Transboundary Emerging and Exotic Animal Disease/ Exotic Animal Disease Practice Exam

What was likely the method of introduction of cerebrospinal elaphostrongylosis to Canadian caribou?

1. Infected reindeer shed the parasite in feces that were ingested by snais

2. Mechanical transmission through flies between reindeer and caribou

3. Nose to nose contact between reindeer and caribou

4. Contaminated boots of herdsmen

The correct answer is: Infected reindeer shed the parasite in feces that were ingested by snais

The correct answer pertains to the lifecycle of the parasite associated with cerebrospinal elaphostrongylosis, which is caused by the nematode *Elaphostrongylus rangiferi*. This parasite primarily resides in the central nervous system of reindeer and is transmitted through gastrointestinal means. When infected reindeer shed the larval stages of the parasite in their feces, snails that come into contact with those feces can ingest the larvae. This ingestion allows the parasite to continue its lifecycle, and subsequently, caribou may become infected by consuming the infected snails. This method of transmission highlights the role that environmental factors and intermediary hosts, like snails, can play in the interspecies spread of parasites. Understanding this transmission route is critical for assessing risks and implementing control measures. Other options, while possible ways of transmission in different contexts, do not align with the primary and established mechanisms by which cerebrospinal elaphostrongylosis is understood to spread in this situation.