scholarly journals The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths

Parasitology ◽  
1994 ◽  
Vol 109 (3) ◽  
pp. 389-396 ◽  
Author(s):  
M. S. Chan ◽  
H. L. Guyatt ◽  
D. A. P. Bundy ◽  
G. F. Medley
Keyword(s):  
Helminth Infection ◽  
Control Strategies ◽  
Intestinal Helminth ◽  
Intestinal Helminths ◽  
Parasite Control ◽  
Age Related ◽  
Control Programmes ◽  
Age Structured ◽  
Development And Validation ◽  
Age Structured Model

SummaryEpidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes for Ascaris lumbricoides and Trichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.

scholarly journals Comparative Analysis of Intestinal Helminth Infections in Colic and Non-Colic Control Equine Patients

Animals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1916 ◽  
Author(s):  
Heidrun Gehlen ◽  
Nadine Wulke ◽  
Antonia Ertelt ◽  
Martin K. Nielsen ◽  
Simone Morelli ◽  
...  
Keyword(s):  
Helminth Infection ◽  
Scientific Evidence ◽  
Age Groups ◽  
Study Groups ◽  
Control Measures ◽  
Anthelmintic Treatment ◽  
Intestinal Helminth ◽  
Intestinal Helminths ◽  
Increased Risk ◽  
Significant Difference

All around the world, intestinal helminths constitute one of the most prevalent life-long occurring infections and re-infections affecting all horse age groups. A range of parasite species among strongyles, ascarids, and tapeworms is known to have the potential to cause colic in horses. However, there is a lack of current scientific evidence on the actual relevance of helminth infection levels in the context of colic in horses kept during prevailing epidemiological conditions. Thus, a prospective case-control study on the occurrence of intestinal helminths in a total of 620 mainly adult equine clinic patients was conducted to investigate the association between colic and helminth infection. For each horse, a range of copromicroscopic, serological, and clinical data was obtained, in addition to a questionnaire on relevant anamnestic data, including previous anthelmintic treatment and husbandry. Using a FLOTAC-based copromicroscopic diagnosis, the highest infection rates were seen for strongyles (41.8%), followed by Anoplocephala perfoliata and Parascaris spp. (both 0.8%), with no significant difference between the two study groups. Employing a real-time PCR a 1.1% S. vulgaris DNA prevalence was found. Considerably higher seroprevalences were observed using S. vulgaris and A. perfoliata ELISAs, with 32.3% and 10.7%, respectively. It was noteworthy that no association concerning either serologic status was encountered with colic status. The shedding of strongyle eggs was associated with a 1.8-times increased risk of S. vulgaris seropositivity. Recent anthelmintic treatment was associated with the onset of colic, as animals who had received an anthelmintic during the previous week had a 2.4-times higher risk of signs of colic compared to those who had been treated at least eight weeks prior. Another noteworthy observation was that ponies were significantly less often affected by colic than warmbloods. The high S. vulgaris and considerable A. perfoliata seroprevalences encountered in this investigation should prompt veterinarians, farm managers, and horse owners to maintain consequent and effective worm control measures.

scholarly journals Parasite Proximity Drives the Expansion of Regulatory T Cells in Peyer's Patches following Intestinal Helminth Infection

2015 ◽  
Vol 83 (9) ◽  
pp. 3657-3665 ◽  
Author(s):  
Ilaria Mosconi ◽  
Lalit Kumar Dubey ◽  
Beatrice Volpe ◽  
Julia Esser-von Bieren ◽  
Mario M. Zaiss ◽  
...  
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Cytokine Production ◽  
Helminth Infection ◽  
Peyer's Patches ◽  
Intestinal Helminth ◽  
Peyer’S Patches ◽  
Intestinal Helminths ◽  
Content Type

Helminth infections are typically chronic in nature; however, the exact molecular mechanisms by which these parasites promote or thwart host immunity remain unclear. Worm expulsion requires the differentiation of CD4+T cells into Th2 cells, while regulatory T cells (Tregs) act to dampen the extent of the Th2 response. Priming of T cells requires drainage or capture of antigens within lymphoid tissues, and in the case of intestinal helminths, such sites include the mucosa-associated Peyer's patches (PPs) and the draining mesenteric lymph nodes (MLN). To gain insight into when and where the activation of the adaptive T cell response takes place following intestinal helminth infection, we analyzed Th2 and Treg responses in the PPs and MLN following infection with the murine intestinal helminthHeligmosomoides polygyrusbakeri. Protective Th2 responses were observed to be largely restricted to the MLN, while a greater expansion of Tregs occurred within the PPs. Interestingly, those PPs that formed a contact with the parasite showed the greatest degree of Treg expansion and no evidence of type 2 cytokine production, indicating that the parasite may secrete products that act in a local manner to selectively promote Treg expansion. This view was supported by the finding thatH. polygyrusbakerilarvae could promote Treg proliferationin vitro. Taken together, these data indicate that different degrees of Treg expansion and type 2 cytokine production occur within the PPs and MLN following infection with the intestinal helminthH. polygyrusbakeriand indicate that these organs exhibit differential responses following infection with intestinal helminths.

