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Keegan SP, Pedersen AB, Fenton A. The impact of within-host coinfection interactions on between-host parasite transmission dynamics varies with spatial scale. Proc Biol Sci 2024; 291:20240103. [PMID: 38628126 PMCID: PMC11021925 DOI: 10.1098/rspb.2024.0103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 03/18/2024] [Indexed: 04/19/2024] Open
Abstract
Within-host interactions among coinfecting parasites can have major consequences for individual infection risk and disease severity. However, the impact of these within-host interactions on between-host parasite transmission, and the spatial scales over which they occur, remain unknown. We developed and apply a novel spatially explicit analysis to parasite infection data from a wild wood mouse (Apodemus sylvaticus) population. We previously demonstrated a strong within-host negative interaction between two wood mouse gastrointestinal parasites, the nematode Heligmosomoides polygyrus and the coccidian Eimeria hungaryensis, using drug-treatment experiments. Here, we show this negative within-host interaction can significantly alter the between-host transmission dynamics of E. hungaryensis, but only within spatially restricted neighbourhoods around each host. However, for the closely related species E. apionodes, which experiments show does not interact strongly with H. polygyrus, we did not find any effect on transmission over any spatial scale. Our results demonstrate that the effects of within-host coinfection interactions can ripple out beyond each host to alter the transmission dynamics of the parasites, but only over local scales that likely reflect the spatial dimension of transmission. Hence there may be knock-on consequences of drug treatments impacting the transmission of non-target parasites, altering infection risks even for non-treated individuals in the wider neighbourhood.
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Affiliation(s)
- Shaun P. Keegan
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 7ZB, UK
| | - Amy B. Pedersen
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - Andy Fenton
- Department of Evolution, Ecology and Behaviour, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 7ZB, UK
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Kirk D, O’Connor MI, Mordecai EA. Scaling effects of temperature on parasitism from individuals to populations. J Anim Ecol 2022; 91:2087-2102. [PMID: 35900837 PMCID: PMC9532350 DOI: 10.1111/1365-2656.13786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 07/15/2022] [Indexed: 11/27/2022]
Abstract
Parasitism is expected to change in a warmer future, but whether warming leads to substantial increases in parasitism remains unclear. Understanding how warming effects on parasitism in individual hosts (e.g. parasite load) translate to effects on population-level parasitism (e.g. prevalence, R0 ) remains a major knowledge gap. We conducted a literature review and identified 24 host-parasite systems that had information on the temperature dependence of parasitism at both individual host and host population levels: 13 vector-borne systems and 11 environmentally transmitted systems. We found a strong positive correlation between the thermal optima of individual- and population-level parasitism, although several of the environmentally transmitted systems exhibited thermal optima >5°C apart between individual and population levels. Parasitism thermal optima were close to vector performance thermal optima in vector-borne systems but not hosts in environmentally transmitted systems, suggesting these thermal mismatches may be more common in certain types of host-parasite systems. We also adapted and simulated simple models for both types of transmission modes and found the same pattern across the two modes: thermal optima were more strongly correlated across scales when there were more traits linking individual- to population-level processes. Generally, our results suggest that information on the temperature dependence, and specifically the thermal optimum, at either the individual or population level should provide a useful-although not quantitatively exact-baseline for predicting temperature dependence at the other level, especially in vector-borne parasite systems. Environmentally transmitted parasitism may operate by a different set of rules, in which temperature dependence is decoupled in some systems, requiring the need for trait-based studies of temperature dependence at individual and population levels.
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Affiliation(s)
- Devin Kirk
- Department of Biology, Stanford University, Stanford, USA
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Mary I. O’Connor
- Department of Zoology, University of British Columbia, Vancouver, Canada
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Brian JI, Aldridge DC. Abundance data applied to a novel model invertebrate host shed new light on parasite community assembly in nature. J Anim Ecol 2021; 90:1096-1108. [PMID: 33522596 DOI: 10.1111/1365-2656.13436] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/08/2021] [Indexed: 11/29/2022]
Abstract
Understanding how environmental drivers influence the assembly of parasite communities, in addition to how parasites may interact at an infracommunity level, are fundamental requirements for the study of parasite ecology. Knowledge of how parasite communities are assembled will help to predict the risk of parasitism for hosts, and model how parasite communities may change under variable conditions. However, studies frequently rely on presence-absence data and examine multiple host species or sites, metrics which may be too coarse to characterise nuanced within-host patterns. We utilised a novel host system, the freshwater mussel Anodonta anatina, to investigate the drivers of community structure and explore parasite interactions. In addition, we aimed to highlight consistencies and inconsistencies between PA and abundance data. Our analysis incorporated 14 parasite taxa and 720 replicate infracommunities. Using Redundancy Analysis, a joint species distribution model and a Markov random field approach, we modelled the impact of both host-level and environment-level characteristics on parasite structure, as well as parasite-parasite correlations after accounting for all other factors. This approach was repeated for both the presence and abundance of all parasites. We demonstrated that the regional species pool, individual host characteristics (mussel length and gravidity) and predicted parasite-parasite interactions are all important but to varying degrees across parasite species, suggesting that applying generalities to parasite community construction is too simplistic. Furthermore, we showed that PA data fail to capture important density-dependent effects of parasite load for parasites with high abundance, and in general performs poorly for high-intensity parasites. Host and parasite traits, as well as broader environmental factors, all contribute to parasite community structure, emphasising that an integrated approach is required to study community assembly. However, care must be taken with the data used to infer patterns, as presence-absence data may lead to incorrect ecological inference.
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Affiliation(s)
- Joshua I Brian
- Aquatic Ecology Group, The David Attenborough Building, Department of Zoology, University of Cambridge, Cambridge, UK
| | - David C Aldridge
- Aquatic Ecology Group, The David Attenborough Building, Department of Zoology, University of Cambridge, Cambridge, UK
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Sweeny AR, Thomason CA, Carbajal EA, Hansen CB, Graham AL, Pedersen AB. Experimental parasite community perturbation reveals associations between Sin Nombre virus and gastrointestinal nematodes in a rodent reservoir host. Biol Lett 2020; 16:20200604. [PMID: 33353521 PMCID: PMC7775983 DOI: 10.1098/rsbl.2020.0604] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Individuals are often co-infected with several parasite species, yet measuring within-host interactions remains difficult in the wild. Consequently, the impacts of such interactions on host fitness and epidemiology are often unknown. We used anthelmintic drugs to experimentally reduce nematode infection and measured the effects on both nematodes and the important zoonosis Sin Nombre virus (SNV) in its primary reservoir (Peromyscus spp.). Treatment significantly reduced nematode infection, but increased SNV seroprevalence. Furthermore, mice that were co-infected with both nematodes and SNV were in better condition and survived up to four times longer than uninfected or singly infected mice. These results highlight the importance of investigating multiple parasites for understanding interindividual variation and epidemiological dynamics in reservoir populations with zoonotic transmission potential.
