Heterogeneity in helminth infections: factors influencing aggregation in a simple host–parasite system

Parasitology ◽  
2019 ◽  
Vol 147 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Richard C. Tinsley ◽  
Hanna Rose Vineer ◽  
Rebecca Grainger-Wood ◽  
Eric R. Morgan
Keyword(s):  
Post Infection ◽  
Evolutionary Biology ◽  
Negative Binomial ◽  
Parasite Population ◽  
Trout Population ◽  
Helminth Infections ◽  
Transmission Period ◽  
Binomial Parameter ◽  
Host Parasite ◽  
Direct Life Cycle

AbstractThe almost universally-occurring aggregated distributions of helminth burdens in host populations have major significance for parasite population ecology and evolutionary biology, but the mechanisms generating heterogeneity remain poorly understood. For the direct life cycle monogenean Discocotyle sagittata infecting rainbow trout, Oncorhynchus mykiss, variables potentially influencing aggregation can be analysed individually. This study was based at a fish farm where every host individual becomes infected by D. sagittata during each annual transmission period. Worm burdens were examined in one trout population maintained in isolation for 9 years, exposed to self-contained transmission. After this year-on-year recruitment, prevalence was 100% with intensities 10–2628, mean 576, worms per host. Parasite distribution, amongst hosts with the same age and environmental experience, was highly aggregated with variance to mean ratio 834 and negative binomial parameter, k, 0.64. The most heavily infected 20% of fish carried around 80% of the total adult parasite population. Aggregation develops within the first weeks post-infection; hosts typically carried intensities of successive age-specific cohorts that were consistent for that individual, such that heavily-infected individuals carried high numbers of all parasite age classes. Results suggest that host factors alone, operating post-infection, are sufficient to generate strongly overdispersed parasite distributions, rather than heterogeneity in exposure and initial invasion.

SPATIAL PATTERN OF THE IMMATURE STAGES OF HYLEMYA BRASSICAE ON CABBAGE

1970 ◽  
Vol 102 (10) ◽  
pp. 1216-1222 ◽  
Author(s):  
M. K. Mukerji ◽  
D. G. Harcourt
Keyword(s):  
Spatial Pattern ◽  
Poisson Distribution ◽  
Negative Binomial ◽  
Immature Stages ◽  
Expected Number ◽  
Chi Square ◽  
Binomial Series ◽  
Binomial Parameter ◽  
Hylemya Brassicae ◽  
Cabbage Maggot

AbstractCounts of the cabbage maggot, Hylemya brassicae (Bouché), on cabbage did not conform to the Poisson distribution, there being an excess of uninfested and highly infested plants over the expected number. But when the negative binomial series was fitted to the observed distribution, the discrepancies were not significant when tested by chi-square. The negative binomial parameter k tended to increase with density. Using a common k, the distribution of the various stages may be described by expansion of (q − p)−k, when values of k are as follows: egg 0.78, larva 0.71, pupa 0.84. Three different transformations are offered for stabilizing the variance of field counts.

scholarly journals Helminths and microbes within the vertebrate gut – not all studies are created equal

Parasitology ◽  
2019 ◽  
Vol 146 (11) ◽  
pp. 1371-1378 ◽  
Author(s):  
Alba Cortés ◽  
Laura E. Peachey ◽  
Timothy P. Jenkins ◽  
Riccardo Scotti ◽  
Cinzia Cantacessi
Keyword(s):  
Gut Microbiota ◽  
Microbial Composition ◽  
Parasitic Helminths ◽  
The Past ◽  
Systems Research ◽  
Helminth Infections ◽  
Methodological Approaches ◽  
Host Parasite ◽  
Gi Helminths ◽  
Research Domain

AbstractThe multifaceted interactions occurring between gastrointestinal (GI) parasitic helminths and the host gut microbiota are emerging as a key area of study within the broader research domain of host-pathogen relationships. Over the past few years, a wealth of investigations has demonstrated that GI helminths interact with the host gut flora, and that such interactions result in modifications of the host immune and metabolic statuses. Nevertheless, whilst selected changes in gut microbial composition are consistently observed in response to GI helminth infections across several host-parasite systems, research in this area to date is largely characterised by inconsistent findings. These discrepancies are particularly evident when data from studies of GI helminth-microbiota interactions conducted in humans from parasite-endemic regions are compared. In this review, we provide an overview of the main sources of variance that affect investigations on helminth-gut microbiota interactions in humans, and propose a series of methodological approaches that, whilst accounting for the inevitable constraints of fieldwork, are aimed at minimising confounding factors and draw biologically meaningful interpretations from highly variable datasets.

