Global prevalence of Ascaris infection in humans (2010–2021): a systematic review and meta-analysis

Identification of immunogenic proteins of Ascaris lung stage larvae through immunoproteomics: towards recombinant-based serodiagnostic assays for humans and pigs

Soil-transmitted helminthiases are recognised by the World Health Organization as one of the 20 neglected tropical diseases, primarily affecting communities with socioeconomic disadvantages in tropical and subtropical regions. Of the four soil-transmitted helminths, Ascaris stands out as the most widespread, affecting more than 700 million people globally. Today, the diagnostic standard for ascariasis is based on microscopic examination of stool, which faces important limitations. Although serological diagnosis is a promising alternative, the current landscape of well-validated commercial serological diagnostics is sobering. An ELISA based on homogenate from Ascaris suum lung stage larvae (AsLungL3-ELISA) showed significant potential to inform human and veterinary prevention and control programs against ascariasis. Therefore, this study aimed to identify the immunogenic proteins in Ascaris lung stage larval homogenate and investigate the antibody response towards recombinantly expressed versions of these proteins. Given the potential of recombinant-based assays for both human and veterinary applications, the study encompasses experiments involving both humans and pigs. First, immuno-affinity purifications were coupled with liquid chromatography-tandem mass spectrometry, resulting in three lists of immunogenic proteins (for children, adults, and pigs). As a proof of concept, four promising immunogenic proteins (polyprotein ABA-1, paramyosin, apolipophorin and an S60 ribosomal protein) were recombinantly produced in Escherichia coli and the antibody response against these recombinants was evaluated using ELISA. While the results for pigs were inconclusive due to non-specific binding of antibodies, the findings for potential human serodiagnostic applications detecting IgG4 appeared promising. For both polyprotein ABA-1 and paramyosin, a notable difference in OD values was observed between children and adults who were AsLungL3-ELISA negative and positive. In conclusion, this study is a steppingstone towards the development of new serodiagnostic assays and demonstrates that recombinant protein production offers an efficient method to produce diagnostic Ascaris antigens without requiring pig studies.

NOD1 signaling regulates early tissue inflammation during helminth infection

The role of innate receptors in initiating the early inflammatory response to helminth larval stages in affected tissues during their life cycle within the host remains poorly understood. Given its pivotal role in detecting microbial elements and eliciting immune responses, exploring the NOD1 receptor could offer crucial insights into immune responses to parasitic infections. By using the larval ascariasis model, the acute model for early Ascaris sp. infection in humans, we report that NOD1 signaling markedly regulates pulmonary tissue inflammation during Ascaris larval migration. Here we show that Ascaris-infected NOD1-deficient mice exhibited a pronounced decrease in macrophage and eosinophil recruitment to the lungs. This diminished cellular recruitment to the lung correlated with impaired production of a mixed cytokine profile including IFN-γ, IL-1β, IL-5, IL-10, IL-17 and IL-33. The attenuated inflammatory response observed in the absence of NOD1 signaling during infection was associated with a notable amelioration in lung dysfunction compared to WT-infected mice. Systemically, NOD1 signaling was also associated with Ascaris-specific IgG2b antibody responses. In summary, our findings highlight a pathogenic role for NOD1 signaling in Ascaris-induced tissue inflammation, underlying hematopoietic cell recruitment and regulating downstream inflammatory cascades associated with the host's innate immune responses in the tissue triggered by helminth larval migration.

Ascaris lumbricoides: prevalence and associated factors among pre-school children in Rukiga district, Uganda: a cross-sectional study

BACKGROUND

Ascaris lumbricoides infestation remains a public health problem worldwide. It mainly affects children resulting into undernutrition, impaired growth and physical development, intestinal obstruction and death. We aimed to determine the prevalence and factors associated with Ascaris lumbricoides infestation among children aged 6-59 months in Rukiga district, Uganda.

METHODS

In this cross-sectional study, we recruited 739 children aged 6-59 months and their caregivers between September and October 2023. Semi-structured questionnaires were used to collect data on sociodemographic characteristics of the caregivers. We examined children's stool for Ascaris lumbricoides ova using the Kato-Katz method. We estimated adjusted odds ratios using multivariable logistic regression to determine the factors associated with Ascaris lumbricoides infestation.

RESULTS

The prevalence of Ascaris lumbricoides infestation was 2.7% (n = 20/739), (95% CI. 1.7-4.1). Factors associated with Ascaris lumbricoides infestation were: Child-related characteristics including: the child having not been dewormed 6 months prior to the study (AOR 2.04, 95% CI: 1.04-4). Household characteristics including: disposal of child's stool in the compound/ garden (AOR 12.53, 95% CI: 3.44-45.64), if there are more than two children under 5 years living in the household (AOR 0.24, 95% CI: 0.11-0.52). Care-giver characteristics including the primary caregiver being: the father (AOR 6.09, 95% CI: 1.21-30.61), a Christian (AOR 0.04, 95% CI: 0.01-0.17).

CONCLUSION AND RECOMMENDATIONS

Ascaris lumbricoides infestation was 2.7% among preschool children. We recommend the inclusion of male partners in health interventions targeting children under the age of five years especially the immunization programs. Community health programs should consider targeted messages in health education campaigns especially the handling and disposal of feces and the importance of deworming children. The association between religion and Ascaris lumbricoides infestation needs further studies.

Harnessing Non-standard Nucleic Acids for Highly Sensitive Icosaplex (20-Plex) Detection of Microbial Threats for Environmental Surveillance

Environmental surveillance and clinical diagnostics heavily rely on the polymerase chain reaction (PCR) for target detection. A growing list of microbial threats warrants new PCR-based detection methods that are highly sensitive, specific, and multiplexable. Here, we introduce a PCR-based icosaplex (20-plex) assay for detecting 18 enteropathogen and two antimicrobial resistance genes. This multiplexed PCR assay leverages the self-avoiding molecular recognition system (SAMRS) to avoid primer dimer formation, the artificially expanded genetic information system (AEGIS) for amplification specificity, and next-generation sequencing for amplicon identification. Using parallelized multitarget TaqMan Array Cards (TAC) to benchmark performance of the 20-plex assay on wastewater, soil, and human stool samples, we found 90% agreement on positive calls and 89% agreement on negative calls. Additionally, we show how long-read and short-read sequencing information from the 20-plex can be used to further classify allelic variants of genes and distinguish subspecies. The strategy presented offers sensitive, affordable, and robust multiplex detection that can be used to support efforts in wastewater-based epidemiology, environmental monitoring, and human/animal diagnostics.

