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Wait LF, Kamiya T, Fairlie-Clarke KJ, Metcalf CJE, Graham AL, Mideo N. Differential drivers of intraspecific and interspecific competition during malaria-helminth co-infection. Parasitology 2021; 148:1030-1039. [PMID: 33971991 PMCID: PMC11010048 DOI: 10.1017/s003118202100072x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 04/14/2021] [Accepted: 05/04/2021] [Indexed: 11/05/2022]
Abstract
Various host and parasite factors interact to determine the outcome of infection. We investigated the effects of two factors on the within-host dynamics of malaria in mice: initial infectious dose and co-infection with a helminth that limits the availability of red blood cells (RBCs). Using a statistical, time-series approach to model the within-host ‘epidemiology’ of malaria, we found that increasing initial dose reduced the time to peak cell-to-cell parasite propagation, but also reduced its magnitude, while helminth co-infection delayed peak cell-to-cell propagation, except at the highest malaria doses. Using a mechanistic model of within-host infection dynamics, we identified dose-dependence in parameters describing host responses to malaria infection and uncovered a plausible explanation of the observed differences in single vs co-infections. Specifically, in co-infections, our model predicted a higher background death rate of RBCs. However, at the highest dose, when intraspecific competition between malaria parasites would be highest, these effects of co-infection were not observed. Such interactions between initial dose and co-infection, although difficult to predict a priori, are key to understanding variation in the severity of disease experienced by hosts and could inform studies of malaria transmission dynamics in nature, where co-infection and low doses are the norm.
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Affiliation(s)
- L. F. Wait
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - T. Kamiya
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | | | - C. J. E. Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - A. L. Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - N. Mideo
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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Furtado LFV, Dos Santos TR, de Oliveira VNGM, Rabelo ÉML. Genotypic profile of benzimidazole resistance associated with SNP F167Y in the beta-tubulin gene of Necator americanus helminths obtained from Brazilian populations. Infect Genet Evol 2020; 86:104594. [PMID: 33080381 DOI: 10.1016/j.meegid.2020.104594] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/06/2020] [Accepted: 10/10/2020] [Indexed: 01/06/2023]
Abstract
Necator americanus is a worm that parasites the small intestine of humans and is highly prevalent in regions with poor sanitary conditions. The main strategy to control this helminth is by mass benzimidazole administration, however, periodic use of these drugs can select strains of parasites resistant to treatment. Single nucleotide polymorphisms (SNPs) in the beta-tubulin isotype 1 gene located at codons 167, 198 and 200 have been associated with benzimidazole resistance in some nematodes. Previously, our group detected the presence of some of these SNPs in populations of soil-transmitted helminths collected in different locations in Brazil. Here, we evaluated the SNP at codon 167, which has recently been shown to be associated with failure of benzimidazoles to treat N. americanus. Our ARMS-PCR analyses were performed using 524 single N. americanus eggs from 48 patients' feces collected in six Brazilian states; however, we did not detect any mutated samples at codon 167. This study builds on previous work, helping us monitor the presence of resistance-related genotypes in Brazilian helminth populations. The data presented here can assist in the implementation of future control strategies.
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Affiliation(s)
- Luis Fernando Viana Furtado
- Universidade do Estado de Minas Gerais, Avenida Juca Stockler, 1130, CEP 37900-106, Nossa Sra. das Graças, Passos, Minas Gerais, Brazil
| | - Talita Rodrigues Dos Santos
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Avenida Presidente Antônio Carlos, 6627, Departamento de Parasitologia, L4 237, Laboratório de Parasitologia Molecular, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil
| | - Valéria Nayara Gomes Mendes de Oliveira
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Avenida Presidente Antônio Carlos, 6627, Departamento de Parasitologia, L4 237, Laboratório de Parasitologia Molecular, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil
| | - Élida Mara Leite Rabelo
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Avenida Presidente Antônio Carlos, 6627, Departamento de Parasitologia, L4 237, Laboratório de Parasitologia Molecular, Pampulha, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
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Zuccherato LW, Furtado LF, Medeiros CDS, Pinheiro CDS, Rabelo ÉM. PCR-RFLP screening of polymorphisms associated with benzimidazole resistance in Necator americanus and Ascaris lumbricoides from different geographical regions in Brazil. PLoS Negl Trop Dis 2018; 12:e0006766. [PMID: 30222749 PMCID: PMC6141064 DOI: 10.1371/journal.pntd.0006766] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 08/17/2018] [Indexed: 11/22/2022] Open
Abstract
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.
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Affiliation(s)
| | - Luis Fernando Furtado
- Departament of Parasitology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Celi da Silva Medeiros
- Departament of Parasitology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Élida M Rabelo
- Departament of Parasitology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Na-Ek P, Sanpool O, Jongthawin J, Anamnart W, Intapan PM, Chamavit P, Maleewong W. Restoration of hookworm egg development after prolonged storage in stool suspension. Parasitol Res 2016; 115:2817-23. [PMID: 27053130 DOI: 10.1007/s00436-016-5031-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 03/23/2016] [Indexed: 11/25/2022]
Abstract
Hookworm infection is still prevalent in southern Thailand despite control measures. Hookworm eggs submerged for an extended period under water from rainfall or in latrines may not survive, but they may recover their ability to develop into infective larvae when exposed to atmospheric air. This study examined the survival of the hookworm eggs in stool suspension and the restoration of development capability after prolonged storage. In stool mass, eggs developed normally and yielded infective filariform larvae (FL) in 7 days. On the contrary, in 1:10 stool suspension, hookworm eggs were found to remain at the 4-8 cell stage; degenerated eggs were observed after 15 days of storage, and the number of degenerated eggs reached 80 % on day 30. Aeration of the suspension, or transferring to a Petri dish or agar plate, restored the capacity of eggs stored for up to 15 days to develop into FL; thereafter, the capacity declined sharply. Retardation of egg development under water or in stool suspension may be due to a lack of atmospheric air. Use of "night soil" from latrines as fertilizer may be one factor in maintaining hookworm transmission, as worm eggs can undergo normal development upon exposure to atmospheric air.
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Affiliation(s)
- Prasit Na-Ek
- School of Medicine, Walailak University, Thasala, Nakhon Si Thammarat, Thailand
| | - Oranuch Sanpool
- Department of Parasitology and Research and Diagnostic Center for Emerging Infectious Diseases, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Jurairat Jongthawin
- Department of Parasitology and Research and Diagnostic Center for Emerging Infectious Diseases, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Witthaya Anamnart
- School of Allied Health Sciences and Public Health, Walailak University, Thasala, Nakhon Si Thammarat, Thailand
| | - Pewpan M Intapan
- Department of Parasitology and Research and Diagnostic Center for Emerging Infectious Diseases, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Pennapa Chamavit
- Department of Parasitology, Faculty of Medical Technology, Huachiew Chalermprakiet University, Samut Prakan, Thailand
| | - Wanchai Maleewong
- Department of Parasitology and Research and Diagnostic Center for Emerging Infectious Diseases, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
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Hasegawa H, Modrý D, Kitagawa M, Shutt KA, Todd A, Kalousová B, Profousová I, Petrželková KJ. Humans and great apes cohabiting the forest ecosystem in central african republic harbour the same hookworms. PLoS Negl Trop Dis 2014; 8:e2715. [PMID: 24651493 PMCID: PMC3961186 DOI: 10.1371/journal.pntd.0002715] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 01/11/2014] [Indexed: 12/02/2022] Open
Abstract
Background Hookworms are important pathogens of humans. To date, Necator americanus is the sole, known species of the genus Necator infecting humans. In contrast, several Necator species have been described in African great apes and other primates. It has not yet been determined whether primate-originating Necator species are also parasitic in humans. Methodology/Principal Findings The infective larvae of Necator spp. were developed using modified Harada-Mori filter-paper cultures from faeces of humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. The first and second internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA and partial cytochrome c oxidase subunit 1 (cox1) gene of mtDNA obtained from the hookworm larvae were sequenced and compared. Three sequence types (I–III) were recognized in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A–C). The combinations determined were I-A, II-B, II-C, III-B and III-C. Combination I-A, corresponding to N. americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans, western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%. Conclusions/Significance The distinctness of ITS sequence variants and high number of pairwise nucleotide differences among cox1 variants indicate the possible presence of several species of Necator in both humans and great apes. We conclude that Necator hookworms are shared by humans and great apes co-habiting the same tropical forest ecosystems. We conducted analyses of DNA sequences obtained from the infective larvae of Necator spp. from humans and great apes inhabiting Dzanga-Sangha Protected Areas, Central African Republic. Three sequence types (I–III) were recognized in the in the ITS region, and 34 cox1 haplotypes represented three phylogenetic groups (A–C). I-A, II-B, II-C, III-B, III-C combinations were determined. Combination I-A, corresponding to Necator americanus, was demonstrated in humans and western lowland gorillas; II-B and II-C were observed in humans (local inhabitants and researchers), western lowland gorillas and chimpanzees; III-B and III-C were found only in humans. Pairwise nucleotide difference in the cox1 haplotypes between the groups was more than 8%, while the difference within each group was less than 2.1%, suggesting that each type represents a distinct species. This is the first molecular evidence that Necator species found in great apes can infect humans and vice versa.
