Friday, April 6, 2012

The Infamous Meningeal Worm

Compiled by Terry and T. Audean Duesphol, Editors of the LAMA Letter, Newsletter of Pennsylvania Llama and Alpaca Assoc. Spring 2000

"The meningeal worm or brain worm should be (expected) wherever white-tailed deer graze lama pastures. The primary host is the white-tailed deer; the inter-mediate host is snails and slugs, and the aberrant hosts are lamas, sheep, goats, etc. The parasite may occur in any state or region where white-tailed deer roam. Larvae cause a severe reaction in the spinal column which interferes with nerve impulses causing loss of muscle control, incoordination, paralysis, and sometimes death." (Evans, C. Norman, DVM Veterinary Lama Field Manual. 1997.)
"The meningeal worm (Parelaphostrongylus) should be considered as a possible diagnosis for a down llama in the eastern United States and Canada where white-tailed deer are found. The llama accidentally ingests infective Parelaphostrongylus larvae in a snail. The worm then migrates up the llama's nerves to the spinal cord and ascends towards the brain. Serious inflammation occurs along the spinal cord in response to the worm migration. Signs begin as rear leg weakness and incoordination and can lead to complete paralysis and death. Your veterinarian should be called as soon as any signs of incoordination are seen so that prompt treatment can begin to try to save the animal's life.
Prevention includes fencing-off llamas from deer and decreasing snail populations around llamas." (Hoffman, Clare, DVM and Asmus, Ingrid: Caring for Llamas and Alpacas : A Health Management Guide, Second Edition, 1996.)
"Parelaphostrongylus is a natural parasite in white-tailed deer. This means that no disease occurs in the deer. The worm is passed from an infected deer through its feces, then develops in a snail which subsequently may be ingested by another deer. The llama or alpaca may become an accidental or abnormal host when it inadvertently eats a snail or slug containing the infective worm. Parelaphostrongylus migrates along the central nervous system thus causing neurologic abnormalities in the llama. Signs include incoordination, paralysis, knuckling or dragging of limbs, blindness, and the disease may worsen to the point of death." (Hoffman, Clare, DVM and Asmus, Ingrid: Caring for Llamas and Alpacas : A Health Management Guide, Second Edition, 1996.)

Dosages, Dosages, What to Do?
By the Duespohls

If you have been reading about parasites recently, there are a great many articles identifying exact dosages for the prevention of meningeal worm infestation. Reputable local and regional veterinarians are advocating a wide range of recommended dosages, which could totally confuse the camelid breeders. At the March PLAA meeting, Dr. Nikki Baird surprised many of the attendees by announcing that research in this area has proven that the previously accepted dosage of Ivermectin was not high enough to prevent the animals from being infected by the meningeal worm. He informed the group that the new recommended dosage was 1 mL per 70 lbs or 1.5 mL per 100 lbs.
In an effort to reinforce the importance of administrating the proper dosage of Ivermectin, Dr. David Anderson was contacted and requested to address the research occurring at Ohio State University in this area. Dr. Anderson's response to the request follows:

Parasite Research At OSU
By David E. Anderson

As you know, we have been performing parasite research fairly intensively for the past 2 years. I would like to share some of the findings we have.

Meningeal Worm Protection

Our pharmacology research indicated that the injectable Ivermectin (IVR) is absorbed well into the blood stream and provides blood levels for about 20 days. Thus, injectable IVR can be given every 30 days for meningeal worm control. Oral IVR gets absorbed less well and provides blood levels for about 12 to 14 days. Therefore, a dosing interval of 21 days is expected for oral IVR. Pour-on IVR is essentially not absorbed and would NOT be expected to provide protection against meningeal worm infection.
LAMAS Editors note: At a veterinary Conference at OSU in Dec 2004, Dr. Anderson indicated that injectable Dormectin (Dectomax) can be given at the same levels as IVR i.e. 1cc / 70 lbs, but provides blood levels longer than IVR. Therefore, Dectomax can be injected every 35-42 days. Plus it doesn't sting like IVR.