Two-photon NAD(P)H-FLIM reveals unperturbed energy metabolism of Ascaris suum larvae, in contrast to host macrophages upon artemisinin derivatives exposure

Soil-transmitted helminths (STH) are widespread, with Ascaris lumbricoides infecting millions globally. Malaria and STH co-infections are common in co-endemic regions. Artemisinin derivatives (ARTs)-artesunate, artemether, and dihydroartemisinin-are standard malaria treatments and are also known to influence the energy metabolism of parasites, tumors, and immune cells. Herein, we explore the potential of ARTs to influence ascariasis either by directly targeting larvae or indirectly by modifying macrophage responses. Ascaris suum third-stage larvae and porcine IL-4 polarized (M2-like) macrophages were exposed to ARTs in vitro, and their metabolism was evaluated using two-photon NAD(P)H-FLIM. Both larvae and M2-like macrophages exhibited a steady-state bioenergetic profile of high oxidative phosphorylation and low anaerobic glycolysis. In A. suum larvae, two metabolically distinct regions were identified, with particularly high DUOX activity in the pharynx compared to the midgut; however, ARTs did not alter these profiles. In contrast, exposure of M2-like macrophages to ARTs induced a metabolic shift towards high anaerobic glycolysis and reduced metabolic activity, suggesting a possible indirect effect of ARTs on the helminth infection. Overall, two-photon NAD(P)H-FLIM proved to be a powerful tool for studying specific metabolic pathways in Ascaris larvae and host macrophages, offering valuable insights into the metabolic mechanisms of drug action on both parasite and host.

Prevalence of Intestinal Parasitic Infections and Associated Factors Among Food Handlers in East Africa: A Systematic Review and Meta-analysis

BACKGROUND

Intestinal parasitic infections are a significant public health concern, especially among food handlers, who can transmit these infections to the public through food preparation and handling. This systematic review and meta-analysis aimed to determine the pooled prevalence and associated factors of intestinal parasitic infections among food handlers in the East African region.

METHODS

A systematic review and meta-analysis on intestinal parasitic infections among food handlers involved a comprehensive search across various databases, including Scopus, PubMed, ScienceDirect, Google Scholar, and the institution's library registers. Forty relevant articles were identified and analyzed using STATA Software version 17.0. Sensitivity analysis, publication bias assessment with Egger's test, and the Trim-and-fill meta-analysis for bias adjustment were conducted. Heterogeneity across the studies was assessed using Cochran's Q statistic and I2 statistics, and subgroup analysis computed for significant heterogeneity (I2 value ≥ 50%). A random effect model was used to determine the pooled prevalence of intestinal parasitic infections.

RESULTS

The pooled prevalence of intestinal parasitic infections among food handlers was 32.27% (95% CI 27.90-36.65). The most prevalent parasites were Entamoeba histolytica/dispar 20.83% (95% CI 13.66-28%), Ascaris lumbricoides 13.84% (95% CI 10-17.68%), Giardia lamblia 8.55% (95% CI 6.03-11.06%), and hookworm 6.43% (95% CI 3.93-8.93%). Using a common knife for cutting raw meat (AOR = 2.27, 95% CI 1.21-4.31), food handler's untrimmed fingernails (AOR = 2.14, 95% CI 1.50-2.78), and no hand washing practices with soap after using the toilet (AOR = 2.25, 95% CI 1.33-3.18) were associated with higher rates of intestinal parasitic infections among food handlers.

CONCLUSIONS

Parasitic infections among food handlers were found to be significantly prevalent. Factors contributing to this high prevalence included food handlers' untrimmed fingernails, poor hand hygiene practices, and using a shared knife for chopping various food items, including raw meat. These findings emphasize the need for proper personal hygiene and sanitation practices among food handlers to prevent transmitting parasitic infections to consumers.

Multimodality imaging of pediatric ascariasis

Ascariasis is a prevalent intestinal helminthic infection caused by Ascaris lumbricoides, commonly known as roundworm. While the disease may remain asymptomatic when the parasites are confined to the intestinal lumen of the small bowel, symptoms and complications can arise when the helminths invade the biliary tree or pancreatic ducts. In cases of severe infection, a mass of roundworms can lead to intestinal complications, such as bowel obstruction. The morphological identification of Ascaris by multimodality imaging techniques plays a crucial role in the diagnosis, as well as in the monitoring and prevention of complications.

Systematic review and meta-analysis of soil-transmitted helminth infections in South America (2000-2024)

Soil-transmitted helminths (STHs) are parasitic nematodes commonly found in tropical and subtropical regions, where poor sanitation makes them a significant public health concern. This study provides a comprehensive review and meta-analysis of human STH infections across 13 South American countries from 2000 to 2023. It covers these infections' prevalence, distribution, and diagnosis, highlighting the environmental factors influencing transmission pathways. The review identified 134 studies on human STH infections, revealing Brazil as the most researched country. The meta-analysis found prevalence rates of Ascaris lumbricoides, Trichuris trichiura, hookworms, and Strongyloides stercoralis below 20 %, with notable heterogeneity across studies. Most studies used conventional microscopy for diagnosis, pointing out the need for implementing advanced diagnostic tools. Environmental and climatic factors, including temperature annual range, vegetation density, soil types, and properties were significant predictors of STH prevalence. The study calls for more research performing advanced diagnostic methods and broader geographical coverage to address existing data gaps. Furthermore, it emphasizes the need for holistic public health policies integrating biomedical and environmental approaches to ensure effective disease management.

Dose-response effects of multiple Ascaris suum exposures and their impact on lung protection during larval ascariasis

BACKGROUND

Human ascariasis is the most prevalent geohelminthiasis worldwide, affecting approximately 446 million individuals. In regions with endemic prevalence, the majority of infected adults are frequently exposed to the parasite and tend to have a low parasite load. Further studies are necessary to provide more evidence on the dynamics of infection and to elucidate the possible mechanisms involved in regulating protection, especially during the acute phase, also known as larval ascariasis. The aim of this study is to compare the impact of lung function between single and multiple infections in a murine model.

METHODS

We infected BALB/c mice considering the frequency of exposures: single-exposure-SI; twice-exposures-RE 2x and thrice-exposures-RE 3x, and considering the doses of infection: 25 eggs-RE 25; 250 eggs-RE 250 and 2,500 eggs-RE 2500, followed by infection challenge with 2,500 eggs. From this, we evaluated: parasite burden in lungs, cellular and humoral response, histopathological and physiological alterations in lungs.

RESULTS

The main results showed a reduction of parasite burden in the reinfected groups compared to the single-infected group, with protection increasing with higher exposure and dose. Furthermore, the RE 250 group exhibited a decrease of parasite burden close to RE 2500, but with less tissue damage, displaying the most favorable prognosis among the reinfected groups.

CONCLUSION

Our research indicates a dose-dependent relationship between antibody production and the intensity of the immune response required to regulate the parasite burden.