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Affiliation(s)
- Hideo Hasegawa
- Department of Biology, Oita University, Yufu, Oita, Japan
| | - David Modrý
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
- Central European Institute of Technology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
- Biology Centre, Institute of Parasitology, Academy of Sciences of the Czech Republic, Ceske Budejovice, Czech Republic
| | | | - Kathryn A. Shutt
- Department of Anthropology, Durham University, Durham, United Kingdom
| | - Angelique Todd
- World Wildlife Foundation (WWF), Dzanga Sangha Protected Areas, Bangui, Central African Republic
| | - Barbora Kalousová
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Ilona Profousová
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - Klára J. Petrželková
- Department of Pathology and Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
- Biology Centre, Institute of Parasitology, Academy of Sciences of the Czech Republic, Ceske Budejovice, Czech Republic
- Liberec Zoo, Liberec, Czech Republic
- Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic
- * E-mail:
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Mason L, Tribolet L, Simon A, von Gnielinski N, Nienaber L, Taylor P, Willis C, Jones MK, Sternberg PW, Gasser RB, Loukas A, Hofmann A. Probing the equatorial groove of the hookworm protein and vaccine candidate antigen, Na-ASP-2. Int J Biochem Cell Biol 2014; 50:146-55. [PMID: 24631931 DOI: 10.1016/j.biocel.2014.03.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 02/23/2014] [Accepted: 03/04/2014] [Indexed: 11/17/2022]
Abstract
Hookworm activation-associated secreted proteins can be structurally classified into at least three different groups. The hallmark feature of Group 1 activation-associated secreted proteins is a prominent equatorial groove, which is inferred to form a ligand binding site. Furthermore, a conserved tandem histidine motif is located in the centre of the groove and believed to provide or support a yet to be determined catalytic activity. Here, we report three-dimensional crystal structures of Na-ASP-2, an L3-secreted activation-associated secreted protein from the human hookworm Necator americanus, which demonstrate transition metal binding ability of the conserved tandem histidine motif. We further identified moderate phosphohydrolase activity of recombinant Na-ASP-2, which relates to the tandem histidine motif. By panning a random 12-mer peptide phage library, we identified a peptide with high similarity to the human calcium-activated potassium channel SK3, and confirm binding of the synthetic peptide to recombinant Na-ASP-2 by differential scanning fluorimetry. Potential binding modes of the peptide to Na-ASP-2 were studied by molecular dynamics simulations which clearly identify a preferred topology of the Na-ASP-2:SK3 peptide complex.
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Affiliation(s)
- Lyndel Mason
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia
| | - Leon Tribolet
- Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Anne Simon
- Université Lyon 1, Villeurbanne cedex, and Laboratoire Chimie et Biologie des Membranes et des Nanoobjets, Université Bordeaux, CBMN, UMR 5248, 33600 Pessac, France
| | - Natascha von Gnielinski
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia
| | - Lisa Nienaber
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia
| | - Paul Taylor
- Institute for Structural Biology, School of Biological Sciences, The University of Edinburgh, Scotland, UK
| | - Charlene Willis
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia; School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Malcolm K Jones
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia; Queensland Institute of Medical Research, Herston, Queensland, Australia
| | - Paul W Sternberg
- Biology Division, California Institute of Technology, Pasadena, CA, USA
| | - Robin B Gasser
- Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia
| | - Alex Loukas
- Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia.
| | - Andreas Hofmann
- Structural Chemistry Program, Eskitis Institute, Griffith University, Brisbane, Queensland, Australia; Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia.
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Keiser J, Tritten L, Silbereisen A, Speich B, Adelfio R, Vargas M. Activity of oxantel pamoate monotherapy and combination chemotherapy against Trichuris muris and hookworms: revival of an old drug. PLoS Negl Trop Dis 2013; 7:e2119. [PMID: 23556013 PMCID: PMC3605275 DOI: 10.1371/journal.pntd.0002119] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 02/01/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND It is widely recognized that only a handful of drugs are available against soil-transmitted helminthiasis, all of which are characterized by a low efficacy against Trichuris trichiura, when administered as single doses. The re-evaluation of old, forgotten drugs is a promising strategy to identify alternative anthelminthic drug candidates or drug combinations. METHODOLOGY We studied the activity of the veterinary drug oxantel pamoate against Trichuris muris, Ancylostoma ceylanicum and Necator americanus in vitro and in vivo. In addition, the dose-effect of oxantel pamoate combined with albendazole, mebendazole, levamisole, pyrantel pamoate and ivermectin was studied against T. muris in vitro and additive or synergistic combinations were followed up in vivo. PRINCIPAL FINDINGS We calculated an ED50 of 4.7 mg/kg for oxantel pamoate against T. muris in mice. Combinations of oxantel pamoate with pyrantel pamoate behaved antagonistically in vitro (combination index (CI) = 2.53). Oxantel pamoate combined with levamisole, albendazole or ivermectin using ratios based on their ED50s revealed antagonistic effects in vivo (CI = 1.27, 1.90 and 1.27, respectively). A highly synergistic effect (CI = 0.15) was observed when oxantel pamoate-mebendazole was administered to T. muris-infected mice. Oxantel pamoate (10 mg/kg) lacked activity against Ancylostoma ceylanicum and Necator americanus in vivo. CONCLUSION/SIGNIFICANCE Our study confirms the excellent trichuricidal properties of oxantel pamoate. Since the drug lacks activity against hookworms it is necessary to combine oxantel pamoate with a partner drug with anti-hookworm properties. Synergistic effects were observed for oxantel pamoate-mebendazole, hence this combination should be studied in more detail. Since, of the standard drugs, albendazole has the highest efficacy against hookworms, additional investigations on the combination effect of oxantel pamoate-albendazole should be launched.
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Affiliation(s)
- Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.
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McSorley HJ, Gaze S, Daveson J, Jones D, Anderson RP, Clouston A, Ruyssers NE, Speare R, McCarthy JS, Engwerda CR, Croese J, Loukas A. Suppression of inflammatory immune responses in celiac disease by experimental hookworm infection. PLoS One 2011; 6:e24092. [PMID: 21949691 PMCID: PMC3174943 DOI: 10.1371/journal.pone.0024092] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 07/29/2011] [Indexed: 01/07/2023] Open
Abstract
We present immunological data from two clinical trials where the effect of experimental human hookworm (Necator americanus) infection on the pathology of celiac disease was evaluated. We found that basal production of Interferon- (IFN-)γ and Interleukin- (IL-)17A from duodenal biopsy culture was suppressed in hookworm-infected participants compared to uninfected controls. Increased levels of CD4+CD25+Foxp3+ cells in the circulation and mucosa are associated with active celiac disease. We show that this accumulation also occurs during a short-term (1 week) oral gluten challenge, and that hookworm infection suppressed the increase of circulating CD4+CD25+Foxp3+ cells during this challenge period. When duodenal biopsies from hookworm-infected participants were restimulated with the immunodominant gliadin peptide QE65, robust production of IL-2, IFN-γ and IL-17A was detected, even prior to gluten challenge while participants were strictly adhering to a gluten-free diet. Intriguingly, IL-5 was produced only after hookworm infection in response to QE65. Thus we hypothesise that hookworm-induced TH2 and IL-10 cross-regulation of the TH1/TH17 inflammatory response may be responsible for the suppression of these responses during experimental hookworm infection.
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Affiliation(s)
- Henry J. McSorley
- Queensland Tropical Health Alliance, James Cook University, Cairns and Townsville, Queensland, Australia
| | - Soraya Gaze
- Queensland Tropical Health Alliance, James Cook University, Cairns and Townsville, Queensland, Australia
| | - James Daveson
- Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Dianne Jones
- Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | | | - Andrew Clouston
- Envoi Specialist Pathologists, Brisbane, Queensland, Australia
| | - Nathalie E. Ruyssers
- Queensland Tropical Health Alliance, James Cook University, Cairns and Townsville, Queensland, Australia
| | - Richard Speare
- Queensland Tropical Health Alliance, James Cook University, Cairns and Townsville, Queensland, Australia
| | - James S. McCarthy
- Queensland Institute of Medical Research, University of Queensland, Brisbane, Queensland, Australia
| | - Christian R. Engwerda
- Queensland Institute of Medical Research, University of Queensland, Brisbane, Queensland, Australia
| | - John Croese
- The Townsville Hospital, Townsville, Queensland, Australia
| | - Alex Loukas
- Queensland Tropical Health Alliance, James Cook University, Cairns and Townsville, Queensland, Australia
- * E-mail:
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Verweij JJ, Brienen EAT, Ziem J, Yelifari L, Polderman AM, Van Lieshout L. Simultaneous detection and quantification of Ancylostoma duodenale, Necator americanus, and Oesophagostomum bifurcum in fecal samples using multiplex real-time PCR. Am J Trop Med Hyg 2007; 77:685-690. [PMID: 17978072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023] Open
Abstract
A multiplex real-time PCR was developed and evaluated for the simultaneous detection of Ancylostoma duodenale, Necator americanus, and Oesophagostomum bifurcum in fecal samples. Using well-defined control samples (N = 150), known positive fecal samples (N = 50), and fecal samples from an area in Ghana where human infections with all 3 nematode species are endemic (N = 339), the method proved to be highly specific and sensitive. Cycle threshold (Ct) values, reflecting parasite-specific DNA load, showed significant correlation with the intensity of infection as measured by microscopy using Kato-Katz fecal smears or by species specific third-stage larval count after coproculture. The multiplex real-time PCR described combined with the simple fecal sample collection procedure and the potential for high throughput makes this approach a powerful diagnostic tool to study species-specific transmission patterns of human hookworm-like infections. Moreover, this procedure facilitates monitoring of intervention programs and allows species-specific detection of treatment failure following rounds of mass treatment.
