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Parasites & Vectors Jan 2016Soil-transmitted helminth (STH) infections of humans fall within the World Health Organization's (WHO) grouping termed the neglected tropical diseases (NTDs). It is... (Review)
Review
Soil-transmitted helminth (STH) infections of humans fall within the World Health Organization's (WHO) grouping termed the neglected tropical diseases (NTDs). It is estimated that they affect approximately 1.4 billion people worldwide. A significant proportion of these infections are in the population of Southeast Asia. This review analyses published data on STH prevalence and intensity in Southeast Asia over the time period of 1900 to the present to describe age related patterns in these epidemiological measures. This is with a focus on the four major parasite species affecting humans; namely Ascaris lumbricoides, Trichuris trichiura and the hookworms; Necator americanus and Ancylostoma duodenale. Data were also collected on the diagnostic methods used in the published surveys and how the studies were designed to facilitate comparative analyses of recorded patterns and changes therein over time. PubMed, Google Scholar, EMBASE, ISI Web of Science, Cochrane Database of Systematic Reviews and the Global Atlas of Helminth Infections search engines were used to identify studies on STH in Southeast Asia with the search based on the major key words, and variants on, "soil-transmitted helminth" "Ascaris" "Trichuris" "hookworm" and the country name. A total of 280 studies satisfied the inclusion criteria from 11 Southeast Asian countries; Brunei, Cambodia, Indonesia, Lao People's Democratic Republic (Lao PDR), Malaysia, Myanmar, Philippines, Singapore, Thailand, Timor-Leste and Vietnam. It was concluded that the epidemiological patterns of STH infection by age and species mix in Southeast Asia are similar to those reported in other parts of the world. In the published studies there were a large number of different diagnostic methods used with differing sensitivities and specificities, which makes comparison of the results both within and between countries difficult. There is a clear requirement to standardise the methods of both STH diagnosis in faecal material and how the intensity of infection is recorded and reported in future STH research and in monitoring and evaluation (M&E) of the impact of continuing and expanding mass drug administration (MDA) programmes.
Topics: Ancylostoma; Ancylostomatoidea; Animals; Ascariasis; Ascaris lumbricoides; Asia, Southeastern; Feces; Helminthiasis; Helminths; Hookworm Infections; Humans; Prevalence; Research; Soil; Surveys and Questionnaires; Trichuriasis; Trichuris
PubMed: 26813007
DOI: 10.1186/s13071-016-1310-2 -
PLoS Neglected Tropical Diseases Oct 2020Intestinal worms, or soil-transmitted helminths (STHs), affect hundreds of millions of people in all tropical and subtropical regions of the world. The most prevalent...
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.
Topics: Animals; Ascariasis; Ascaris lumbricoides; Enzyme-Linked Immunosorbent Assay; Feces; Female; Helminth Proteins; Humans; Male; Swine; Swine Diseases
PubMed: 33057357
DOI: 10.1371/journal.pntd.0008807 -
Bulletin of Mathematical Biology Apr 2016The Anderson-May model of human parasite infections and specifically that for the intestinal worm Ascaris lumbricoides is reconsidered, with a view to deriving the...
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.
Topics: Animals; Ascariasis; Ascaris lumbricoides; Binomial Distribution; Digestive System; Humans; Mathematical Concepts; Models, Biological; Nonlinear Dynamics; Parasite Egg Count; Stochastic Processes
PubMed: 27066982
DOI: 10.1007/s11538-016-0164-2 -
PLoS Neglected Tropical Diseases Sep 2018Ascaris lumbricoides and Necator americanus are soil-transmitted parasites with global geographic distribution, and they represent some of the most common and neglected...
Ascaris lumbricoides and Necator americanus are soil-transmitted parasites with global geographic distribution, and they represent some of the most common and neglected infections in the world. Periodic treatment with mass drug administration (MDA) in endemic areas is the recommended action put forth by the World Health Organization. However, MDA can cause the selection of subpopulations that possess the genetic ability to overcome the mechanism of drug action. In fact, beta-tubulin gene mutations (codons 167, 198 and 200) are correlated with benzimidazole resistance in nematodes of veterinary importance. It is possible that these SNPs also have strong correlation with treatment resistance in the human geohelminths A. lumbricoides, Trichuris trichiura and hookworms. Here, we aimed to investigate the presence of some of these canonical molecular markers associated with parasite resistance to benzimidazole in N. americanus and A. lumbricoides collected from six Brazilian states. Nested-PCR and PCR-RFLP were used to detect mutations at codons 167 and 198 in 601 individual eggs of A. lumbricoides collected from 62 human stool samples; however, no mutations were found. Codons 198 and 200 were tested in 552 N. americanus eggs collected from 48 patients using the same methodology, which presented a relative frequency of 1.4% and 1.1%, respectively. The presence of these SNPs in N. americanus eggs is an important finding, indicating that with high benzimidazole drug pressure there is potential for benzimidazole resistance to be selected in this hookworm. However, at these low frequencies it does not indicate that there is at present any benzimidazole resistance problem. This is the first systematic study performed in South America, and the study yielded a landscape of the genetic variants in the beta-tubulin gene and anthelmintic resistance to soil-transmitted parasites detected by a simple, rapid and affordable genotyping assay of individual eggs.
