Meningeal worm is a common parasite of white-tailed deer that occasionally infects small ruminants and camelids. The scientific name of this parasite is Parelaphostrongylus tenuis (P. tenuis). This small worm infects deer when they eat a snail or slug that is infected with P. tenuis. The worm travels to the brain of the deer where it lives in the membranes surrounding the brain. The female worms lay eggs in the veins of those tissues. The eggs travel to the lungs where they hatch. The subsequent larva are coughed up, swallowed and passed in the feces. From there, the larva are ingested by snails or slugs. The cycle starts again when the snails are eaten by deer.
P. tenuis can affect small ruminants and camelids when they ingest the infected snail or slug. Small ruminants are not the normal host of P tenuis, so when ingested, the worm travels places other than the brain (as it would in the white-tailed deer). Most of the time, the worm travels to the spinal cord and causes damage.
Clinical signs of P. tenuis in small ruminants and camelids include stumbling, inability to walk, knuckling (walking on the tops of their feet), and eventually inability to get up.
P. tenuis is treatable, however, not all animals will recover. Animals that are treated before they are unable to rise have the best outcomes. Additionally, goats have better outcomes than sheep and camelids. Prompt treatment gives the patient the best chance at recovery.
Treatment for P. tenuis is similar for small ruminants and camelids. High doses of dewormer is necessary for several days to kill the offending worms. Additionally, anti-inflammatories are given to reduce the inflammation from migrating worms and from those dying. Good supportive care such as lifting, or rolling from side to side, access to clean water and good hay is also important for recovery.
Preventing meningeal worm in small ruminants and camelids is difficult, given the prevalence of white-tailed deer, snails and slugs. Limiting these species from grazing pastures is not generally practical. Therefore, the best defense careful monitoring for signs of meningeal worm so that affected animals can be treated as soon as possible.
If you have any questions about meningeal worm please contact your veterinarian.
Emily Dutton