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

Abstract

Background: 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)(2009)(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.

Prevalence, fecal egg counts, and species identification of gastrointestinal nematodes in replacement dairy heifers in Canada

“…This is likely because differences in climate (such as temperature, precipitation, humidity) and management (such as grazing and pasture management, use of anthelmintic products) affect the risk of GIN infection but were not captured in this study. For example, the risk of parasite transmission in cattle was less in the southeastern part of AB, Canada, compared with the northwestern part of that province (Beck et al, 2015). However, the magnitude of FEC variations between the statistically significantly different values was small.…”

“…Management and environmental conditions also influence the GIN prevalence and FEC intensity (Eysker et Wilson et al, 1998;Beck et al, 2015). Although epidemiologic studies on GIN larvae survival and transmission patterns from Canada are scarce, it is possible that climate differences (e.g., long, cold winters; dry hot summers) reduce the risk of GIN infection in cattle and contribute to the lower FEC intensity in the heifers here compared with studies in Europe (Areskog et al, 2013;Geurden et al, 2015).…”

Has it become warmer in Alberta? Mapping temperature changes for the period 1950–2010 across Alberta, Canada

“…An increased risk of a Mountain Pine Beetle ( Dendroctonus ponderosae ) infestation exists in large stretches of Alberta's forest ecoregions (#6, #8, #10, #12, #17, #18). In the Cypress Hills Uplands ecoregion (#7), the previously non‐existent lancet liver fluke ( Dicrocoelium dendriticum ) has recently been found for the first time in Canada (Beck et al ); it is hypothesized that climate change induced a change in the ecosystem and has resulted in favourable conditions for this parasite. Major agricultural areas—distributed over the southern grasslands (Ecoregion # 1, #2, #3), the Aspen Parkland (#4), and the Peace Lowland (#12)—have undergone a lengthening of the growing season and an increase in growing degree days, providing new opportunities for farmers and ranchers.…”

“…Stresses from gradual climate warming also include increased occurrences of pests and diseases (Gregory et al ), because some of these were, or still are, limited by low winter temperatures. Examples are the Mountain Pine Beetle ( Dendroctonus ponderosae ) infestation concentrating in British Columbia (Parkins and MacKendrick ), and the occurrence of the lancet liver fluke ( Dicrocoelium dendriticum ) recently found for the first time in Canada in the Cypress Hills (Beck et al ), which infects domestic and wild ruminants. Other pests that will spread across Alberta are, among many others, mosquitoes and ticks.…”

Seasonal epidemiology of gastrointestinal nematodes of cattle in the northern continental climate zone of western Canada as revealed by internal transcribed spacer-2 ribosomal DNA nemabiome barcoding

“…Recent work has shown that L3 of both Ostertagia ostertagi and Cooperia oncophora can survive over the winter in significant numbers on pastures in western Canada, despite the very low temperatures and low humidity at this time of the year, with the fecal pat being an important refuge [ 13 ]. Fecal egg counts are known to increase over the summer grazing season in beef cattle in western Canada, and there is some evidence that temperature and accumulated precipitation are significant predictors of O. ostertagi serum antibody concentrations [ 17 , 18 ]. However, there is very limited information on the pasture dynamics of infective larvae over the grazing season in these northerly regions, and on whether there are differences between the major GIN species.…”