Evaluation of copromicroscopy and serology to measure the exposure to Ascaris infections across age groups and to assess the impact of 3 years of biannual mass drug administration in Jimma Town, Ethiopia

Serological diagnosis of soil-transmitted helminth (Ascaris, Trichuris and hookworm) infections: A scoping review

BACKGROUND

The World Health Organization emphasizes the importance of integrated monitoring and evaluation in neglected tropical disease (NTD) control programs. Serological assays offer a potential solution for integrated diagnosis of NTDs, particularly for those requiring mass drug administration (MDA) as primary control and elimination strategy. This scoping review aims (i) to provide an overview of assays using serum or plasma to detect infections with soil-transmitted helminths (STHs) in both humans and animals, (ii) to examine the methodologies used in this research field and (iii) to discuss advancements in serological diagnosis of STHs to guide prevention and control programs in veterinary and human medicine.

METHODOLOGY

We conducted a systematic search in the Ovid MEDLINE, Embase and Cochrane Library databases, supplemented by a Google search using predefined keywords to identify commercially available serological assays. Additionally, we performed a patent search through Espacenet.

PRINCIPAL FINDINGS

We identified 85 relevant literature records spanning over 50 years, with a notable increased interest in serological assay development in recent years. Most of the research efforts concentrated on diagnosing Ascaris infections in both humans and pigs, primarily using ELISA and western blot technologies. Almost all records targeted antibodies as analytes, employing proteins and peptides as analyte detection agents. Approximately 60% of sample sets described pertained to human samples. No commercially available tests for Trichuris or hookworms were identified, while for Ascaris, there are at least seven different ELISAs on the market.

CONCLUSIONS

While a substantial number of assays are employed in epidemiological research, the current state of serological diagnosis for guiding STH prevention and control programs is limited. Only two assays designed for pigs are used to inform efficient deworming practices in pig populations. Regarding human diagnosis, none of the existing assays has undergone extensive large-scale validation or integration into routine diagnostics for MDA programs.

Protocol for a cluster randomised placebo-controlled trial of adjunctive ivermectin mass drug administration for malaria control on the Bijagós Archipelago of Guinea-Bissau: the MATAMAL trial

INTRODUCTION

As malaria declines, innovative tools are required to further reduce transmission and achieve elimination. Mass drug administration (MDA) of artemisinin-based combination therapy (ACT) is capable of reducing malaria transmission where coverage of control interventions is already high, though the impact is short-lived. Combining ACT with ivermectin, an oral endectocide shown to reduce vector survival, may increase its impact, while also treating ivermectin-sensitive co-endemic diseases and minimising the potential impact of ACT resistance in this context.

METHODS AND ANALYSIS

MATAMAL is a cluster-randomised placebo-controlled trial. The trial is being conducted in 24 clusters on the Bijagós Archipelago, Guinea-Bissau, where the peak prevalence of Plasmodium falciparum (Pf) parasitaemia is approximately 15%. Clusters have been randomly allocated to receive MDA with dihydroartemisinin-piperaquine and either ivermectin or placebo. The primary objective is to determine whether the addition of ivermectin MDA is more effective than dihydroartemisinin-piperaquine MDA alone in reducing the prevalence of P. falciparum parasitaemia, measured during peak transmission season after 2 years of seasonal MDA. Secondary objectives include assessing prevalence after 1 year of MDA; malaria incidence monitored through active and passive surveillance; age-adjusted prevalence of serological markers indicating exposure to P. falciparum and anopheline mosquitoes; vector parous rates, species composition, population density and sporozoite rates; prevalence of vector pyrethroid resistance; prevalence of artemisinin resistance in P. falciparum using genomic markers; ivermectin's impact on co-endemic diseases; coverage estimates; and the safety of combined MDA.

ETHICS AND DISSEMINATION

The trial has been approved by the London School of Hygiene and Tropical Medicine's Ethics Committee (UK) (19156) and the Comite Nacional de Eticas de Saude (Guinea-Bissau) (084/CNES/INASA/2020). Results will be disseminated in peer-reviewed publications and in discussion with the Bissau-Guinean Ministry of Public Health and participating communities.

TRIAL REGISTRATION NUMBER

NCT04844905.