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Affiliation(s)
- Amy R Sweeny
- Institute of Evolutionary Biology and Centre of Infection, School of Biological Sciences, Kings Buildings, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh, UK
| | - Courtney A Thomason
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.,Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - Edwin A Carbajal
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.,Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Christina B Hansen
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA
| | - Amy B Pedersen
- Institute of Evolutionary Biology and Centre of Infection, School of Biological Sciences, Kings Buildings, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh, UK
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Modeling the Effects of Helminth Infection on the Transmission Dynamics of Mycobacterium tuberculosis under Optimal Control Strategies. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:8869377. [PMID: 33281922 PMCID: PMC7688359 DOI: 10.1155/2020/8869377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/19/2020] [Accepted: 10/28/2020] [Indexed: 11/17/2022]
Abstract
A deterministic mathematical model for the transmission and control of cointeraction of helminths and tuberculosis is presented, to examine the impact of helminth on tuberculosis and the effect of control strategies. The equilibrium point is established, and the effective reproduction number is computed. The disease-free equilibrium point is confirmed to be asymptotically stable whenever the effective reproduction number is less than the unit. The analysis of the effective reproduction number indicates that an increase in the helminth cases increases the tuberculosis cases, suggesting that the control of helminth infection has a positive impact on controlling the dynamics of tuberculosis. The possibility of bifurcation is investigated using the Center Manifold Theorem. Sensitivity analysis is performed to determine the effect of every parameter on the spread of the two diseases. The model is extended to incorporate control measures, and Pontryagin's Maximum Principle is applied to derive the necessary conditions for optimal control. The optimal control problem is solved numerically by the iterative scheme by considering vaccination of infants for Mtb, treatment of individuals with active tuberculosis, mass drug administration with regular antihelminthic drugs, and sanitation control strategies. The results show that a combination of educational campaign, treatment of individuals with active tuberculosis, mass drug administration, and sanitation is the most effective strategy to control helminth-Mtb coinfection. Thus, to effectively control the helminth-Mtb coinfection, we suggest to public health stakeholders to apply intervention strategies that are aimed at controlling helminth infection and the combination of vaccination of infants and treatment of individuals with active tuberculosis.
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Abstract
BACKGROUND Ascaris lumbricoides is a common infection, and mainly affects children living in low-income areas. Water and sanitation improvement, health education, and drug treatment may help break the cycle of transmission, and effective drugs will reduce morbidity. OBJECTIVES To compare the efficacy and safety of anthelmintic drugs (albendazole, mebendazole, ivermectin) for treating people with Ascaris infection. SEARCH METHODS We searched the Cochrane Infectious Disease Group Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, three other databases, and reference lists of included studies, without language restrictions, up to 4 July 2019. SELECTION CRITERIA Randomized controlled trials (RCT) that compared albendazole, mebendazole, and ivermectin in children and adults with confirmed Ascaris infection. DATA COLLECTION AND ANALYSIS Two review authors independently assessed studies for inclusion, assessed risk of bias, and extracted data from the included trials. A third review author checked the quality of data extraction. We used the Cochrane 'Risk of bias' assessment tool to determine the risk of bias in included trials. We used risk ratios (RRs) with 95% confidence intervals (CIs) to compare dichotomous outcomes in treatment and control groups. We used the fixed-effect model for studies with low heterogeneity and the random-effects model for studies with moderate to high heterogeneity. We assessed the certainty of the evidence using the GRADE approach. We used the control rate average to provide illustrative cure rates in the comparison groups. MAIN RESULTS We included 30 parallel-group RCTs, which enrolled 6442 participants from 17 countries across Africa, Asia, Central America and the Caribbean, and South America. Participants were from 28 days to 82 years of age, recruited from school, communities, and health facilities. Twenty studies were funded or co-funded by manufacturers, while 10 studies were independent of manufacturer funding. Twenty-two trials had a high risk of bias for one or two domains (blinding, incomplete outcome data, selective reporting). Single dose of albendazole (four trials), mebendazole (three trials) or ivermectin (one trial) was compared to placebo. Parasitological cure at 14 to 60 days was high in all the studies (illustrative cure of 93.0% in the anthelmintic group and 16.1% in the placebo group; RR 6.29, 95% CI 3.91 to 10.12; 8 trials, 1578 participants; moderate-certainty evidence). Single dose of albendazole is as effective as multiple doses of albendazole (illustrative cure of 93.2% with single dose, 94.3% with multiple doses; RR 0.98, 95% CI 0.92 to 1.05; 3 trials, 307 participants; high-certainty evidence); or as single dose of mebendazole (illustrative cure of 98.0% with albendazole, 96.9% with mebendazole; RR 1.01, 95% CI 1.00 to 1.02; 6 trials, 2131 participants; high-certainty evidence). Studies did not detect a difference between a single dose of albendazole and a single dose of ivermectin (cure rates of 87.8% with albendazole, 90.2% with ivermectin; RR 0.99, 95% CI 0.91 to 1.08; 3 trials, 519 participants; moderate-certainty evidence). Across all the studies, failure after single dose of albendazole ranged from 0.0% to 30.3%, mebendazole from 0.0% to 22.2%, and ivermectin from 0.0% to 21.6%. The egg reduction rate (ERR) measured up to 60 days after the treatment was high in all treated groups, regardless of the anthelmintic used (range 96% to 100%). It was not possible to evaluate parasitological cure by classes of infection intensity. No included trials reported complication or serious adverse events. Other adverse events were apparently similar among the compared anthelmintic groups (moderate- to low-certainty evidence). The most commonly reported other adverse events were nausea, vomiting, abdominal pain, diarrhoea, headache, and fever. AUTHORS' CONCLUSIONS Single-dose of albendazole, mebendazole, and ivermectin all appeared effective against Ascaris lumbricoides infection, yielding high parasitological cure and large reductions in eggs excreted, with no differences detected between them. The drugs appear to be safe to treat children and adults with confirmed Ascaris infection. There is little to choose between drugs and regimens in terms of cure or adverse events.
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Affiliation(s)
- Lucieni O Conterno
- State University of Campinas (UNICAMP)Medical School, Department of Internal Medicine, Infectious Diseases DivisionRua Tessália Vieira de Camargo, 126Cidade Universitária "Zeferino Vaz"CampinasSão PauloBrazil13083‐887
| | - Marilia D Turchi
- Federal University of GoiasDepartment of Public Health, Institute of Tropical Pathology and Public HealthRua Amorinopolis QdR2 Lt13 Residencial GoiasAlphaville FlamboyantGoianiaGoiasBrazil74884‐540
| | - Ione Corrêa
- Botucatu Medical School, UNESP ‐ Univ Estadual PaulistaDepartment of NursingDistrito de Rubião Júnior, s/nBotucatuSão PauloBrazil18603‐970
| | - Ricardo Augusto Monteiro de Barros Almeida
- Botucatu Medical School, UNESP ‐ Univ Estadual PaulistaDepartment of Tropical Diseases and Imaging DiagnosisAv. Prof. Montenegro, s/nDistrito de Rubiao JrBotucatuSao PauloBrazil18618‐970
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Rynkiewicz EC, Fenton A, Pedersen AB. Linking community assembly and structure across scales in a wild mouse parasite community. Ecol Evol 2019; 9:13752-13763. [PMID: 31938479 PMCID: PMC6953566 DOI: 10.1002/ece3.5785] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/23/2019] [Accepted: 09/21/2019] [Indexed: 01/03/2023] Open
Abstract
Understanding what processes drive community structure is fundamental to ecology. Many wild animals are simultaneously infected by multiple parasite species, so host-parasite communities can be valuable tools for investigating connections between community structures at multiple scales, as each host can be considered a replicate parasite community. Like free-living communities, within-host-parasite communities are hierarchical; ecological interactions between hosts and parasites can occur at multiple scales (e.g., host community, host population, parasite community within the host), therefore, both extrinsic and intrinsic processes can determine parasite community structure. We combine analyses of community structure and assembly at both the host population and individual scales using extensive datasets on wild wood mice (Apodemus sylvaticus) and their parasite community. An analysis of parasite community nestedness at the host population scale provided predictions about the order of infection at the individual scale, which were then tested using parasite community assembly data from individual hosts from the same populations. Nestedness analyses revealed parasite communities were significantly more structured than random. However, observed nestedness did not differ from null models in which parasite species abundance was kept constant. We did not find consistency between observed community structure at the host population scale and within-host order of infection. Multi-state Markov models of parasite community assembly showed that a host's likelihood of infection with one parasite did not consistently follow previous infection by a different parasite species, suggesting there is not a deterministic order of infection among the species we investigated in wild wood mice. Our results demonstrate that patterns at one scale (i.e., host population) do not reliably predict processes at another scale (i.e., individual host), and that neutral or stochastic processes may be driving the patterns of nestedness observed in these communities. We suggest that experimental approaches that manipulate parasite communities are needed to better link processes at multiple ecological scales.
