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Snails Pose Health Risk for Llamas and Alpacas


Pet Column for the week of August 31, 2009

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Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Ashley Mitek
Information Specialist

Source - Varsha Ramoutar
It's hard to believe that those slow-moving slugs and snails you find in your garden can harbor a deadly parasite. Meningeal worm, or more formally Parelaphostrongylus tenuis, pass their eggs in white tailed deer feces. Snails pick up these eggs and allow the parasite to complete its life cycle. The white tailed deer is the natural host for the parasite, but camelids (alpacas and llamas) are not. A hungry alpaca grazing a field of lush pasture might not even notice it has accidentally taken a bite of a gourmet meal of deadly worms.

Dr. Varsha Ramoutar recently completed a residency in large animal internal medicine at the University of Illinois Veterinary Teaching Hospital in Urbana. She says, "we most commonly see meningeal worm infection in the spring and fall, but it can occur anytime." During the summer, when temperatures are soaring, heat stress can also worsen the problem in down animals.

How the worm infects its host sounds like a scene out of a sci-fi movie. After the alpaca ingests a contaminated snail or slug, the meningeal worm migrates through the animal's spinal cord and central nervous system and gets lost. It's called the meningeal worm because the meninges are the layers of thin material that surround nervous system tissue.

As one might expect, a worm crawling through a spinal cord inflicts damage to the fragile structure and causes neurological signs and symptoms. "These patients typically present to us at the clinic as recumbent animals unable to stand," notes Dr. Ramoutar. Although there are many reasons why an alpaca may have an abnormal gate or be unable to move, meningeal worm infection is tentatively diagnosed if the alpaca has unusual neurological behavior with an abnormal cerebral spinal fluid (CSF) tap.

Even with these diagnostics, a veterinarian cannot officially diagnose meningeal worm unless a necropsy (autopsy) is performed. But that doesn't mean that animals contracting the parasite may not survive.

Owners can have a vital role in the prognosis for their animal by early detection. Dr. Ramoutar advises "If you notice your alpaca or llama walking abnormally, stumbling, having a difficult time getting up, acting blind or appears depressed or acting strangely--which can be subtle--contact your veterinarian and seek help. The earlier the animal is treated the better."

Even if an animal survives, "there may be some scarring in the brain and spinal cord," notes Dr. Ramoutar. But she goes on to mention that despite having minor neurological deficits, these animals can still become productive members of a breeding herd.

One way to prevent alpacas from contracting the disease is to fence the entirety of your property to keep deer out. This can also be coupled with a vegetation free zone covered with gravel greater than 6 feet wide on the inside perimeter of the fence and can also act as fire zone. One can also have ducks on the property, who act as a biological control by feeding on the snails. Lastly, talk to your veterinarian about developing a monthly or regular deworming program that will drastically reduce the chance of your camelids succumbing to the disease.

On a final note, llamas and alpacas aren't the only animals that can contract a meningeal worm infection. Nearly a century ago people noticed that occasionally a moose would be found walking in a constant circle. This disease later became known as "moose sickness," which is the same as meningeal worm infection.

For more information on meningeal disease and its prevention, contact your local veterinarian.