scholarly journals The development of an age structured model for schistosomiasis transmission dynamics and control and its validation for Schistosoma mansoni

1995 ◽  
Vol 115 (2) ◽  
pp. 325-344 ◽  
Author(s):  
M. S. Chan ◽  
H. L. Guyatt ◽  
D. A. P. Bundy ◽  
M. Booth ◽  
A. J. C. Fulford ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Control Programme ◽  
Transmission Dynamics ◽  
Parasitic Diseases ◽  
Infection Prevalence ◽  
Control Programmes ◽  
Dynamics And Control ◽  
Age Structured ◽  
Age Structured Model ◽  
And Control

SummaryMathematical models are potentially useful tools to aid in the design of control programmes for parasitic diseases. In this paper, a fully age structured epidemiological model of human schistosomiasis is developed and parameterized, and used to predict trends in infection prevalence, intensity and prevalence of heavy infections over age and time during several rounds of mass and age targeted treatment. The model is validated against data from a Schistosoma mansoni control programme in Kenya.

scholarly journals An age-structured model to evaluate the potential of novel malaria-control interventions: a case study of fungal biopesticide sprays

2008 ◽  
Vol 276 (1654) ◽  
pp. 71-80 ◽  
Author(s):  
P.A Hancock ◽  
M.B Thomas ◽  
H.C.J Godfray
Keyword(s):  
Fungal Pathogens ◽  
Adult Mortality ◽  
Risk Of Mortality ◽  
Relative Value ◽  
Fungal Entomopathogens ◽  
Control Programmes ◽  
Fungal Biopesticides ◽  
Age Structured ◽  
The Many ◽  
Age Structured Model

It has recently been proposed that mosquito vectors of human diseases, particularly malaria, may be controlled by spraying with fungal biopesticides that increase the rate of adult mortality. Though fungal pathogens do not cause instantaneous mortality, they can kill mosquitoes before they are old enough to transmit disease. A model is developed (i) to explore the potential for fungal entomopathogens to reduce significantly infectious mosquito populations, (ii) to assess the relative value of the many different fungal strains that might be used, and (iii) to help guide the tactical design of vector-control programmes. The model follows the dynamics of different classes of adult mosquitoes with the risk of mortality due to the fungus being assumed to be a function of time since infection (modelled using the Weibull distribution). It is shown that substantial reductions in mosquito numbers are feasible for realistic assumptions about mosquito, fungus and malaria biology and moderate to low daily fungal infection probability. The choice of optimal fungal strain and spraying regime is shown to depend on local mosquito and malaria biology. Fungal pathogens may also influence the ability of mosquitoes to transmit malaria and such effects are shown to further reduce vectorial capacity.

scholarly journals Insight into One Health Approach: Endoparasite Infections in Captive Wildlife in Bangladesh

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 250
Author(s):  
Tilak Chandra Nath ◽  
Keeseon S. Eom ◽  
Seongjun Choe ◽  
Shahadat Hm ◽  
Saiful Islam ◽  
...  
Keyword(s):  
One Health ◽  
Control Strategies ◽  
Limited Resource ◽  
Cross Sectional Study ◽  
Cox1 Gene ◽  
Parasite Control ◽  
Cross Sectional ◽  
Zoo Animals ◽  
Health Concept ◽  
Control Knowledge

Introduction: Endoparasites in captive wildlife might pose a threat to public health; however, very few studies have been conducted on this issue, and much remains to be learned, especially in limited-resource settings. This study aimed to investigate endoparasites of captive wildlife in Bangladesh. Perception and understanding of veterinarians regarding one health and zoonoses were also assessed. Materials and Methods: A cross-sectional study was conducted from October 2019 to August 2020. A total of 45 fecal samples from 18 different species of wild animals (i.e., 11 species of mammals: herbivores, carnivores, and omnivores, six birds, and a single reptile species) were collected randomly. Parasitological assessments were done by modified formalin ether sedimentation technique and rechecked by Sheather’s sugar floatation technique. Molecular identification of Spirometra spp. was conducted by amplifying the cytochrome c oxidase 1 (cox1) gene. Questionnaire surveys among 15 veterinarians and an in-depth interview (IDI) with a zoo officer were conducted. Results: Helminths (Spirometra sp., Capillaria sp., Ascaridia/Heterakis, opisthorchiid, strongyles, acuariid, hookworms, roundworms, and unidentified nematode larvae) and protozoa (coccidian oocyst) were identified, and the overall prevalence was 48.9% (22/45). The cox1 sequences (341 bp) of the Bangladesh-origin Spirometra species from lion showed 99.3–99.7% similarity to the reference sequences of Spirometra decipiens (GenBank No: KJ599679.1; MT122766). The majority of study participants (86.6%) agreed about the importance of endoparasite control in zoo animals, and 73.3% expressed that the one health concept should be promoted in Bangladesh. Only 6.7% of veterinarians perceived confidence in diagnosing parasitic diseases and preventing antiparasiticidal resistance. Conclusions: In the present survey, we found a considerable prevalence of endoparasites in captive wildlife. For the first time, zoonotically important S. decipiens from lion was molecularly characterized in Bangladesh. Veterinarian training is required to improve parasite control knowledge and practice. This study highlights the need for routine parasitological assessment, promotion of one health, and improvement of the implementation of current parasite control strategies in zoo animals.