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Affiliation(s)
- Evelyn C. Rynkiewicz
- Department of Science and MathematicsFashion Institute of TechnologyState University of New YorkNew YorkNYUSA
- Institute of Evolutionary Biology & Centre for Immunity, Infection and EvolutionSchool of Biological ScienceUniversity of EdinburghEdinburghUK
| | - Andy Fenton
- Institute of Integrative BiologyUniversity of LiverpoolLiverpoolUK
| | - Amy B. Pedersen
- Institute of Evolutionary Biology & Centre for Immunity, Infection and EvolutionSchool of Biological ScienceUniversity of EdinburghEdinburghUK
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Mohamed N, Muse A, Wordofa M, Abera D, Mesfin A, Wolde M, Desta K, Tsegaye A, Taye B. Increased Prevalence of Cestode Infection Associated with History of Deworming among Primary School Children in Ethiopia. Am J Trop Med Hyg 2019; 101:641-649. [PMID: 31333166 DOI: 10.4269/ajtmh.19-0284] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Mass deworming of school-aged children with anthelmintics has been recognized as an effective approach for reducing the burden of soil-transmitted helminth (STH) infections. However, the consequences of this intervention on nontargeted parasite populations sharing the same gastrointestinal niche are unclear. We conducted a cross-sectional survey among three primary schools in Sululta town, Ethiopia, to examine the association between students' histories of deworming treatment in the past 6 months and the prevalence of cestode and protozoan infections. An interviewer-led questionnaire administered to parents provided information on sociodemographic factors, and deworming status was ascertained from school records. Stool samples were collected from 525 children for microscopic examination. The independent associations of "any cestode" (positive either for Hymenolepis nana or Taenia spp. eggs) and "any protozoan" (positive either for Giardia lamblia or Entamoeba histolytica/Entamoeba dispar) with history of deworming were examined using logistic regression. Overall, 25.9% of children were infected with at least one intestinal parasite of which H. nana was the most common. In multivariate analyses, deworming in the past 6 months was positively associated with increased odds of both "any protozoan" and "any cestode" infections; the latter reached statistical significance (AOR = 1.83, 95% CI: 0.69-4.86, P = 0.220, AOR = 3.82, 95% CI: 1.17-12.73, P = 0.029, respectively). If this observed association is causal, a greater understanding of interspecies interactions within the gastrointestinal niche may elucidate possible consequences of mass deworming treatments against STHs on coexisting nontargeted parasites.
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Affiliation(s)
- Nader Mohamed
- Department of Biology, Colgate University, Hamilton, New York
| | - Anna Muse
- Department of Biology, Colgate University, Hamilton, New York
| | - Moges Wordofa
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Dessie Abera
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Abiyot Mesfin
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Mistire Wolde
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Kassu Desta
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Aster Tsegaye
- Department of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Bineyam Taye
- Department of Biology, Colgate University, Hamilton, New York
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Chard AN, Baker KK, Tsai K, Levy K, Sistrunk JR, Chang HH, Freeman MC. Associations between soil-transmitted helminthiasis and viral, bacterial, and protozoal enteroinfections: a cross-sectional study in rural Laos. Parasit Vectors 2019; 12:216. [PMID: 31064387 PMCID: PMC6505259 DOI: 10.1186/s13071-019-3471-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 04/29/2019] [Indexed: 12/12/2022] Open
Abstract
Background Humans are susceptible to over 1400 pathogens. Co-infection by multiple pathogens is common, and can result in a range of neutral, facilitative, or antagonistic interactions within the host. Soil-transmitted helminths (STH) are powerful immunomodulators, but evidence of the effect of STH infection on the direction and magnitude of concurrent enteric microparasite infections is mixed. Methods We collected fecal samples from 891 randomly selected children and adults in rural Laos. Samples were analyzed for 5 STH species, 6 viruses, 9 bacteria, and 5 protozoa using a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay. We utilized logistic regression, controlling for demographics and household water, sanitation, and hygiene access, to examine the effect of STH infection on concurrent viral, bacterial, and protozoal infection. Results We found that STH infection was associated with lower odds of concurrent viral infection [odds ratio (OR): 0.48, 95% confidence interval (CI): 0.28–0.83], but higher odds of concurrent bacterial infections (OR: 1.81, 95% CI: 1.06–3.07) and concurrent protozoal infections (OR: 1.50, 95% CI: 0.95–2.37). Trends were consistent across STH species. Conclusions The impact of STH on odds of concurrent microparasite co-infection may differ by microparasite taxa, whereby STH infection was negatively associated with viral infections but positively associated with bacterial and protozoal infections. Results suggest that efforts to reduce STH through preventive chemotherapy could have a spillover effect on microparasite infections, though the extent of this impact requires additional study. The associations between STH and concurrent microparasite infection may reflect a reverse effect due to the cross-sectional study design. Additional research is needed to elucidate the exact mechanism of the immunomodulatory effects of STH on concurrent enteric microparasite infection. Electronic supplementary material The online version of this article (10.1186/s13071-019-3471-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna N Chard
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322, USA
| | - Kelly K Baker
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, 52242, USA
| | - Kevin Tsai
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa, 52242, USA
| | - Karen Levy
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322, USA
| | - Jeticia R Sistrunk
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322, USA
| | - Howard H Chang
- Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322, USA
| | - Matthew C Freeman
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, 30322, USA.
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Clerc M, Babayan SA, Fenton A, Pedersen AB. Age affects antibody levels and anthelmintic treatment efficacy in a wild rodent. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2019; 8:240-247. [PMID: 30923672 PMCID: PMC6423487 DOI: 10.1016/j.ijppaw.2019.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 02/25/2019] [Accepted: 03/09/2019] [Indexed: 12/22/2022]
Abstract
The role of the host immune system in determining parasite burdens and mediating within-host parasite interactions has traditionally been studied in highly controlled laboratory conditions. This does, however, not reflect the diversity of individuals living in nature, which is often characterised by significant variation in host demography, such as host age, sex, and infection history. Whilst studies using wild hosts and parasites are beginning to give insights into the complex relationships between immunity, parasites and host demography, the cause-and-effect relationships often remain unknown due to a lack of high resolution, longitudinal data. We investigated the infection dynamics of two interacting gastrointestinal parasites of wild wood mice (Apodemus sylvaticus), the nematode Heligmosomoides polygyrus and the coccidian Eimeria hungaryensis, in order to assess the links between infection, coinfection, and the immunological dynamics of two antibodies (IgG1 and IgA). In an anthelmintic treatment experiment, mice were given a single oral dose of an anthelmintic treatment, or control dose, and then subsequently followed longitudinally over a period of 7–15 days to measure parasite burdens and antibody levels. Anthelmintic treatment successfully reduced burdens of H. polygyrus, but had no significant impact on E. hungaryensis. Treatment efficacy was driven by host age, with adult mice showing stronger reductions in burdens compared to younger mice. We also found that the relationship between H. polygyrus-specific IgG1 and nematode burden changed from positive in young mice to negative in adult mice. Our results highlight that a key host demographic factor like age could account for large parts of the variation in nematode burden and nematode-specific antibody levels observed in a naturally infected host population, possibly due to different immune responses in young vs. old animals. Given the variable success in community-wide de-worming programmes in animals and humans, accounting for the age-structure of a population could increase overall efficacy. Anthelmintic treatment reveals strong force of infection for H. polygyrus in wild wood mice. Anthelmintic treatment is more successful in younger compared to older mice. Relationship between IgG1 and H. polygyrus burden reverts with host age.