Topics: Animals; Anthelmintics; Ascariasis; Ascaris lumbricoides; Benzimidazoles; Brazil; Codon; Drug Resistance; Feces; Genetic Testing; Genotype; Humans; Mutation; Necator americanus; Necatoriasis; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; Tubulin
PubMed: 30222749
DOI: 10.1371/journal.pntd.0006766 -
The Cochrane Database of Systematic... Jun 2022It is estimated that 1.5 billion people are infected with soil-transmitted helminths (STHs) worldwide. Re-infection occurs rapidly following deworming, and interruption... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
It is estimated that 1.5 billion people are infected with soil-transmitted helminths (STHs) worldwide. Re-infection occurs rapidly following deworming, and interruption of transmission is unlikely without complementary control efforts such as improvements in water, sanitation, and hygiene (WASH) access and behaviours.
OBJECTIVES
To assess the effectiveness of WASH interventions to prevent STH infection.
SEARCH METHODS
We used standard, extensive Cochrane search methods. The latest search date was 19 October 2021.
SELECTION CRITERIA
We included interventions to improve WASH access or practices in communities where STHs are endemic. We included randomized controlled trials (RCTs), as well as trials with an external control group where participants (or clusters) were allocated to different interventions using a non-random method (non-RCTs). We did not include observational study designs. Our primary outcome was prevalence of any STH infection. Prevalence of individual worms was a secondary outcome, including for Ascaris lumbricoides, Trichuris trichiura, hookworm (Ancylostoma duodenale or Necator americanus), or Strongyloides stercoralis. Intensity of infection, measured as a count of eggs per gram of faeces for each species, was another secondary outcome.
DATA COLLECTION AND ANALYSIS
Two review authors independently reviewed titles and abstracts and full-text records for eligibility, performed data extraction, and assessed risk of bias using the Cochrane risk of bias assessment tool for RCTs and the EPOC tool for non-RCTs. We used a random-effects meta-analysis to pool study estimates. We used Moran's I² statistic to assess heterogeneity and conducted subgroup analyses to explore sources of heterogeneity. We assessed the certainty of the evidence using the GRADE approach.
MAIN RESULTS
We included 32 studies (16 RCTs and 16 non-RCTs) involving a total of 52,944 participants in the review. Twenty-two studies (14 RCTs (16 estimates) and eight non-RCTs (11 estimates)) reported on our primary outcome, prevalence of infection with at least one STH species. Twenty-one studies reported on the prevalence of A lumbricoides (12 RCTs and 9 non-RCTs); 17 on the prevalence of T trichiura (9 RCTs and 8 non-RCTs); 18 on the prevalence of hookworm (10 RCTs and 8 non-RCTs); and one on the prevalence of S stercoralis (1 non-RCT). Sixteen studies measured the intensity of infection for an individual STH type. Ten RCTs and five non-RCTs reported on the intensity of infection of A lumbricoides; eight RCTs and five non-RCTs measured the intensity of infection of T trichiura; and eight RCTs and five non-RCTs measured the intensity of hookworm infection. No studies reported on the intensity of infection of S stercoralis. The overall pooled effect estimates showed that the WASH interventions under study may result in a slight reduction of any STH infection, with an odds ratio (OR) of 0.86 amongst RCTs (95% confidence interval (CI) 0.74 to 1.01; moderate-certainty evidence) and an OR of 0.71 amongst non-RCTs (95% CI 0.54 to 0.94; low-certainty evidence). All six of the meta-analyses assessing individual worm infection amongst both RCTs and non-RCTs had pooled estimates in the preventive direction, although all CIs encapsulated the null, leaving the possibility of the null or even harmful effects; the certainty of the evidence ranged from very low to moderate. Individual studies assessing intensity of infection showed mixed evidence supporting WASH. Subgroup analyses focusing on narrow specific subsets of water, sanitation, and hygiene interventions did very little to elucidate which interventions might be better than others. Data on intensity of infection (e.g. faecal egg count) were reported in a variety of ways across studies, precluding the pooling of results for this outcome. We did not find any studies reporting adverse events resulting from the WASH interventions under study or from mass drug administration (MDA).
