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.

The first report on the prevalence of soil-transmitted helminth infections and associated risk factors among traditional pig farmers in Bali Province, Indonesia

Background and Aim:

Pigs are the main livestock commodity in Bali Province, Indonesia, where traditional farming practices are widely used. Traditional pig farmers are often closely associated with poverty and a perceived lack of knowledge regarding health and hygiene. Data on soil-transmitted helminthiasis (STH) and risk factors associated with STH worm infection among traditional pig farmers in Bali were previously unavailable. This study aimed to analyze the prevalence and risk factors for STH infections among traditional pig farmers in Bali Province, Indonesia.

Materials and Methods:

This study involved the fecal examination of 238 traditional pig farmers from all areas of Bali Province in Indonesia. In addition, several pig feces samples were combined into one pooled sample belonging to each farm. All fresh fecal samples were stored in a 5% formaldehyde solution before being analyzed using concentration flotation techniques. Subsequently, risk factors were determined through an interview and a questionnaire. The odds ratio (OR) and Chi-square tests were used to determine the risk factors associated with STH infections.

Results:

The result showed that there was a high prevalence of STH infections among traditional pig farmers and pig farms in Bali, with rates of 21.8% and 76.5%, respectively. This could be due to risk factors, such as personal hygiene (OR: 5.756; confidence interval [CI]: 2.96-11.193; p=0.00), sanitation (OR: 1.914; CI: 1.024-3.576; p=0.042), education level (OR: 7.579; CI: 2.621-21.915; p=0.00), household income (OR: 2.447; CI: 1.122-5.338; p=0.025), and occupation (OR: 2.95; CI: 1.356-6.415; p=0.006).

Conclusion:

The infections seen in farmers were distributed among hookworm, Ascaris spp., and Trichuris spp., at 15.1%, 9.2%, and 4.2%, respectively. The risk factors associated with infections of STH and Ascaris spp. were personal hygiene, home sanitation, education level, household income, and having a primary occupation as a traditional pig farmer. In contrast, personal hygiene, education level, and primary occupation were the only risk factors for hookworm infection, while personal hygiene and home sanitation were the risk factors associated with Trichuris spp. infection. The limitation of this study was that the number of samples was relatively small due to the difficulty of obtaining stool samples from traditional pig farmers, with many individuals refusing to provide their stool for inspection. We suggest that future research focus on identifying the species of worms that infect traditional pig farmers and to better identify the zoonotic link of STH transmission from pigs to humans.

Immunoinformatics driven construction of multi-epitope vaccine candidate against Ascaris lumbricoides using its entire immunogenic epitopes

OBJECTIVE

Ascaris lumbricoides infects 80 million people per year, causing malnutrition, stunted growth of children etc., but there is no vaccine available against it. We aimed to design a multimeric-subunit vaccine using comprehensive immunoinformatic approach.

RESEARCH DESIGN AND METHODS

The T and B cell epitopes were shortlisted on antigenicity, allergenicity, and toxicity from proteome data and joined with appropriate linkers. The physical characteristics of vaccine candidate was calculated and docking/molecular dynamic simulation performed to validate its robustness. The multimeric protein was codon optimized and in-silico cloned in pET28b.

RESULTS

From the 23,604 proteins of Ascaris, we filtered based on epitope prediction, localization, antigenicity, and allergenicity. Prepared a vaccine of 534 amino acid long, 56.31 kD weight and pI 4.52. Physiochemical features showed it is soluble, highly antigenic and non-allergenic. Its tertiary structure was forecasted, certified, and refined. The immunoinformatic simulation studies showed it to be potent T and B cell stimulator.

CONCLUSIONS

We identified highly antigenic peptides of Ascaris from its proteome with good potential to induce innate as well as humoral immune response. These peptides were used to design a chimeric vaccine against Ascariasis infection, which can be used for prophylactic purpose but needs experimental and clinical validation.