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Affiliation(s)
- Jaco J Verweij
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands.
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10
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Geiger SM, Caldas IR, Mc Glone BE, Campi-Azevedo AC, De Oliveira LM, Brooker S, Diemert D, Corrêa-Oliveira R, Bethony JM. Stage-specific immune responses in human Necator americanus infection. Parasite Immunol 2007; 29:347-58. [PMID: 17576364 PMCID: PMC1976388 DOI: 10.1111/j.1365-3024.2007.00950.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe how hookworms interact with their human hosts by comparing lymphocyte phenotyping, proliferative responses, and cytokine and chemokine secretion patterns in adults who are either mono-infected with Necator americanus or egg-negative controls resident in an area of high transmission in Brazil. Cellular immune responses against crude hookworm antigen extracts from different developmental stages were evaluated simultaneously. Principal component analysis (PCA) was used to reduce the standardized immune responses. Random effects multivariate regression was then used to investigate whether principal components (PC) differ between the two groups once potential confounders and effect modifiers have been accounted for. Although hookworm patients had reduced percentages of T and B cells, they had higher levels of activated CD4+ T and CD19+ B cells. This state of ‘immune activation’ coincided with lower proliferative responses, especially to third-stage larval antigen. Cytokine levels in mono-infected adults were also lower and characterized by a mixed Th1/Th2-type profile. Excretory/secretory antigen from adult worms was a potent modulator of the immune response, resulting in diminished TNF-α and IL-10 secretion in peripheral blood mononuclear cells (PBMC) from hookworm infected patients. We propose that the longevity of hookworms in their human hosts results from a stage-specific, down-modulation of the immune response.
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Affiliation(s)
- S M Geiger
- Fundação Oswaldo Cruz, Centro de Pesquisas René Rachou, Belo Horizonte-MG, Brazil
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12
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Schwenkenbecher JM, Kaplan RM. Development and characterization of microsatellite markers for the canine hookworm, Ancylostoma caninum. Parasitol Res 2006; 100:1015-21. [PMID: 17136387 DOI: 10.1007/s00436-006-0367-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 10/24/2006] [Indexed: 11/24/2022]
Abstract
Microsatellites are repetitive genomic elements that show high levels of variation and therefore provide excellent tools to study the genetics of eukaryotic organisms. Hookworms are extremely common and important nematode parasites of humans and animals, causing potentially serious disease morbidity. Control of hookworms in dogs is achieved by frequent treatment with anthelmintics, and in humans, anthelmintics are frequently administered in a mass-treatment community-wide approach. Understanding the population genetics of hookworms has important implications for studies on the development and spread of drug resistance. We investigated the genome of Ancylostoma caninum for microsatellites by developing and then screening an enriched genomic library as well as by data mining published sequences of a whole genome shotgun library. Investigations revealed a high abundance of trinucleotide repeats. Dinucleotide repeats were characterized by a high number of AT, GA, and GT repeats. After testing and optimization of 68 markers, a panel of 34 polymorphic microsatellite markers were selected. Microsatellite analysis of hookworm isolates revealed a high degree of polymorphism, which was not influenced by the length of the repeats. This panel of microsatellite markers makes it possible to pursue investigations on the population genetics of A. caninum. Furthermore, a number of the markers demonstrated suitability for analysis of the human hookworm species Necator americanus and A. duodenale.
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Affiliation(s)
- J M Schwenkenbecher
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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13
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Sianto L, Reinhard KJ, Chame M, Chaves S, Mendonça S, Gonçalves MLC, Fernandes A, Ferreira LF, Araújo A. The finding of Echinostoma (Trematoda: Digenea) and hookworm eggs in coprolites collected from a Brazilian mummified body dated 600-1,200 years before present. J Parasitol 2006; 91:972-5. [PMID: 17089781 DOI: 10.1645/ge-3445rn.1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The identification of parasites from ancient cultures expands our list of parasites infective to extant humans. A partially mummified human body from the archeological site of Lapa do Boquete, Minas Gerais State, Brazil, was recently discovered. It was interred between 600 and 1,200 yr ago. Dietary analysis showed that the mummified body was from a society that had a mixed subsistence of agriculture and gathering of wild foods. Coprolites from the body contained numerous helminth eggs. The eggs were identified as those of Echinostoma sp. and hookworm. Hookworm infection in pre-Columbian populations is already established, but this is the first evidence of Echinostoma sp. eggs found in human coprolites. The diagnosis of a true infection, as opposed to false parasitism, is discussed. The possibility of Echinostoma ilocanum infection is discussed, as this is a common species found in humans in the Asiatic region, which could have been introduced in South America in the pre-Columbian period. Alternative possibilities are also considered, including indigenous Brazilian Echinostoma species.
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Affiliation(s)
- L Sianto
- Escola Nacional de Saude Publica-Fundacao Oswaldo Cruz, Rio de Janeiro, Brazil
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Croese J, Wood MJ, Melrose W, Speare R. Allergy controls the population density of Necator americanus in the small intestine. Gastroenterology 2006; 131:402-9. [PMID: 16890593 DOI: 10.1053/j.gastro.2006.05.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Accepted: 05/04/2006] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Nearly 700 million people remain infected with hookworms. Although allergy is intuitively linked to immunity against helminths, few positive examples have been characterized. Larval migration through the lungs has been considered the likely interface at which hookworm attrition occurs. As part of a study evaluating a potential role for hookworms in the modulation of human autoimmunity, we examined parasite migration and intestinal colonization. METHODS Capsule and conventional endoscopies supplemented the evaluation of healthy volunteers and Crohn's disease patients recently inoculated with larvae of the human hookworm Necator americanus. Two healthy volunteers with a previously established and stable hookworm infection were inoculated with 50 larvae and had serial capsule endoscopies performed. RESULTS Eosinophilic enteritis developed in all subjects after the initial inoculation. Newly inoculated larvae in the 2 subjects with an established infection reliably reached the intestine within 4 weeks. Thereafter, the colony diminished to the host's constitutive status quo because mostly immature worms failed to attach. The intensity of the eosinophilic response correlated negatively with the time available for hookworms to feed and positively with hookworm attrition. CONCLUSIONS Necator larval migration to the intestine is uncontested. We propose that allergic inflammation purposefully degrades the hookworm's bite, causing premature detachment, restricted feeding, and expulsion. This novel biological dynamic suggests a new paradigm of hookworm resistance.
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Affiliation(s)
- John Croese
- The Department of Gastroenterology, The Townsville Hospital, Townsville, Australia.
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15
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Stiles CHW, Altman WL. Hookworm disease. 1913. Public Health Rep 2006; 121 Suppl 1:59-69; discussion 58. [PMID: 16550766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023] Open
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16
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Ezeamama AE, Friedman JF, Olveda RM, Acosta LP, Kurtis JD, Mor V, McGarvey ST. Functional Significance of Low‐Intensity Polyparasite Helminth Infections in Anemia. J Infect Dis 2005; 192:2160-70. [PMID: 16288383 DOI: 10.1086/498219] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Accepted: 07/18/2005] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND We wanted to quantify the impact that polyparasite infections, including multiple concurrent low-intensity infections, have on anemia. METHODS Three stool samples were collected and read in duplicate by the Kato-Katz method in a cross-sectional sample of 507 children from Leyte, The Philippines. The number of eggs per gram of stool was used to define 3 infection intensity categories--uninfected, low, and moderate/high (M+)--for 3 geohelminth species and Schistosomiasis japonicum. Four polyparasite infection profiles were defined in addition to a reference profile that consisted of either no infections or low-intensity infection with only 1 parasite. Logistic regression models were used to quantify the effect that polyparasitism has on anemia (hemoglobin level <11 g/dL). RESULTS The odds of having anemia in children with low-intensity polyparasite infections were nearly 5-fold higher (P = .052) than those in children with the reference profile. The odds of having anemia in children infected with 3 or 4 parasite species at M+ intensity were 8-fold greater than those in children with the reference profile (P < .001). CONCLUSION Low-intensity polyparasite infections were associated with increased odds of having anemia. In most parts of the developing world, concurrent infection with multiple parasite species is more common than single-species infections. This study suggests that concurrent low-intensity infections with multiple parasite species result in clinically significant morbidity.
