Cysticercus bovis is the larval stage (cysticercoid, metacestode) of Taenia saginata, a human tapeworm parasite, that has cattle, buffaloes, llamas, and various wild ruminants as intermediate hosts.
Cysticercus bovis occurs worldwide, mainly in poorly developed rural regions with insufficient sanitary conditions.
The disease caused by this and other cysticercoids is called cysticercosis. In this particular case it is also called beef measles.
Cysticercus bovis does not affect dogs, cats, horses, sheep, goats, swine or poultry.
Is livestock infected with Cysticercus bovis contagious for humans?
YES. Humans can become infected with Taenia saginata tapeworms after eating uncooked meat or other tissues from infected cattle or buffaloes. Simple contact with the animal or its feces is not contagious. See the life cycle below.
Final location of Cysticercus bovis
Cysticercoids of Taenia saginata are found mainly in the muscles of cattle and buffaloes. The predilection site of adult tapeworms in their human hosts is the small intestine.
Anatomy of Cysticercus bovis
In cattle Cysticercus ovis appears as small whitish cysts filled with fluid that contain an immature worm. They have the size of a pea (5 to 8 mm). Infected beef can have dozens of such cysts. They are found mainly in the muscles of the heart, the diaphragm, the tongue, and the jaws. Several months after infection the cysts die and become calcified.
Visit the page on Taenia species for additional information of the anatomy of adult Taenia tapeworms.
As all tapeworms, Taenia saginata has an indirect life cycle, with humans as final hosts, and cattle, buffaloes and other bovids as intermediate hosts.
Cattle become infested when ingesting food or water contaminated with eggs or gravid segments of Taenia saginata. Contamination of cattle feed can occur through undue defecation of humans in the pastures or stables, but also indirectly through irrigation with contaminated human sewage. The eggs can remain infective for more than six months.
Once ingested by cattle the young larvae hatch out of the eggs in the gut, go through the intestinal wall, reach the blood stream and migrate to a muscle, where they encyst. The cysts need 10 to 12 weeks to complete development. The cysts may remain infective for humans for up to one year.
Humans become infected when eating insufficiently cooked meat contaminated with cysts. Once in the human gut, the cysts release the young tapeworm, which attach to the gut's wall and start producing segments. Within 5 to 12 weeks the tapeworms mature and start shedding eggs (prepatent period).
Harm caused by Cysticercus bovis, symptoms and diagnosis
Cysticercus bovis is not pathogenic for cattle and usually the infection causes no clinical signs, unless a vital organ (e.g. the heart) is massively infected, which is very unsusual. In case of massive infections muscle stiffness has been reported. However, infections have a substantial economic impact because the whole carcass is condemned at slaughter. This is needed to prevent that humans become infected when consuming beef insufficiently cooked.
So far diagnosis on cattle is only possible post-mortem after carcass examination.
Human infections with Taenia saginata are usually benign. They can cause diarrhea and loss of appetite, but they often cause no clinical signs.
Prevention and control of Cysticercus bovis
Although beef measles is not harmful for cattle, prevention is important to avoid transmission to humans and carcass condemnation at slaughter.
Best prevention consists in avoiding the contamination of cattle feed (fresh pasture as well as hay and silage, etc.) or water with human feces that may contain tapeworm eggs. This requires providing adequate latrines for workers and ensuring that sewage water used for pasture irrigation is not contaminated. It must be considered that the eggs may remain infective in the feed after silage or other processing of hey or fodder (pelletizing, fermentation, etc.).
The regular use of anthelmintics is usually not indicated to prevent cattle infections with Cysticercus bovis. There are reports that albendazole, ricobendazole and praziquantel, are effective, but often at dose significantly higher than the therapeutic one, and results can be unreliable.
Several classic livestock anthelmintics such as macrocyclic lactones (e.g. ivermectin, selamectin, etc.), levamisole, tetrahydropyrimidines (e.g. pyrantel, morantel) and piperazine derivatives are not effective at all against Cysticercus bovis or whatever adult tapeworm or cysticercoid.
There are so far no vaccines that would protect cattle against Cysticercus bovis. A lot of research is being done in the development of a vaccine against beef measles, but so far there are no commercial vaccines in most countries.To learn more about vaccines against parasites of livestock and pets click here.
Biological control of Taenia tapeworms respectively Cysticercus bovis (i.e. using its natural enemies) is so far not feasible.
You may be interested in an article in this site on medicinal plants against external and internal parasites.
Resistance of Taenia spp to anthelmintics
So far there are no reports on resistance of Taenia spp, respectively Cysticercus bovis to anthelmintics.
This means that if aa anthelmintic flukicide fails to achieve the expected efficacy, chance is very high that it is not due to resistance. Either the product was used incorrectly or it was unsuited for the control of these parasites. Incorrect use is the most frequent reason for failure of antiparasitic drugs.
Ask your veterinary doctor! If available, follow more specific national or regional recommendations for Cysticercus bovis control.