Environmental modulators on the development of the raccoon roundworm (Baylisascaris procyonis): Effects of temperature on the embryogenesis

Members of the Ascarididae family are common zoonotic pathogens in humans and play an economic role in domestic and livestock animal husbandry. This family includes the obligatorily parasitic nematodes of the genus Baylisascaris, with the raccoon roundworm Baylisascaris procyonis being the most well-known representative. B. procyonis uses the raccoon (Procyon lotor) as its primary host and can utilise a broad range of mammals as paratenic hosts. Sexual reproduction of the adult nematodes occurs in the small intestine. Eggs are excreted into the environment through feces, where they develop into the infectious stage under suitable conditions within a few days to weeks. Infection of primary and paratenic hosts occurs through the oral ingestion of these infectious eggs. Raccoons can also become infected by ingesting infected paratenic hosts. Humans serve as accidental hosts and can suffer significant damage to organ tissues, the visual system, and the central nervous system after ingesting infectious eggs. The aim of the study was to investigate the effects of ambient temperature on embryonic development and to document the morphological changes during embryogenesis. Live specimens were collected from the raccoon intestine and incubated. Single-celled eggs were collected during this process. The eggs were decorticated and then preserved. To test the effects of ambient temperature, the eggs were incubated at 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, and 38 °C and monitored at 24-h intervals for their developmental stages. Detailed photographic documentation of the developmental stages was conducted. An increase in ambient temperature led to a reduction in development time. The temperature range within which embryogenesis proceeded to the L1 larval stage was between 10 °C and 30 °C. Incubation at 5 °C did not produce L1 larvae even after 11 months. Incubation at 35 °C and 38 °C resulted in the complete degeneration of the eggs before reaching the L1 larval stage.

Detection of the levels of immune cytokines (IL4, IL5, TNF-α) in school-age and preschoolers with an Ascaris lumbricoides infection

Gastrointestinal parasite infections have been identified as a significant public health concern in regions with high humidity levels globally. Ascaris lumbricoides, a prevalent human pathogen, is widely distributed throughout several regions globally. It is estimated that around 1.5 billion cases are attributed only to A. Lumbricoides. These types of disorders are associated with a wide range of diseases. Several animal studies have demonstrated the significance of T helper cell type 2 responses to helminths in the digestive system, as well as the crucial role of specific interleukins (ILs), such as IL-4 and IL-5, in eliminating parasites and combating infections. However, there is a limited body of research examining the response of human cytokines to gut helminths, particularly in relation to the cellular reactions to Ascariasis in populations where it is prevalent. This is a case-control study and included 100 children suffering from Ascaris infection, aged between 4 and 15 years, and 50 healthy children as a control group. Samples were collected at Al-Habobbi Teaching Hospital after ethical approval. The children were diagnosed by stool examination and the concentration method was performed. Five milliliter of blood was collected from each participant, and the levels of interleukins 4, interleukins 5 and TNF-α were measured by ELISA. The levels of TNF-α and IL-5 exhibited statistically significant variance between the preschool and school-age groups at P = <0.01. The difference in the level of IL-4 was non-significant between preschool and school-age groups at P > 0.05. The difference in the levels of TNF-α and IL-5 was significant between control and moderate infection (P = <0.05), while that of IL-4 was non-significant (P > 0.05). When comparing control, the modest groups showed significantly higher IL-5 and IL-4 levels (P = >0.05). The difference in TNF-α, IL-5 and IL4 levels between mild and control groups was significant (P < 0.001), except for TNF-α which was not significant (P = 0.86). The difference in levels of interleukins in children according to age group and severity of infection indicates the role of the cellular immune response in the emergence and development of the disease and its severity in children.

Prevalence of human Schistosoma mansoni infection in endemic regions (2010-2024): a systematic review and meta-analysis

Background

Schistosoma mansoni infection poses a substantial public health challenge globally, and the World Health Organization (WHO) aims for the elimination of schistosomiasis by 2030. This study aimed to assess the current prevalence of human S. mansoni infection in endemic regions worldwide between 2010 and 2024.

Methods

We conducted a comprehensive search in PubMed/Medline and Scopus databases as well as other public sources from 1 January 2010 to 15 July 2024. Population-based studies reporting the prevalence of S. mansoni infection were eligible. We undertook a random-effects meta-analysis to estimate pooled prevalences with 95% confidence intervals (CIs) in WHO-defined regions and assessed potential risk factors associated with S. mansoni infection. The protocol for this study was registered on PROSPERO (CRD42023438455).

Findings

We identified a total of 542 eligible studies involving 1,163,866 individuals who had been tested for S. mansoni infection in 38 countries. The overall, pooled global prevalence of S. mansoni infection in endemic region was 14.8% (95% CI, 13.5%-16.1%). The pooled prevalences (95% CI) in specific regions were: 15.3% (13.9-16.8%) in sub-Saharan Africa, 12.4% (8.9-16.4%) in South America and 9.5% (5.4-14.6%) in the Eastern Mediterranean region. There was a 52.6% decrease in prevalence of S. mansoni infection and a 37% decrease in high-intensity infection for studies conducted between 2010 and 2014 compared to those conducted between 2020 and 2023. The present analysis revealed that factors including male gender, bathing or swimming in natural water bodies, crossing rivers or lakes, and engaging in water irrigation activities such as fishing, working in rice paddies or maintaining irrigation canals were significantly associated with S. mansoni infection.

Interpretation

The findings of this investigation revealed that, despite a decline in prevalence and high-intensity infection, 7-12% of people in endemic regions, notably in sub-Saharan Africa, remained affected by schistosomiasis mansoni between 2020 and 2024. This study provides data of relevance to policymakers to support efforts to eliminate this disease.

Funding

This study received no funding.

Elevated circulating group-2 innate lymphoid cells expressing activation markers and correlated tryptase AB1 levels in active ascariasis

Introduction

Ascaris lumbricoides infection is one of the most common soil-transmitted helminthiasis and IgE response to this helminth may increase the risk of asthma, bronchial hyperreactivity and atopy. There is not enough evidence showing the role of group-2 innate lymphoid cells (ILC2) in the pathogenesis of helminth infections in humans. Here, we aimed to investigate and characterize the influence of Ascaris lumbricoides infection on circulating ILCs in endemically exposed subjects.

Methods

Non-infected (NI; n=16) and Ascaris-infected (AI; n=16) subjects from an endemic area were included. Two consecutive stool samples from each subject were examined by Kato-Katz to define parasite infection. Antibodies to the ABA-1 antigen of Ascaris and Ascaris extract were measured by ELISA. ILC subsets and their activation markers (CD25, CD69, thymic stromal lymphopoietin receptor (TSLPR) were evaluated in its PBMC by flow cytometry. Proximity extension assay (PEA) was performed to explore plasma proteins associated to infection.