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Affiliation(s)
- Amara E Ezeamama
- International Health Institute, Brown University, Providence, RI 02912, USA.
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Xue J, Hui-Qing Q, Jun-Ming Y, Fujiwara R, Zhan B, Hotez P, Shu-Hua X. Necator americanus: Optimization of the golden hamster model for testing anthelmintic drugs. Exp Parasitol 2005; 111:219-23. [PMID: 16198341 DOI: 10.1016/j.exppara.2005.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Revised: 08/11/2005] [Accepted: 08/12/2005] [Indexed: 11/23/2022]
Abstract
Laboratory golden hamsters (Mesocricetus auratus) were infected with Necator americanus under several different parasite and host conditions to optimize the model for testing anthelminthic drugs. The results confirmed that male hamsters were more susceptible to infection than females. Host age in the range of 5-15 weeks was not a factor that impacted on adult worm burden, and similar worm burdens were achieved using doses of 150, 250 or 500 N. americanus L3 (NaL3). The largest numbers of adult hookworms were recovered on days 21-28 post-infection, with a significant decrease at days 40-50 post-infection. Therefore adult worm recovery is maximal approximately 11-18 days prior to patency and host blood loss. From these studies a drug evaluation protocol was developed using 150 NaL3 as the infectious dose and then evaluating the anthelminthic effects of the drugs albendazole, tribendimidine, and pyrantel pamoate on days 21-28 post-infection. The model confirms the anthelminthic activity of albendazole, tribendimidine, and pyrantel pamoate and has the potential as a laboratory animal model to detect emerging drug resistance.
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Affiliation(s)
- Jian Xue
- National Institute of Parasitic Diseases, Chinese Center for Disease Control (CCDC), 207 Rui Jin Er Lu, Shanghai 200025, PR China
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18
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Abstract
A vaccine against the human hookworm Necator americanus is urgently required to reduce hookworm-induced morbidity in endemic areas. In the present study, recombinant hookworm calreticulin, a nominated vaccine candidate, has been tested in mice. Mice given calreticulin had 43-49% fewer worms in their lungs, compared to non-vaccinated controls, following challenge infection with infective hookworm larvae. These levels of protection were achieved in the absence of adjuvant following intraperitoneal administration of three doses of 15 microg antigen. Antigen was also encapsulated in PLG microparticles. Encapsulated calreticulin elicited higher levels of anti-calreticulin IgG1 than free antigen but failed to induce protective immunity. The protection induced by free calreticulin was associated with low levels of serum IgE and moderate lung eosinophilia whilst administration of calreticulin-loaded microparticles was associated with high levels of serum IgE and higher lung eosinophil activity, suggesting that the classical Th2 phenotype may not always be associated with protective immunity, albeit in experimental necatoriasis.
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Affiliation(s)
- J A Winter
- University of Nottingham, School of Pharmacy, University Park, Nottingham, NG7 2RD, UK
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19
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Kotze AC, Coleman GT, Mai A, McCarthy JS. Field evaluation of anthelmintic drug sensitivity using in vitro egg hatch and larval motility assays with Necator americanus recovered from human clinical isolates. Int J Parasitol 2005; 35:445-53. [PMID: 15777920 DOI: 10.1016/j.ijpara.2004.12.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Revised: 12/08/2004] [Accepted: 12/13/2004] [Indexed: 11/25/2022]
Abstract
A field-applicable assay for testing anthelmintic sensitivity is required to monitor for anthelmintic resistance. We undertook a study to evaluate the ability of three in vitro assay systems to define drug sensitivity of clinical isolates of the human hookworm parasite Necator americanus recovered from children resident in a village in Madang Province, Papua New Guinea. The assays entailed observation of drug effects on egg hatch (EHA), larval development (LDA), and motility of infective stage larvae (LMA). The egg hatch assay proved the best method for assessing the response to benzimidazole anthelmintics, while the larval motility assay was suitable for assessing the response to ivermectin. The performance of the larval development assay was unsatisfactory on account of interference caused by contaminating bacteria. A simple protocol was developed whereby stool samples were subdivided and used for immediate egg recovery, as well as for faecal culture, in order to provide eggs and infective larvae, respectively, for use in the egg hatch assay and larval motility assay systems. While the assays proved effective in quantifying drug sensitivity in larvae of the drug-susceptible hookworms examined in this study, their ability to indicate drug resistance in larval or adult hookworms remains to be determined.
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Affiliation(s)
- A C Kotze
- CSIRO Livestock Industries, Queensland Bioscience Precinct, 306 Carmody Road, St Lucia, Qld 4067, Australia.
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20
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Haas W, Haberl B, Idris I, Kallert D, Kersten S, Stiegeler P. Behavioural strategies used by the hookworms Necator americanus and Ancylostoma duodenale to find, recognize and invade the human host. Parasitol Res 2004; 95:30-9. [PMID: 15614587 DOI: 10.1007/s00436-004-1257-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Accepted: 10/08/2004] [Indexed: 11/28/2022]
Abstract
The infective third-stage larvae of the hookworms Necator americanus and Ancylostoma duodenale infect their human hosts by active skin invasion, but A. duodenale is in addition capable of oral infection. The behaviour of the larvae when crawling on surfaces has already been described. Here we analyse in various in vitro systems the other behavioural invasion phases: activation, penetration, and orientation within the host. The larvae normally remained in a motionless, energy-saving, resting posture. An activation to sinusoidal locomotion was stimulated in both species by similar cues such as touch, vibration, water currents, heat, light, and chemicals. Human breath in addition stimulated searching and waving ("nictating") behaviour, which facilitates a change-over to the host. Activating cues in air streams were warmth and moisture; CO2 activated only in combination with warmth and/or moisture. Penetration behaviour in both species was stimulated by warmth and skin extracts. The stimulating components of skin extracts were fatty acids, but their stimulating characteristics differed from those inducing schistosome cercarial skin penetration. After penetration into agar substrates, both species showed thermo-orientation, but only A. duodenale followed gradients of serum. The directing serum cues were not amino acids and glucose (the supposed cues for schistosome blood vessel localization), but Ringer's solution attracted the larvae. The host-finding and host-invasion behaviour of both hookworm species is well adapted to the invasion of the human skin, and there seems to be no particular adaptation of A. duodenale behaviour to the oral infection mode. Hookworm host-finding behaviour is not as complex as that of schistosome cercariae but seems well adapted to the ecological conditions in the transmission sites.
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Affiliation(s)
- Wilfried Haas
- Institute for Zoology I, University Erlangen-Nuernberg, Staudtstrasse 5, 91058, Erlangen, Germany.
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Abstract
Advances in hookworm immunoepidemiology are reviewed. Recent studies demonstrate a mixed Th1/Th2 response in human hookworm infection, with immunosuppression of specific and nonspecific IFN-gamma responses. There is increasing evidence for protective immunity in human hookworm infection, including anti-larval IL-5- and IgE-dependent mechanisms, and for immunological interactions between hookworm infection and other diseases.
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Affiliation(s)
- R J Quinnell
- School of Biology, University of Leeds, Leeds LS2 9JT, UK.
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22
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Abstract
PURPOSE OF REVIEW Hookworm infection remains a major health burden in developing countries. Successful control will likely be achieved through continued advances in our understanding of the epidemiology, molecular biology and immunopathogenesis of hookworm infection. This review summarizes recent advances in each of these fields, and discusses ongoing efforts to develop vaccines against hookworm anemia and growth delay. RECENT DEVELOPMENTS Revised estimates indicate that hookworms afflict over 700 million persons in tropical and subtropical regions. Prevalence and intensity often vary considerably at both the regional and local levels, and may be influenced by climate, soil composition, education, and socioeconomic status. Immunoepidemiological studies suggest that hookworm infection likely induces a complex mixture of host-protective and pathological immune responses. There has been substantial progress in elucidating the molecular pathogenesis of hookworm disease, primarily through the identification of a number of parasite virulence factors. Mass chemotherapy remains a mainstay of hookworm control strategies although continued use of benzimidazole anthelminthics is perhaps contributing to the development of anthelminthic resistance. Consequently, there remains a need for innovative approaches, including the development of vaccines and new chemotherapeutic agents, in order to provide effective global control of hookworm disease. SUMMARY Hookworm infection and disease is a significant threat to global health. Recent advances, particularly those at the molecular level, have provided a wealth of opportunities to better understand pathogenesis. This will likely allow for the development of novel measures such as vaccines to complement existing control methods.