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Affiliation(s)
- Melanie Clerc
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK.,MRC Centre for Inflammation Research, Queen´s Medical Research Institute, University of Edinburgh UK, EH16 4TJ, UK
| | - Simon A Babayan
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, Liverpool, L69 7ZB, UK
| | - Amy B Pedersen
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
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Abstract
Coinfecting parasites and pathogens remain a leading challenge for global public health due to their consequences for individual-level infection risk and disease progression. However, a clear understanding of the population-level consequences of coinfection is lacking. Here, we constructed a model that includes three individual-level effects of coinfection: mortality, fecundity, and transmission. We used the model to investigate how these individual-level consequences of coinfection scale up to produce population-level infection patterns. To parameterize this model, we conducted a 4-y cohort study in African buffalo to estimate the individual-level effects of coinfection with two bacterial pathogens, bovine tuberculosis (bTB) and brucellosis, across a range of demographic and environmental contexts. At the individual level, our empirical results identified bTB as a risk factor for acquiring brucellosis, but we found no association between brucellosis and the risk of acquiring bTB. Both infections were associated with reductions in survival and neither infection was associated with reductions in fecundity. The model reproduced coinfection patterns in the data and predicted opposite impacts of coinfection at individual and population scales: Whereas bTB facilitated brucellosis infection at the individual level, our model predicted the presence of brucellosis to have a strong negative impact on bTB at the population level. In modeled populations where brucellosis was present, the endemic prevalence and basic reproduction number ([Formula: see text]) of bTB were lower than in populations without brucellosis. Therefore, these results provide a data-driven example of competition between coinfecting pathogens that occurs when one pathogen facilitates secondary infections at the individual level.
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Taylor CH, Wanelik KM, Friberg IM, Lowe A, Hall AJ, Ralli C, Birtles RJ, Begon M, Paterson S, Jackson JA, Bradley JE. Physiological, but not fitness, effects of two interacting haemoparasitic infections in a wild rodent. Int J Parasitol 2018; 48:463-471. [PMID: 29476867 DOI: 10.1016/j.ijpara.2017.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 11/07/2017] [Accepted: 11/17/2017] [Indexed: 10/18/2022]
Abstract
In contrast to the conditions in most laboratory studies, wild animals are routinely challenged by multiple infections simultaneously, and these infections can interact in complex ways. This means that the impact of a parasite on its host's physiology and fitness cannot be fully assessed in isolation, and requires consideration of the interactions with other co-infections. Here we examine the impact of two common blood parasites in the field vole (Microtus agrestis): Babesia microti and Bartonella spp., both of which have zoonotic potential. We collected longitudinal and cross-sectional data from four populations of individually tagged wild field voles. This included data on biometrics, life history, ectoparasite counts, presence/absence of microparasites, immune markers and, for a subset of voles, more detailed physiological and immunological measurements. This allowed us to monitor infections over time and to estimate components of survival and fecundity. We confirm, as reported previously, that B. microti has a preventative effect on infection with Bartonella spp., but that the reverse is not true. We observed gross splenomegaly following B. microti infection, and an increase in IL-10 production together with some weight loss following Bartonella spp. infection. However, these animals appeared otherwise healthy and we detected no impact of infection on survival or fecundity due to the two haemoparasite taxa. This is particularly remarkable in the case of B. microti which induces apparently drastic long-term changes to spleen sizes, but without major adverse effects. Our work sheds light on the ecologies of these important zoonotic agents, and more generally on the influence that interactions among multiple parasites have on their hosts in the wild.
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Affiliation(s)
| | - Klara M Wanelik
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Ida M Friberg
- School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK
| | - Ann Lowe
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Amy J Hall
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Catriona Ralli
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Richard J Birtles
- School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK
| | - Mike Begon
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Steve Paterson
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Joseph A Jackson
- School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK
| | - Janette E Bradley
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK
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Abstract
Tuberculosis is a significant global disease today, so understanding its origins and history is important. It is primarily a lung infection and is transmitted by infectious aerosols from person to person, so a high population density encourages its spread. The causative organism is Mycobacterium tuberculosis, an obligate pathogen in the M. tuberculosis complex that also contains closely related species, such as Mycobacterium bovis, that primarily infect animals. Typical bone lesions occur in about 5% of untreated infections. These can be recognized in historical and archaeological material, along with nonspecific paleopathology such as new bone formation (periostitis), especially on ribs. Based on such lesions, tuberculosis has been found in ancient Egypt, pre-Columbian America, and Neolithic Europe. The detection of M. tuberculosis ancient DNA (aDNA) by using PCR led to the development of the new field of paleomicrobiology. As a result, a large number of tuberculosis cases were recognized in mummified tissue and bones with nonspecific or no lesions. In parallel with these developments, M. tuberculosis cell wall lipid biomarkers have detected tuberculosis suggested by paleopathology and confirmed aDNA findings. In well-preserved cases, molecular typing has identified M. tuberculosis lineages and genotypes. The current interest in targeted enrichment, shotgun sequencing, and metagenomic analysis reveals ancient mixed infections with different M. tuberculosis strains and other pathogens. Identification of M. tuberculosis lineages from samples of known age enables the date of the emergence of strains and lineages to be calculated directly rather than by making assumptions on the rate of evolutionary change.
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14
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Wuerthner VP, Hua J, Hoverman JT. The benefits of coinfection: trematodes alter disease outcomes associated with virus infection. J Anim Ecol 2017; 86:921-931. [PMID: 28317105 DOI: 10.1111/1365-2656.12665] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 02/18/2017] [Indexed: 11/30/2022]
Abstract
Coinfections are increasingly recognized as important drivers of disease dynamics. Consequently, greater emphasis has been placed on integrating principles from community ecology with disease ecology to understand within-host interactions among parasites. Using larval amphibians and two amphibian parasites (ranaviruses and the trematode Echinoparyphium sp.), we examined the influence of coinfection on disease outcomes. Our first objective was to examine how priority effects (the timing and sequence of parasite exposure) influence infection and disease outcomes in the laboratory. We found that interactions between the parasites were asymmetric; prior infection with Echinoparyphium reduced ranaviral loads by 9% but there was no reciprocal effect of prior ranavirus infection on Echinoparyphium load. Additionally, survival rates of hosts (larval gray treefrogs; Hyla versicolor) infected with Echinoparyphium 10 days prior to virus exposure were 25% greater compared to hosts only exposed to virus. Our second objective was to determine whether these patterns were generalizable to multiple amphibian species under more natural conditions. We conducted a semi-natural mesocosm experiment consisting of four larval amphibian hosts [gray treefrogs, American toads (Anaxyrus americanus), leopard frogs (Lithobates pipiens) and spring peepers (Pseudacris crucifer)] to examine how prior Echinoparyphium infection influenced ranavirus transmission within the community, using ranavirus-infected larval wood frogs (Lithobates sylvaticus) as source of ranavirus. Consistent with the laboratory experiment, we found that prior Echinoparyphium infection reduced ranaviral loads by 19 to 28% in three of the four species. Collectively, these results suggest that macroparasite infection can reduce microparasite replication rates across multiple amphibian species, possibly through cross-reactive immunity. Although the immunological mechanisms driving this outcome are in need of further study, trematode infections appear to benefit hosts that are exposed to ranaviruses. Additionally, these results suggest that consideration of priority effects and timing of exposure are vital for understanding parasite interactions within hosts and disease outcomes.