Targeting a highly repeated germline DNA sequence for improved real-time PCR-based detection of Ascaris infection in human stool

Background

With the expansion of soil transmitted helminth (STH) intervention efforts and the corresponding decline in infection prevalence, there is an increased need for sensitive and specific STH diagnostic assays. Previously, through next generation sequencing (NGS)-based identification and targeting of non-coding, high copy-number repetitive DNA sequences, we described the development of a panel of improved quantitative real-time PCR (qPCR)-based assays for the detection of Necator americanus, Ancylostoma duodenale, Ancylostoma ceylanicum, Trichuris trichiura, and Strongyloides stercoralis. However, due to the phenomenon of chromosome diminution, a similar assay based on high copy-number repetitive DNA was not developed for the detection of Ascaris lumbricoides. Recently, the publication of a reference-level germline genome sequence for A. lumbricoides has facilitated our development of an improved assay for this human pathogen of vast global importance.

Methodology/Principal findings

Repurposing raw DNA sequence reads from a previously published Illumina-generated, NGS-based A. lumbricoides germline genome sequencing project, we performed a cluster-based repeat analysis utilizing RepeatExplorer2 software. This analysis identified the most prevalent repetitive DNA element of the A. lumbricoides germline genome (AGR, Ascaris germline repeat), which was then used to develop an improved qPCR assay. During experimental validation, this assay demonstrated a fold increase in sensitivity of ~3,100, as determined by relative Cq values, when compared with an assay utilizing a previously published, frequently employed, ribosomal internal transcribed spacer (ITS) DNA target. A comparative analysis of 2,784 field-collected samples was then performed, successfully verifying this improved sensitivity.

Conclusions/Significance

Through analysis of the germline genome sequence of A. lumbricoides, a vastly improved qPCR assay has been developed. This assay, utilizing a high copy-number repeat target found in eggs and embryos (the AGR repeat), will improve prevalence estimates that are fundamental to the programmatic decision-making process, while simultaneously strengthening mathematical models used to examine STH infection rates. Furthermore, through the identification of an optimal target for PCR, future assay development efforts will also benefit, as the identity of the optimized repeat DNA target is likely to remain unchanged despite continued improvement in PCR-based diagnostic technologies.

With an at-risk population in the billions, Ascaris lumbricoides is a pathogen of great global importance. In recent years, efforts to control the spread of this parasitic helminth have expanded, resulting in declining infection rates and worm burdens in some regions. While immeasurably important for global health, these declines have also served to expose the shortcomings of traditional diagnostic methods, as low-levels of pathogen generate a need for more sensitive tools, and microscopy-based techniques are proving ill-suited to the task at hand. Thankfully, improved sensitivity can be achieved through the careful selection of optimal repetitive DNA targets for PCR. However, previous attempts to identify such targets in A. lumbricoides were unsuccessful, largely due to chromosome diminution, an unusual phenomenon occurring in the Ascaridida, whereby large portions of the germline genome are reproducibly eliminated during early development, resulting in their absence in larvae or adult worms. As the stool-based molecular diagnosis of A. lumbricoides infection is primarily dependent upon the identification of egg-derived DNA, utilizing genomic DNA from adult worms for molecular target selection eliminates germline candidates and results in suboptimal target sequence choices. Recently, the publication of a pre-diminution germline genome of A. lumbricoides has provided us with an opportunity to re-evaluate target selection, facilitating the development of a novel quantitative real-time PCR assay with greatly improved sensitivity (~3100-fold as determined by relative Cq value) over previously developed assays that were based on ribosomal repeat DNA sequences with lower copy numbers.

Ascaris lumbricoides: challenges in diagnosis, treatment and prevention strategies in a European refugee camp

OBJECTIVES

 The roundworm Ascaris lumbricoides is one of the most prevalent parasites belonging to the class of the soil-transmitted helminths. Infections are most common in developing countries with a tropical climate where sanitation and hygiene are poor. However, prevalence of ascariasis in industrialized countries is increasing because of immigration and increasing number of refugees.

METHODS

 We report a case of ascariasis in a female patient who was admitted to our hospital after she had left the informal refugee camp of Calais in the north of France.