AUTHORS' CONCLUSIONS
Whilst the available evidence suggests that the WASH interventions under study may slightly protect against STH infection, WASH also serves as a broad preventive measure for many other diseases that have a faecal oral transmission route of transmission. As many of the studies were done in addition to MDA/deworming (i.e. MDA was ongoing in both the intervention and control arm), our data support WHO recommendations for implementation of improvements to basic sanitation and adequate access to safe water alongside MDA. The biological plausibility for improved access to WASH to interrupt transmission of STHs is clear, but WASH interventions as currently delivered have shown impacts that were lower than expected. There is a need for more rigorous and targeted implementation research and process evaluations in order that future WASH interventions can better provide benefit to users. Inconsistent reporting of the intensity of infection underscores the need to define the minimal, standard data that should be collected globally on STHs to enable pooled analyses and comparisons.
Topics: Animals; Ascaris lumbricoides; Humans; Hygiene; Observational Studies as Topic; Sanitation; Soil; Water
PubMed: 35726112
DOI: 10.1002/14651858.CD012199.pub2 -
Anais Da Academia Brasileira de Ciencias 2023Enteroparasites are an important public health problem and the treatment seeks to cure and reduce transmission. The aim of this study was to evaluate the therapeutic...
Enteroparasites are an important public health problem and the treatment seeks to cure and reduce transmission. The aim of this study was to evaluate the therapeutic efficacy of anthelmintic treatment in individuals living in a rural community area in Camamu, Bahia, Brazil. The parasitological diagnosis was performed by spontaneous sedimentation, Baermann-Moraes and Agar Plate Culture methods. A total of 212 individuals were evaluated. The most frequent helminth was Trichuris trichiura, 24.5% (52/212), followed by Ascaris lumbricoides, 21.2% (45/212), hookworms, 16.5% (35/212), and S. stercoralis, 4.7% (10/212). In the anthelmintic treatment follow up, T. trichiura infection presented the lowest parasitological cure rate, only 60.6% (20/33). Hookworm, Ascaris lumbricoides and Strongyloides stercoralis infections demonstrated cure rates of 70.5 (12/17), 78.1 (25/32) and 100% (5/5), respectively. Individuals who remained infected underwent a new drug therapy. The second parasitological cure rate for T. trichiura was 38.5% (5/13), and 66.7% (2/3) and 75% (3/4) for hookworms and Ascaris lumbricoides, respectively. Trichuris trichiura infection presented the lowest parasitological cure rate at this second evaluation. This reinforces the need to perform a follow-up of all treated individuals. The possibility of drug resistance denotes the necessity for studies to clarify the mechanisms and to evaluate new therapeutic approaches.
Topics: Animals; Humans; Follow-Up Studies; Brazil; Rural Population; Anthelmintics; Hookworm Infections; Ancylostomatoidea; Ascaris lumbricoides; Feces; Prevalence
PubMed: 37909545
DOI: 10.1590/0001-3765202320230323 -
The American Journal of Tropical... Dec 2017This randomized, double-blind, placebo-controlled study evaluated the efficacy and safety of a new chewable, rapidly-disintegrating mebendazole (MBZ) 500 mg tablet for... (Randomized Controlled Trial)
Randomized Controlled Trial
Efficacy and Safety of a Single-Dose Mebendazole 500 mg Chewable, Rapidly-Disintegrating Tablet for and Infection Treatment in Pediatric Patients: A Double-Blind, Randomized, Placebo-Controlled, Phase 3 Study.