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Affiliation(s)
- Vanessa P Wuerthner
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, 47907, USA
| | - Jessica Hua
- Biological Sciences Department, Binghamton University, Binghamton, NY, 13902, USA
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, 47907, USA
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15
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Romansic JM, Johnson JE, Wagner RS, Hill RH, Gaulke CA, Vredenburg VT, Blaustein AR. Complex interactive effects of water mold, herbicide, and the fungus Batrachochytrium dendrobatidis on Pacific treefrog Hyliola regilla hosts. DISEASES OF AQUATIC ORGANISMS 2017; 123:227-238. [PMID: 28322209 DOI: 10.3354/dao03094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Infectious diseases pose a serious threat to global biodiversity. However, their ecological impacts are not independent of environmental conditions. For example, the pathogenic fungus Batrachochytrium dendrobatidis (Bd), which has contributed to population declines and extinctions in many amphibian species, interacts with several environmental factors to influence its hosts, but potential interactions with other pathogens and environmental contaminants are understudied. We examined the combined effects of Bd, a water mold (Achlya sp.), and the herbicide Roundup® Regular (hereafter, Roundup®) on larval Pacific treefrog Hyliola regilla hosts. We employed a 2 wk, fully factorial laboratory experiment with 3 ecologically realistic levels (0, 1, and 2 mg l-1 of active ingredient) of field-formulated Roundup®, 2 Achlya treatments (present and absent), and 2 Bd treatments (present and absent). Our results were consistent with sublethal interactive effects involving all 3 experimental factors. When Roundup® was absent, the proportion of Bd-exposed larvae infected with Bd was elevated in the presence of Achlya, consistent with Achlya acting as a synergistic cofactor that facilitated the establishment of Bd infection. However, this Achlya effect became nonsignificant at 1 mg l-1 of the active ingredient of Roundup® and disappeared at the highest Roundup® concentration. In addition, Roundup® decreased Bd loads among Bd-exposed larvae. Our study suggests complex interactive effects of a water mold and a contaminant on Bd infection in amphibian hosts. Achlya and Roundup® were both correlated with altered patterns of Bd infection, but in different ways, and Roundup® appeared to remove the influence of Achlya on Bd.
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Affiliation(s)
- John M Romansic
- Department of Integrative Biology, 3029 Cordley Hall, Oregon State University, Corvallis, Oregon 97331, USA
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16
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Northover AS, Godfrey SS, Lymbery AJ, Morris K, Wayne AF, Thompson RCA. Evaluating the Effects of Ivermectin Treatment on Communities of Gastrointestinal Parasites in Translocated Woylies (Bettongia penicillata). ECOHEALTH 2017; 14:117-127. [PMID: 26719294 DOI: 10.1007/s10393-015-1088-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 09/23/2015] [Accepted: 11/02/2015] [Indexed: 06/05/2023]
Abstract
Wildlife species are often treated with anti-parasitic drugs prior to translocation, despite the effects of this treatment being relatively unknown. Disruption of normal host-parasite relationships is inevitable during translocation, and targeted anti-parasitic drug treatment may exacerbate this phenomenon with inadvertent impacts on both target and non-target parasite species. Here, we investigate the effects of ivermectin treatment on communities of gastrointestinal parasites in translocated woylies (Bettongia penicillata). Faecal samples were collected at three time points (at the time of translocation, and 1 and 3 months post-translocation) and examined for nematode eggs and coccidian oocysts. Parasite prevalence and (for nematodes) abundance were estimated in both treated and untreated hosts. In our study, a single subcutaneous injection of ivermectin significantly reduced Strongyloides-like egg counts 1 month post-translocation. Strongyle egg counts and coccidia prevalence were not reduced by ivermectin treatment, but were strongly influenced by site. Likewise, month of sampling rather than ivermectin treatment positively influenced body condition in woylies post-translocation. Our results demonstrate the efficacy of ivermectin in temporarily reducing Strongyloides-like nematode abundance in woylies. We also highlight the possibility that translocation-induced changes to host density may influence coinfecting parasite abundance and host body condition post-translocation.
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Affiliation(s)
- Amy S Northover
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia.
| | - Stephanie S Godfrey
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
| | - Alan J Lymbery
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
| | - Keith Morris
- Science and Conservation Division, Western Australian Department of Parks and Wildlife, Woodvale, WA, 6946, Australia
| | - Adrian F Wayne
- Science and Conservation Division, Western Australian Department of Parks and Wildlife, Manjimup, WA, 6258, Australia
| | - R C Andrew Thompson
- School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, WA, 6150, Australia
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17
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Hoffmann S, Horak IG, Bennett NC, Lutermann H. Evidence for interspecific interactions in the ectoparasite infracommunity of a wild mammal. Parasit Vectors 2016; 9:58. [PMID: 26830510 PMCID: PMC4735965 DOI: 10.1186/s13071-016-1342-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/26/2016] [Indexed: 11/10/2022] Open
Abstract
Background Co-infection with multiple parasite species is commonly observed in nature and interspecific interactions are likely to occur in parasite infracommunities. Such interactions may affect the distribution of parasites among hosts but also the response of infracommunities to perturbations. However, the response of infracommunities to perturbations has not been well studied experimentally for ectoparasite communities of small mammal hosts. Methods In the current study we used experimental perturbations of the ectoparasite infracommunity of sengis from Africa. We suppressed tick recruitment by applying an acaride and monitored the effects on the ectoparasite community. Results Our treatment affected the target as well as two non-target species directly. The experimental removal of the dominant tick (Rhipicephalus spp.) resulted in increases in the abundance of chiggers and lice. However, while these effects were short-lived in chiggers, which are questing from the environment, they were long-lasting for lice which spend their entire life-cycle on the host. In addition, the recruitment rates of some ectoparasite species were high and did not always correspond to total burdens observed. Conclusion These findings indicate that infracommunity interactions may contribute to patterns of parasite burdens. The divergent responses of species with differing life-history traits suggest that perturbation responses may be affected by parasite life-history and that the ectoparasite infracommunity of sengis may lack resilience to perturbations. The latter observation contrasts with the high resilience reported previously for endoparasite communities and also suggests that anti-parasite treatments can affect the distribution of non-target species. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1342-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sasha Hoffmann
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - Ivan G Horak
- Department of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa.
| | - Nigel C Bennett
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - Heike Lutermann
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
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18
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Johnson PTJ, de Roode JC, Fenton A. Why infectious disease research needs community ecology. Science 2015; 349:1259504. [PMID: 26339035 DOI: 10.1126/science.1259504] [Citation(s) in RCA: 256] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Infectious diseases often emerge from interactions among multiple species and across nested levels of biological organization. Threats as diverse as Ebola virus, human malaria, and bat white-nose syndrome illustrate the need for a mechanistic understanding of the ecological interactions underlying emerging infections. We describe how recent advances in community ecology can be adopted to address contemporary challenges in disease research. These analytical tools can identify the factors governing complex assemblages of multiple hosts, parasites, and vectors, and reveal how processes link across scales from individual hosts to regions. They can also determine the drivers of heterogeneities among individuals, species, and regions to aid targeting of control strategies. We provide examples where these principles have enhanced disease management and illustrate how they can be further extended.