Seroprevalence of Ascaris suum compared to milk spot prevalence at slaughter in Italian fattening pigs

Ascaris suum is one of the most important parasites of pigs. Apart from liver condemnation due to lesions caused by migrating larvae ("milk spots"), A. suum infections can compromise weight gain, feed conversion efficacy, as well as meat quality. The true prevalence of infection depends on the diagnostic test used and is often underestimated. We compared liver inspection at slaughter with serology, based on the recognition of a purified A. suum haemoglobin or complete homogenate of the 3rd stage larvae isolated from lungs, in nine pig farms in northern Italy. Liver lesions were found on all farms with prevalence ranging from 3.8% to 98.3%. All farms were also positive for circulating antibodies against As-Hb and As-Lung-L3, with prevalence among pigs on each farm ranging from 36.4-100% and 54.5-100%, respectively. Seroprevalence was consistently higher when compared to the prevalence of milk spots at slaughter. The higher sensitivity of the ELISA tests combined with their ease of use makes them an interesting tool to evaluate A. suum infection levels.

Comparison of coproprevalence and seroprevalence to guide decision-making in national soil-transmitted helminthiasis control programs: Ethiopia as a case study

BACKGROUND

WHO recommends periodical assessment of the prevalence of any soil-transmitted helminth (STH) infections to adapt the frequency of mass drug administration targeting STHs. Today, detection of eggs in stool smears (Kato-Katz thick smear) remains the diagnostic standard. However, stool examination (coprology) has important operational drawbacks and impedes integrated surveys of multiple neglected tropical diseases. Therefore, the aim of the present study was to assess the potential of applying serology instead of coprology in STH control program decision-making.

METHODOLOGY

An antibody-ELISA based on extract of Ascaris lung stage larvae (AsLungL3-ELISA) was applied in ongoing monitoring activities of the Ethiopian national control program against schistosomiasis and soil-transmitted helminthiasis. Blood and stool samples were collected from over 6,700 students (median age: 11) from 63 schools in 33 woredas (districts) across the country. Stool samples of two consecutive days were analyzed applying duplicate Kato-Katz thick smear.

PRINCIPAL FINDINGS

On woreda level, qualitative (seroprevalence) and quantitative (mean optical density ratio) serology results were highly correlated, and hence seroprevalence was chosen as parameter. For 85% of the woredas, prevalence based on serology was higher than those based on coprology. The results suggested cross-reactivity of the AsLungL3-ELISA with Trichuris. When extrapolating the WHO coproprevalence thresholds, there was a moderate agreement (weighted κ = 0.43) in program decision-making. Using the same threshold values would predominantly lead to a higher frequency of drug administration.

SIGNIFICANCE

This is the first time that serology for soil-transmitted helminthiasis is applied on such large scale, thereby embedded in a control program context. The results underscore that serology holds promise as a tool to monitor STH control programs. Further research should focus on the optimization of the diagnostic assay and the refinement of serology-specific program decision-making thresholds.

Assessment of the nail contamination with soil-transmitted helminths in schoolchildren in Jimma Town, Ethiopia

Background

Large-scale deworming programs have been successful in reducing the burden of disease due to soil-transmitted helminth (STH; Ascaris lumbricloides, Trichuris trichiura and hookworm) infections, but re-infection in absence of other measures is unavoidable. We assessed the role of nail contamination as a source of infection with the goal to evaluate the potential of nail clipping as a simple measure to further reduce STH-attributable morbidity.

Methods

A cross-sectional study was conducted in Jimma Town (Ethiopia). Both stool samples and clipped nails were collected from 600 schoolchildren and microscopically screened for the presence of STHs. We also interviewed the children to gain insights into their hygiene practices. Subsequently, we explored any associations between infection, nail contamination and personal hygiene.

Results

Any STH infections were observed in 24.3% of the children (A. lumbricoides: 18.5%; T. trichiura: 9.8%; hookworm: 0.5%). The intensity of the infections was mainly low, only in a few cases a moderate-to-heavy intensity infection was observed (A. lumbricoides: 4.3%; T. trichiura: 0.2%). Other helminth species observed were Schistosoma mansoni (5.0%), Hymenolepis nana (2.7%), Taenia spp. and Enterobius vermicularis (<1.0%). The analysis of the nail material revealed the presence of A. lumbricoides (1.7%), Taenia spp. (1.0%), T. trichiura (0.5%), E. vermicularis (0.5%) and H. nana (0.2%). The odds of infection with any STH increased as the frequency of trimming decreased. The odds of nail contamination with any STH and A. lumbricoides were higher for younger children.

