Analysis of variables associated with the Ichthyophonus hoferi epizootics in Norwegian spring spawning herring, 1992–2008

2010 ◽  
Vol 67 (11) ◽  
pp. 1862-1873 ◽  
Author(s):  
Stephanie Kramer-Schadt ◽  
Jens Christian Holst ◽  
Dankert Skagen
Keyword(s):  
Body Condition ◽  
Disease Ecology ◽  
Infected Fish ◽  
Reproductive Capacity ◽  
Infection Prevalence ◽  
Migration Routes ◽  
Reduced Body ◽  
Long Term Study ◽  
The Individual

We present a long-term study of epizootics in a migratory fish species that shows major advancements in our understanding of marine disease ecology. On the individual macroscopic level, Ichthyophonus hoferi infections in herring significantly reduced body condition (p < 0.01) and reproductive capacity (gonad weight, p < 0.001). Infection prevalence increased with age (p < 0.001, R adj2  = 0.71). Prevalence in the catches strongly depended on target school size and was thus higher in trawl catches. We found strong seasonality in infection prevalence within years, with peaks in summer and winter. Summer peaks spatially formed an “infectious belt” off the west coast of Norway, consisting of infected fish unable to follow the migration routes to the feeding grounds. Prevalence varied also between years (p ≤ 0.001). Since 1992, it had declined from stock prevalence levels of 10%, down to almost extinction, with another major peak in 1999. The annual peaks could best be associated with strong year classes (Pearson’s r = 0.56), a good overall body condition (r = 0.86), and plastic wintering behaviour.

scholarly journals Seasonal dynamics and repeatability of gastrointestinal parasite burdens in wild Soay sheep

2021 ◽  
Author(s):  
Amy R. Sweeny ◽  
Yolanda Corripio-Miyar ◽  
Xavier Bal ◽  
Adam Hayward ◽  
Jill G. Pilkington ◽  
...  
Keyword(s):  
Seasonal Dynamics ◽  
Disease Ecology ◽  
Gastrointestinal Parasites ◽  
Reproductive Status ◽  
Gastrointestinal Parasite ◽  
Short Term ◽  
Soay Sheep ◽  
Long Term Study ◽  
Faecal Samples

AbstractSeasonality is a ubiquitous feature of wildlife disease ecology, but is determined by a complex interplay of environmental, parasitological and host factors. Gastrointestinal parasites often exhibit strong seasonal dynamics in wild vertebrate populations due to, for example, environmental influences on free-living or vectored life stages, and variation in the physiological and immune status of hosts across their annual cycle. At the same time, wild populations are typically infected with multiple parasites. The seasonal dynamics of co-infecting parasites may differ depending on age and reproductive status, and associations among parasites may be driven by short-term within-individual changes or longer-term interactions that are consistent among hosts. Here, we used faecal samples and egg counts collected repeatedly from individually marked and monitored wild Soay sheep that were part of a long-term study to investigate seasonal dynamics of six gastrointestinal parasite groups (strongyle nematodes, coccidian protozoa, Capillaria, Strongyloides, Nematodirus, and Moniezia). Prevalence and abundance generally tended to be higher spring and summer, and burdens were higher in lambs than adults. Within the highly prevalent strongyle nematode group, we found differences in seasonality of egg counts depending on adult reproductive status. Reproductive ewes had increased counts in spring around the time of birth followed by a drop in abundance in summer, while barren ewes showed little evidence of seasonality. Males showed a sustained rise in egg counts through spring and summer, and sex differences were only strongly apparent in summer. In contrast, in similarly prevalent coccidia we found a peak in faecal oocyst counts in spring but no differences in seasonality among males, barren and pregnant ewes. Using multivariate mixed-effects models, we went on to show that both strongyle and coccidia counts are moderately repeatable across seasons among individuals. We further show that apparent positive correlation between strongyle and coccidia counts was driven by short-term within-individual changes in both parasite burdens rather than long-term among-individual covariation. Overall, our results demonstrate that seasonality varies across demographic and parasite groups and highlight the value of investigating fluctuating susceptibility and exposure over time for understanding epidemiology of a population.