RESULTS

 After colonoscopic removal of the worm and treatment with mebendazole during three days the patient's symptoms had completely resolved. Medical treatment with benzimidazole derivatives is easy and inexpensive. To prevent parasitic infections in larger populations, mass drug administration should be repeated periodically and must be implemented along with additional measures such as improvements to water, sanitation and hygiene (WASH). These WASH programs have been proven to be highly effective, but access and follow-up are expensive and very difficult to organize in refugee camps, even in wealthy, industrialized countries.

CONCLUSIONS

Despite being an old, well-known parasitic disease, ascariasis might reappear in certain populations at risk in industrialized countries. Detection, treatment and follow-up of these patients, and the organization of preventive measures remain challenging.

Enterobius vermicularis as a Novel Surrogate for the Presence of Helminth Ova in Tertiary Wastewater Treatment Plants

Significant effort has gone into assessing the fate and removal of viruses, bacteria, and protozoan parasites during wastewater treatment to provide data addressing potential health risks associated with reuse options. Comparatively less is known about the fate of parasitic worm species ova in these complex systems. It is largely assumed that these helminths settle, are removed with the sludge, and consequently represent a relatively low risk for wastewater reuse applications. However, helminths are a highly diverse group of organisms that display a wide range of physical properties that complicate the application of a single treatment for helminth reduction during wastewater treatment. Moreover, their diverse biological and physical properties make some ova highly resistant to both disinfection (i.e., with chlorine or UV treatment) and physical removal (settling) through the wastewater treatment train, indicating that there may be reason to broaden the scope of our investigations into whether parasitic worm eggs can be identified in treated wastewater. The ubiquitous human parasitic nematode Enterobius vermicularis (pinworm) produces small, buoyant ova. Utilizing a novel diagnostic quantitative PCR (qPCR), this study monitored E. vermicularis presence at two full-scale wastewater treatment plants over the course of 8 months and demonstrated incomplete physical removal of E. vermicularis ova through tertiary treatment, with removal efficiencies approximating only 0.5 and 1.6 log10 at the two wastewater treatment plants based on qPCR. These findings demonstrate the need for more-diverse surrogates of helminthic ova to fully assess treatment performance with respect to reclaimed wastewaters.IMPORTANCE Helminths, despite being a diverse and environmentally resistant class of pathogens, are often underestimated and ignored when treatment performance at modern wastewater treatment plants is considered. A one-size-fits-all surrogate for removal of helminth ova may be inappropriate to adequately assess risk and ensure public safety when treated and partially treated wastewaters are encountered. This study argues for the use of human pinworm as a conservative indicator of the presence of helminth ova due to its small size, buoyancy, prevalence in humans, and environmental resistance.

The Dynamics of Ascaris lumbricoides Infections

The Anderson-May model of human parasite infections and specifically that for the intestinal worm Ascaris lumbricoides is reconsidered, with a view to deriving the observed characteristic negative binomial distribution which is frequently found in human communities. The means to obtaining this result lies in reformulating the continuous Anderson-May model as a stochastic process involving two essential populations, the density of mature worms in the gut, and the density of mature eggs in the environment. The resulting partial differential equation for the generating function of the joint probability distribution of eggs and worms can be partially solved in the appropriate limit where the worm lifetime is much greater than that of the mature eggs in the environment. Allowing for a mean field nonlinearity, and for egg immigration from neighbouring communities, a negative binomial worm distribution can be predicted, whose parameters are determined by those in the continuous Anderson-May model; this result assumes no variability in predisposition to the infection.

Proteomic analysis of adult Ascaris suum fluid compartments and secretory products

Background

Strategies employed by parasites to establish infections are poorly understood. The host-parasite interface is maintained through a molecular dialog that, among other roles, protects parasites from host immune responses. Parasite excretory/secretory products (ESP) play major roles in this process. Understanding the biology of protein secretion by parasites and their associated functional processes will enhance our understanding of the roles of ESP in host-parasite interactions.

