Whitetails carry brain worms that can be fatal to moose.
QUESTION: I live in southern Maine, and someone told me the reason we don’t have more moose where I live is because they get a brain worm from deer. If that’s true, why doesn’t it kill deer too? — Todd H.
ANSWER: What you’re referring to is a parasitic nematode Parelaphostrongylus tenuis sometimes called a meningeal worm, or brainworm. White-tailed deer are, indeed, a host, but over eons have developed an immunity to it. Because moose occur primarily north of the parasite’s natural range, they have not developed immunity, and increased rates of infection occur where deer and moose range overlap.
The parasite has a complex life cycle but eventually ends up in the meningeal tissue of the central nervous system — brain and spinal cord — of a moose. Mild symptoms begin with slower movements and response time, frequent stumbling, an unusually tilted head and emaciation.
As the infection spreads, symptoms progress to include extreme weakness, lameness, walking in circles, partial or whole blindness and a loss of fear for humans. In most cases the moose eventually dies, either directly from infection or as a result of its weak and vulnerable state.
— Photo Courtesy of NYSDEC
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