Conclusions

The presence of helminth eggs under the nails of children highlights a poor personal hygiene. The association between any STH infection and frequency of nail trimming needs to be explored in an intervention study. The recent prevalence of any STH infections indicated that scaling down of the frequency of deworming is justified but that STH is still a public health problem.

Evaluation of antibody serology to determine current helminth and Plasmodium falciparum infections in a co-endemic area in Southern Mozambique

Background

Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure.

Methodology

We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference.

Principal findings

IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed.

Conclusions

We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens.

Parasitic worms and Plasmodium falciparum, the causal agent of malaria, are among the most relevant parasitic diseases of our time and efforts are under way for their control and, ultimately, elimination. An accurate diagnosis is relevant for case management, but also allows calculating the prevalence and evaluating the effectiveness of treatment and control measures. Unfortunately, current diagnostic methods for parasitic worms are not optimal and many infections remain undetected. As for P. falciparum, current diagnostic techniques are satisfactory but do not allow for ascertaining exposure, which is relevant for evaluating control measures. Here we investigated the utility of measuring antibodies to these parasites as a diagnostic method. Our results indicate that it is possible to detect current infection with parasitic worms and P. falciparum using antibody detection with a moderate to high accuracy. We also show that antibodies against the antigens in this study have potential as markers of exposure. Importantly, we used a platform that allows for the simultaneous detection of immunoglobulins to different parasites, which would be extremely useful as a tool to integrate control and elimination programs for several pathogens.

Assessment of environmental contamination with soil-transmitted helminths life stages at school compounds, households and open markets in Jimma Town, Ethiopia

Background

It remains largely unknown where and how infections with soil-transmitted helminths (STHs; Ascaris, Trichuris, Necator and Ancylostoma) occur. We therefore aimed to identify possible sources of infection by assessing the environmental contamination in an STH-endemic area.

Methods

We first performed a series of laboratory experiments designed to optimize a soil straining-flotation method to detect and quantify Ascaris and Trichuris eggs in soil, and to validate the diagnostic performance of the optimized method when followed by microscopy and qPCR. In a second phase, we applied this method to assess the level of STH contamination in 399 environmental samples collected from 10 school compounds, 50 households and 9 open markets in Jimma Town (Ethiopia). Subsequently, we explored associations between the environmental contamination and both the corresponding STH epidemiology at the level of the schools and the household characteristics. Finally, we assessed the knowledge, attitude and practice (KAP) towards STHs in school children.

Principal findings

Our soil straining-flotation method has an analytical sensitivity of 50 eggs per 100 grams of soil and egg recovery rate of 36.0% (Ascaris) and 8.0% (Trichuris). The analysis of field samples with both microscopy and qPCR revealed the presence of 8 different helminth species of medical importance, including but not limited to the human STHs. There was a significant association between the environmental contamination and prevalence of any STH infections at the school level only. The KAP indicated a lack of knowledge and awareness of STHs.

Conclusions/Significance

Our optimized straining-flotation method has a moderate diagnostic performance and revealed that life stages of helminths are ubiquitous in the environment, which might be due to the poor sanitary facilities at both the schools and the households, and a poor level of KAP towards STHs. Further research is required to gain more insights into the contribution of these life stages to transmission.

The recent strategies to control the morbidity caused by intestinal worms have mainly been focusing on large scale deworming programs during which drugs are administered to at-risk populations. Although these large-scale deworming programs have been successful in reducing the disease burden, re-infection in the absence of other intervention measures is unavoidable. Although there is a consensus on how infections with intestinal worms are transmitted, it remains unclear where hot spots of infectious life stages can be found in endemic communities, which in turn impedes both the design and the validation of interventions that prevent (re-)infection. We optimized a laboratory method to detect life stages in soil samples and applied this method to examine soil contamination at school compounds, households and open markets in Jimma Town (Ethiopia). Finally, we assessed the household characteristics, and the knowledge, attitude, and practice towards intestinal worms among school children. Generally, our results indicated (i) a moderate performance of our laboratory method, (ii) the ubiquitous presence of life stages in the environment, (iii) a poor level of sanitary facilities at both the schools and the households and (iv) a poor level of knowledge, attitude and practices towards intestinal worms.

