To Deworm or Not to Deworm… the Meningeal Worm Question

By Lindsay Chandler

In this issue, I have featured articles about the meningeal worm, what it is, how it spreads, it affects our llamas, and what to do if an animal gets it. I admit I used to be pretty lax about my routine. We've had llamas for 20 years, we have deer, and we have wet pastures. For a long time, it did not seem as if our deer had the worm. Very few cases occurred in this area. This all changed a few years ago, when I started hearing about losing llamas and alpacas to this parasite. The scariest concern to me was the fact that the cases happened in January & February. I had always done my last shots in November, after the ground froze and when my llamas were in their winter barn, then I would wait until May to start the shots again. How can the animal get it in February?? The slugs should be deep in the soil or frozen!! This is a question yet to be answered. Can the parasite survive in the animal, wait until Ivermectin is out of its system, then attack?? Can it be in the hay?? Or are we dealing with something else?? Often, a case of meningeal worm infection occurs after we slip a little on our shot routine. If the whole herd is behind on shots, the whole herd is eating in the same pasture, and the deer scatter their pellets, with lots of slugs around... Why do we have only 1 case out of a herd of 30?? I rarely hear about more than 1 case occurring in a herd at one time. It is almost as if it is "luck of the draw" (or unluck). I personally feel there are still many questions concerning this parasite, but I now give shots to the whole herd every 5-6 weeks faithfully, and continue all winter.

So the next worry is about parasites becoming resistant. When the Ivermectin type drug first hit the market, we were told that the way it worked, there was no chance of the parasite building a tolerance to the drug... but my belief was and is Nature Will Find a Way. Years ago, there were rumors of parasite resistance in Oregon, but not much was said about it. If you have meningeal worm, you have to use this chemical. What else can we do?? I'm afraid what else can happen has begun. For the whole story, check out the new issue of LLAMA LIFE II, winter 2005-06 Issue 76. The article is “Dewormer-Resistant Parasites Threaten Herds, a Georgia Breeder Fights Back,” by Gayle M. Woodsum. To summarize the information, the recipe for disaster was:

1. Excessive rain, causing the parasites to float to the top of the pasture grazes.
2. Heat lingering into September. The llamas thus congregated near fans, creating congestion and fewer dung piles, thus the parasites gathered also.
3. Resistance to dewormers. The parasites that infected this ranch were "haemonchus, a particularly deadly, blood sucking stomach parasite, and coccidia, a protozoan parasite known to inhabit wet areas with congested animal conditions, and usually problematic in young or previously compromised llamas." This ranch, with many years of a healthy herd that never had a case of coccidia before, now became a "helpless victim." This farm, through the diligence and work of the owners and vets, took "all the factors they had discovered about their situation, including knowledge of their own llamas, and step into action for both the short and long term".

For short term saving the infected animals, check out the article.

Long Term Answers

• Find the parasites. Regular microscopic checking of each individual's feces is mandatory, treating the animal with parasites, not a blanket procedure for the whole herd.
• Consider changing deworming products.
• In areas where white-tailed deer thrive, you must still utilize the prescribed treatment for meningeal worm prevention. This ranch has chosen to not give shots as frequently as in the past. They have added a perimeter fence. (Editor’s Note: Poultry, ducks and guinea hens are also great to keep populations down.)
• Be fastidious in deworming procedures. The "llamas to be dewormed are fasted the night before and not fed until the afternoon following administration of the dewormer. They are kept on a dry lot for 24 hours following treatment."
• Increase quality and type of feed supplements. "Hay with high tannins present is mixed into hay consumed by the entire herd." Results of research on small ruminants state that, "short term consumption of a forage containing condensed tannins reduces fecal parasite egg output". Working with experts, they also designed a new mineral mix including extra vitamin C &B, thiamine, detoxins and probiotics Cleanliness is crucial. Enough said!

I highly suggest that everyone read the original article. So, what to do? We do need to treat for the meningeal parasite… I guess it is a gamble and each owner gets to choose. Deworm less frequently, and see if one of your animals gets the parasite, or deworm every 5-6 weeks, but chance resistant parasites later… To deworm or not deworm, that is the question.