| E mac or I mac Q and A |
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by Country Animal Hospital
Questions and answers provided by Christopher Cebra, VMD, MA, MS, DACVIM Oregon State University School of Veterinary Medicine Italic comments by Country Animal Hospital (“CAH”) 1. What does E. mac look like? a. E. mac is a large coccidian, with eggs about 5 times bigger than the other alpaca coccidia and about the same size as strongyle worm eggs. It is also darker and pear/watermelon seed-shaped. 2. What percentage of North American herds have E. mac? a. Nobody knows. Prevalence was probably underestimated for years based on inadequate testing, and perhaps failure to recognize the cyst. Julie Jarvinin found it in 28% of Midwestern herds in 1999, and we find it in most herds that we sample. 3. Is it really that big a deal? a. Early reports from So. America are equivocal: Some suggest it is not that important, and others list it with E. lamae as highly pathogenic. Its lifecycle is longer that other coccidian, so it is likely that in areas where coccidian are rampant, E. lamae kills the camelids faster than E. mac. In No. America, it is the most common coccidian that we see as a cause of death. 4. Does it just affect crias? a. No. Although it can cause morbitity and mortality in all ages, we see it most commonly in adults. 5. Can it cause weight loss or poor weight gain, or should I expect diarrhea? a. The most common clinical signs are the various ill-thrift syndromes, due to enteritis and protein-losing enteropathy. Diarrhea is transient or relatively rare. More severely affected camelids also develop anorexia, weakness, occasional dysphagia (might look like drooling), and occasional neurologic signs. Blood work is also suggestive, with hypoalbuminemia and panhypoproteinemia disproportionate to any degree of anemia being the most characteristic finding. 6. What’s the best test for E. mac? a. Fecal analysis by centrifugation. ( They’ve done some studies at Oregon this past year to figure out some new details on timing of the different steps of the fecal, we won’t torture you with the findings, but we have made some changes in our protocols so that we are getting maximum “return.” The only change you may notice is that most of your results may not be available until the day after you drop them off.) 7. An alpaca recently moved from one farm to another and died. Necropsy showed E. mac, but neither farm has E. mac. Both farms have run numerous fecals and never found E. mac. Where did it come from? a. Use your common sense, it is easy to miss E. mac due to it’s long pre-patent period, poor flotation characteristics, and strange appearance. (ie, he’s saying it was missed on one of the farms rather than it appearing out of the blue). 8. Is a fecal done on admission a good way of screening incoming camelids for E. mac? a. That depends partially on the fecal analysis method, but more importantly, one must acknowledge the prepatent period. Camelids may not shed for up to 43 days. (ie they may be negative on arrival, but positive 40 days later, depending on when they were exposed to it) 9. If a herd does not have E. mac and wants to quarantine incoming camelids, how long should they be quarantined? a. Assuming reinfection does not occur (ie, good poop management), camelids infected shortly before testing can shed E. mac up to about 80 days later. Remember, they may not start shedding for up to about 43 days. Once they start, shedding can last up to about 40 days. 10. I have a good parasite control program. Is E. mac likely to be a problem? a. That depends. Many people center their control programs around P. tenuis or strongyles. Medications against these worms have no effect on E. mac. 11. If I find a few E. mac on a herd screening, what should I do? a. Congratulations, you have found E. mac. You now officially have a positive herd. Like other coccidian, a few E. mac are not a big deal, and we believe most alpacas develop immunity after exposure. If everyone’s body condition score looks OK, weight gain is good, management is good, and numbers are low, you probably don’t need to anything but basic surveillance. If anyone looks suspect, I would consider follow-up bloodwork or possibly empirical treatment for that animal. Heightened future fecal surveillance. 12. If I find few or no E. mac in a camelid showing characterisitic clinical signs (or just plain old ill-thrift) what should I do? a. This is a matter of choice, in our area it is very common, so we treat on suspicion. Remember the long pre-patent period, meaning that it can make the animal sick before the fecal becomes positive. We often repeat fecals on suspect animals every 3 days for 3-4 times, but we still usually treat on first suspicion. This is not paranoia in our area. “Suspect” camelids almost always become confirmed within a week or two. 13. What are a few E.mac? a. We don’t like to see more than 100 opg (ova (eggs) per gram) from adults or 500 opg from crias. (we at CAH will be starting to report your samples like this so you can compare numbers to these) We don’t even like to see that many, and typically consider camelids near these border points good candidates for treatment or increased vigilance. 