Reducing Risks of Wildlife/Livestock Parasite Transmission

View the project final report

Commodities

• Animals: camelids, goats, sheep

Practices

• Animal Production: animal protection and health, parasite control
• Education and Training: extension, on-farm/ranch research, workshop
• Natural Resources/Environment: wildlife
• Pest Management: disease vectors, field monitoring/scouting, prevention

White-tailed deer (Odocoileus virginianus; WTD) pose a risk to livestock health due to a parasite, meningeal worm (Parelaphostrongylus tenuis; P. tenuis) also called brainworm. Farms where livestock grazing systems overlap with WTD habitat (P .tenuis definitive host) and that harbor high numbers of terrestrial gastropods (P. tenuis intermediate hosts) face elevated risk of brainworm infection. The parasite often causes severe neurologic disease or death in livestock, primarily to small ruminants (sheep, goats, llamas and alpacas)¹. Small-scale farmers face a large risk of production loss due to meningeal worm, as even a small increase in mortality can have a large financial impact.

The objectives of this project include; 1) estimating risk of P. tenuis infection to small ruminants in overlapping grazing systems with WTD; 2) proposing risk management and preventive applications to producers and 3) exploring possible antemortem diagnostic methods for P. tenuis infection of small ruminants.  In preliminary work, gastropods and WTD fecal pellets were collected from two different Maine farms; all WTD pellets and 4% of snails carried P. tenuis larvae. The study will continue with a survey for United States farmers about their pasture systems and if they have had P. tenuis related symptoms or deaths. Deer fecal pellets and gastropods will be collected on Maine farms to determine meningeal worm prevalence in pasture systems. Producer education will be developed to minimize risk, to aid early detection, and to direct producers to seek appropriate veterinary treatment.

1) Establish the risk factors associated with brainworm to determine likelihood of infection to livestock.

Farmers across the north east utilize various grazing strategies which often overlap with WTD habitat. This, in combination with high gastropod numbers, is the basis of infection on any farm. Weather trends, grass height, wetness, topography, and woody debris may change gastropod behavior or abundance.

These factors, once quantified, can be entered into a statistical model to determine the likelihood of infection to animals exposed to different grazing systems, climatic events, and preventive treatments. These factors will be explored across several farms in Maine where pastures support deer and small ruminant livestock, such as sheep and goats. This study will be the first evaluation of P.tenuis on Maine livestock farms.

2) Document perceived and real incidence and prevalence of brainworm on Maine farms.

Results from our nation-wide survey will give general insight to the perceived incidence of P.tenuis on farms. Examining fecal samples and gastropods in the lab will indicate the prevalence of brainworm on farms. To explore incidence of brainworm-associated disease in small ruminants, serological samples from a representative sample of small ruminants will be collected and sent to a lab at University of Tennessee that has developed an assay for use in moose; other diagnostic assays will be pursued as they become available. Necropsy followed by histology will be performed as appropriate, using the UMaine VDL resources.

3) Create management strategies for farmers.

After analyzing the risk factors associated with increased prevalence of brainworm, preventive measures to combat the parasite will be suggested in project publications. In a separate but linked effort, integrated pest management using poultry (ducks, other species) will be explored by an undergraduate member of the Lichtenwalner lab.