Longitudinal assessment of the exposure to Ascaris lumbricoides through copromicroscopy and serology in school children from Jimma Town, Ethiopia

Background

We previously demonstrated that serology holds promise as an alternative diagnostic tool to copromicroscopy to monitor and evaluate deworming programs targeting soil-transmitted helminths (STHs). Here we explored the dynamics of anti-Ascaris antibodies (Ab) and evaluated the Ab-isotype of choice to assess the longitudinal exposure to Ascaris in Ethiopian school children.

Methodology

Between October 2018 and February 2020, stool and blood samples were collected every four months from school children (4 to 6 years of age). Stool samples were analyzed by duplicate Kato-Katz to assess the presence and intensity of any STH infection. Plasma Ab-responses against the total extract of Ascaris suum lung third stage larvae were measured through in-house Ab-ELISA’s for seven different Ab-isotypes.

Principal findings

At baseline, 42.4% of the 66 children were excreting eggs of any STH, Trichuris (37.9%) being the most prevalent. The cumulative prevalence (proportion of children tested that positive at least once over the entire study period) was 56.1% for Trichuris and 31.8% for Ascaris. For Ascaris, re-infections were frequently observed, whereas for Trichuris, children often remained excreting eggs following drug administration. When measuring anti-Ascaris Ab-levels, the cumulative seroprevalence was generally higher (IgG4: 60.6%; IgG1: 50.0%; IgE: 36.4%). The individual anti-Ascaris IgG4 levels at baseline were positively associated with the fecal egg counts averaged over the study period, the rate of egg-appearance and the number of positive test results. There was no apparent cross-reactivity between the anti-Ascaris IgG4 Ab-ELISA and Trichuris.

Conclusions/Significance

We demonstrate that the children are exposed to STH before the age of four and that the exposure to Ascaris is underestimated when measured with copromicroscopy. Compared to other Ab-isotypes, IgG4 is the Ab-isotype of choice to measure Ascaris exposure in STH endemic settings. Finally, the results also highlight that measuring anti-Ascaris IgG4 levels holds promise as a tool to identify individuals at higher risk for continued exposure to this STH.

World-wide large-scale deworming programs are being implemented to control the morbidity attributable to intestinal worms. Our group has recently shown that diagnostic tools that detect anti-parasite antibodies hold promise as an alternative to the current diagnostic standard (detecting worm eggs in stool using microscopy) to monitor and evaluate the progress of these programs towards the set targets. In the present study, we further explored the potential of antibody-based assays by monitoring the exposure of Ethiopian school children during a 17-month period to worm infections. Our results indicated that children in this area are exposed to intestinal worms from an early age onwards and that, based on serological results, more children are exposed to worm infections than measured by the current diagnostic standard. In addition, we demonstrated that test results of the antibody assay at the start of the study were positively associated with mean egg counts averaged over the study period, the rate of egg-appearance and the number of positive stool tests, highlighting that such assay holds promise as a tool to identify individuals at higher high risk for continued exposure to worms, and ultimately improve control programs.

Functional Analysis of Human and Feline Coronavirus Cross-Reactive Antibodies Directed Against the SARS-CoV-2 Fusion Peptide

To face the continuous emergence of SARS-CoV-2 variants, broadly protective therapeutic antibodies are highly needed. We here focused on the fusion peptide (FP) region of the viral spike antigen since it is highly conserved among alpha- and betacoronaviruses. First, we found that coronavirus cross-reactive antibodies are commonly formed during infection, being omnipresent in sera from COVID-19 patients, in ~50% of pre-pandemic human sera (rich in antibodies against endemic human coronaviruses), and even in feline coronavirus-infected cats. Pepscan analyses demonstrated that a confined N-terminal region of the FP is strongly immunogenic across diverse coronaviruses. Peptide-purified human antibodies targeting this conserved FP epitope exhibited broad binding of alpha- and betacoronaviruses, besides weak and transient SARS-CoV-2 neutralizing activity. Being frequently elicited by coronavirus infection, these FP-binding antibodies might potentially exhibit Fc-mediated effector functions and influence the kinetics or severity of coronavirus infection and disease.