14. Why do some camelids get sick from E.mac and others do not? a. It probably relates to ingested dose and host immunity. Camelids more likely to eat more oocysts include camelids in heavily contaminated environments, camelids who feed off ground, outcasts (eating off the ground again), and curious crias. Camelids with worse immunity include the young, old, and infirm, outcasts, new arrivals, and otherwise stressed camelids. One common history is adult females sent to breeding farms. We believe the alpaca is immunosupressed from shipping and stress, and potentially exposed to new, infected animals. Alternatively, an alpaca with an ongoing infection may just become more sick because of the immunosuppression. 15. How do we treat E. mac as a preventive? a. Sulfa and Amprolium (eg Corid) may play some role. Decoquinate milled into other feeds appears to also be safe and effective. 16. How do we treat E. mac in sick camelids? a. Oral sulfas (Country Animal Hospital recommends using the injectable Albon 40% and give it by mouth at a rate of 1 cc per 30 lb body weight for 5-10 days) or Amprolium (We use Corid 9.6% undiluted for ease of administration at 1 cc per 15 lb body weight by mouthfor 5 to 10 days. If you treat over 5 days, also give Vitamin B complex at 3 cc per 100 lb every day) are the most established treatments. Both work best against the younger stages of the parasite and hence will not immediately decrease fecal shedding. Triazines (ponazuril and others) have also been used and appear to work, though the dose is still up in the air. Doses of anywhere from 5 to 20 mg/kg of ponazuril have been suggested by various sources (At Country Animal Hospital, we usually use Marquis and give 1.5 ml per 50# body weight for 3 days). Remember that the equine form does not guarantee homogeneous distribution of the medication through the paste. (Because of this, you need to squirt the tube out, mix well, then draw up the amount you need out of the mixed sample). Some people dilute it with water because of anecdotal reports that it is caustic. 17. Do we treat everyone or just clinical/shedding camelids? a. This is dependent on the level of concern and the previous management. In a well-managed herd with low counts, no one may require treatment. In a herd of unknown history, or with clinical cases arising, or of suspect management (lack of previous screening, high numbers of high-risk animals, lack of coccidial control program), a proactive, mass treatment may prevent losses. In general, camelids housed with high-degree shedders or clinical camelids become good candidates for increased vigilance, including physical exams, weight and/or body condition scoring, and possibly bloodwork. 18. Should we treat new arrivals? a. Their stress may make them more susceptible, but no known treatment completely eliminates shedding. Ponazuril (eg Marquis) has the best shot at this, but has not been tested. When a new arrival comes on the farm, she could (a) bring E. mac with her, or (b) become infected with E. mac at your farm. If she sheds eggs in less than 33 days, she brought it with her. If she sheds longer than about 40 days, she got infected on your farm. Between 33-40 days is the grey zone. If you are trying to treat possibility (a), treatment on admission during the quarantine period makes the most sense. If you are trying to treat (b), waiting about 2 weeks makes sense. We have seen alpacas die within 20 days of exposure, so you don’t want to wait that long! Additionally, a fecal done within a few days of admission will show what the animal was shedding on arrival, but you need a fecal done at about 30 days (and before 33 days) to say if the alpaca brought E. mac with it or not. The 30 day test would be for an insurance type issue to demonstrate that a complication came with the animal, rather than was caused by “negligence.” (We will summarize specific farm plans at the meeting) 19. How do we eliminate E. mac? a. Thermonuclear devices. We generally cannot eliminate parasites, only control them. With its thick cyst wall and lack of a free-living stage, E.mac is probably more resistant to most environmental stresses than other coccidian or nematodes. 20. How do we control E.mac? a. Hygiene is paramount. The shed oocyst does not sporulate (and become infective to the animal that eats it) for approximately 13 to 21 days, meaning weekly poop removal could eliminate most of the danger. Feeding off the ground also should decrease risk, but is impractical in camelids on pastures. Young crias are the biggest shedders (so, pay extra attention to poop pick-up in the cria/weanling areas, try not to house immunosuppressed animals in those areas, and pay a lot of attention to visiting crias—not just to their moms that you are trying to get bred!) "A friendly reminder: You and your veterinarian are ultimately responsible for the care of your alpacas. All drug dosages should be confirmed prior to using medications unfamiliar to you." Add this page to your favorite Social Bookmarking websites       |
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