Methodology/Principal Findings

ESP was collected after culturing 10 adult female Ascaris suum. Perienteric fluid (PE) and uterine fluid (UF) were collected directly from adult females by dissection. Using SDS-PAGE coupled with LC-MS/MS, we identified 175, 308 and 274 proteins in ESP, PE and UF, respectively. Although many proteins were shared among the samples, the protein composition of ESP was distinct from PE and UF, whereas PE and UF were highly similar. The distribution of gene ontology (GO) terms for proteins in ESP, PE and UF supports this claim. Comparison of ESP composition in A. suum, Brugia malayi and Heligmosoides polygyrus showed that proteins found in UF were also secreted by males and by larval stages of other species, suggesting that multiple routes of secretion may be used for homologous proteins. ESP composition of nematodes is both phylogeny- and niche-dependent.

Conclusions/Significance

Analysis of the protein composition of A. suum ESP and UF leads to the conclusion that the excretory-secretory apparatus and uterus are separate routes for protein release. Proteins detected in ESP have distinct patterns of biological functions compared to those in UF. PE is likely to serve as the source of the majority of proteins in UF. This analysis expands our knowledge of the biology of protein secretion from nematodes and will inform new studies on the function of secreted proteins in the orchestration of host-parasite interactions.

Ascaris lumbricoides, the most prevalent metazoan parasite of humans, is a public health concern in resource-limited countries. Survival of this parasite in its host is mediated at least in part by parasite materials secreted into the host. Little is known about the composition of these secretions; defining their contents and functions will illuminate host-parasite interactions that lead to parasite establishment. Ascaris suum, a parasite of pigs, was used as a model organism because its genome has been sequenced and it is very closely related to A. lumbricoides. Excretory/secretory products (ESP), uterine fluid (UF) and perienteric fluid (PE) were collected from adult A. suum. Proteins were subjected to LC-MS/MS. ESP proteins (the ‘secretome’) included many also present in UF. Proteins in ESP but not in UF had considerably different characteristics than those in PE or UF, which were similar to each other. We conclude that proteins released from the secretory apparatus have distinct patterns of biological function and that UF proteins are likely derived from PE. Comparing the protein composition of A. suum ESP to ESP from B. malayi and H. polygyrus suggests that the secretome is conserved at the level of both phylogeny and host predilection site.

Ascaris lumbricoides infection and its relation to environmental factors in the Mbeya region of Tanzania, a cross-sectional, population-based study

Background

With one quarter of the world population infected, the intestinal nematode Ascaris lumbricoides is one of the most common infectious agents, especially in the tropics and sub-tropics. Infection is caused by oral intake of eggs and can cause respiratory and gastrointestinal problems. To identify high risk areas for intervention, it is necessary to understand the effects of climatic, environmental and socio-demographic conditions on A. lumbricoides infection.

Methodology

Cross-sectional survey data of 6,366 study participants in the Mbeya region of South-Western Tanzania were used to analyze associations between remotely sensed environmental data and A. lumbricoides infection. Non-linear associations were accounted for by using fractional polynomial regression, and socio-demographic and sanitary data were included as potential confounders.

Principal Findings

The overall prevalence of A. lumbricoides infection was 6.8%. Our final multivariable model revealed a significant non-linear association between rainfall and A. lumbricoides infection with peak prevalences at 1740 mm of mean annual rainfall. Mean annual land surface temperature during the day was linearly modeled and negatively associated with A. lumbricoides infection (odds ratio (OR) = 0.87, 95% confidence interval (CI) = 0.78–0.97). Furthermore, age, which also showed a significant non-linear association (infection maximum at 7.7 years), socio-economic status (OR = 0.82, CI = 0.68–0.97), and latrine coverage around the house (OR = 0.80, CI = 0.67–0.96) remained in the final model.

Conclusions

A. lumbricoides infection was associated with environmental, socio-demographic and sanitary factors both in uni- and multivariable analysis. Non-linear analysis with fractional polynomials can improve model fit, resulting in a better understanding of the relationship between environmental conditions and helminth infection, and more precise predictions of high prevalence areas. However, socio-demographic determinants and sanitary conditions should also be considered, especially when planning public health interventions on a smaller scale, such as the community level.