This randomized, double-blind, placebo-controlled study evaluated the efficacy and safety of a new chewable, rapidly-disintegrating mebendazole (MBZ) 500 mg tablet for and infection treatment. Pediatric patients (1-15 years; = 295; from Ethiopia and Rwanda) excreting and/or eggs were enrolled. The study had a screening phase (3 days), a double-blind treatment phase (DBP, 19 days), and an open-label phase (OLP, 7 days). Patients received MBZ or placebo on day 1 of DBP and open-label MBZ on day 19 ± 2 after stool sample collection. Cure rates (primary endpoint), defined as species-specific egg count of 0 at the end of DBP, were significantly higher in the MBZ group than placebo for (83.7% [72/86; 95% CI: 74.2%; 90.8%] versus 11.1% [9/81; 95% CI: 5.2%; 20.1%], < 0.001) and for (33.9% [42/124; 95% CI: 25.6%; 42.9%] versus 7.6% [9/119; 95% CI: 3.5%; 13.9%], < 0.001). Egg reduction rates (secondary endpoint) were significantly higher in the MBZ group than placebo for (97.9% [95% CI: 94.4; 99.9] versus 19.2% [95% CI: -5.9; 41.5]; < 0.001) and (59.7% [95% CI: 33.9; 78.8] versus 10.5% [95% CI: -16.8; 32.9]; = 0.003). Treatment-emergent adverse events (TEAEs) in MBZ group occurred in 6.3% (9/144) of patients during DBP and 2.5% (7/278) during OLP. No deaths, serious TEAEs, or TEAEs leading to discontinuations were reported. A 500 mg chewable MBZ tablet was more efficacious than placebo for the treatment of and infections in pediatric patients, and no safety concerns were identified.
Topics: Adolescent; Animals; Antinematodal Agents; Ascariasis; Ascaris lumbricoides; Child; Child, Preschool; Dose-Response Relationship, Drug; Double-Blind Method; Ethiopia; Feces; Female; Humans; Infant; Male; Mebendazole; Parasite Egg Count; Rwanda; Species Specificity; Tablets; Treatment Outcome; Trichuriasis; Trichuris
PubMed: 29016336
DOI: 10.4269/ajtmh.17-0108 -
Infectious Diseases of Poverty Jan 2024Mass drug administration (MDA) program of albendazole to at-risk populations as preventive chemotherapy is the core public health intervention to control...
Reduced efficacy of single-dose albendazole against Ascaris lumbricoides, and Trichuris trichiura, and high reinfection rate after cure among school children in southern Ethiopia: a prospective cohort study.
BACKGROUND
Mass drug administration (MDA) program of albendazole to at-risk populations as preventive chemotherapy is the core public health intervention to control soil-transmitted helminths (STHs). Achieving this goal relies on drug effectiveness in reducing the parasite reservoirs in the community and preventing reinfection. We assessed the efficacy of albendazole against STH parasite infection and reinfection status after cure.
METHODS
A total of 984 schoolchildren infected with at least one type of STH parasite (hookworm, Ascaris lumbricoides, Trichuris trichiura) in southern Ethiopia were enrolled and received albendazole and praziquantel in MDA campaign conducted from January to March 2019. Stool exams at week-4 and at week-8 of post-MDA were done using Kato Katz technique. The primary outcome was efficacy assessed by cure rate (CR) and fecal egg reduction rates (ERRs) at four weeks of post-MDA. The secondary outcome was reinfection status defined as parasite egg positivity at eight weeks among those who were cured at 4 weeks of post-MDA. Group comparisons in CR and related factors were assessed with chi-square or Fisher's exact tests. Predictors of CR were examined through univariate and multivariate regression analyses.
RESULTS
The overall CR and ERR for hookworm infection were 97.2% (95% CI 94.6-99.4) and 97.02%, respectively. The overall CR and ERR for A. lumbricoides were 71.5% (95% CI 68.3-74.6) and 84.5% respectively. The overall CR and ERR and for T. trichiura were 49.5% (95% CI 44.8-54.2) and 68.3%, respectively. The CR among moderate T. trichiura infection intensity was 28.6%. Among children cured of hookworm, A. lumbricoides and T. trichiura at week 4 post-MDA, 4.6%, 18.3% and 52.4% became reinfected at week-8 post-MDA, respectively. Significantly lower CR (36.6%) and higher reinfection after cure (60.6%) among A. lumbricoides and T. trichiura coinfected children than A. lumbricoides only (CR = 69.6%, reinfection rate = 15.1%) or T. trichiura only infected children (CR = 55.6%, reinfection rate = 47.1%) was observed. Pre-treatment coinfection with ≥ two types of STH parasites was significantly associated with re-infection after cure.
CONCLUSION
Albendazole MDA is efficacious against hookworm but has reduced efficacy against A. lumbricoides and is not effective against T. trichiura. The low drug efficacy and high reinfection rate after cure underscore the need for alternative treatment and integration of other preventive measures to achieve the target of eliminating STHs as a public health problem by 2030.