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Affiliation(s)
- Pieter T J Johnson
- Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
| | | | - Andy Fenton
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
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19
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Hellard E, Fouchet D, Vavre F, Pontier D. Parasite-Parasite Interactions in the Wild: How To Detect Them? Trends Parasitol 2015; 31:640-652. [PMID: 26440785 DOI: 10.1016/j.pt.2015.07.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 07/06/2015] [Accepted: 07/31/2015] [Indexed: 01/26/2023]
Abstract
Inter-specific interactions between parasites impact on parasite intra-host dynamics, host health, and disease management. Identifying and understanding interaction mechanisms in the wild is crucial for wildlife disease management. It is however complex because several scales are interlaced. Parasite-parasite interactions are likely to occur via mechanisms at the within-host level, but also at upper levels (host population and community). Furthermore, interactions occurring at one level of organization spread to upper levels through cascade effects. Even if cascade effects are important confounding factors, we argue that we can also benefit from them because upper scales often provide a way to survey a wider range of parasites at lower cost. New protocols and theoretical studies (especially across scales) are necessary to take advantage of this opportunity.
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Affiliation(s)
- Eléonore Hellard
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon I, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5558, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France; Percy FitzPatrick Institute, DST-NRF Centre of Excellence, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
| | - David Fouchet
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon I, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5558, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France; LabEx Ecofect, Ecoevolutionary Dynamics of Infectious Diseases, University of Lyon, France
| | - Fabrice Vavre
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon I, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5558, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France; LabEx Ecofect, Ecoevolutionary Dynamics of Infectious Diseases, University of Lyon, France
| | - Dominique Pontier
- Laboratoire de Biométrie et Biologie Evolutive, Université de Lyon, Université Lyon I, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 5558, 43 Boulevard du 11 Novembre 1918, 69622, Villeurbanne, France; LabEx Ecofect, Ecoevolutionary Dynamics of Infectious Diseases, University of Lyon, France
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20
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Kepha S, Nuwaha F, Nikolay B, Gichuki P, Mwandawiro CS, Mwinzi PN, Odiere MR, Edwards T, Allen E, Brooker SJ. Effect of Repeated Anthelminthic Treatment on Malaria in School Children in Kenya: A Randomized, Open-Label, Equivalence Trial. J Infect Dis 2015; 213:266-75. [PMID: 26170395 PMCID: PMC4690148 DOI: 10.1093/infdis/jiv382] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/06/2015] [Indexed: 11/12/2022] Open
Abstract
Background. School children living in the tropics are often concurrently infected with plasmodium and helminth parasites. It has been hypothesized that immune responses evoked by helminths may modify malaria-specific immune responses and increase the risk of malaria. Methods. We performed a randomized, open-label, equivalence trial among 2436 school children in western Kenya. Eligible children were randomized to receive either 4 repeated doses or a single dose of albendazole and were followed up during 13 months to assess the incidence of clinical malaria. Secondary outcomes were Plasmodium prevalence and density, assessed by repeat cross-sectional surveys over 15 months. Analysis was conducted on an intention-to-treat basis with a prespecified equivalence range of 20%. Results. During 13 months of follow-up, the incidence rate of malaria was 0.27 episodes/person-year in the repeated treatment group and 0.26 episodes/person-year in the annual treatment group (incidence difference, 0.01; 95% confidence interval, −.03 to .06). The prevalence and density of malaria parasitemia did not differ by treatment group at any of the cross-sectional surveys. Conclusions. Our findings suggest that repeated deworming does not alter risks of clinical malaria or malaria parasitemia among school children and that school-based deworming in Africa may have no adverse consequences for malaria. Clinical Trials Registration. NCT01658774.
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Affiliation(s)
- Stella Kepha
- School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Fred Nuwaha
- School of Public Health, Makerere University College of Health Sciences, Kampala, Uganda
| | - Birgit Nikolay
- London School of Hygiene and Tropical Medicine, United Kingdom
| | - Paul Gichuki
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI)
| | - Charles S Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI)
| | - Pauline N Mwinzi
- Neglected Tropical Diseases Research Unit, Center for Global Health Research, KEMRI, Kisumu, Kenya
| | - Maurice R Odiere
- Neglected Tropical Diseases Research Unit, Center for Global Health Research, KEMRI, Kisumu, Kenya
| | - Tansy Edwards
- London School of Hygiene and Tropical Medicine, United Kingdom
| | - Elizabeth Allen
- London School of Hygiene and Tropical Medicine, United Kingdom
| | - Simon J Brooker
- London School of Hygiene and Tropical Medicine, United Kingdom KEMRI-Wellcome Trust Research Programme, Nairobi
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21
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González-Fernández D, Koski KG, Sinisterra OT, Del Carmen Pons E, Murillo E, Scott ME. Interactions among urogenital, intestinal, skin, and oral infections in pregnant and lactating Panamanian Ngäbe women: a neglected public health challenge. Am J Trop Med Hyg 2015; 92:1100-10. [PMID: 25825387 PMCID: PMC4458810 DOI: 10.4269/ajtmh.14-0547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 02/21/2015] [Indexed: 01/09/2023] Open
Abstract
Interrelationships among bacteria, protozoa, helminths, and ectoparasites were explored in a cross-sectional survey of 213 pregnant and 99 lactating indigenous women. Prevalences in pregnancy and lactation, respectively, were: vaginitis (89.2%; 46.8%), vaginal trichomoniasis (75.3%; 91.1%), bacterial vaginosis (BV; 60.6%; 63.3%), hookworm (56.6%; 47.8%), asymptomatic bacteriuria/urinary tract infection (AB/UTI; 56.2%; 36.2%), cervicitis (33.3%; 6.3%), vaginal yeast (24.9%; 11.4%), Ascaris (32.5%; 17.4%), vaginal diplococci (20.4%; 31.6%), caries (19.7%; 18.2%), scabies (17.4%; 8.1%), and Trichuris (12.5%; 8.7%). Multiple regressions revealed positive associations during pregnancy (trichomoniasis and AB/UTI; diplococci and Ascaris) and lactation (yeast and scabies). Negative associations were detected in pregnancy (BV and trichomoniasis; hookworm and diplococci) and lactation (BV and yeast). Vaginal Lactobacillus reduced odds of diplococci in pregnancy and lactation, but increased Ascaris eggs per gram (epg) and odds of trichomoniasis in pregnancy and yeast in lactation. These associations raised a concern that treatment of one condition may increase the risk of another.