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Affiliation(s)
- Richard Bungiro
- Program in International Child Health, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8081, USA
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Li TH, Guo XR, Xue J, Hu L, Qiang HQ, Xue HC, Bin Z, Hawdon JM, Xiao SH. Comparison of mitochondrial cytochrome oxidase 1 DNA sequences from Necator americanus hookworms maintained for 100 generations in golden hamsters (Mesocricetus auratus) and hookworms from natural human infections. Acta Trop 2004; 92:71-5. [PMID: 15301977 DOI: 10.1016/j.actatropica.2004.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2003] [Accepted: 04/06/2004] [Indexed: 10/26/2022]
Abstract
The human hookworm Necator americanus was maintained through one hundred generations in the golden hamsters. The strain is now routinely maintained in laboratory hamsters through serial passage, and is the laboratory strain of choice for vaccine studies. Comparison of the mitochondrial cytochrome oxidase 1 (cox-1) sequences was shown previously to be useful for comparing the genetic structure of populations of N. americanus in China. Cytochrome oxidase 1 genes were amplified by the polymerase chain reaction, and the sequences compared to those of N. americanus recovered from infected humans from several regions in China. Sequence comparison revealed little difference between the laboratory strain and the field isolates at the cox-1 locus, but also indicated that the laboratory strain is represented by a single cox-1 haplotype. These results suggest that the laboratory strain of N. americanus has undergone a severe genetic bottleneck, and that the genetic diversity in other genes, including potential vaccine antigens, could be similarly limited.
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Affiliation(s)
- Tie-Hua Li
- Institute of Parasitic Diseases, Chinese Centers for Disease Control (CCDC), 207 Rui Jin Er Lu, Shanghai 200025, PR China
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Maizels RM, Balic A. Resistance to Helminth Infection: The Case for Interleukin‐5–Dependent Mechanisms. J Infect Dis 2004; 190:427-9. [PMID: 15243913 DOI: 10.1086/422262] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Accepted: 04/16/2004] [Indexed: 11/03/2022] Open
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Quinnell RJ, Pritchard DI, Raiko A, Brown AP, Shaw MA. Immune Responses in Human Necatoriasis: Association between Interleukin‐5 Responses and Resistance to Reinfection. J Infect Dis 2004; 190:430-8. [PMID: 15243914 DOI: 10.1086/422256] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Accepted: 01/13/2004] [Indexed: 11/04/2022] Open
Abstract
Cytokine and proliferative responses to Necator americanus infection were measured in a treatment-reinfection study of infected subjects from an area of Papua New Guinea where N. americanus is highly endemic. Before treatment, most subjects produced detectable interleukin (IL)-4 (97%), IL-5 (86%), and interferon (IFN)- gamma (64%) in response to adult N. americanus antigen. Pretreatment IFN- gamma responses were negatively associated with hookworm burden, decreasing by 18 pg/mL for each increase of 1000 eggs/gram (epg) (n=75; P<.01). Mean IFN- gamma responses increased significantly after anthelmintic treatment, from 166 to 322 pg/mL (n=42; P<.01). The intensity of reinfection was significantly negatively correlated with pretreatment IL-5 responses, decreasing by 551 epg for each 100 pg/mL increase in production of IL-5 (n=51; P<.01). These data indicate that there is a mixed cytokine response in necatoriasis, with worm burden-associated suppression of IFN- gamma responses to adult N. americanus antigen. Resistance to reinfection is associated with the parasite-specific IL-5 response.
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Jian X, Shu-Hua X, Hui-Qing Q, Sen L, Hotez P, Bing-Gui S, Hai-Chou X, Tie-Hua L, Bin Z. Necator americanus: maintenance through one hundred generations in golden hamsters (Mesocricetus auratus). II. Morphological development of the adult and its comparison with humans. Exp Parasitol 2004; 105:192-200. [PMID: 14990312 DOI: 10.1016/j.exppara.2003.12.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2003] [Revised: 11/25/2003] [Accepted: 12/24/2003] [Indexed: 11/29/2022]
Abstract
Through 100 passages, the human hookworm Necator americanus was adapted to the golden hamster, Mesocricetus auratus, without either the requirement for exogenous steroids or other immunosuppressive agents, nor the requirement to infect hamsters as pups. Adult N. americanus recovered from infected hamsters were morphologically similar to those from infected humans in Sichuan Province, China, although they were smaller and the females produced fewer eggs. The natural history and kinetics of N. americanus infection was different in female and male hamsters. Female hamsters supported low intensity infections that lasted for approximately two months. In contrast, the peak intensity of infection in male hamsters was high, but this situation lasted less than for 4 weeks at which time many of the hookworms were expelled. However, even after the major parasite expulsion, the total number of hookworms consistently remained higher in chronically infected male hamsters compared with female hamsters. The hamster model of N. americanus is potentially useful for studying the development of new anthelminthic drugs and vaccines.
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Affiliation(s)
- Xue Jian
- National Institute of Parasitic Diseases, Chinese Centers for Disease Control and Prevention (CCDC), 207 Rui Jin Er Lu, Shanghai 200025, People's Republic of China
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Hu M, Chilton NB, Abs El-Osta YG, Gasser RB. Comparative analysis of mitochondrial genome data for Necator americanus from two endemic regions reveals substantial genetic variation. Int J Parasitol 2003; 33:955-63. [PMID: 12906879 DOI: 10.1016/s0020-7519(03)00129-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Necator americanus is a blood-sucking, intestinal nematode of major human health importance in many tropical and subtropical regions of the world. The aim of the present study was to compare the complete mitochondrial genome sequence from one N. americanus individual from Togo with another from China, in order to estimate the magnitude of genetic variability for different mitochondrial genes and non-coding regions. For the 12 protein genes, this comparison revealed sequence differences at both the nucleotide (3-7%) and amino acid (1-7%) levels. The most conserved of these was the nad4L gene, whereas the nad1 gene was least conserved at both the nucleotide and amino acid levels. Nucleotide differences were also detected in 14 of the 22 transfer RNAs (trns) (1-13%), the AT-rich region ( approximately 8%), non-coding regions (8-25%) and in the small (rrnS) and large (rrnL) subunits of mitochondrial ribosomal RNA (rrn) ( approximately 1%). Comparison of the rrnL sequences among multiple individual worms revealed nine unequivocal nucleotide differences between N. americanus from the two countries. Consistent with previous studies, these findings provide evidence for substantial genetic variation within N. americanus, which may have implications for the transmission and control of hookworm disease.
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Affiliation(s)
- Min Hu
- Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
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Jian X, Sen L, Hui-Qin Q, Hai-Nan R, Tie-Hua L, Hai-Chou X, Hotez PJ, Shu-Hua X. Necator americanus: maintenance through one hundred generations in golden hamsters (Mesocricetus auratus). I. Host sex-associated differences in hookworm burden and fecundity. Exp Parasitol 2003; 104:62-6. [PMID: 12932761 DOI: 10.1016/s0014-4894(03)00094-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The human hookworm Necator americanus was maintained through one hundred generations in the golden hamster (Mesocricetus auratus). The parasite strain employed here was ultimately adapted to hamsters without the requirement for exogenous steroids or other immunosuppressive agents. Moreover, there was no requirement to use neonatal hamsters--successful infections were obtained in 9- to 10-week-old hamsters infected subcutaneously with 250 hookworm larvae. This unique adaptation of N. americanus to hamsters permits its use for purposes of anthelminthic drug and vaccine development.
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Affiliation(s)
- Xue Jian
- Institute of Parasitic Diseases, Chinese Centers for Disease Control and Prevention, 207 Rui Jin Er Lu, Shanghai 200025, PR China
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Abstract
OBJECTIVE To describe associations between anemia and hookworm (Necator americanus) infection in hospitalized women in rural Chiapas, Mexico. MATERIAL AND METHODS We retrospectively reviewed the hospital records of 68 anemic women (defined as having a hemoglobin level < 10 mg/dl) or with intestinal parasitism, identified through hospital discharge and transfusion records for the calendar year 1999. The medical charts of 86 cases were located, 18 of which were not confirmed as anemia cases. The hospital is located in Altamirano, Chiapas. Characteristics of subjects were compared using Student's t-test (for continuous variables) and the chi 2 test (for categorical variables). A p-value < or = 0.01 was used for statistical significance. Chart review and data analysis took place during the year 2000. RESULTS Fifty percent of women who had stool examinations were infected with N. americanus. Necator often coexisted with other potential causes of anemia, such as pregnancy and hemorrhage. Hemoglobin levels in hookworm-infected women (mean 4.1 g/dl) were significantly lower than in uninfected women (mean 7.0 gm/dl), and Necator prevalence was significantly higher in the anemic women (50%) than in the overall hospital population (1.9%). CONCLUSIONS Anemic women should be offered stool testing where Necator is present, and should be considered for antihelminthic treatment even if pregnant. Further investigation is recommended among women in Chiapas, and probably elsewhere in Mexico. The English version of this paper is available too at: http://www.insp.mx/salud/index.html.
