E. mac Coccidiosis

E. mac is shorthand for Eimeria macusaniensis, a single-celled parasite that lives in the gut of New World camelids: alpacas, llamas, guanacos and vicuñas. Camelids carry several species of coccidia, the group name for these parasites, and most of them cause little trouble in a healthy adult. E. mac is the exception. It settles into the intestinal lining, particularly toward the ileum, and destroys the cells there, so an affected animal loses nutrients and blood protein through a damaged gut wall even while it may still be eating. Animals become infected by swallowing oocysts, tough egg-like stages shed in manure that need time outside the body before they become infective, and that can then linger on pasture, feed and water for a good while afterwards.

What sets E. mac apart from the smaller camelid coccidia is that it isn't only a disease of youngsters. It was once thought of mainly as a cria problem, but it's now recognised as a cause of illness and death in camelids of any age, a point underlined by a case series of 15 llamas and 34 alpacas published in the Journal of the American Veterinary Medical Association. Even when treated, mortality has been reported as high as 50 percent, and serious illness can take hold in the weeks before any oocysts appear in the droppings. That means a single clean faecal test doesn't rule the disease out: some camelids have shown prolonged weight loss with no oocysts ever detected on flotation before they died, which is why vets often repeat testing in an animal that's doing badly for no obvious reason.

Reasons to get a camelid seen promptly include:

• losing condition or weight despite a normal appetite
• dullness, quietness or going off feed
• soft manure or diarrhoea, or signs of belly pain such as repeated lying down and getting up
• fluid swelling under the jaw or along the belly, which can point to low blood protein
• a sudden death in the group, which is reason enough to check the rest

Diagnosis and treatment

Vets diagnose E. mac by finding its oocysts on faecal examination. They are unusually large and dense, so the lab needs a flotation solution strong enough to float them, and blood work often shows low protein from the gut damage. Once the parasite is confirmed, the Merck Veterinary Manual describes treating with the anticoccidial drug ponazuril followed by a course of a sulfonamide antibiotic. Related triazine drugs such as toltrazuril act on the same parasite life stages and are used against coccidiosis in other species. Which products are available for camelids and how they may be prescribed differs by country, and much of this use is off-label, so it's a decision for your vet rather than something to source yourself. Sick animals often need fluids, nursing and nutritional support alongside the drug itself.

Day to day management matters as much as medication. Overstocking and poor body condition go along with heavier coccidia burdens, so sensible stocking density, feeding off the ground, clean water and prompt manure removal all cut the load animals face while their own immunity develops. Stress around weaning, transport and birth seems to raise the risk too, so easing those transitions helps. New arrivals are worth quarantining with repeat faecal testing over the following weeks rather than trusting one clean sample, and treatment is best guided by testing rather than dosing the whole herd as routine.

This is general information. If a camelid in your care is losing condition or scouring, a vet with camelid experience is the right next step.