Results

No significant differences in the relative or absolute frequencies of total ILCs, ILC1, ILC2 and ILC3 cells were observed regarding the infection status. However, within AI group, IgE-sensitized subjects to ABA-1 had higher frequencies and counts of ILC2 (p<0.05). Frequencies of CD25+, CD69+ and TSLPR+ ILC2 were higher in AI compared to the NI (p<0.01). Additionally, egg burden was positively correlated with CD69+ ILC2 frequencies (r=0.67; p=0.005). Tryptase alpha/beta 1 (TPSAB1), GP6 and several plasma proteins associated with cell growth and granulocyte chemotaxis were highly expressed in the AI group (p<0.05). Interestingly, TPSAB1 levels were positively correlated with ILC2 expressing activation markers frequencies, egg burden and IgE levels against Ascaris.

Discussion

Ascaris infection is associated with increased expression of ILC2 activation markers and TPSAB1, which may contribute to the type-2 response.

Contribution of socio-demographic factors in prevalence of soil-transmitted helminth infections among newly arrived laborers in Jeddah, Saudi Arabia

Background

Soil-transmitted diseases are caused by intestinal worms transmitted via various routes into the human body resulting in various clinical manifestations. This study aimed to investigate the socio-demographic factors contributing mainly to the prevalence of soil-transmitted helminths (STHs) among newly arrived laborers in Jeddah, Saudi Arabia.

Methods

A total of 188 stool specimens were collected and examined macroscopically and microscopically using different techniques. In addition, real-time PCR was used as a molecular tool to detect several STHs. The descriptive analysis was used to evaluate demographic data and categorical variables in association with STHs infection.

Results

Of all participants, the mean age was 26.08 ± 2.67 years, including 103 females and 85 males. A total of 86 (45.70%) were illiterate, followed by 60 (31.90%) of participants belonging to elementary level. STHs and other intestinal parasites were detected among 35 newly arrived laborers (18.61%). Nineteen cases (10.11%) were infected with STHs, including 15 cases with one STHs (four A. lumbricoides, four N. americanus, four T. trichiura, two S. stercoralis, one A. duodenale) and four cases with two STHs (two T. trichiura and N. americanus; one S. stercoralis and A. duodenale; one T. trichiura and S. stercoralis). High rates of STHs infection were detected among drivers (11.70%) followed by housemaids (11.20%), but with no significant association to occupation. Higher rates of STHs infection were detected among those used to walk on soil barefoot in their home countries before arriving in Jeddah.

Conclusion

This study found that none of the newly arrived expatriate laborers in Jeddah was aware of STHs. About 10% of them had infection with one or two STHs, mainly among newly arrived laborers from Asian countries. There is a need for awareness programs and regular screening for STHs and other intestinal parasites among newly arrived expatriate laborers.

Harnessing non-standard nucleic acids for highly sensitive icosaplex (20-plex) detection of microbial threats

Environmental surveillance and clinical diagnostics heavily rely on the polymerase chain reaction (PCR) for target detection. A growing list of microbial threats warrants new PCR-based detection methods that are highly sensitive, specific, and multiplexable. Here, we introduce a PCR-based icosaplex (20-plex) assay for detecting 18 enteropathogen and two antimicrobial resistance genes. This multiplexed PCR assay leverages the self-avoiding molecular recognition system (SAMRS) to avoid primer dimer formation, the artificially expanded genetic information system (AEGIS) for amplification specificity, and next-generation sequencing for amplicon identification. We benchmarked this assay using a low-cost, portable sequencing platform (Oxford Nanopore) on wastewater, soil, and human stool samples. Using parallelized multi-target TaqMan Array Cards (TAC) to benchmark performance of the 20-plex assay, there was 74% agreement on positive calls and 97% agreement on negative calls. Additionally, we show how sequencing information from the 20-plex can be used to further classify allelic variants of genes and distinguish sub-species. The strategy presented offers sensitive, affordable, and robust multiplex detection that can be used to support efforts in wastewater-based epidemiology, environmental monitoring, and human/animal diagnostics.

Leveraging wastewater-based epidemiology to monitor the spread of neglected tropical diseases in African communities

Neglected tropical diseases continue to cause a significant burden worldwide, with Africa accounting for more than one-third of the global burden. Over the past decade, progress has been made in eliminating, controlling, and eradicating these diseases in Africa. By December 2022, 47 out of 54 African countries had eliminated at least one neglected tropical disease, and more countries were close to achieving this milestone. Between 2020 and 2021, there was an 80 million reduction in people requiring intervention. However, continued efforts are needed to manage neglected tropical diseases and address their social and economic burden, as they deepen marginalisation and stigmatisation. Wastewater-based epidemiology involves analyzing wastewater to detect and quantify biomarkers of disease-causing pathogens. This approach can complement current disease surveillance systems in Africa and provide an additional layer of information for monitoring disease spread and detecting outbreaks. This is particularly important in Africa due to limited traditional surveillance methods. Wastewater-based epidemiology also provides a tsunami-like warning system for neglected tropical disease outbreaks and can facilitate timely intervention and optimised resource allocation, providing an unbiased reflection of the community's health compared to traditional surveillance systems. In this review, we highlight the potential of wastewater-based epidemiology as an innovative approach for monitoring neglected tropical disease transmission within African communities and improving existing surveillance systems. Our analysis shows that wastewater-based epidemiology can enhance surveillance of neglected tropical diseases in Africa, improving early detection and management of Buruli ulcers, hookworm infections, ascariasis, schistosomiasis, dengue, chikungunya, echinococcosis, rabies, and cysticercosis for better disease control.

Human Ascaris infection is associated with higher frequencies of IL-10 producing B cells

INTRODUCTION

Ascaris lumbricoides has dual effects on the immune system of infected hosts. The IgE response to this parasite has been thoroughly studied, but little is known about cellular responses induced by infection. This study aims to explore the interplay between A. lumbricoides infection and B cell responses, especially B regulatory cells.

METHODS

Participants from Santa Catalina, Bolívar, Colombia, a helminth-endemic town, were screened for soil-transmitted helminthiasis (STH) using stool examinations. Eighteen A. lumbricoides-infected and 11 non-infected subjects were selected. Blood samples were analyzed for Breg cells and related cytokines, and immunoglobulins specific to the A. lumbricoides excretory/secretory product, ABA-1.

RESULTS

Infected subjects exhibited higher frequencies of Breg cells, especially those with a higher A. lumbricoides egg burden. Higher frequencies of different Breg subsets were observed in infected individuals, with CD25+CD71+CD73- B cells being notably increased in strongly infected individuals. Additionally, A. lumbricoides infection was associated with reduced levels of circulating ABA-1-specific IgG1 and IgE. IL-10+ B cell frequencies correlated inversely with ABA-1-specific IgE.