Immunoendocrine host-parasite interactions during helminth infections: from the basic knowledge to its possible therapeutic applications.

2010 ◽  
pp. no-no ◽  
Author(s):  
Romel Hernández-Bello ◽  
Galileo Escobedo ◽  
Carolina Guzmán ◽  
Elizabeth G. Ibarra-Coronado ◽  
Lorena López-Griego ◽  
...  
Keyword(s):  
Basic Knowledge ◽  
Therapeutic Applications ◽  
Host Parasite Interactions ◽  
Helminth Infections ◽  
Host Parasite

A Series Approximation for Negative Binomial Parameter Estimation

1969 ◽  
Vol 6 (3) ◽  
pp. 355-356 ◽  
Author(s):  
Donald G. Morrison
Keyword(s):  
Parameter Estimation ◽  
Negative Binomial Distribution ◽  
Negative Binomial ◽  
Search Procedure ◽  
Iterative Search ◽  
Implicit Equation ◽  
Series Approximation ◽  
Binomial Parameter ◽  
Nbd Model ◽  
Parameter Values

One parameter of the negative binomial distribution (NBD) model of repeat purchase loyalty is obtained by an iterative search procedure on an implicit equation. This note presents an extremely accurate explicit series approximation for this parameter. When solving for the parameters by hand, one can use some very efficient table to look up procedures. However, when a researcher is solving for many sets of parameter values, our procedure is much easier to program.

Patterns of macroparasite aggregation in wildlife host populations

Parasitology ◽  
1998 ◽  
Vol 117 (6) ◽  
pp. 597-610 ◽  
Author(s):  
D. J. SHAW ◽  
B. T. GRENFELL ◽  
A. P. DOBSON
Keyword(s):  
Poisson Distribution ◽  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Goodness Of Fit ◽  
Negative Binomial ◽  
Data Sets ◽  
Frequency Distributions ◽  
System A ◽  
Host Sex ◽  
Host Parasite

Frequency distributions from 49 published wildlife host–macroparasite systems were analysed by maximum likelihood for goodness of fit to the negative binomial distribution. In 45 of the 49 (90%) data-sets, the negative binomial distribution provided a statistically satisfactory fit. In the other 4 data-sets the negative binomial distribution still provided a better fit than the Poisson distribution, and only 1 of the data-sets fitted the Poisson distribution. The degree of aggregation was large, with 43 of the 49 data-sets having an estimated k of less than 1. From these 49 data-sets, 22 subsets of host data were available (i.e. host data could be divided by either host sex, age, where or when hosts were sampled). In 11 of these 22 subsets there was significant variation in the degree of aggregation between host subsets of the same host–parasite system. A common k estimate was always larger than that obtained with all the host data considered together. These results indicate that lumping host data can hide important variations in aggregation between hosts and can exaggerate the true degree of aggregation. Wherever possible common k estimates should be used to estimate the degree of aggregation. In addition, significant differences in the degree of aggregation between subgroups of host data, were generally associated with significant differences in both mean parasite burdens and the prevalence of infection.

scholarly journals Rapid change in parasite infection traits over the course of an epidemic in a wild host-parasite population

Oikos ◽  
2013 ◽  
Vol 123 (2) ◽  
pp. 232-238 ◽  
Author(s):  
Stuart K. J. R. Auld ◽  
Philip J. Wilson ◽  
Tom J. Little
Keyword(s):  
Rapid Change ◽  
Parasite Infection ◽  
Parasite Population ◽  
Wild Host ◽  
Host Parasite

The effect of cyclosporin A on the course ofParagonimus miyazakiiinfection in rats

1988 ◽  
Vol 62 (3) ◽  
pp. 251-256 ◽  
Author(s):  
Yoshihisa Hashiguchi ◽  
Yoshisuke Okamura
Keyword(s):  
Cyclosporin A ◽  
Post Infection ◽  
Recovery Rate ◽  
Cyst Formation ◽  
Fungal Metabolite ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Host Parasite ◽  
Time Of Administration ◽  
Lower Recovery

ABSTRACTThe effect of the immunomodulatory fungal metabolite cyclosporin A (CyA) on the course ofParagonimus miyazakiiinfection in rats was studied. Administration of CyA 15 to 19 days post-infection resulted in a significantly lower recovery rate of worms and cyst formation in the host's lungs than in controls. Administration of CyA − 1 to + 3 days post-infection enhanced the growth and maturation ofP. miyazakii, expressed as weight of worms and the number of worms with eggs in uteri with respect to control values. This study shows that administration of CyA to rats affects the host-parasite relationship, depending on the time of administration of the drug.

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