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Indian Journal of Dermatology,... 2013
Topics: Ancylostomatoidea; Animals; Anthelmintics; Female; Fingers; Humans; Larva Migrans; Middle Aged; Skin
PubMed: 23619447
DOI: 10.4103/0378-6323.110770 -
International Journal of Infectious... Apr 2013The purpose of this study is to present the 'chronic' or 'persistent' form of hookworm-related cutaneous larva migrans.
OBJECTIVES
The purpose of this study is to present the 'chronic' or 'persistent' form of hookworm-related cutaneous larva migrans.
METHODS
From 1998 to 2011, 13 patients were seen in our department with clinically typical hookworm-related cutaneous larva migrans that had been present for more than 5 months and that, because of the absence of pruritus, had never been treated.
RESULTS
The duration of hookworm-related cutaneous larva migrans ranged from 5 to 14 months (mean 7.8 months) in these 13 patients (10 males and three females, aged 23-55 years). The infestation was acquired in Brazil (three patients), Jamaica (three patients), Mexico (two patients), Tanzania (two patients), Thailand (two patients), and Martinique (one patient). The infestation was located on the feet in 10 patients; one of these patients also presented tracks on the back and another presented tracks on a knee. The chest (two patients) and thigh (two patients) were also involved. All patients presented with clinically typical hookworm-related cutaneous larva migrans: seven patients had one track and six patients had two tracks. Laboratory and instrumental examinations were within the normal range or negative. Histopathological examination revealed edema in the papillary and upper dermis, and a perivascular and perifollicular infiltrate in the upper dermis, consisting mainly of lymphocytes and eosinophils. No larvae were detected.
CONCLUSIONS
This can be considered the 'chronic' or 'persistent' form of hookworm-related cutaneous larva migrans. Some pathogenetic hypotheses are suggested.
Topics: Adult; Ancylostomatoidea; Animals; Brazil; Chronic Disease; Female; Hookworm Infections; Humans; Larva; Larva Migrans; Male; Middle Aged; Pruritus; Time Factors; Young Adult
PubMed: 23218549
DOI: 10.1016/j.ijid.2012.11.002 -
Nature Genetics Mar 2014The hookworm Necator americanus is the predominant soil-transmitted human parasite. Adult worms feed on blood in the small intestine, causing iron-deficiency anemia,...
The hookworm Necator americanus is the predominant soil-transmitted human parasite. Adult worms feed on blood in the small intestine, causing iron-deficiency anemia, malnutrition, growth and development stunting in children, and severe morbidity and mortality during pregnancy in women. We report sequencing and assembly of the N. americanus genome (244 Mb, 19,151 genes). Characterization of this first hookworm genome sequence identified genes orchestrating the hookworm's invasion of the human host, genes involved in blood feeding and development, and genes encoding proteins that represent new potential drug targets against hookworms. N. americanus has undergone a considerable and unique expansion of immunomodulator proteins, some of which we highlight as potential treatments against inflammatory diseases. We also used a protein microarray to demonstrate a postgenomic application of the hookworm genome sequence. This genome provides an invaluable resource to boost ongoing efforts toward fundamental and applied postgenomic research, including the development of new methods to control hookworm and human immunological diseases.
Topics: Animals; Caenorhabditis elegans; Female; Gene Expression Regulation, Developmental; Genome, Helminth; Host-Parasite Interactions; Humans; Male; Molecular Sequence Data; Necator americanus; Necatoriasis; Pregnancy; Species Specificity
PubMed: 24441737
DOI: 10.1038/ng.2875 -
Parasites & Vectors Jul 2022Although there is unprecedented interest in experimental human hookworm infection, details of hookworm manufacture and characterisation have been sparsely reported. In...
BACKGROUND
Although there is unprecedented interest in experimental human hookworm infection, details of hookworm manufacture and characterisation have been sparsely reported. In this report, we detail the production and characterisation of Necator americanus larvae for use in a recently published clinical trial.
METHODS
Faeces was obtained from an experimentally infected donor. Faecal hookworm DNA was determined by quantitative PCR. Paired samples were incubated in either sterile water or sterile water mixed with antimicrobials (amphotericin and gentamicin). Coproculture was performed by modified Harada-Mori method. The harvested larvae were then processed in either sterile water or antiseptic solution. Larval yield was then calculated (larvae per gram), larval viability was determined by thermally induced motility assay and microbial burden was determined at the day of harvest, at 48 h and at 7 days.