CONCLUSIONS

A. lumbricoides infection has a significant impact on the immune response, particularly on Breg cell populations and antibody responses. Our findings suggest that A. lumbricoides infection mediates a dose-dependent immunosuppressive response characterized by an increase in Breg cells and concomitant suppression of ABA-1-specific humoral responses.

Small bowel obstruction caused by massive (>250) ascariasis worms in adult female patient, a case report

INTRODUCTION AND IMPORTANCE

Intestinal obstruction from ascariasis is a rare but fatal surgical emergency in endemic areas, such as Ethiopia. Reports of ascariais causing complete bowel obstruction in adults are rare while having a high rate of morbidity and mortality. Here we present a case of a 35 years old female patient who presented with complete small bowel obstruction caused by >250 ascariasis worm.

CASE PRESENTATION

We report on a case of a 35-year-old female who presented with intermittent crampy abdominal pain of 2 days duration associated with frequent vomiting of ingested matter and failure to pass feces and flatus. The patient underwent an exploratory laparotomy for acute complete small bowel obstruction and the intraoperative finding of a volvulated viable ileum with a visible and palpable ascariasis worms in the lumen of ileum. Enterotomy was done to extract >250 adult ascariasis worms.

CLINICAL DISCUSSION

There are few reports of ascariasis causing complete small bowel obstruction in adults and there is no reported case of a massive number of adult worms from one patient.

CONCLUSION

Though World Health Organization integrated approach, which includes sanitation, hygiene education and preventive chemotherapy brings a significant decrement on prevalence of soil-transmitted helminth, our case indicates that, clinicians should consider ascariasis as a differential diagnosis for SBO even in adult age groups.

Th2-biased immune responses to body migrating Ascaris larvae in primary infection are associated with pathology but not protection

Helminth infections lead to an overdispersion of the parasites in humans as well as in animals. We asked whether early immune responses against migrating Ascaris larvae are responsible for the unequal distribution of worms in natural host populations and thus investigated a susceptible versus a resistant mouse strain. In mice, the roundworm larvae develop until the lung stage and thus early anti-Ascaris immune responses against the migrating larvae in the liver and lung can be deciphered. Our data show that susceptible C57BL/6 mice respond to Ascaris larval migration significantly stronger compared to resistant CBA mice and the anti-parasite reactivity is associated with pathology. Increased eosinophil recruitment was detected in the liver and lungs, but also in the spleen and peritoneal cavity of susceptible mice on day 8 post infection compared to resistant mice. In serum, eosinophil peroxidase levels were significantly higher only in the susceptible mice, indicating functional activity of the recruited eosinophils. This effect was associated with an increased IL-5/IL-13 production by innate lymphoid cells and CD4+ T cells and a pronounced type 2 macrophage polarization in the lungs of susceptible mice. Furthermore, a comparison of wildtype BALB/c and eosinophil-deficient dblGATA-1 BALB/c mice showed that eosinophils were not essential for the early control of migrating Ascaris larvae. In conclusion, in primary infection, a strong local and systemic type 2 immune response during hepato-tracheal helminth larval migration is associated with pathology rather than protection.

Acute Ascaris infection impairs the effector functions of natural killer cells in single and Salmonella co-infected pigs

Natural killer (NK) cells play a key role in defense against Salmonella infections during the early phase of infection. Our previous work showed that the excretory/secretory products of Ascaris suum repressed NK activity in vitro. Here, we asked if NK cell functionality was influenced in domestic pigs during coinfection with Ascaris and Salmonella enterica serotype Typhimurium. Ascaris coinfection completely abolished the IL-12 and IL-18 driven elevation of IFN-γ production seen in CD16 + CD8α + perforin + NK cells of Salmonella single-infected pigs. Furthermore, Ascaris coinfection prohibited the Salmonella-driven rise in NK perforin levels and CD107a surface expression. In line with impaired effector functions, NK cells from Ascaris-single and coinfected pigs displayed elevated expression of the inhibitory KLRA1 and NKG2A receptors genes, contrasting with the higher expression of the activating NKp46 and NKp30 receptors in NK cells during Salmonella single infection. These differences were accompanied by the highly significant upregulation of T-bet protein expression in NK cells from Ascaris-single and Ascaris/Salmonella coinfected pigs. Together, our data strongly indicate a profound repression of NK functionality by an Ascaris infection which may hinder infected individuals from adequately responding to a concurrent bacterial infection.

Evaluation of copromicroscopy, multiplex-qPCR and antibody serology for monitoring of human ascariasis in endemic settings

BACKGROUND

The standard diagnosis of Ascaris lumbricoides and other soil-transmitted helminth (STH) infections relies on the detection of worm eggs by copromicroscopy. However, this method is dependent on worm patency and shows only limited accuracy in low-intensity infection settings. We aimed to decipher the diagnostic accuracy of different antibodies using various Ascaris antigens in reference to copromicroscopy and quantitative PCR (qPCR), four months after national STH preventative chemotherapy among school children in western Kenya.

METHODOLOGY

STH infection status of 390 school children was evaluated via copromicroscopy (Kato-Katz and mini-FLOTAC) and qPCR. In parallel, Ascaris-specific antibody profiles against larval and adult worm lysates, and adult worm excretory-secretory (ES) products were determined by enzyme-linked immunosorbent assay. Antibody cross-reactivity was evaluated using the closely related zoonotic roundworm species Toxocara cati and Toxocara canis. The diagnostic accuracy of each antibody was evaluated using receiver operating curve analysis and the correspondent area under the curve (AUC).

PRINCIPAL FINDINGS

Ascaris was the predominant helminth infection with an overall prevalence of 14.9% (58/390). The sensitivity of mini-FLOTAC and Kato-Katz for Ascaris diagnosis reached only 53.5% and 63.8%, respectively compared to qPCR. Although being more sensitive, qPCR values correlated with microscopic egg counts (R = -0.71, P<0.001), in contrast to antibody levels. Strikingly, IgG antibodies recognizing the ES products of adult Ascaris worms reliably diagnosed active Ascaris infection as determined by qPCR and microscopy, with IgG1 displaying the highest accuracy (AUC = 0.83, 95% CI: 0.75-0.91).

CONCLUSION

IgG1 antibody responses against adult Ascaris-ES products hold a promising potential for complementing the standard fecal and molecular techniques employed for monitoring Ascaris infections. This is of particular importance in the context of deworming programs as the antibody diagnostic accuracy was independent of egg counts.

Worldwide absence of canonical benzimidazole resistance-associated mutations within β-tubulin genes from Ascaris

BACKGROUND

The giant roundworm Ascaris is an intestinal nematode, causing ascariasis by infecting humans and pigs worldwide. Recent estimates suggest that Ascaris infects over half a billion people, with chronic infections leading to reduced growth and cognitive ability. Ascariasis affects innumerable pigs worldwide and is known to reduce production yields via decreased growth and condemnation of livers. The predominant anthelminthic drugs used to treat ascariasis are the benzimidazoles. Benzimidazoles interact with β-tubulins and block their function, and several benzimidazole resistance-associated mutations have been described in the β-tubulins of ruminant nematodes. Recent research on ascarids has shown that these canonical benzimidazole resistance-associated mutations are likely not present in the β-tubulins of Ascaris, Ascaridia or Parascaris, even in phenotypically resistant populations.

