Population biology of Meiogymnophallus minutus (Trematoda: Gymnophallidae) in cockles from the Exe Estuary

Spatial, seasonal and age-related differences in infection of the cockle, Cerastoderma edule, with the trematode Meiogymnophallus minutus were studied on the Exe Estuary, England. Prevalence of infection was 100% across all samples with mean abundances between approximately 300 and 1000 larvae per host (maximum=4930 larvae). Aggregration of M. minutus in cockles was extremely high (variancermean ratios >100) and increased linearly as abundance increased. Mean abundance was highest in cockles collected from muddy substrates where the average age of cockles was high. In summer, numbers of larvae fell to less than half of spring levels and then increased after infection by a new wave of cercariae in August. Cockles accumulated larvae for up to 2 y but not thereafter, and levels of aggregation fell in the oldest age class. A peaked pattern of mean abundance and aggregation with age may be a result of parasite-induced death of older hosts or may be due to the inability of cercariae to establish in older host

Where’s the risk? Landscape epidemiology of gastrointestinal parasitism in Alberta beef cattle

Sherpa Romeo green journal; open accessBackground: Gastrointenstinal nematodes (GIN) present a serious challenge to the health and productivity of grazing stock around the globe. However, the epidemiology of GIN transmission remains poorly understood in northern climates. Combining use of serological diagnostics, GIS mapping technology, and geospatial statistics, we evaluated ecological covariates of spatial and temporal variability in GIN transmission among bovine calves pastured in Alberta, Canada. Methods: Sera were collected from 1000 beef calves across Alberta, Canada over three consecutive years (2008–2010) and analyzed for presence of anti-GIN antibodies using the SVANOVIR Ostertagia osteragi-Ab ELISA kit. Using a GIS and Bayesian multivariate spatial statistics, we evaluated the degree to which variation in specific environmental covariates (e.g. moisture, humidity, temperature) was associated with variation in spatial and temporal heterogeneity in exposure to GIN (Nematodirus and other trichostrongyles, primarily Ostertagia and Cooperia). Results: Variation in growing degree days above a base temperature of 5 °C, humidity, air temperature, and accumulated precipitation were found to be significant predictors of broad–scale spatial and temporal variation in serum antibody concentrations. Risk model projections identified that while transmission in cattle from southeastern and northwestern Alberta was relatively low in all years, rate of GIN transmission was generally higher in the central region of Alberta. Conclusions: The spatial variability in risk is attributed to higher average humidity, precipitation and moderate temperatures in the central region of Alberta in comparison with the hot, dry southeastern corner of the province and the cool, dry northwestern corner. Although more targeted sampling is needed to improve model accuracy, our projections represent an important step towards tying treatment recommendations to actual risk of infection.Ye

Population biology of Meiogymnophallus minutus (Trematoda: Gymnophallidae) in cockles from the Exe Estuary

Spatial, seasonal and age-related differences in infection of the cockle, Cerastoderma edule, with the trematode Meiogymnophallus minutus were studied on the Exe Estuary, England. Prevalence of infection was 100% across all samples with mean abundances between approximately 300 and 1000 larvae per host (maximum=4930 larvae). Aggregration of M. minutus in cockles was extremely high (variancermean ratios >100) and increased linearly as abundance increased. Mean abundance was highest in cockles collected from muddy substrates where the average age of cockles was high. In summer, numbers of larvae fell to less than half of spring levels and then increased after infection by a new wave of cercariae in August. Cockles accumulated larvae for up to 2 y but not thereafter, and levels of aggregation fell in the oldest age class. A peaked pattern of mean abundance and aggregation with age may be a result of parasite-induced death of older hosts or may be due to the inability of cercariae to establish in older host

A congeneric and non-randomly associated pair of larval trematodes dominates the assemblage of co-infecting parasites in fathead minnows (Pimephales promelas)

Individual hosts are often co-infected with multiple parasite species. Evidence from theoretical and empirical studies supports the idea that co-occurring parasites can impact each other and their hosts via synergistic or antagonistic interactions. The fundamental aim of understanding the consequences of co-infection to hosts and parasites requires an understanding of patterns of species co-occurrence within samples of hosts. We censused parasite assemblages in 755 adult, male fathead minnows collected from 7 lakes/ponds in southern Alberta, Canada between 2018 and 2020. Fifteen species of endoparasites infected fathead minnows, 98% of which were co-infected with between 2 and 9 parasite species (mean species richness: 4.4 ± 1.4). Non-random pairwise associations were detected within the overall parasite community. There were particularly strong, positive associations in the occurrences and intensities of the 2 congeneric larval trematodes Ornithodiplostomum sp. and Ornithodiplostomum ptychocheilus that comprised >96% of the 100 000+ parasites counted in the total sample of minnows. Furthermore, the occurrence of Ornithodiplostomum sp. was a strong predictor of the occurrence of O. ptychocheilus, and vice versa. Positive covariation in the intensities of these 2 dominants likely arises from their shared use of physid snails as first intermediate hosts in these waterbodies. These 2 species represent a predictable and non-random component within the complex assemblage of parasites of fathead minnows in this region

Raw data - Parasites and a host’s sense of smell

This file includes raw data from a study in which olfactory chamber of fathead minnows was experimentally infected withDactylogyrus olfactorius. The data includes parasite intensity, olfactory acuity of the host (post-exposure and after treatment with anti-parasite), and density of rodlet and mucous cells on the olfactory chamber of infected animals

Data from: Parasites and a host's sense of smell: reduced chemosensory performance of fathead minnows (Pimephales promelas) infected with a monogenean parasite

1. Parasites residing within the central nervous system of their hosts have the potential to reduce various components of host performance, but such effects are rarely evaluated. 2. We assessed the olfactory acuity of fathead minnows (Pimephales promelas) infected experimentally with the monogenean Dactylogyrus olfactorius, the adults of which live within the host's olfactory chambers. 3. Olfactory acuity was compared between infected and uninfected hosts by assessing electro-olfactography (EOG) neural responses to chemical stimuli that indicate the presence of food (L-alanine) or the presence of conspecifics (taurocholic acid). We also compared differences in gross morphology of the olfactory epithelium in infected and uninfected minnows. 4. Differences in EOG responses between infected and uninfected minnows to both cue types were non-significant at 30 d post-exposure. By days 60 and 90, coincident with a two times increase in parasite intensity in the olfactory chambers, the EOG responses of infected minnows were 70-90% lower than controls. When infected fish were treated with a parasiticide (Prazipro), olfactory acuity returned to control levels by day 7 post-treatment. 5. The observed reduction in olfactory acuity is best explained by the reduced density of cilia covering the olfactory chambers of infected fish, or by the concomitant increase in the density of mucous cells that cover the olfactory chambers. These morphological changes are likely due to the direct effects of attachment and feeding by individual worms or by indirect effects associated with host responses. Our results show that infection of a commonly occurring monogenean in fathead minnows reduces olfactory acuity. Parasite-induced interference with olfactory performance may reduce a fish's ability to detect, or respond to, chemical cues originating from food, predators, competitors, or mates