RESULTS
Twenty-eight faecal cultures were performed over 16 months. The faecal hookworm DNA content was variable over this time. There was no association of larval yield with faecal hookworm DNA content. Pre-treatment of faeces with antimicrobials did not influence larval yield. Larval motility was 85.3% (95% CI 79.3-91.3%). Incubation of larvae in antiseptics did not reduce viability at 14 days with a marginal mean of 68.6% (95% CI 59.1-78.1%) washed in water vs. 63.3% (95% CI 53.8 - 72.9%) when incubated in betadine (p = 0.38). Larvae washed in sterile water did not meet microbial bioburden criteria. Incubation in antiseptic resulted in acceptable microbial bioburden at 48 h but not at 7 days. Although the addition of gentamicin did reduce the microbial bio-burden acceptable levels, it was found to significantly lower larval motility at 7 days compared to incubation in sterile water and motility at 7 days 37.8% (95% CI 4.7-70.9%) vs. 67.3% (95% CI 35.2-99.3%, p < 0.001), respectively.
CONCLUSIONS
Despite standardised culture methodologies and the use of a single donor, larval yield varied considerably between batches and had no association with faecal hookworm DNA. Larval viability decreases over time and the age of larvae at time of use are likely to be important. Microbial bioburden maybe temporarily reduced by incubation in antiseptics and has little effect on viability. Incubation of larvae in gentamicin is effective at reducing microbial bioburden but is deleterious to larval viability.
Topics: Ancylostomatoidea; Animals; Anti-Infective Agents, Local; Gentamicins; Hookworm Infections; Humans; Larva; Necator; Necator americanus; Necatoriasis; Water
PubMed: 35804460
DOI: 10.1186/s13071-022-05371-y -
International Journal For Parasitology Apr 2018Some nematode species are economically important parasites of livestock, while others are important human pathogens causing some of the most important neglected tropical...
Some nematode species are economically important parasites of livestock, while others are important human pathogens causing some of the most important neglected tropical diseases. In both humans and animals, anthelmintic drug administration is the main control strategy, but the emergence of drug-resistant worms has stimulated the development of alternative control approaches. Among these, vaccination is considered to be a sustainable and cost effective strategy. Currently, Barbervax® for the ruminant strongylid Haemonchus contortus is the only registered subunit vaccine for a nematode parasite, although a vaccine for the human hookworm Necator americanus is undergoing clinical trials (HOOKVAC consortium). As both these vaccines comprise a limited number of proteins, there is potential for selection of nematodes with altered sequences or expression of the vaccine antigens. Here we compared the transcriptome of H. contortus populations from sheep vaccinated with Barbervax® with worms from control animals. Barbervax® antigens are native integral membrane proteins isolated from the brush border of the intestinal cells of the adult parasite and many of those are proteases. Our findings provide no evidence for changes in expression of genes encoding Barbervax® antigens in the surviving parasite populations. However, surviving parasites from vaccinated animals showed increased expression of other proteases and regulators of lysosome trafficking, and displayed up-regulated lipid storage and defecation abilities that may have circumvented the effect of the vaccine. Implications for other potential vaccines for human and veterinary nematodes are discussed.
Topics: Animals; Gene Expression Profiling; Necator americanus; Necatoriasis; Sheep; Sheep Diseases; Vaccines
PubMed: 29534987
DOI: 10.1016/j.ijpara.2018.01.004 -
Parasites & Vectors Jan 2018Strongyloides stercoralis and hookworm are two soil-transmitted helminths (STH) that are highly prevalent in Cambodia. Strongyloides stercoralis causes long-lasting...
BACKGROUND
Strongyloides stercoralis and hookworm are two soil-transmitted helminths (STH) that are highly prevalent in Cambodia. Strongyloides stercoralis causes long-lasting infections and significant morbidity but is largely neglected, while hookworm causes the highest public health burden among STH. The two parasites have the same infection route, i.e. skin penetration. The extent of co-distribution, which could result in potential high co-morbidities, is unknown in highly endemic settings like Cambodia. The aim of this study was to predict the spatial distribution of S. stercoralis-hookworm co-infection risk and to investigate determinants of co-infection in Preah Vihear Province, North Cambodia.