Equine obesity and the role of the veterinary nurse

UK-Vet Equine ◽  
2021 ◽  
Vol 5 (6) ◽  
pp. 265-268
Author(s):  
Clarissa Seeley ◽  
Stella Chapman
Keyword(s):  
Body Condition ◽  
The Body ◽  
Body Condition Scoring ◽  
Client Education ◽  
Inherent Problem ◽  
Equine Obesity ◽  
The Individual ◽  
The Uk

Equine obesity is defined as a medical disease in which excess body fat has accumulated to such an extent that it has an adverse effect on the general health of the horse. Obesity is a cause for concern, with one-third of the equine population in the UK being regarded as obese, although owner recognition of obesity in horses is an inherent problem, with many underestimating the body condition or weight of their horse. This is further complicated by the fact that with larger framed horses, or horses that are already overweight, assessing body condition is more difficult. There are a number of ways to assess body condition and the most practical means of regular assessment is body condition scoring, although this is regarded as subjective. As with many diseases and disorders, the cause of obesity is multifactorial. However, the most common reason for a horse to become obese is overfeeding, coupled with a lack of exercise. Obesity can be addressed with client education and veterinary nurses can provide advice on weight management programmes. However, these need to be tailored to the individual horse and owners need to recognise that they are entering into a long-term commitment.

On the calculation of reference change values, with examples from a long-term study

1993 ◽  
Vol 39 (7) ◽  
pp. 1398-1403 ◽  
Author(s):  
J M Queraltó ◽  
J C Boyd ◽  
E K Harris
Keyword(s):  
Serial Correlation ◽  
Original Method ◽  
Repeated Measurements ◽  
Term Study ◽  
Simplified Approach ◽  
Long Term Study ◽  
True Variance ◽  
The Individual ◽  
Repeated Test

Abstract Reference change values (sometimes called critical differences) indicate statistically important changes between test values obtained on two occasions. They are commonly computed from the median (or mean) within-subject variance observed in repeated test measurements on a number of subjects. With this computational approach, all observed within-subject variances are assumed to be estimates of a constant true variance, the same for all individuals. Moreover, any possible correlation between successive values is almost always ignored. This simplified methodology differs from the method originally proposed for computing reference change values, which accounts for variability in true variances and for serial correlation. From data obtained from repeated measurements over 2 to 5 years in 72 physically healthy subjects, we computed and compared reference change values in 18 serum analytes, using the simplified method and the originally proposed procedure. Although the original method is more complicated and requires a computer program, we believe that it produces more-reliable reference change values than those obtained by the simplified approach. The former are generally larger, but remain sensitive to clinically important changes in the individual.

scholarly journals The drivers and consequences of unstablePlasmodiumdynamics: a long-term study of three malaria parasite species infecting a tropical lizard

Parasitology ◽  
2018 ◽  
Vol 146 (4) ◽  
pp. 453-461 ◽  
Author(s):  
Luisa Otero ◽  
Jos J. Schall ◽  
Virnaliz Cruz ◽  
Kristen Aaltonen ◽  
Miguel A. Acevedo
Keyword(s):  
Body Condition ◽  
Parasite Species ◽  
Early Years ◽  
Environmental Drivers ◽  
Host Body ◽  
Long Term Study ◽  
Linear Relationships ◽  
Individual Probability ◽  
Parasite Dynamics

AbstractUnderstanding the consequences of environmental fluctuations for parasite dynamics requires a long-term view stretching over many transmission cycles. Here we studied the dynamics of three malaria parasites (Plasmodium azurophilum,P. leucocyticaandP. floridense) infecting the lizardAnolis gundlachi, in the rainforest of Puerto Rico. In this malaria–anole system we evaluated temporal fluctuations in individual probability of infection, the environmental drivers of observed variation and consequences for host body condition andPlasmodiumparasites assemblage. We conducted a total of 15 surveys including 10 from 1990 to 2002 and five from 2015 to 2017. During the early years, a lizard's probability of infection by allPlasmodiumspecies appeared stable despite disturbances ranging from two hurricanes to short droughts. Over a longer timescale, probability of infection and overall prevalence varied significantly, following non-linear relationships with temperature and rainfall such that highest prevalence is expected at intermediate climate measures. A perplexing result was that host body condition was maximized at intermediate levels of rainfall and/or temperature (when risk of infection was highest), yet we found no significant decreases in body condition due to infection.Plasmodiumparasite species composition varied through time with a reduction and near local extinction ofP. floridense. Our results emphasize the need for long-term studies to reveal host–parasite dynamics, their drivers and consequences.

scholarly journals The drivers and consequences of unstable Plasmodium dynamics: A long-term study of three malaria species infecting a tropical lizard

2017 ◽  
Author(s):  
Luisa Otero ◽  
Jos. J. Schall ◽  
Virnaliz Cruz ◽  
Kristen Aaltonen ◽  
Miguel A. Acevedo
Keyword(s):  
Body Condition ◽  
Early Years ◽  
Environmental Drivers ◽  
Severe Drought ◽  
List Type ◽  
Infected Female ◽  
Long Term Study ◽  
Individual Probability ◽  
Parasite Dynamics

