E. mac Coccidiosis

E. mac is shorthand for Eimeria macusaniensis, a microscopic single-celled parasite that lives in the gut of New World camelids: alpacas, llamas, and their wild relatives. Camelids carry several species of Eimeria, a group of parasites known collectively as coccidia, and most of them cause little trouble in a healthy adult. E. mac is the exception, and it is considered the most damaging of the camelid coccidia. It multiplies inside the cells lining the small intestine and destroys them, so an affected animal loses nutrients and blood protein through a damaged gut wall even while it is still eating. Animals pick it up by swallowing oocysts, tough egg-like stages shed in manure that survive well on pasture and contaminate feed and water.

What makes E. mac different from the smaller camelid coccidia is that it is not just a problem of youngsters. A case series of 15 llamas and 34 alpacas published in the Journal of the American Veterinary Medical Association included animals from three weeks to 18 years old, and 19 of them arrived at the clinic already dead. The signs are frustratingly vague: dullness, weight loss, poor appetite, and diarrhoea that may or may not be present. It also has an unusually long development time inside the body, and disease or death can occur up to two weeks before any oocysts show up in a faecal sample. A single clear faecal test therefore does not rule it out, which is why vets often repeat samples in an animal that is doing badly for no obvious reason.

Reasons to get a camelid seen promptly include:

• losing condition or weight despite a good appetite
• unusual quietness, separating from the herd, or reluctance to get up
• going off feed
• soft manure or diarrhoea, or straining and signs of belly pain such as teeth grinding or repeated lying down and rising
• fluid swelling under the jaw or along the belly, which can point to low blood protein
• a sudden death in the group, which is a reason to check the others

Diagnosis usually combines faecal examination, where the large dark oocysts are recognisable under the microscope, with blood work that often shows low protein. The Merck Veterinary Manual advises treating promptly once E. mac is found on a faecal test, because infection can leave an animal badly debilitated, and describes treatment with the anticoccidial drug ponazuril followed by a sulfonamide antibiotic. Related drugs such as toltrazuril are also used. Which products are licensed and how they may be prescribed differs from country to country, and much camelid use is off-label, so this is your vet's call rather than something to source yourself. Sick animals often need fluids, nursing and nutritional support alongside the drug.

Day to day, management does more than medication. Keeping stocking density sensible, picking up manure, feeding off the ground, providing clean water, and easing stress around weaning, transport and birthing all reduce the parasite load animals face while their own immunity builds. New arrivals are worth quarantining with repeated faecal checks over the following weeks. Routine dosing of the whole herd is discouraged, since it encourages resistance and gives animals less chance to develop immunity of their own.

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.