Intestinal Worm Protection

We have found that Ivermectin at 1 cc per 100 pounds body weight does not do as good a job as we would like in eliminating some intestinal worms. Of particular interest are whipworms and Nematodirus worms - these can cause severe problems including weight loss and low blood protein. At 1.5 to 2 cc per 100 pounds, we see a better response, but these two worms can persist. The same is true for Dormectin - no real difference between it and IVR.
We have found that fenbendazole (Safeguard or Panacur) given at label doses (cattle 5mg/kg, sheep 10mg/kg) does not do as well as we would expect. At 20 mg/kg we see excellent response and the whipworm and Nematodirus are controlled. Thus, we use 1cc per 100 lbs of the 10% suspension when using Safeguard. If there is an established whipworm problem, you probably need to use this product 3 to 5 days in a row!
We do not feel that fenbendazole is reliable in preventing meningeal worm infection, as is IVR. Thus, we are currently recommending that you use IVR monthly to prevent meningeal worm infection and use fenbendazole every 3-4 months to control whipworm and Nematodirus. As always, consult with your veterinarian and have fecal egg counts and parasite identification done to see what types of worms you have on the farm. This is critical to developing a FARM SPECIFIC parasite control strategy.
If you have a low stocking density, you may find that you do not need to deworm as much. If you have a high stocking density, you may find that things are getting out of control!

The Ohio State University Veterinary Hospital Treatment Plan for Meningeal Worm

This is the treatment plan for meningeal worm disease that was approved by the doctors at OSU in August 2005 for the use in a suspected case of meningeal in this area. The amounts of drugs given below are for a 350-pound llama. Dr. Anderson no longer includes the use of Dectomax or Ivomectin for the first three days of treatment because he believes that those drugs do not cross the blood/ brain barrier. However, the use of these drugs is believed to effectively kill any larvae that could be in the system to prevent them from entering the spinal cord in the first place.

Medicines and supportives:
  • Banamine - Give SQ, 3cc 2x/day for 3 days and then 1x/day for 3 days (to minimize inflammation and pain)
  • BOSE - 5cc used only once as a single injection, SQ, (to improve tissue healing)
  • Safeguard Liquid - 90cc 1x/day for 5 days (to kill infective Meningeal Worm Larvae in the spinal column)
  • Probios - 2x/day, one click each time for 7 to 10 days (to maintain a healthy stomach bacterial environment)
  • Vitamin E - At least 1000mg/day for a couple of weeks then cut back to 400mg/day for a few months (to promote muscle and tissue healing and re-growth)
  • Prilosec - (Gastroguard or Omniprosole) 1 tab crushed with treat 1x/day for 10 days (to prevent ulceration of the 3rd stomach compartment)
  • Vitamin B - Give SQ, 3cc injection, 1x/day for 2-3 days depending on situation (to promote healthy appetite and energy level and maintain thiamine levels – is especially useful in hot weather when heat stress can become a factor with a camelid that is down)
  • Gatorade - If suspected MW happens in summer, give 120cc/day for 2 days (to help maintain healthy electrolyte level) 

Physical Therapy:
  • Llama should be made to rise every 3-4 hours to maintain circulation and muscle health. Use sling device if necessary.
  • Massage the left rear leg (most compromised leg) every 3-4 hours until he is returned to a normal state of being able to rise and ambulate with minimal incoordination. This is essential to keep muscles from becoming contracted and to improve circulation to boost healing.
  • In hot weather keep as cool as possible. Monitor temperature.
  • Maintain access to cool , clean water at all times. Put water bowl where llama has free access to drink, even if llama is in sternal (cushed) position. Keep as hydrated as possible. Urinations are a good sign according to the doctor - many times the ability to urinate becomes compromised with meningeal worm. Monitor to be sure urination continues. Do not allow llama to lie in wet bedding - wet bedding can lead to urine scald.
  • Feed the best grass hay available. Observe to be sure he is ruminating (chewing cud).
  • Keep one or more of his buddies with him at all times.
  • Prayer: no need for discussion.
(This article was submitted to the GALA Newsletter Oct 05 Issue by GALA member Cynthia Rossi. If you have any questions concern-ing this article, please contact her directly.)

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