METHODS

To further determine the putative absence of key β-tubulin polymorphisms, we screened two β-tubulin isotypes of Ascaris, highly expressed in adult worms. Using adult and egg samples of Ascaris obtained from pigs and humans worldwide, we performed deep amplicon sequencing to look for canonical resistance-associated mutations in Ascaris β-tubulins. Subsequently, we examined these data in closer detail to study the population dynamics of Ascaris and genetic diversity within the two isotypes and tested whether genotypes appeared to partition across human and pig hosts.

RESULTS

In the 187 isolates, 69 genotypes were found, made up of eight haplotypes of β-tubulin isotype A and 20 haplotypes of isotype B. Single nucleotide polymorphisms were seen at 14 and 37 positions for β-tubulin isotype A and isotype B, respectively. No evidence of any canonical benzimidazole resistance-associated mutations was found in either human- or pig-derived Ascaris isolates. There was, however, a difference in the genetic diversity of each isotype and distribution of β-tubulin genotypes between human- and pig-derived Ascaris. Statistical tests of population differentiation show significant differences (p < 0.001) between pig- and human-derived worms; however, more diversity was seen between worms from different populations than worms from different hosts.

CONCLUSIONS

Our work suggests an absence of canonical β-tubulin mutations within Ascaris, but alternative modes of anthelminthic resistance may emerge necessitating continued genetic scrutiny alongside monitoring of drug efficacy.

The global prevalence of Trichuris trichiura infection in humans (2010-2023): A systematic review and meta-analysis

This systematic review and meta-analysis study aimed to evaluate global Trichuris infection prevalence, assessing progress towards the WHO's 2030 target. We searched international databases from 2010-2023, categorizing data by regions and socio-economic variables using a random-effects model. Analyzing 757 articles covering 7154,842 individuals from 78 countries, the study found a pooled global prevalence of (6.64-7.57%), with the highest rates in the Caribbean (21.72%; 8.90-38.18%) and South-East Asia (20.95; 15.71-26.71%) regions. Southern Africa (9.58; 2.11-21.46%), Latin America (9.58; 2.11-21.46%), and Middle Africa Middle Africa (8.94; 6.31-11.98%) also exhibited high prevalence. Eastern Europe had the lowest prevalence at 0.16% (0.09-0.24). Approximately 513 (480-547) million people worldwide were estimated to harbor Trichuris. Moreover ∼1.5% of people tested worldwide (2010-2023) had a moderate to heavy intensity of infection. The study emphasizes the persistent global health threat of Trichuris infection, urging tailored strategies for effective control and prevention on a global scale.

Structure-activity relationship and target investigation of 2-aryl quinolines with nematocidal activity

Within the context of our anthelmintic discovery program, we recently identified and evaluated a quinoline derivative, called ABX464 or obefazimod, as a nematocidal candidate; synthesised a series of analogues which were assessed for activity against the free-living nematode Caenorhabditis elegans; and predicted compound-target relationships by thermal proteome profiling (TPP) and in silico docking. Here, we logically extended this work and critically evaluated the anthelmintic activity of ABX464 analogues on Haemonchus contortus (barber's pole worm) - a highly pathogenic nematode of ruminant livestock. First, we tested a series of 44 analogues on H. contortus (larvae and adults) to investigate the nematocidal pharmacophore of ABX464, and identified one compound with greater potency than the parent compound and showed moderate activity against a select number of other parasitic nematodes (including Ancylostoma, Heligmosomoides and Strongyloides species). Using TPP and in silico modelling studies, we predicted protein HCON_00074590 (a predicted aldo-keto reductase) as a target candidate for ABX464 in H. contortus. Future work aims to optimise this compound as a nematocidal candidate and investigate its pharmacokinetic properties. Overall, this study presents a first step toward the development of a new nematocide.

When Diagnosis Curls a Little: Partial Bowel Obstruction Due to Ascaris. L in a Young Man

Ascaris lumbricoides is a helminth commonly infecting humans, particularly in developing countries. It causes a range of clinical symptoms; However, many patients are asymptomatic. This article presents a case study of a young man who experienced diffuse abdominal pain and constipation, eventually being diagnosed with partial bowel obstruction due to Ascaris lumbricoides infection. The article emphasizes the importance of considering helminthic infections like ascariasis as a potential cause of intestinal obstruction, especially in endemic areas. Early diagnosis and intervention, including conservative management and anthelminthic drugs, can lead to a full recovery and avoid unnecessary surgery.

Cystatin from the helminth Ascaris lumbricoides upregulates mevalonate and cholesterol biosynthesis pathways and immunomodulatory genes in human monocyte-derived dendritic cells

Background

Ascaris lumbricoides cystatin (Al-CPI) prevents the development of allergic airway inflammation and dextran-induced colitis in mice models. It has been suggested that helminth-derived cystatins inhibit cathepsins in dendritic cells (DC), but their immunomodulatory mechanisms are unclear. We aimed to analyze the transcriptional profile of human monocyte-derived DC (moDC) upon stimulation with Al-CPI to elucidate target genes and pathways of parasite immunomodulation.

Methods

moDC were generated from peripheral blood monocytes from six healthy human donors of Denmark, stimulated with 1 µM of Al-CPI, and cultured for 5 hours at 37°C. RNA was sequenced using TrueSeq RNA libraries and the NextSeq 550 v2.5 (75 cycles) sequencing kit (Illumina, Inc). After QC, reads were aligned to the human GRCh38 genome using Spliced Transcripts Alignment to a Reference (STAR) software. Differential expression was calculated by DESEq2 and expressed in fold changes (FC). Cell surface markers and cytokine production by moDC were evaluated by flow cytometry.

Results

Compared to unstimulated cells, Al-CPI stimulated moDC showed differential expression of 444 transcripts (|FC| ≥1.3). The top significant differences were in Kruppel-like factor 10 (KLF10, FC 3.3, PBH = 3 x 10-136), palladin (FC 2, PBH = 3 x 10-41), and the low-density lipoprotein receptor (LDLR, FC 2.6, PBH = 5 x 10-41). Upregulated genes were enriched in regulation of cholesterol biosynthesis by sterol regulatory element-binding proteins (SREBP) signaling pathways and immune pathways. Several genes in the cholesterol biosynthetic pathway showed significantly increased expression upon Al-CPI stimulation, even in the presence of lipopolysaccharide (LPS). Regarding the pathway of negative regulation of immune response, we found a significant decrease in the cell surface expression of CD86, HLA-DR, and PD-L1 upon stimulation with 1 µM Al-CPI.