METHODS
A cross-sectional survey was conducted in 2010 in 60 villages of Preah Vihear Province. Diagnosis was performed on two stool samples, using combined Baermann technique and Koga agar culture plate for S. stercoralis and Kato-Katz technique for hookworm. Bayesian multinomial geostatistical models were used to assess demographic, socioeconomic, and behavioural determinants of S. stercoralis-hookworm co-infection and to predict co-infection risk at non-surveyed locations.
RESULTS
Of the 2576 participants included in the study, 48.6% and 49.0% were infected with S. stercoralis and hookworm, respectively; 43.8% of the cases were co-infections. Females, preschool aged children, adults aged 19-49 years, and participants who reported regularly defecating in toilets, systematically boiling drinking water and having been treated with anthelmintic drugs had lower odds of co-infection. While S. stercoralis infection risk did not appear to be spatially structured, hookworm mono-infection and co-infection exhibited spatial correlation at about 20 km. Co-infection risk was positively associated with longer walking distances to a health centre and exhibited a small clustering tendency. The association was only partly explained by climatic variables, suggesting a role for underlying factors, such as living conditions and remoteness.
CONCLUSIONS
Both parasites were ubiquitous in the province, with co-infections accounting for almost half of all cases. The high prevalence of S. stercoralis calls for control measures. Despite several years of school-based de-worming programmes, hookworm infection levels remain high. Mebendazole efficacy, as well as coverage of and compliance to STH control programmes should be investigated.
Topics: Adolescent; Adult; Ancylostomatoidea; Animals; Anthelmintics; Bayes Theorem; Cambodia; Child; Child, Preschool; Coinfection; Cross-Sectional Studies; Feces; Female; Hookworm Infections; Humans; Male; Middle Aged; Models, Statistical; Prevalence; Risk Factors; Rural Population; Soil; Strongyloides stercoralis; Strongyloidiasis; Surveys and Questionnaires; Young Adult
PubMed: 29329561
DOI: 10.1186/s13071-017-2604-8 -
International Journal For Parasitology Aug 2021Soil-transmitted helminths (STHs) are parasitic intestinal worms that infect almost a fifth of the global population. Sustainable control of STHs requires understanding...
Soil-transmitted helminths (STHs) are parasitic intestinal worms that infect almost a fifth of the global population. Sustainable control of STHs requires understanding the complex interaction of factors contributing to transmission. Identifying risk factors has mainly relied on logistic regression models where the underlying assumption of independence between variables is not always satisfied. Previously demonstrated risk factors including water, sanitation and hygiene (WASH) access and behaviours, and socioeconomic status are intrinsically linked. Similarly, environmental factors including climate, soil and land attributes are often strongly correlated. Alternative methods such as recursive partitioning and Bayesian networks can handle correlated variables, but there are no published studies comparing these methods with logistic regression in the context of STH risk factor analysis. Baseline cross-sectional data from school-aged children in the (S)WASH-D for Worms study were used to compare risk factors identified from modelling the same data using three different statistical techniques. Outcomes of interest were infection with Ascaris spp. and any hookworm species (Necator americanus, Ancylostoma duodenale, and Ancylostoma ceylanicum). Mixed-effects logistic regression identified the fewest risk factors. Recursive partitioning identified the most WASH and demographic risk factors, while Bayesian networks identified the most environmental risk factors. Recursive partitioning produced classification trees that visualised potentially at-risk population sub-groups. Bayesian networks helped visualise relationships between variables and enabled interactive modelling of outcomes based on different scenarios for the predictor variables of interest. Model performance was similar across all techniques. Risk factors identified across all techniques were vegetation for Ascaris spp., and cleaning oneself with water after defecating for hookworm. This study adds to the limited body of evidence exploring alternative data modelling approaches in identifying risk factors for STH infections. Our findings suggest these approaches can provide novel insights for more robust interpretation.
Topics: Animals; Bayes Theorem; Cross-Sectional Studies; Feces; Helminthiasis; Necator americanus; Prevalence; Risk Factors; Sanitation; Soil; Timor-Leste
PubMed: 33798561
DOI: 10.1016/j.ijpara.2021.01.005 -
International Journal For Parasitology.... Aug 2018Hookworms are intestinal nematode parasites that infect nearly half a billion people and are globally one of the most important contributors to iron-deficiency anemia....