Comparison of different detection methods for Ascaris suum infection on Austrian swine farms

Background

Ascaris suum, the large roundworm of pigs, is one of the economically most important pig parasites worldwide. In Austria it is commonly diagnosed by monitoring livers for milk spots at the slaughterhouse and intravital diagnosis (flotation for detection of fecal egg shedding). Recently, serological diagnosis based on the detection of specific antibodies with an ELISA (SERASCA®) with high sensitivity has been developed. To introduce and evaluate serology for A. suum screening in Austrian pigs, blood (for serology) (n = 177) and feces (for copromicroscopy) (n = 177) were taken from randomly selected slaughter pig batches from 18 farms at a slaughterhouse in Lower Austria. In addition, livers presented at slaughter (n = 844; max. 70/farm) were evaluated for milk spots.

Results

Overall, 19% of the livers were milk spot-positive (22% of those with complete diagnostic evaluations). Thirteen percent of the fecal samples contained A. suum eggs, while 69% of the blood samples were serologically positive. Despite we did not determine the sensitivity of the ELISA specifically, results ouf our study confirmed the high sensitivity of the ELISA, which was claimed by the manufacturer prior to our work (sensitivity: liver assessment: 23.5–27.0%; copromicroscopy: 8.5–9.0%; ELISA: 99.5%), and a high percentage of A. suum infections that remained undetected by standard liver assessment.

Conclusions

This suggests that the current method of roundworm diagnostics is insufficient and antibody detection at the end of the fattening period should be established as the standard procedure.

Assessment of the required performance and the development of corresponding program decision rules for neglected tropical diseases diagnostic tests: Monitoring and evaluation of soil-transmitted helminthiasis control programs as a case study

Recently, the World Health Organization established the Diagnostic Technical Advisory Group to identify and prioritize diagnostic needs for neglected tropical diseases, and to ultimately describe the minimal and ideal characteristics for new diagnostic tests (the so-called target product profiles (TPPs)). We developed two generic frameworks: one to explore and determine the required sensitivity (probability to correctly detect diseased persons) and specificity (probability to correctly detect persons free of disease), and another one to determine the corresponding samples sizes and the decision rules based on a multi-category lot quality assurance sampling (MC-LQAS) approach that accounts for imperfect tests. We applied both frameworks for monitoring and evaluation of soil-transmitted helminthiasis control programs. Our study indicates that specificity rather than sensitivity will become more important when the program approaches the endgame of elimination and that the requirements for both parameters are inversely correlated, resulting in multiple combinations of sensitivity and specificity that allow for reliable decision making. The MC-LQAS framework highlighted that improving diagnostic performance results in a smaller sample size for the same level of program decision making. In other words, the additional costs per diagnostic tests with improved diagnostic performance may be compensated by lower operational costs in the field. Based on our results we proposed the required minimal and ideal diagnostic sensitivity and specificity for diagnostic tests applied in monitoring and evaluating of soil-transmitted helminthiasis control programs.

The World Health Organization established an advisory group to identify and prioritize diagnostic needs for neglected tropical diseases, and to ultimately describe the minimal and ideal characteristics for new diagnostic tests. To support this advisory group, we developed two generic frameworks, which we applied to soil-transmitted helminthiases: one to explore and determine the required sensitivity (probability to correctly detect a diseased person) and specificity (probability to correctly detect a person free of disease), and another one to determine the corresponding samples size and decision rules during surveys. We showed that specificity rather than sensitivity will become more important when the program approaches the endgame of elimination and that the requirements for both parameters are inversely correlated, resulting in multiple combinations of sensitivity and specificity that allow for reliable decision making. We also highlighted that improving diagnostic performance results in smaller sample sizes for the same level of program decision making. In other words, the additional costs per diagnostic tests with improved diagnostic performance can be compensated by the lower operational costs in the field. Based on our results we proposed to the advisory group the required performance characteristics of diagnostic tests for soil-transmitted helminthiasis control programs.