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Affiliation(s)
- Doris González-Fernández
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Kristine G Koski
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Odalis Teresa Sinisterra
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Emérita Del Carmen Pons
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Enrique Murillo
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Marilyn E Scott
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
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22
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Jolles AE, Beechler BR, Dolan BP. Beyond mice and men: environmental change, immunity and infections in wild ungulates. Parasite Immunol 2015; 37:255-66. [PMID: 25354672 PMCID: PMC4414670 DOI: 10.1111/pim.12153] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/16/2014] [Indexed: 02/06/2023]
Abstract
In the face of rapid environmental change, anticipating shifts in microparasite and macroparasite dynamics, including emergence events, is an enormous challenge. We argue that immunological studies in natural populations are pivotal to meeting this challenge: many components of environmental change--shifts in biotic assemblages, altered climate patterns and reduced environmental predictability--may affect host immunity. We suggest that wild ungulates can serve as model systems aiding the discovery of immunological mechanisms that link environmental change with parasite transmission dynamics. Our review of eco-immunological studies in wild ungulates reveals progress in understanding how co-infections affect immunity and parasite transmission and how environmental and genetic factors interact to shape immunity. Changes in bioavailability of micronutrients have been linked to immunity and health in wild ungulates. Although physiological stress in response to environmental change has been assessed, downstream effects on immunity have not been studied. Moreover, the taxonomic range of ungulates studied is limited to bovids (bighorn sheep, Soay sheep, chamois, musk oxen, bison, African buffalo) and a few cervids (red deer, black-tailed deer). We discuss areas where future studies in ungulates could lead to significant contributions in understanding the patterns of immunity and infection in natural populations and across species.
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Affiliation(s)
- Anna E. Jolles
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR 97331
- Department of Integrative Biology, Oregon State University, Corvallis, OR 97331
| | - Brianna R. Beechler
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR 97331
| | - Brian P. Dolan
- Department of Biomedical Sciences, Oregon State University, Corvallis, OR 97331
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23
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Rynkiewicz EC, Pedersen AB, Fenton A. An ecosystem approach to understanding and managing within-host parasite community dynamics. Trends Parasitol 2015; 31:212-21. [PMID: 25814004 DOI: 10.1016/j.pt.2015.02.005] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/24/2015] [Accepted: 02/24/2015] [Indexed: 10/23/2022]
Abstract
Hosts are typically coinfected by multiple parasite species, resulting in potentially overwhelming levels of complexity. We argue that an individual host can be considered to be an ecosystem in that it is an environment containing a diversity of entities (e.g., parasitic organisms, commensal symbionts, host immune components) that interact with each other, potentially competing for space, energy, and resources, ultimately influencing the condition of the host. Tools and concepts from ecosystem ecology can be applied to better understand the dynamics and responses of within-individual host-parasite ecosystems. Examples from both wildlife and human systems demonstrate how this framework is useful in breaking down complex interactions into components that can be monitored, measured, and managed to inform the design of better disease-management strategies.
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Affiliation(s)
- Evelyn C Rynkiewicz
- Institute of Evolutionary Biology, and Centre for Immunity, Infection and Evolution, Kings Buildings, Ashworth Laboratories, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK.
| | - Amy B Pedersen
- Institute of Evolutionary Biology, and Centre for Immunity, Infection and Evolution, Kings Buildings, Ashworth Laboratories, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Andy Fenton
- Institute of Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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Kinung'hi SM, Magnussen P, Kishamawe C, Todd J, Vennervald BJ. The impact of anthelmintic treatment intervention on malaria infection and anaemia in school and preschool children in Magu district, Tanzania: an open label randomised intervention trial. BMC Infect Dis 2015; 15:136. [PMID: 25887977 PMCID: PMC4391149 DOI: 10.1186/s12879-015-0864-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 03/02/2015] [Indexed: 01/12/2023] Open
Abstract
Background Some studies have suggested that helminth infections increase the risk of malaria infection and are associated with increased number of malaria attacks and anaemia. Thus interventions to control helminth infections may have an impact on incidence of clinical malaria and anaemia. The current study assessed the impact of two anthelmintic treatment approaches on malaria infection and on anaemia in school and pre-school children in Magu district, Tanzania. Methods A total of 765 children were enrolled into a prospective randomized anthelmintic intervention trial following a baseline study of 1546 children. Enrolled children were randomized to receive either repeated treatment with praziquantel and albendazole four times a year (intervention group, 394 children) or single dose treatment with praziquantel and albendazole once a year (control group, 371 children). Follow up examinations were conducted at 12 and 24 months after baseline to assess the impact of the intervention. Stool and urine samples were collected and examined for schistosome and soil transmitted helminth infections. Blood samples were also collected and examined for malaria parasites and haemoglobin concentrations. Monitoring of clinical malaria attacks was performed at each school during the two years of the intervention. Results Out of 1546 children screened for P. falciparum, S. mansoni, S. haematobium, hookworm and T. Trichiura at baseline, 1079 (69.8%) were infected with at least one of the four parasites. There was no significant difference in malaria infection (prevalence, parasite density and frequency of malaria attacks) and in the prevalence of anaemia between the repeated and single dose anthelmintic treatment groups at 12 and 24 months follow up (p > 0.05). However, overall, there was significant improvement in mean haemoglobin concentrations (p < 0.001) from baseline levels of 122.0g/L and 123.0g/L to 136.0g/L and 136.8g/L for the repeated and single dose treatment groups, respectively, at 24 months follow-up which resulted in significant reduction in prevalence of anaemia. Conclusions These results suggest that repeated anthelmintic treatment did not have an impact on malaria infection compared to single dose treatment. However, both treatment approaches had overall impact in terms of improvements of haemoglobin levels and hence reductions in prevalence of anaemia.
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Affiliation(s)
- Safari M Kinung'hi
- National Institute for Medical Research (NIMR), Mwanza Centre, Isamilo Road, PO Box 1462, Mwanza, Tanzania.
| | - Pascal Magnussen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 15 DK-1870 Frederiksberg C, Copenhagen, Denmark.
| | - Coleman Kishamawe
- National Institute for Medical Research (NIMR), Mwanza Centre, Isamilo Road, PO Box 1462, Mwanza, Tanzania.
| | - Jim Todd
- Depatment of Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E, 7HT, London, UK.
| | - Birgitte J Vennervald
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 15 DK-1870 Frederiksberg C, Copenhagen, Denmark.
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25
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Pedersen AB, Fenton A. The role of antiparasite treatment experiments in assessing the impact of parasites on wildlife. Trends Parasitol 2015; 31:200-11. [PMID: 25778845 DOI: 10.1016/j.pt.2015.02.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/18/2015] [Accepted: 02/20/2015] [Indexed: 12/13/2022]
Abstract
It has become increasingly clear that parasites can have significant impacts on the dynamics of wildlife populations. Recently, researchers have shifted from using observational approaches to infer the impact of parasites on the health and fitness of individuals to using antiparasite drug treatments to test directly the consequences of infection. However, it is not clear the extent to which these experiments work in wildlife systems, or whether the results of these individual-level treatment experiments can predict the population-level consequences of parasitism. Here, we assess the results of treatment experiments, laying out the benefits and limitations of this approach, and discuss how they can be used to improve our understanding of the role of parasites in wildlife populations.