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Affiliation(s)
- Paula E Brentlinger
- International Health Program, School of Public Health and Community Medicine, University of Washington, Seattle, Washington, USA
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Girod N, Brown A, Pritchard DI, Billett EE. Successful vaccination of BALB/c mice against human hookworm (Necator americanus): the immunological phenotype of the protective response. Int J Parasitol 2003; 33:71-80. [PMID: 12547348 DOI: 10.1016/s0020-7519(02)00248-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this murine (BALB/c) model of necatoriasis, high levels of protection against challenge infection by Necator americanus larvae (n=300) were afforded by successive vaccinations at 14-day intervals, either subcutaneously or percutaneously, with gamma-irradiated N. americanus larvae (n=300). Percutaneous vaccination was significantly more effective than the subcutaneous route, with pulmonary larval burdens at 3 days post-infection being reduced by 97.8 vs. 89.3%, respectively, after three immunisations (P<0.05). No worms were recovered from the intestines of thrice vaccinated mice. Two percutaneous vaccinations also reduced worm burdens, by 57% in the lungs and 98% in the intestines; P<0.05. In vaccinated animals, lung pathology (mainly haemorrhage) following infection was greatly reduced compared with non-vaccinated animals. In vaccinated mice (but not in non-vaccinated mice) mast cells accumulated in the skin and were degranulated. RT-PCR analyses of mRNAs in the skin of vaccinated animals indicated increased expression of interleukin (IL)-4 relative to gamma-interferon (gamma-IFN). Lymphocytes from the axillary (skin-draining) lymph nodes of vaccinated mice, stimulated in vitro with concanavalin A, exhibited enhanced secretion of IL-4 protein and a higher IL-4/gamma-IFN protein ratio than lymphocytes from non-vaccinated animals. In vaccinated mice, levels of IgG1 and IgG3 (directed against larval excretory/secretory products) were elevated for the most part compared with those in non-vaccinated animals. These data demonstrate the successful vaccination of BALB/c mice against human hookworm infection and suggest that a localised Th2 response may be important for conferring protection against necatoriasis.
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Affiliation(s)
- N Girod
- Department of Life Sciences, Faculty of Science, The Nottingham Trent University, Clifton Lane, UK
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31
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Abstract
Passage of helminth larvae through the lungs can cause pulmonary eosinophilia that may have evolved as a means of parasite attrition. If allergic responses represent a misdirected activation of this arm of the immune system, then mechanisms governing eosinophil recruitment during infection would be expected to be closely related to those seen in allergy. We studied primary Necator americanus infection and compared this to multiply-infected or vaccinated mice. The arrival of larvae in the lungs triggered rapid eosinophil recruitment, which was greatly enhanced in previously sensitized mice. Interestingly, the presence of larvae in the lung was sufficient to trigger eosinophil chemoattractant production, including the chemokines eotaxin and MIP-1alpha, and was not enhanced by prior exposure to the parasites. Infection stimulated IL-5 production in all groups; however, this and IgE production were greatly enhanced in sensitized animals. Elevated IL-5 increased bone marrow production of eosinophils, and eosinophilia was abrogated by treatment with anti-IL-5 antibody. Therefore, trapping of larvae in the pulmonary vasculature is sufficient to trigger eosinophil recruitment, by induction of chemokines and IL-5. Primed cognate Th2 immunity does not increase local chemokine production, but does increase IL-5 production, which greatly enhances the availability of eosinophils for recruitment to the lung.
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Affiliation(s)
- Fiona J Culley
- Leukocyte Biology Section, Biomedical Sciences Division, Imperial College Faculty of Medicine, London, GB.
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32
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Abstract
Significant differences in the life histories of the human hookworms Ancylostoma duodenale and Necator americanus necessitate their differentiation for epidemiological studies and the design of control programs. Current methods of identification require time-consuming, labor-intensive techniques. A polymerase chain reaction (PCR)-based method that enables rapid species identification is described. The mitochondrial cytochrome oxidase I genes of both species were sequenced, and species-specific primer sets were designed. The primers were used in PCR to amplify 585-bp fragments of the cytochrome oxidase gene from individual hookworm eggs, larvae, and adults. The technique was also able to identify mixed infections containing equal amounts of eggs from each species. The technique is rapid, technically simple, and sensitive and will permit the accurate identification of human hookworms in epidemiological field studies.
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Affiliation(s)
- B Zhan
- Department of Microbiology and Tropical Medicine, George Washington University Medical Center, Washington, DC 20037, USA
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33
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Pit DS, Polderman AM, Baeta S, Schulz-Key H, Soboslay PT. Parasite-specific antibody and cellular immune responses in human infected with Necator americanus and Oesophagostomum bifurcum. Parasitol Res 2001; 87:722-9. [PMID: 11570557 DOI: 10.1007/s004360100419] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In this study parasite-specific antibody, cellular reactivity and Thl-type or Th2-type cytokine responses were investigated in humans concurrently infected with Necator americanus and Oesophagostomum bifurcum. The prospects for O. bifurcum-specific serodiagnosis based on IgG4 and IgE were evaluated. IgG4 showed low specificity for O. bifurcum due to antigen cross-reactivity with N. americanus, while IgE specifically distinguished between hookworm and O. bifurcum, and, in doubly infected patients, levels of O. bifurcum-specific as well as N. americanus-specific IgE were significantly elevated compared to those with N. americanus mono-infections. Cellular immunity was not strictly dominated by a Thl- or Th2- type reactivity. In co-infected patients cellular unresponsiveness to parasite antigens was observed, while cellular production of tumour necrosis factor alpha (TNF-alpha) and gamma-interferon (IFN-gamma) was greater in those doubly infected. Th2-type cytokines (interleukin-5 and interleukin-10) were produced in equal amounts by peripheral blood mononuclear cells from individuals with mono- and coinfections. Such mixed Thl-type and Th2-type immune responsiveness associated with persisting gastrointestinal parasitic nematodes may reflect a state of infection at which parasite-induced inflammatory and enteropathogenic responses co-exist, and furthermore, helminth coinfection will not only suppress parasite-specific cellular responsiveness but may also direct cytokine production towards a "permissive Th1-type cytokine profile" that favours parasite persistence.
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Affiliation(s)
- D S Pit
- Department of Parasitology, Faculty of Medicine, University of Leiden, The Netherlands
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34
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Abstract
The hookworm Necator americanus establishes infections of impressive longevity in the immunologically hostile environment of its human host. In the process, it promotes pronounced T-helper 2 (Th2) cell activity, which in turn seemingly affords the host at least a degree of protection. Given the relatively asymptomatic nature of infection, we argue here that Necator americanus might be approaching a mutualistic symbiotic relationship with humans. In our view, infection is controlled by the immune system while being supported by a subtle immune-evasion strategy that is tolerated and possibly beneficial to the host in certain immunological circumstances, such as in counterbalancing potentially damaging Th1 responses.
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Affiliation(s)
- D I Pritchard
- Boots Science Institute, School of Pharmaceutical Sciences, University of Nottingham, University Park, NG7 2RD, Nottingham, UK.
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35
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Abstract
Reinfection with hookworm (Necator americanus) following chemotherapy was studied over 8 years in a rural village in Madang Province, Papua New Guinea. Faecal egg counts were performed on up to 202 individuals in July 1988, August 1990 and November 1996; the study population was treated after sampling in 1988 and 1990. Reinfection burdens in 1996 did not differ significantly from pretreatment burdens (in 1988), and were significantly higher than burdens in 1990. However, the prevalence of hookworm infection was significantly lower in 1996 than in either 1988 or 1990. There was significant predisposition to high or low hookworm burden between 1990 and 1996; this predisposition was stronger in children than adults. However, there was no detectable predisposition between 1988 and 1996 in individuals who had been treated 2 or more times between surveys. The mean weight of adult hookworms in individual hosts was measured in 1988 and 1990 using worms expelled after chemotherapy. There was a significant positive correlation between mean male hookworm weight in the 2 years, suggesting that individual hosts are predisposed to infection with heavy or light hookworms. These data suggest that differences in host susceptibility are involved in generating predisposition, but that longer-term variation in either exposure or susceptibility limits the period over which significant predisposition can be detected.
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Affiliation(s)
- R J Quinnell
- School of Biology, University of Leeds, Leeds, UK.