Identification of antigenic linear peptides in the soil-transmitted helminth and Schistosoma mansoni proteome

The scientific community identified non stool-based biomarkers as the way forward to support soil-transmitted helminth (STH; Ascaris lumbricoides, Trichuris trichiura and the hookworms Ancylostoma duodenale and Necator americanus) and schistosome (S. mansoni and S. haematobium) deworming programs. This support is needed in making the decision of whether or not to stop preventive chemotherapy intervention efforts and to ultimately transition towards a post-intervention surveillance phase. We applied a two-step micro-array approach to identify antigenic linear epitopes in the STH and S. mansoni proteomes. In a first experiment, we identified antigenic peptides by applying sera from 24 STH and/or S. mansoni infected Ethiopian children on a high-density peptide microarray containing 3.3 million peptides derived from the complete STH and S. mansoni proteomes. A second array experiment with 170,185 peptides that were recognized in the first array was designed to identify non-specific antibody reactivity by applying sera from 24 healthy individuals from Belgium (a non-endemic country). From this array testing cascade, several peptides were identified for STH but none of them appeared to be unique for one species. We therefore concluded that for STH, none of the peptides revealed to be sufficiently sensitive or species specific. For S. mansoni, some promising peptides were identified prompting future investigation. Based on these results, it is unlikely that linear epitopes would be highly useful in detecting species-specific antibody responses to STH in endemic communities. For S. mansoni, one particular peptide of the micro-exon gene 12 (MEG-12) protein deserves further research. In addition, this study emphasizes the need of well-characterized biobanks for biomarker discovery, particularly when the integration of multiple disease programs is envisioned.

Today, infections with intestinal (roundworms, whipworm and hookworms) and blood-dwelling worms (schistosomes) are traditionally diagnosed by demonstrating worm eggs in stool. This current practice comes with some important challenges, including but not limited to the low-throughput and the need of skilled operators. Especially in the context of monitoring and evaluation, there is a need for alternative tools. Therefore, one of the recommendations of the scientific community was to develop tests that are based on the detection of antibodies in blood, which reflect the natural immune response of the host to worm-specific components or antigens. In the present study, we screened the antigenicity of all the peptides that build up the proteome of intestinal and blood-dwelling worms. For intestinal worms, our results revealed that the antibody response to these peptides was either not unique for the worm species or absent in infected subjects. For blood-dwelling worms, the findings were less sobering, with a number of peptides inducing an antibody response that was only observed in infected subjects.

Detection of Ascaris lumbricoides infection by ABA-1 coproantigen ELISA

Intestinal worms, or soil-transmitted helminths (STHs), affect hundreds of millions of people in all tropical and subtropical regions of the world. The most prevalent STH is Ascaris lumbricoides. Through large-scale deworming programs, World Health Organization aims to reduce morbidity, caused by moderate-to-heavy intensity infections, below 2%. In order to monitor these control programs, stool samples are examined microscopically for the presence of worm eggs. This procedure requires well-trained personnel and is known to show variability between different operators interpreting the slides. We have investigated whether ABA-1, one of the excretory-secretory products of A. lumbricoides can be used as a coproantigen marker for infection with this parasite. Polyclonal antibodies were generated and a coproantigen ELISA was developed. Using this ELISA, it was found that ABA-1 in stool detected Ascaris infection with a sensitivity of 91.5% and a specificity of 95.3%. Our results also demonstrate that there is a correlation between ABA-1 levels in stool and A. lumbricoides DNA detected in stool. Using a threshold of 18.2 ng/g stool the ABA-1 ELISA correctly assigned 68.4% of infected individuals to the moderate-to-heavy intensity infection group, with a specificity of 97.1%. Furthermore, the levels of ABA-1 in stool were shown to rapidly and strongly decrease upon administration of a standard anthelminthic treatment (single oral dose of 400 mg albendazole). In an Ascaris suum infection model in pigs, it was found that ABA-1 remained undetectable until day 28 and was detected at day 42 or 56, concurrent with the appearance of worm eggs in the stool. This report demonstrates that ABA-1 can be considered an Ascaris -specific coproantigen marker that can be used to monitor infection intensity. It also opens the path for development of point-of-care immunoassay-based tests to determine A. lumbricoides infection in stool at the sample collection site.