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Affiliation(s)
- Amy B Pedersen
- Institute of Evolutionary Biology & Centre for Immunity, Infection, and Evolution, School of Biological Sciences, Kings Buildings, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh, EH9 3FL, UK.
| | - Andy Fenton
- Institute of Integrative Biology, Biosciences Building, Crown Street, Liverpool, L69 7ZB, UK
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The effect of anthelmintic treatment on coccidia oocyst shedding in a wild mammal host with intermittent cestode infection. ScientificWorldJournal 2014; 2014:302903. [PMID: 25506065 PMCID: PMC4258359 DOI: 10.1155/2014/302903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 11/26/2022] Open
Abstract
While hosts are routinely exploited by a community of parasite species, the principles governing host responses towards parasites are unclear. Identifying the health outcomes of coinfections involving helminth macroparasites and microparasites is one area of importance for public and domestic animal health. For instance, it is controversial how deworming programmes affect incidence and severity of such important microparasite diseases as malaria. One problem is that most study systems involve domestic and laboratory animals with conditions hardly comparable to those of free-living animals. Here, we study the effect of anthelmintic treatment on coccidia infection intensity in wild Alpine marmots, M. marmota. Our results lend support to the hypothesis that helminth infection has a positive effect on concurrent microparasite infection. However, our work also points to the fact that within-host interactions between helminths and microparasites are context-dependent and can turn to negative ones once helminth burdens increase. Our study suggests that coccidia benefit from intermittent helminth infection in marmots due to the protective effects of helminth infection only during the early phase of the host's active season. Also, the marmot's response towards coccidia infection appears optimal only under no helminth infection when the host immune response towards coccidia would not be compromised, thereby pointing to the importance of regular intestinal helminth elimination by marmots just before hibernation.
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Risco D, Serrano E, Fernández-Llario P, Cuesta JM, Gonçalves P, García-Jiménez WL, Martínez R, Cerrato R, Velarde R, Gómez L, Segalés J, Hermoso de Mendoza J. Severity of bovine tuberculosis is associated with co-infection with common pathogens in wild boar. PLoS One 2014; 9:e110123. [PMID: 25350002 PMCID: PMC4211659 DOI: 10.1371/journal.pone.0110123] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 09/16/2014] [Indexed: 01/13/2023] Open
Abstract
Co-infections with parasites or viruses drive tuberculosis dynamics in humans, but little is known about their effects in other non-human hosts. This work aims to investigate the relationship between Mycobacterium bovis infection and other pathogens in wild boar (Sus scrofa), a recognized reservoir of bovine tuberculosis (bTB) in Mediterranean ecosystems. For this purpose, it has been assessed whether contacts with common concomitant pathogens are associated with the development of severe bTB lesions in 165 wild boar from mid-western Spain. The presence of bTB lesions affecting only one anatomic location (cervical lymph nodes), or more severe patterns affecting more than one location (mainly cervical lymph nodes and lungs), was assessed in infected animals. In addition, the existence of contacts with other pathogens such as porcine circovirus type 2 (PCV2), Aujeszky's disease virus (ADV), swine influenza virus, porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Haemophilus parasuis and Metastrongylus spp, was evaluated by means of serological, microbiological and parasitological techniques. The existence of contacts with a structured community of pathogens in wild boar infected by M. bovis was statistically investigated by null models. Association between this community of pathogens and bTB severity was examined using a Partial Least Squares regression approach. Results showed that adult wild boar infected by M. bovis had contacted with some specific, non-random pathogen combinations. Contact with PCV2, ADV and infection by Metastrongylus spp, was positively correlated to tuberculosis severity. Therefore, measures against these concomitant pathogens such as vaccination or deworming, might be useful in tuberculosis control programmes in the wild boar. However, given the unexpected consequences of altering any community of organisms, further research should evaluate the impact of such measures under controlled conditions. Furthermore, more research including other important pathogens, such as gastro-intestinal nematodes, will be necessary to complete this picture.
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Affiliation(s)
- David Risco
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
- * E-mail:
| | - Emmanuel Serrano
- Centre for Environmental and Marine Studies (CESAM), Departamento de Biología, Universidade de Aveiro, Aveiro, Portugal
- Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Pedro Fernández-Llario
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Jesús M. Cuesta
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Pilar Gonçalves
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Waldo L. García-Jiménez
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Remigio Martínez
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Rosario Cerrato
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Roser Velarde
- Servei d'Ecopatologia de Fauna Salvatge (SEFaS), Departament de Medicina i Cirurgia Animals, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Luis Gómez
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
| | - Joaquím Segalés
- Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona – l″Institut de Recerca i Tecnologia Agroalimentàries, Bellaterra, Spain
- Departament de Sanitat i Anatomia Animals, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Javier Hermoso de Mendoza
- Red de Grupos de Investigación en Recursos Faunísticos, Facultad de Veterinaria, Universidad de Extremadura, Cáceres, Spain
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Hürlimann E, Houngbedji CA, N'Dri PB, Bänninger D, Coulibaly JT, Yap P, Silué KD, N'Goran EK, Raso G, Utzinger J. Effect of deworming on school-aged children's physical fitness, cognition and clinical parameters in a malaria-helminth co-endemic area of Côte d'Ivoire. BMC Infect Dis 2014; 14:411. [PMID: 25060173 PMCID: PMC4131038 DOI: 10.1186/1471-2334-14-411] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2014] [Accepted: 07/09/2014] [Indexed: 12/13/2022] Open
Abstract
Background Malaria and helminth infections are thought to negatively affect children’s nutritional status and to impair their physical and cognitive development. Yet, the current evidence-base is weak. The purpose of this study was to determine the effect of deworming against soil-transmitted helminthiasis and schistosomiasis on children’s physical fitness, cognition and clinical parameters in a malaria-helminth co-endemic setting of Côte d’Ivoire. Methods We designed an intervention study with a 5-month follow-up among schoolchildren aged 5–14 years from Niablé, eastern Côte d’Ivoire. In late 2012, a baseline cross-sectional survey was conducted. Finger-prick blood, stool and urine samples were subjected to standardised, quality-controlled techniques for the diagnosis of Plasmodium spp., Schistosoma spp., soil-transmitted helminths and intestinal protozoa infections. Haemoglobin level was determined and anthropometric measurements were taken for appraisal of anaemia and nutritional status. Children underwent memory (digit span) and attention (code transmission) cognitive testing, and their physical fitness and strength were determined (20 m shuttle run, standing broad jump and grip strength test). All children were treated with albendazole (against soil-transmitted helminthiasis) and praziquantel (against schistosomiasis) after the baseline cross-sectional survey and again 2 months later. Five months after the initial deworming, the same battery of clinical, cognitive and physical fitness tests was performed on the same children. Results Lower scores in strength tests were significantly associated with children with harbouring nutritional deficiencies. Surprisingly, boys infected with Schistosoma mansoni achieved longer jumping distances than their non-infected counterparts. Light-intensity infection with S. mansoni was associated with slightly better aerobic capacity. Deworming showed no effect on haemoglobin levels and anaemia, but children with moderate- to heavy-intensity Schistosoma infection at baseline gained weight more pronouncedly than non-infected children. Interestingly, children with soil-transmitted helminth or Schistosoma infection at baseline performed significantly better in the sustained attention test than their non-infected counterparts at the 5-month follow-up. Conclusions This study revealed conflicting results regarding clinical parameters and cognitive behaviour of children after two rounds of deworming. We speculate that potential beneficial effects of deworming are likely to be undermined in areas where malaria is co-endemic and nutritional deficiencies are widespread. Electronic supplementary material The online version of this article (doi:10.1186/1471-2334-14-411) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Giovanna Raso
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.
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The reliability of observational approaches for detecting interspecific parasite interactions: comparison with experimental results. Int J Parasitol 2014; 44:437-45. [DOI: 10.1016/j.ijpara.2014.03.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Revised: 02/27/2014] [Accepted: 03/02/2014] [Indexed: 11/22/2022]
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