Topics: Child; Animals; Humans; Ascaris lumbricoides; Trichuris; Albendazole; Ethiopia; Prospective Studies; Reinfection; Coinfection
PubMed: 38246985
DOI: 10.1186/s40249-024-01176-6 -
PloS One 2013Helminth infections and allergy have evolutionary and clinical links. Infection with the nematode Ascaris lumbricoides induces IgE against several molecules including...
Helminth infections and allergy have evolutionary and clinical links. Infection with the nematode Ascaris lumbricoides induces IgE against several molecules including invertebrate pan-allergens. These antibodies influence the pathogenesis and diagnosis of allergy; therefore, studying parasitic and non-parasitic allergens is essential to understand both helminth immunity and allergy. Glutathione transferases (GSTs) from cockroach and house dust mites are clinically relevant allergens and comparative studies between them and the GST from A. lumbricoides (GSTA) are necessary to evaluate their allergenicity. We sought to analyze the allergenic potential of GSTA in connection with the IgE response to non-parasitic GSTs. IgE to purified GSTs from Ascaris (nGSTA and rGSTA), house dust mites (rDer p 8, nBlo t 8 and rBlo t 8), and cockroach (rBla g 5) was measured by ELISA in subjects from Cartagena, Colombia. Also, multidimensional proteomic approaches were used to study the extract of A. lumbricoides and investigate the existence of GST isoforms. We found that among asthmatics, the strength of IgE levels to GSTA was significantly higher than to mite and cockroach GSTs, and there was a strong positive correlation between IgE levels to these molecules. Specific IgE to GSTA was found in 13.2% of controls and 19.5% of asthmatics. In addition nGSTA induced wheal and flare in skin of sensitized asthmatics indicating that it might be of clinical relevance for some patients. Frequency and IgE levels to GSTA were higher in childhood and declined with age. At least six GST isoforms in A. lumbricoides bind human IgE. Four isoforms were the most abundant and several amino acid substitutions were found, mainly on the N-terminal domain. In conclusion, a new allergenic component of Ascaris has been discovered; it could have clinical impact in allergic patients and influence the diagnosis of mite and cockroach allergy in tropical environments.
Topics: Adolescent; Adult; Allergens; Amino Acid Sequence; Amino Acid Substitution; Animals; Antigen-Antibody Reactions; Antigens, Dermatophagoides; Ascaris lumbricoides; Asthma; Cockroaches; Colombia; Female; Glutathione Transferase; Helminth Proteins; Humans; Immunochemistry; Immunoglobulin E; Insect Proteins; Isoenzymes; Male; Middle Aged; Models, Molecular; Molecular Sequence Data; Protein Structure, Tertiary; Proteomics; Pyroglyphidae
PubMed: 24223794
DOI: 10.1371/journal.pone.0078353 -
Epidemics Mar 2017The predictions of two mathematical models of the transmission dynamics of Ascaris lumbricoides and hookworm infection and the impact of mass drug administration (MDA)... (Comparative Study)
Comparative Study
The predictions of two mathematical models of the transmission dynamics of Ascaris lumbricoides and hookworm infection and the impact of mass drug administration (MDA) are compared, using data from India. One model has an age structured partial differential equation (PDE) deterministic framework for the distribution of parasite numbers per host and sexual mating. The second model is an individual-based stochastic model. Baseline data acquired prior to treatment are used to estimate key transmission parameters, and forward projections are made, given the known MDA population coverage. Predictions are compared with observed post-treatment epidemiological patterns. The two models could equally well predict the short-term impact of deworming on A. lumbricoides and hookworm infection levels, despite being fitted to different subsets and/or summary statistics of the data. As such, the outcomes give confidence in their use as aids to policy formulation for the use of PCT to control A. lumbricoides and hookworm infection. The models further largely agree in a qualitative sense on the added benefit of semi-annual vs. annual deworming and targeting of the entire population vs. only children, as well as the potential for interruption of transmission. Further, this study also illustrates that long-term predictions are sensitive to modelling assumptions about which age groups contribute most to transmission, which depends on human demography and age-patterns in exposure and contribution to the environmental reservoir of infection, the latter being notoriously difficult to empirically quantify.
Topics: Animals; Anthelmintics; Ascariasis; Ascaris lumbricoides; Hookworm Infections; Humans; India; Mass Drug Administration; Models, Theoretical; Reproducibility of Results
PubMed: 28279454
DOI: 10.1016/j.epidem.2017.02.001