Hookworms are intestinal nematode parasites that infect nearly half a billion people and are globally one of the most important contributors to iron-deficiency anemia. These parasites have significant impacts in developing children, pregnant women and working adults. Of all the soil-transmitted helminths or nematodes (STNs), hookworms are by far the most important, with disease burdens conservatively estimated at four million DALYs (Disability-Adjusted Life Years) and with productivity losses of up to US$139 billion annually. To date, mainly one drug, albendazole is used for hookworm therapy in mass drug administration, which has on average ∼80% cure rate that is lower (<40%) in some places. Given the massive numbers of people needing treatment, the threat of parasite resistance, and the inadequacy of current treatments, new and better cures against hookworms are urgently needed. Cry5B, a pore-forming protein produced by the soil bacterium Bacillus thuringiensis (Bt) has demonstrated good efficacy against Ancylostoma ceylanicum hookworm infections in hamsters. Here we broaden studies of Cry5B to include tests against infections of Ancylostoma caninum hookworms in dogs and against infections of the dominant human hookworm, Necator americanus, in hamsters. We show that Cry5B is highly effective against all hookworm parasites tested in all models. Neutralization of stomach acid improves Cry5B efficacy, which will aid in practical application of Cry5B significantly. Importantly, we also demonstrate that the anti-nematode therapeutic efficacy of Cry5B is independent of the host immune system and is not itself negated by repeated dosing. This study indicates that Bt Cry5B is a pan-hookworm anthelmintic with excellent properties for use in humans and other animals.
Topics: Ancylostoma; Ancylostomatoidea; Ancylostomiasis; Animals; Anthelmintics; Bacillus thuringiensis; Bacillus thuringiensis Toxins; Bacterial Proteins; Cricetinae; Dogs; Endotoxins; Hemolysin Proteins; Hookworm Infections; Intestinal Diseases, Parasitic; Necator americanus; Necatoriasis
PubMed: 29772478
DOI: 10.1016/j.ijpddr.2018.05.001 -
The Brazilian Journal of Infectious... 2021Describe the diagnostic characteristics of a conventional multiplex PCR for the diagnosis of S. stercoralis, N. americanus and Ancylostomas spp.
OBJECTIVES
Describe the diagnostic characteristics of a conventional multiplex PCR for the diagnosis of S. stercoralis, N. americanus and Ancylostomas spp.
METHODS
Fecal samples were collected from a cross-sectional study in Orán department, Salta province, Argentina. The stool samples were analyzed using concentration-sedimentation, Harada Mori, McMaster, and Baermann techniques. DNA was extracted from 50 mg fecal sample using the FastPrep® Spin Kit for Soil. Three pairs of primers were used for the amplification of three products of 101, 330, and 577 base pairs (bp) for S. stercoralis, N. americanus and Ancylostoma spp, respectively. The sensitivity and analytical specificity of multiplex PCR were evaluated, as well as the sensitivity and diagnostic specificity, using a composite standard and Bayesian approach.
RESULTS AND CONCLUSIONS
Multiplex PCR did not present cross-reaction with other intestinal parasites, and the detection limit for multiplex PCR was between 2 and 20 pg of genomic DNA. In addition it presented a diagnostic sensitivity of 97.4% for S. stercoralis and 90.3% for hookworms with a specificity of 100% and 87.6%, respectively. PCR identified a higher proportion (p <0.01) of coinfections (15.3%) than microscopic techniques (3.5%). Also, multiplex PCR showed that there was a positive association between S. stercoralis and hookworms (odds ratio = 2.12). However, this association was due to N. americanus (odds ratio= 3.22), since no association was observed between S. stercoralis and Ancylostoma spp. Neither was an association observed between the two species of hookworms.
Topics: Ancylostomatoidea; Animals; Bayes Theorem; Cross-Sectional Studies; Feces; Humans; Intestinal Diseases, Parasitic; Multiplex Polymerase Chain Reaction; Sensitivity and Specificity; Strongyloides stercoralis; Strongyloidiasis
PubMed: 34774469
DOI: 10.1016/j.bjid.2021.101649 -
PLoS Neglected Tropical Diseases Apr 2024The World Health Organization emphasizes the importance of integrated monitoring and evaluation in neglected tropical disease (NTD) control programs. Serological assays... (Review)
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.
Topics: Humans; Animals; Swine; Ancylostomatoidea; Trichuris; Ascaris; Soil; Ascaris lumbricoides; Helminths; Feces; Helminthiasis; Prevalence
PubMed: 38574166
DOI: 10.1371/journal.pntd.0012049