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36
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Lili Z, Bingxiang Z, Hong T, Shuhua X, Hotez P, Bing Z, Yangzhong L, Ying L, Haichou X, Hawdon J, Hui Y, Huizhen W, Zhen F. Epidemiology of human geohelminth infections (ascariasis, trichuriasis and necatoriasis) in Lushui and Puer Counties, Yunnan Province, China. Southeast Asian J Trop Med Public Health 2000; 31:448-53. [PMID: 11288999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Between April and June of 1998, the prevalence and intensity of geohelminth infections caused by hookworm, Ascaris and Trichuris were investigated in two rural Yunnan villages. In Liuku, a village of Lisu indigenous people in Lushui County, there was an overall geohelminth prevalence of 72% (48%, 43% and 16% for hookworm infection, ascariasis, and trichuriasis, respectively). The prevalence of ascariasis was greatest among preschool and school aged children, whereas the prevalence of trichuriasis was greatest among teenagers and the prevalence of hookworm increased until the age of 10-15 and then remained high throughout adulthood. In Linger, a village of Han Chinese, located in Puer County, there was an overall geohelminth prevalence of 77% (30%, 60% and 36% for hookworm infection, ascariasis, and trichuriasis, respectively). The differences in prevalence for hookworm and ascariasis were statistically significant. The prevalence of hookworm in Linger increased steadily with age and did not plateau, but there were no discernible patterns of prevalence versus age for either ascariasis or trichuriasis. Heavy trichuriasis infections were noted to occur in Linger. In both villages, more than 98% of the hookworm infections were of light and moderate intensity. Both by morphologic identification of third-stage infective larvae (L3) from eggs as well as identification of adult hookworms recovered from adult residents after treatment with quantrel, Necator americanus was identified as the exclusive hookworm in each village. Geohelminth infections caused by Ascaris, Trichuris and hookworm remain highly endemic to the rural areas of Yunnan Province in southwestern China.
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Affiliation(s)
- Z Lili
- Sanitary and Anti-epidemic Station of Yunnan Province, Kunming, PR China
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37
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Abstract
Two hookworm parasites, Necator americanus and Ancylostoma duodenale, infect approximately one billion people worldwide. These hookworms are one of the leading causes of iron-deficiency anaemia especially in children, resulting directly from intestinal capillary blood loss following the feeding activities of fourth-stage (L(4)) larva and adult worms. If ignored, human hookworm infections can retard growth and the intellectual development of children. Another clinical manifestation often associated with hookworm infections is cutaneous larva migrans (CLM). It is a well recognised, usually self-limiting condition caused by the infectious larvae of nematodes, especially Ancylostoma spp. CLM is characterised by skin eruption and represents a clinical description rather than a definitive diagnosis. Of the hookworm parasites, the dog and cat worm A. braziliense and A. caninum are the most common nematodes causing CLM, although many other species have also been implicated. The major subject of this review article will be discussion of the evolution of therapies and treatment of human necatoriasis and the development of experimental infections with N. americanus. Difference in the clinical efficacy of mebendazole and albendazole will be discussed along with drug resistance of N. americanus.
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Affiliation(s)
- V S Georgiev
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, 7600-B Rockledge Drive, Room 2102, Bethesda, Maryland 20892, USA.
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Changhua L, Xiaorong Z, Dongchuan Q, Shuhua X, Hotez PJ, Defu Z, Hulian Z, Mingden L, Hainan R, Bing Z, Haichou X, Hawdon J, Zheng F. Epidemiology of human hookworm infections among adult villagers in Hejiang and Santai Counties, Sichuan Province, China. Acta Trop 1999; 73:243-9. [PMID: 10546842 DOI: 10.1016/s0001-706x(99)00035-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Hookworm infection as well as other intestinal nematodiases are endemic to Sichuan Province in China. In order to research the prevalence and intensity of these infections we visited two villages in Hejiang County (southern Sichuan Province) and Santai County (northwestern Sichuan Province) between July and October of 1997. Fecal examinations were performed on adult villagers over the age of 15 years (currently children under this age are dewormed annually with anthelmintic drugs). Among 310 residents of Lugao Village (Hejiang County), 87, 63 and 60% were infected with hookworm, Ascaris or Trichuris, respectively. The prevalence of hookworm determined to rise linearly with age (r = 0.97). High intensity infections with hookworm still occur in this region as 22% of the residents have over 3000 eggs per gram (PEG) of feces as determined by quantitative egg counts. The majority of these individuals harbored mixed infection with Necator americanus and Ancylostoma duodenale, although the former predominated when adult hookworms were collected from 30 village residents treated with pyrantel pamoate. In contrast, among the 334 Xinjian villagers examined (Santai County) the majority harbored predominantly light hookworm infections--66.1% of the residents has less than 400 EPG by quantitative fecal examination and only 3.7% exhibited greater than 3000 EPG. Again, N. americanus was the predominant hookworm seen after worm expulsion. We have round that despite economic development which is occurring in some parts of China, significant hookworm infections and clinical hookworm anemia still exist in areas of Sichuan Province. In Hejiang County we found that the intensity of hookworm infection has actually risen within the last 10 years. Hookworm is a medical problem among the elderly in Sichuan.
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Affiliation(s)
- L Changhua
- Sichuan Institute of Parasitic Diseases, PR China
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39
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Abstract
Immmoglobulin E-rich plasma from patients from Papua New Guinea infected with Necator americanus has been used to probe an adult N. americanus cDNA library for the presence of hookworm allergens. Using this approach, one hookworm allergen has been identified as calreticulin, which was subsequently expressed in Escherichia coli. Little serological cross reactivity was seen between the recombinant calreticulins of this hookworm and its host. Prospective roles for hookworm calreticulin in the host-parasite relationship are discussed in depth.
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Affiliation(s)
- D I Pritchard
- School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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40
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Brown A, Girod N, Billett EE, Pritchard DI. Necator americanus (human hookworm) aspartyl proteinases and digestion of skin macromolecules during skin penetration. Am J Trop Med Hyg 1999; 60:840-7. [PMID: 10344662 DOI: 10.4269/ajtmh.1999.60.840] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The infective larvae of Necator americanus were shown to secrete all mechanistic classes of proteolytic enzymes with two overall pH optima of 6.5 and 8.5 using fluorescein isothiocyanate-labeled casein as the substrate. Since infective larvae are obligate skin penetrators, the effect of each of these enzyme classes against macromolecules derived from human skin was examined. Larval secretions were shown to degrade collagen types I, III, IV, and V, fibronectin, laminin, and elastin. All the skin macromolecules tested were hydrolyzed by aspartyl proteinase activity, which was inhibitable by pepstatin A. Collagen and elastin was also hydrolyzed by metalloproteinase activity, while the serine proteinase activity hydrolyzed only elastin. As a consequence of these experiments, the effect of proteinase inhibitors on the penetration of live larvae through hamster skin was tested. Larval penetration was significantly inhibited only by pepstatin A, confirming the importance of the aspartyl proteinase activity during the skin penetration process.
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Affiliation(s)
- A Brown
- Department of Life Sciences, Nottingham Trent University, Nottingham, United Kingdom
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41
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Romstad A, Gasser RB, Nansen P, Polderman AM, Chilton NB. Necator americanus (Nematoda: Ancylostomatidae) from Africa and Malaysia have different ITS-2 rDNA sequences. Int J Parasitol 1998; 28:611-5. [PMID: 9602384 DOI: 10.1016/s0020-7519(97)00213-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The nucleotide sequences of the second internal transcribed spacer of rDNA were determined for adult worms of Necator americanus originating from Togo (Africa) and Sarawak (Malaysia). The length of the sequences of specimens from Togo (325 bp) were shorter than those from Sarawak (327 bp). There were six fixed genetic differences in the aligned sequences of N. americanus from Sarawak and Togo, excluding one or two polymorphic sites within the sequence of N. americanus from each geographical region. These findings suggest that there is either population variation in the sequence of N. americanus, or that N. americanus from the two countries may represent genetically distinct but morphologically similar (i.e. cryptic) species, however, comparison of the sequence differences among other hookworm species supports the latter conclusion.
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Affiliation(s)
- A Romstad
- Department of Veterinary Science, University of Melbourne, Werribee, Victoria, Australia
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42
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Romstad A, Gasser RB, Nansen P, Polderman AM, Monti JR, Chilton NB. Characterization of Oesophagostomum bifurcum and Necator americanus by PCR-RFLP of rDNA. J Parasitol 1997; 83:963-6. [PMID: 9379311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Esophagostomiasis in humans due to infection with Oesophagostomum bifurcum (nodular worm) is of major human health significance in northern Togo and Ghana, where Necator americanus (human hookworm) also exists at high prevalence. Yet, very little is known about the transmission patterns of O. bifurcum, which is in part due to the difficulties in diagnosis and in differentiating some life-cycle stages of O. bifurcum from N. americanus using morphological features. As a first step toward developing a molecular-diagnostic assay, it was evaluated whether ribosomal (r)DNA could provide genetic markers for the identification of O. bifurcum and N. americanus to species. Internal transcribed spacer rDNA (plus flanking and intervening sequences) was analyzed by polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) using several restriction endonucleases. The analysis showed that there was no detectable intraspecific difference in the size of the PCR products among multiple samples, that there was a consistent size difference in the products (of 110 bp or 350 bp, depending on region amplified) between the species, and that there was no significant variation in restriction patterns within each species. These results indicate that the rDNA spanning the internal transcribed spacers provides useful genetic markers for the identification of O. bifurcum and N. americanus to species, which has important implications for developing PCR-based tools to study the epidemiology and population biology of O. bifurcum.