Conclusion

Al-CPI modifies the transcriptome of moDC, increasing several transcripts encoding enzymes involved in cholesterol biosynthesis and SREBP signaling. Moreover, Al-CPI target several transcripts in the TNF-alpha signaling pathway influencing cytokine release by moDC. In addition, mRNA levels of genes encoding KLF10 and other members of the TGF beta and the IL-10 families were also modified by Al-CPI stimulation. The regulation of the mevalonate pathway and cholesterol biosynthesis suggests new mechanisms involved in DC responses to helminth immunomodulatory molecules.

Getting around the roundworms: Identifying knowledge gaps and research priorities for the ascarids

The ascarids are a large group of parasitic nematodes that infect a wide range of animal species. In humans, they cause neglected diseases of poverty; many animal parasites also cause zoonotic infections in people. Control measures include hygiene and anthelmintic treatments, but they are not always appropriate or effective and this creates a continuing need to search for better ways to reduce the human, welfare and economic costs of these infections. To this end, Le Studium Institute of Advanced Studies organized a two-day conference to identify major gaps in our understanding of ascarid parasites with a view to setting research priorities that would allow for improved control. The participants identified several key areas for future focus, comprising of advances in genomic analysis and the use of model organisms, especially Caenorhabditis elegans, a more thorough appreciation of the complexity of host-parasite (and parasite-parasite) communications, a search for novel anthelmintic drugs and the development of effective vaccines. The participants agreed to try and maintain informal links in the future that could form the basis for collaborative projects, and to co-operate to organize future meetings and workshops to promote ascarid research.

An update on the current and emerging pharmacotherapy for the treatment of human ascariasis

INTRODUCTION

Globally, Ascaris lumbricoides is the commonest helminthic infection that affects people in underdeveloped countries and returning immigrants in industrialized nations. This article aims to provide latest updates on the epidemiology, clinical manifestations, and pharmacotherapy of ascariasis.

AREAS COVERED

A PubMed search was conducted using Clinical Queries and the key terms 'human ascariasis' OR 'Ascaris lumbricoides.' Ascaris lumbricoides is highly endemic in tropical and subtropic regions and among returning immigrants in industrialized nations. Predisposing factors include poor sanitation and poverty. The prevalence is greatest in young children. Most infected patients are asymptomatic. Patients with A. lumbricoides infection should be treated with anti-helminthic drugs to prevent complications from migration of the worm. Mebendazole and albendazole are indicated for children and nonpregnant women. Pregnant individuals should be treated with pyrantel pamoate.

EXPERT OPINION

Cure rates with anthelmintic treatment are high. No emerging pharmacotherapy can replace these existing drugs of good efficacy, safety profile and low cost for public health. It is opinioned that advances in the management of ascariasis include diagnostic accuracy at affordable costs, Emodepside is highly effective in single doses against ascarids in mammals and in human trials. The drug could be registered for human use in multiple neglected tropical diseases.

Surveillance of Soil-Transmitted Helminth Infection in Preschool Child Population: Do Changes in Behavior and Immunological Responses Affect Prevalence?

Soil-transmitted helminths (STHs) persist as a significant global public health issue among neglected tropical diseases (NTDs), particularly in children. STH infection can induce immune responses that affect the course of the disease; if treatment fails, chronic infection can lead to stunting, especially among children aged 24-59 months, which is a vulnerable period for growth and development. We conducted a correlational, cross-sectional data collection study to evaluate the characteristics and association of 25(OH)D, interleukin-5 (IL-5), and interleukin-13 (IL-13) with the prevalence of STH infection in children aged 24-59 months in Bandung District, Indonesia, in October 2019-January 2023. We recruited 694 subjects (401 stunted and 293 normal-height children). The prevalence of STH infection among the stunted and normal-height groups was 5.7% (95% CI: 3.85-8.46%) and 3.4% (95% CI; 1.86-6.17%) (p = 0.156), respectively. The probability of the prevalence of STH infection in children with levels of 25(OH)D, IL-5, and IL-13 below the cut-off point was 6,93 to 16.71 times higher. We found a relationship between IL-5, IL-13, and environmental factors and the prevalence of STH infection in stunted children.

Influence of tides on the dissemination and related health risks of intestinal helminths along the Kribi beaches (Atlantic Coast, Southern Cameroon)

Kribi is a seaside town that welcomes thousands of tourists each year. However, the poor sanitation condition of its beaches along the Atlantic coast is not without risk for visitors. In this study, we used the formol-ether concentration technique to identify and quantify larvae or eggs of intestinal helminths in waters of three regularly visited Kribi beaches (Mpalla, Ngoyè, and Mboamanga). Results revealed that all identified larvae and eggs were cestodes (Hymenolepis nana) and nematodes (Strongyloides sp., Ascaris sp., Ancylostoma duodenale and Trichuris trichiura). All the helminth eggs and larvae showed high abundance at low tide during rainy seasons. Ancylostoma duodenale eggs, totally absent at Mpalla, were densely present at low tide at Ngoyè (301 ± 15 eggs/L). Trichuris trichiura eggs showed the lowest abundance (0 to 62 eggs/L) at all sites. Abiotic variables indicated that waters at the various beaches were basic (pH: 8.75-9.77), generally warmer (32.44°C at Mpalla in the Short Rainy Season), more oxygenated at low tide, and moderately mineralized at high tide. Positive and significant correlations were observed at Ngoyè at low tide between Strongyloides sp. larvae and dissolved oxygen (P ˂ 0.05); and between Ancylostoma duodenale eggs and temperature (P ˂ 0.05). The overall results indicated that the beaches studied are subjected to fecal pollution. This pollution is more accentuated during low tides than during high tides. Depending on tidal movements, swimmers risk exposure to helminth eggs and larvae known to be responsible for gastroenteritis.

Implications of the prevalence of Ascaris sp. in the funerary context of a Late Antique population (5th-7th c.) in Granada (Spain)

OBJECTIVE

To evaluate the prevalence of gastro-intestinal parasites in human remains from Late Antiquity (5th - 7th c.) Granada (Spain).

MATERIALS

The study included pelvic and cranial control samples from 17 skeletons from the archaeological sites of Los Mondragones (n = 13) and Rafael Guillén (n = 4).

METHODS

In the paleoparasitological study, soil samples from pelvic area and cranium were analyzed using the rehydration, homogenization, and micro-sieving method and visualization under brightfield microscopy.

RESULTS

Ascaris sp. eggs were detected in pelvic samples from seven individuals.

CONCLUSIONS

These findings may indicate that this parasite was endemic. Its detection frequency is one of the highest reported at group level in an osteological series from Late Antiquity.