ABSTRACTThe dynamics of vector-borne parasites are driven by interactions between factors intrinsic to the parasite, its host, as well as environmental fluctuations. Understanding these interactions requires a long-term view, especially to predict the consequences of climate change on parasite dynamics.The goal of this study is to evaluate temporal fluctuations in individual probability of infection, its environmental drivers and consequences for host body condition, of three malaria parasites (Plasmodium azurophilum, P. leucocytica, and P. floridense) infecting the lizard, Anolis gundlachi, in the rainforest of Puerto Rico.We conducted 13 surveys totaling N > 8000 lizards over 26 years. During the early years of the study, the lizard’s probability of infection by all three Plasmodium species appeared stable despite disturbances from short droughts and small to moderate hurricanes.Over a longer timescale, we found that the individual lizard probability of infection and overall prevalence varied significantly over the years, and this fluctuation was driven in non-linear ways by variations in temperature and rainfall. The probability of infection was maximized at intermediate levels of temperature and precipitation. This temporal variability in Plasmodium prevalence driven by environmental factors had two important consequences. First, temperature-mediated a decrease in body condition in infected female lizards relative to non-infected ones. Second, Plasmodium parasite species composition varied through time.Overall, the results show how environmental conditions, such a severe drought, can drive disease dynamics outside of their apparent stable equilibrium and mediate the potential negative effects of parasite infection on the host. Our results also emphasize the need for long-term studies to reveal host-parasite dynamics, their drivers and consequences.

scholarly journals Measuring customer satisfaction with the controllable elements of the in-store shopping experience

2001 ◽  
Vol 32 (4) ◽  
pp. 11-20 ◽  
Author(s):  
N. S. Terblanche ◽  
C. Boshoff
Keyword(s):  
Customer Satisfaction ◽  
Convergent Validity ◽  
Discriminant Validity ◽  
Current Form ◽  
Five Dimensions ◽  
Long Term Study ◽  
Shopping Experience ◽  
Store Environment ◽  
The Individual

Evidence from various sources suggests that satisfaction with the individual components of an in-store shopping experience will result in customer satisfaction which will lead to customer retention and loyalty over the long term. It is argued that the in-store shopping experience (ISE) at store level consists of a variety of different dimensions that can be controlled by the retailer. This study reports on two phases of a long-term study on the controllable elements of the in-store shopping experience. Closely following the guidelines for multi-item scale development suggested by Churchill (1979) and based on the results of two empirical surveys, it is concluded that there are five dimensions of importance to consumers when assessing their satisfaction with an in-store shopping experience. These dimensions are merchandise value, personal interaction, merchandise variety, internal store environment and complaint handling. The proposed instrument in its current form demonstrates high levels of reliability, discriminant validity, convergent validity and construct validity.

scholarly journals Divergent Sapovirus Strains and Infection Prevalence in Wild Carnivores in the Serengeti Ecosystem: A Long-Term Study

PLoS ONE ◽  
2016 ◽  
Vol 11 (9) ◽  
pp. e0163548 ◽  
Author(s):  
Ximena A. Olarte-Castillo ◽  
Heribert Hofer ◽  
Katja V. Goller ◽  
Vito Martella ◽  
Patricia D. Moehlman ◽  
...  
Keyword(s):  
Infection Prevalence ◽  
Term Study ◽  
Serengeti Ecosystem ◽  
Wild Carnivores ◽  
Long Term Study

Body condition and head size in snakes

2011 ◽  
Vol 32 (4) ◽  
pp. 565-567 ◽  
Author(s):  
Thomas Madsen
Keyword(s):  
Body Condition ◽  
Positive Relationship ◽  
Good Condition ◽  
Adaptive Significance ◽  
Head Size ◽  
Systematic Bias ◽  
Term Study ◽  
Long Term Study ◽  
The Relationship

AbstractOn several occasions during my many years of working with various snake species, I observed a significant positive relationship between body condition and head size (the former calculated from residual scores from a general linear regression of ln-transformed mass on ln-transformed snout-vent length). Based on results from my long-term study of water pythons (Liasis fuscus) this relationship is, however, most likely caused by a condition-dependent bias when recording snake snout-vent length (SVL). Water pythons in good condition were recorded as being "shorter" and hence having relatively larger head size, whereas snakes in poor condition were recorded as being "longer" with concomitant smaller head relative head size. Such a systematic bias may lead to spurious conclusions concerning the adaptive significance of the relationship between snake body condition and head size.

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