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Affiliation(s)
- A Romstad
- Department of Veterinary Science, University of Melbourne, Werribee, Australia
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43
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De Clercq D, Sacko M, Behnke J, Gilbert F, Dorny P, Vercruysse J. Failure of mebendazole in treatment of human hookworm infections in the southern region of Mali. Am J Trop Med Hyg 1997; 57:25-30. [PMID: 9242313 DOI: 10.4269/ajtmh.1997.57.25] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Preliminary studies indicated that single-dose (500 mg) mebendazole gave disappointing results in the treatment of hookworm infections (Necator americanus) in Mali. A placebo-controlled, randomized trial conducted with the participation of 103 infected subjects (background hookworm prevalence > 50%) confirmed that mebendazole (Vermox) did not reduce parasite burdens significantly, as assessed through fecal egg counts. In contrast, a group of subjects treated with pyrantel (Combantrin) experienced a significant reduction in fecal worm egg counts (overall, both sexes combined showed a 75% reduction). Male subjects carried significantly more intense infections compared with females, but there was no gender difference in response to treatment. A standard egg hatch assay showed that N. americanus from our subjects in Mali was more resistant to benzimidazoles compared with a laboratory-maintained strain that had not been exposed to anthelmintics in more than 100 generations (50% effective dose = 0.12 and 0.07 microg/ml of thiabendazole, respectively), suggesting that, among other possibilities, the development of resistance to the benzimidazoles by N. americanus may have contributed to the drug failure. Whatever the underlying explanation, our results indicate that single-dose treatment with mebendazole is an ineffective treatment for hookworm infections and despite its relatively cheap cost and wide availability, mebendazole should not be considered a drug of choice in the mass treatment of hookworm infections in this region of Mali.
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Affiliation(s)
- D De Clercq
- Institut National de Recherche en Santé Publique (INRSP), Project Universiteit Gent-INRSP, Bamako-Coura, Mali
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44
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Conn DB. Wrong hookworm. Science 1996; 272:1086. [PMID: 8638147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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45
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Palmer DR, Bradley M, Bundy DA. IgG4 responses to antigens of adult Necator americanus: potential for use in large-scale epidemiological studies. Bull World Health Organ 1996; 74:381-6. [PMID: 8823959 PMCID: PMC2486892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Described is an epidemiological investigation of hookworm infections in a rural community in Zimbabwe, where Necator americanus is the only human helminth species present. Among a cohort of 120 individuals the overall prevalence of infection was 78%. Intensity of infection was quantified both as egg counts (range: 0-2563 eggs per g of stool) and worm burden (range: 0-100 worms). Although both these measures provide useful quantitative data, they are tedious to determine in large-scale epidemiological studies and may present social and logistic difficulties. As an alternative screening method, we therefore investigated isotype-specific responses to adult worm antigens of N. americanus. The results show that specific IgG4 responses correlate positively and significantly with both measures of intensity and may be a useful marker of hookworm infection.
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Affiliation(s)
- D R Palmer
- Walter Reed Army Institute of Research, Department of Immunology, Washington DC 20307-5100, USA
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46
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Abstract
In this paper we describe the relationship between antibodies to Necator americanus stage-specific antigens and parasite burden in an endemically-infected population in Papua New Guinea. Using an age-structured analysis, we show that the correlation coefficient between levels of IgG against adult worm excretory-secretory (ES) antigen and parasite burden declined significantly with host age from positive in younger hosts to significantly negative in older hosts. A trend towards similar patterns was present for anti-larval IgG both pretreatment and after reinfection, and for anti-ES IgM and anti-ES IgE pretreatment. These patterns are consistent with a role for these isotypes in a protective immune response, although parasite-induced immunosuppression may provide an alternate explanation. This is another demonstration of possibly protective responses to N. americanus infection.
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Affiliation(s)
- R J Quinnell
- Department of Medical Parasitology, London School of Hygiene and Tropical Medicine, UK
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47
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Abstract
The population dynamic parameters of Necator americanus infections were estimated from longitudinal intensity and prevalence data from a village in south-eastern China. The theoretical predictions of a deterministic model incorporating these parameters were then compared with observed, horizontal, age-prevalence data from an infected population (N = 565), and an estimate of the basic reproduction rate (R0 = 3.7) of N. americanus was obtained. The findings indicate that populations of N. americanus might be easier to control by mass-treatment chemotherapy (eradication requiring only 63% of the population to be treated every year for 4 years) than those of Ascaris lumbricoides and Trichuris trichiura.
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Affiliation(s)
- X P Ye
- Centre for the Epidemiology of Infectious Diseases, University of Oxford, U.K
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48
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Nolan TJ, Bhopale VM, Megyeri Z, Schad GA. Cryopreservation of human hookworms. J Parasitol 1994; 80:648-50. [PMID: 8064535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
First-stage larvae (L1) of the human hookworms Ancylostoma duodenale and Necator americanus were frozen over liquid nitrogen after a 1-hr incubation in a cryoprotectant (10% DMSO and 10% dextran). Thawed larvae developed to the infective third stage (L3) on agar plates. In the case of A. duodenale, the larvae were infective to dogs. The infectivity of N. americanus L3 was not tested.
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Affiliation(s)
- T J Nolan
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104
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49
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Abstract
Laboratory bred DSN hamsters were exposed to varying doses of infective larvae of Ancylostoma ceylanicum (orally) or Necator americanus (percutaneously) and were autopsied at times which corresponded to a period immediately before cessation of growth of worms or soon afterwards. A total of 829 (404 male and 425 female) A. ceylanicum and 1582 (781 male and 801 female) N. americanus were measured. At worm burdens of fewer than 100, the length of A. ceylanicum appeared to increase with infection intensity and no evidence was found that growth was retarded under crowded conditions. In an experiment comparing directly low (mean worm burden = 22) and heavy infections (mean worm burden = 180) significant negative associations between both weight and width, and worm burden were detected, but length again increased with worm burden. In contrast, 5 experiments with N. americanus indicated negative relationships between measures of worm size (length, width, wet and dry weight) and worm burden. It was concluded that N. americanus is subject to regulation by density-dependent processes within the host while A. ceylanicum is not sensitive to the same degree.
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50
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Pritchard DI, Brown A, Toutant JP. The molecular forms of acetylcholinesterase from Necator americanus (Nematoda), a hookworm parasite of the human intestine. Eur J Biochem 1994; 219:317-23. [PMID: 8306998 DOI: 10.1111/j.1432-1033.1994.tb19943.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Necator americanus (Nematoda: Strongyloidea), a human hookworm parasite, is known to release considerable amounts of acetylcholinesterase (AChE) [Pritchard, D. I., Leggett K. V., Rogan, M. T., McKean, P. G. & Brown, A. (1991) Necator americanus secretory acetylcholinesterase and its purification from excretory/secretory products by affinity chromatography, Parasite Immunol. 13, 187-199]. The present study deals with AChE activity recovered in sequential somatic extracts, and excretory/secretory products, of the adult stage of the parasite. 97% of AChE was extractable in low-salt and high-salt detergent-free buffers, and only 3% was solubilised by a further extraction in the presence of Triton X-100. AChE in all three extracts was affected by the AChE inhibitors eserine, bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide and edrophonium chloride, but was resistant to the effects of tetramonoisopropylpyrophosphortetramide, a butyrylcholinesterase inhibitor. Sucrose density centrifugation revealed that AChE in all somatic extracts (low-salt, high-salt and detergent) resolved almost exclusively as a single peak between 6.9-7.5 S, while excretory/secretory products resolved at 8.2 S. These values are all compatible with dimers of catalytic subunits and no evidence was found for the presence of higher oligomers such as asymmetric forms. The only sample to show a shift in sedimentation following the inclusion of detergent (Triton X-100, Brij 96) in the gradient was a component of the detergent-soluble extract, indicating the existence of a minor amphiphilic form. In low-salt-soluble and high-salt-soluble extracts, AChE was solubilised as a hydrophilic globular form, probably a dimeric G2. The analysis of diisopropylfluorophosphate-labelled extracts by SDS/PAGE, and unlabelled extracts by immunoblotting using a polyvalent antiserum to N. americanus AChE, indicated that the AChE isolated in each extract was biochemically and immunologically similar. The banding patterns obtained were comparable to that seen when purified AChE was analysed by SDS/PAGE and immunoblotted. This suggests that the basic catalytic subunit has a mass of 66-70 kDa with the active site being located in a 30-kDa domain. All experimental data indicate the existence of only one AChE class in Necator homologous to AChE of class B from Caenorhabditis elegans. The solubility characteristics and globular nature of this hookworm AChE suggest that its major function is as an excretory or secretory product. This again raises the question of the true biological function of this 'non-cholinergenic' nematode secretion.
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Affiliation(s)
- D I Pritchard
- Department of Life Science, University of Nottingham, England
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