SIGNIFICANCE

The prevalence of Ascaris sp. associated with skeletal remains has implications for assessing the lifestyle and health of populations in southern Spain during the Late Antique period.

LIMITATIONS

The number of individuals is small and taphonomic processes could have limited paleoparasitological findings SUGGESTIONS FOR FURTHER RESEARCH: Future interdisciplinary studies of this type are warranted in larger osteological series to improve knowledge of parasitosis in the past.

Ascariasis causing small bowel obstruction in an adult female: A case report

INTRODUCTION AND IMPORTANCE

Ascariasis is a helminthic infection of humans caused by Ascaris lumbricoides. Intestinal obstruction from ascariasis can result in a rare but severe and often fatal surgical emergency of intestinal perforation and peritonitis in endemic areas. There have been reports of ascariasis causing Small Bowel Obstruction (SBO) in children in endemic areas but this phenomenon has not been studied in adults. The objective of this study was to describe the case of ascariasis causing SBO in a 25-year-old female.

CASE PRESENTATION

A 25-year-old female from southwest Ethiopia presented with a complaint of intermittent crampy abdominal pain of 02 days duration associated with vomiting of ingested matter of 02 to 03 episodes, progressive abdominal distension and failure to pass feces and flatus. On examination, she was acutely sick looking. She has mild abdominal distention and a hyperactive bowel sound. Subsequently, she was resuscitated, broad spectrum antibiotic started, consent taken & operated. Patient discharged on the 7th postoperative day.

CLINICAL DISCUSSION

There have been reports of Ascariasis causing SBO in endemic areas of the tropics and sub-tropics. SBO secondary to the ascaris ball in an adult is very rare and is relevant to present as it adds key clinical lessons in the consideration as a differential diagnosis, investigation clues and patient management.

CONCLUSION

In a patient presented with symptoms and signs suggestive of bowel obstruction, Ascariasis should be considered as a differential diagnosis for those from endemic areas. The treating physician should have a high index of suspicion.

Quantifying metabolic activity of Ascaris suum L3 using resazurin reduction

BACKGROUND

Helminth infections are an important public health problem in humans and have an even greater impact on domestic animal and livestock welfare. Current readouts for anthelmintic drug screening assays are stage development, migration, or motility that can be subjective, laborious, and low in throughput. The aim of this study was to apply and optimize a fluorometric technique using resazurin for evaluating changes in the metabolic activity of Ascaris suum third-stage larvae (L3), a parasite of high economic relevance in swine.

METHODS

Ascaris suum L3 were mechanically hatched from 6- to 8-week embryonated and sucrose-gradient-enriched eggs. Resazurin dye and A. suum L3 were titrated in 96-well microtiter plates, and resazurin reduction activity was assessed by fluorometry after 24 h of incubation. Fluorescence microscopy was used to localize the resazurin reduction site within the larvae. Finally, we exposed A. suum L3 to various stress conditions including heat, methanol, and anthelmintics, and investigated their impact on larval metabolism through resazurin reduction activity.

RESULTS

We show that the non-fluorescent dye resazurin is reduced inside vital A. suum L3 to fluorescent resorufin and released into the culture media. Optimal assay parameters are 100-1000 L3 per well, a resazurin concentration of 7.5 µg/ml, and incubation at 37 °C/5% CO₂ for 24 h. An intact L2 sheath around the L3 of A. suum completely prevents the uptake of resazurin, while in unsheathed L3, the most intense fluorescence signal is observed along the larval midgut. L3 exposed to methanol or heat show a gradually decreased resazurin reduction activity. In addition, 24 h exposure to ivermectin at 0.625 µM, mebendazole at 5 µM, and thiabendazole from 10 to 100 µM significantly decreased larval metabolic activity by 55%, 73%, and 70% to 89%, respectively.

CONCLUSIONS

Together, our results show that both metabolic stressors and anthelmintic drugs significantly and reproducibly reduce the resazurin reduction activity of A. suum L3, making the proposed assay a sensitive and easy-to-use method to evaluate metabolic activity of A. suum L3 in vitro.

Prevalence of soil-transmitted helminth infections in HIV patients: a systematic review and meta-analysis

Soil-transmitted Helminth (STH) infections have been found associated with people living with human immunodeficiency virus (HIV) but little is known about the overall burden of STH coinfection in HIV patients. We aimed to assess the burden of STH infections among HIV patients. Relevant databases were systematically searched for studies reporting the prevalence of soil-transmitted helminthic pathogens in HIV patients. Pooled estimates of each helminthic infection were calculated. The odds ratio was also determined as a measure of the association between STH infection and the HIV status of the patients. Sixty-one studies were finally included in the meta-analysis, consisting of 16,203 human subjects from all over the world. The prevalence of Ascaris lumbricoides infection in HIV patients was found to be 8% (95% CI 0.06, 0.09), the prevalence of Trichuris trichiura infection in HIV patients was found to be 5% (95% CI 0.04, 0.06), the prevalence of hookworm infection in HIV patients was found to be 5% (95% CI 0.04, 0.06), and prevalence of Strongyloides stercoralis infection in HIV patients was found to be 5% (95% CI 0.04, 0.05). Countries from Sub-Saharan Africa, Latin America & Caribbean and Asia were identified with the highest burden of STH-HIV coinfection. Our analysis indicated that people living with HIV have a higher chance of developing Strongyloides stercoralis infections and decreased odds of developing hookworm infections. Our findings suggest a moderate level of prevalence of STH infections among people living with HIV. The endemicity of STH infections and HIV status both are partially responsible for the burden of STH-HIV coinfections.

Programmed DNA elimination in the parasitic nematode Ascaris

In most organisms, the whole genome is maintained throughout the life span. However, exceptions occur in some species where the genome is reduced during development through a process known as programmed DNA elimination (PDE). In the human and pig parasite Ascaris, PDE occurs during the 4 to 16 cell stages of embryogenesis, when germline chromosomes are fragmented and specific DNA sequences are reproducibly lost in all somatic cells. PDE was identified in Ascaris over 120 years ago, but little was known about its molecular details until recently. Genome sequencing revealed that approximately 1,000 germline-expressed genes are eliminated in Ascaris, suggesting PDE is a gene silencing mechanism. All germline chromosome ends are removed and remodeled during PDE. In addition, PDE increases the number of chromosomes in the somatic genome by splitting many germline chromosomes. Comparative genomics indicates that these germline chromosomes arose from fusion events. PDE separates these chromosomes at the fusion sites. These observations indicate that PDE plays a role in chromosome karyotype and evolution. Furthermore, comparative analysis of PDE in other parasitic and free-living nematodes illustrates conserved features of PDE, suggesting it has important biological significance. We summarize what is known about PDE in Ascaris and its relatives. We also discuss other potential functions, mechanisms, and the evolution of PDE in these parasites of humans and animals of veterinary importance.