA-approved drug to treat cryptosporidiosis in immunocompetent people, but it is not fully effective. There is no drug approved by FDA for use in immunocompromised patients or in animals. In the present study, we conducted phenotypic screening of 800 nature products with defined chemical structures for potential novel activity against the growth of C. parvum in vitro. We identified a large number of compounds showing low to sub-micromolar anti-cryptosporidial activity, and fully characterized 16 top hits for anti-parasitic efficacies in vitro [EC₅₀ values from 0.122 to 3.940 μM, cytotoxicity (TC₅₀) values from 6.31 to >100 μm] and their safety margins. Among them, 11 compounds were derived from plants with EC₅₀ values from 0.267 to 3.940 μM [i.e., cedrelone, deoxysappanone B 7,4'-dimethyl ether (Deox B 7,4), tanshinone IIA, baicalein, deoxysappanone B 7,3'-dimethyl ether acetate, daunorubicin, dihydrogambogic acid, deacetylgedunin, deacetoxy-7-oxogedunin, dihydrotanshinone I, 2,3,4'-trihydroxy-4-methoxybenzophenone, and 3-deoxo-3beta-hydroxy-mexicanolide 16-enol ether]. Three compounds with sub-micromolar EC₅₀ values (i.e., cedrelone, Deox B 7,4, and baicalein) were further investigated for their effectiveness on various parasite developmental stages in vitro. Cedrelone and baicalein were more effective than Dexo B 7,4 when treating parasite for shorter periods of time, but all three compounds could kill the parasite irreversibly. These findings provide us a large selection of new structures derived from natural products to be explored for developing anti-cryptosporidial therapeutics.

Novel lactate dehydrogenase inhibitors with in vivo efficacy against Cryptosporidium parvum

Cryptosporidium parvum is a highly prevalent zoonotic and anthroponotic protozoan parasite that causes a diarrheal syndrome in children and neonatal livestock, culminating in growth retardation and mortalities. Despite the high prevalence of C. parvum, there are no fully effective and safe drugs for treating infections, and there is no vaccine. We have previously reported that the bacterial-like C. parvum lactate dehydrogenase (CpLDH) enzyme is essential for survival, virulence and growth of C. parvum in vitro and in vivo. In the present study, we screened compound libraries and identified inhibitors against the enzymatic activity of recombinant CpLDH protein in vitro. We tested the inhibitors for anti-Cryptosporidium effect using in vitro infection assays of HCT-8 cells monolayers and identified compounds NSC158011 and NSC10447 that inhibited the proliferation of intracellular C. parvum in vitro, with IC₅₀ values of 14.88 and 72.65 μM, respectively. At doses tolerable in mice, we found that both NSC158011 and NSC10447 consistently significantly reduced the shedding of C. parvum oocysts in infected immunocompromised mice’s feces, and prevented intestinal villous atrophy as well as mucosal erosion due to C. parvum. Together, our findings have unveiled promising anti-Cryptosporidium drug candidates that can be explored further for the development of the much needed novel therapeutic agents against C. parvum infections.

Cryptosporidium parvum is a protozoan parasite that can cause a life-threatening gastrointestinal disease in children and in immunocompromised adults. The only approved drug for treatment of Cryptosporidium infections in humans is nitazoxanide, but it is not effective in immunocompromised individuals or in children with malnutrition. C. parvum possesses a unique lactate dehydrogenase (CpLDH) enzyme that it uses for generating metabolic energy (ATP) via the glycolytic pathway to fuel its growth and proliferation in the host. We have identified novel inhibitors for the enzymatic activity of CpLDH. Further, we have demonstrated that two of the CpLDH inhibitors effectively block the growth, proliferation and pathogenicity of C. parvum at tolerable doses in immunocompromised mice. Together, our findings have unveiled novel CpLDH inhibitors that can be explored for the development of efficacious therapeutic drugs against C. parvum infections.

Cryptosporidium Sp. Findings and Its Symptomatology among Immunocompromised Patients

BACKGROUND

Cryptosporidium sp. is an apicomplexan protozoa, and it is related to an immunocompromised state. As it develops diverse clinical manifestations, mild to life-threatening conditions, administration of anti-parasitic medication and its management remain problematic.

AIM

The study aimed to provide Cryptosporidiosis symptomatology and its prevalence among HIV-infected patients in a tertiary referral hospital, Haji Adam Malik General Hospital, Medan, Indonesia.

MATERIAL AND METHODS

Symptomatology was noted using short-questionnaire, and laboratory findings were obtained from the hospital medical record registry on the same day of admission. We enrolled 24 patients were suffered from HIV infection for a certain period and more than one-week diarrhoea including 18 males and 6 females. Routine faeces examination using wet mount, Kinyoun-gabet, and trichrome staining was performed for all samples in Parasitology Department, Faculty of Medicine, Universitas Sumatera Utara, Medan, Indonesia. Numerical data were evaluated using the Mann-Whitney test while Fisher Exact test was used to determine any association between categorical variables.

RESULTS

Our study found that 8 of 24 patients were positive with Cryptosporidium sp. while its symptomatology including abdominal cramp (66.7%), nausea and vomiting (70.8%), and fever (62.5%) is prevalent from our study. We obtained significant association between CD4 cell count (p = 0.006), diarrhea duration (p = 0.007), abdominal pain (p = 0.005), and nausea and vomiting (p = 0.021) with cryptosporidiosis.

CONCLUSION

High consideration of several symptoms related to cryptosporidiosis leads a clinician to initiate prompt management particularly in a high-risk population.