scholarly journals Comorbidity of Geo-Helminthes among Malaria Outpatients of the Health Facilities in Ethiopia: Systematic Review and Meta-Analysis

2021 ◽  
Vol 18 (3) ◽  
pp. 862
Author(s):  
Minyahil Tadesse Boltena ◽  
Ziad El-Khatib ◽  
Abraham Sahlemichael Kebede ◽  
Benedict Oppong Asamoah ◽  
Andualem Tadesse Boltena ◽  
...  
Keyword(s):  
Systematic Review ◽  
Meta Analysis ◽  
Protein Energy Malnutrition ◽  
Random Effect ◽  
Plasmodium Species ◽  
Intestinal Helminth ◽  
Parasitic Infections ◽  
Intestinal Helminths ◽  
Soil Transmitted Helminths ◽  
Pooled Prevalence

Background: Coinfection of malaria and intestinal helminths affects one third of the global population, largely among communities with severe poverty. The spread of these parasitic infections overlays in several epidemiological locations and the host shows different outcomes. This systematic review and meta-analysis determine the pooled prevalence of malaria and intestinal helminthiases coinfections among malaria suspected patients in Ethiopia. Methods: Primary studies published in English language were retrieved using appropriate search terms on Google Scholar, PubMed/MEDLINE, CINHAL, Scopus, and Embase. The Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) was used for critical appraisal of studies. A pooled statistical meta-analysis was conducted using STATA Version 14.0 software. The heterogeneity and publication bias were assessed using the I2 statistics and Egger’s test, respectively. Duval and Tweedie’s nonparametric trim and fill analysis using the random-effect analysis. The Random effects model was used to estimate the summary prevalence of comorbidity of malaria and soil transmitted helminthiases and the corresponding 95% confidence intervals (CI). The review protocol has registered in PROSPERO number CRD42019144803. Results: We identified ten studies (n = 6633 participants) in this study. The overall pooled result showed 13% of the ambulatory patients infected by malaria and intestinal helminths concurrently in Ethiopia. The pooled prevalence of Plasmodium falciparum and Plasmodium vivax, and mixed infections were 12, 30, and 6%, respectively. The most common intestinal helminth parasites detected were Hookworm, Ascaris lumbricoides, and Tirchuris trichiura. Conclusions: The comorbidity of malaria and intestinal helminths causes lower hemoglobin level leading to maternal anemia, preterm delivery, and still birth in pregnant women and lactating mother. School-aged children and neonates coinfected by plasmodium species and soil transmitted helminths develop cognitive impairment, protein energy malnutrition, low birth weight, small for gestational age, and gross motor delay. The Ministry of Health of Ethiopia and its international partners working on malaria elimination programs should give more emphasis to the effect of the interface of malaria and soil transmitted helminths, which calls for an integrated disease control and prevention.

scholarly journals The emergence of rabbit haemorrhagic disease virus: will a non-pathogenic strain protect the UK?

2001 ◽  
Vol 356 (1411) ◽  
pp. 1087-1095 ◽  
Author(s):  
P.J. White ◽  
R.A. Norman ◽  
R.C. Trout ◽  
E.A. Gould ◽  
P.J. Hudson
Keyword(s):  
Disease Virus ◽  
Pathogenic Strain ◽  
Rabbit Haemorrhagic Disease Virus ◽  
Rabbit Haemorrhagic Disease ◽  
Seroprevalence Data ◽  
Age Structured ◽  
Reproductive Rates ◽  
The Uk ◽  
Haemorrhagic Disease ◽  
Age Structured Model

Rabbit haemorrhagic disease virus emerged in China in 1984, and has killed hundreds of millions of wild rabbits in Australia and Europe. In the UK there appears to be an endemic non–pathogenic strain, with high levels of seroprevalence being recorded, in the absence of associated mortality. Using a seasonal, age–structured model we examine the hypothesis that differences in rabbit population demography differentially affect the basic reproductive rates ( R 0 ) of the pathogenic and non–pathogenic strains, leading to each dominating in some populations and not others. The strain with the higher R 0 excluded the other, with the dynamics depending upon the ratio of the two R 0 values. When the non–pathogenic strain dominated, the pathogenic strain caused only transient mortality, although this could be significant when the two R 0 values were similar. When the pathogenic strain dominated, repeated epidemics led to host eradication. Seroprevalence data suggest that the non–pathogenic strain may be protecting some, but not all UK populations, with half being ‘at risk’ from invasion by the pathogenic strain and a fifth prone to significant transient mortality. We identify key questions for empirical research to test this prediction.

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