What is the Moniezia expansa?
It is a tapeworm (a parasite) whose subsistence resembles, likely as a lottery...
Having several stages of growth, Moniezia eggs must be absorbed first by an intermediate host (a Oribatid moth; a small moth that lives on the prairies and especially if they are moist).
The eggs have little time before they dry out. On the other hand, once absorbed by the oribatid, they can coexist until 2 years!
The infected moth eaten by a mammal (an alpaca!), in pastures, allows the Moniezia to implant itself in the digestive tract, well attached to the walls with plunger.
The Moniezia then feeds on its host's predigested nutrients until the worm reaches adulthood. The worm can, at the end, measure several meters (I read up to 10 m!).
It is said that about 3% of the moth in a pasture may be infected; But at the scale of millions of moth, including several thousands ingested per kg of grazing, it is rather difficult to completely miss out on this annoying parasite when it is present on a land...
Between 6 and 16 weeks later, once grown, the worm produces triangular eggs of about 55 microns that fall by the thousands with the animal's feces in "proglotides", or segments of the body of the Moniezia (resembling a grain of rice)...
Moniezia would not really cause physical damage to alpaca, except in severe cases of infestation where it can cause diarrhea and slimming. It is also assumed that crias or the already diseased animals could have complications more easily. The rare cases of death by Moniezia would be due to obstruction of the intestine.
The Moniezia is treated with deworming containing fenbendazole (Safeguard or Panacur).
Should we treat the Moniezia or not?
Many veterinarians around the world regard Moniezia as a very secondary problem since it usually does not lead to serious problems.
How to prevent the appearance of the tapeworm in alpacas?
The treated animals reject the eggs, so naturally recontaminate the pasture. So it's hard to get rid of it completely. It seems that a pasture where there would previously have been sheep could be much more infested than another.
Drought in a pasture reduces the amount of moths as an essential intermediate host and dries out Moniezia eggs (within a day); So there are times and places where the risks are not so great.
Good pasture development could also help (this is what is recommended for sheep). The articles read are contradictory in relation to some immunity after contamination. It seems that the sheep develops it... on my side, it has never happened that an alpaca catches it more than once...