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Cystericercus bovis (C. bovis) – tapeworm cysts in cattle

Cystericercus bovis (C.bovis) is rare in New Zealand. It is the larval form of a parasitic tapeworm that infests the muscles of cattle and is caused by cattle ingesting eggs of the human tapeworm Taenia saginata. The parasite cannot be spread from person to person, or between cattle. Humans are infected with Taenia saginata by ingesting raw or inadequately cooked beef containing viable tapeworm cysts.

How do cattle become infected?

Cystericercus bovis is the larval stage of Taenia saginata, a species of tapeworm found in humans. Infected people can shed as many as one million tapeworm eggs each day in faeces. Cattle become infested by ingesting materials contaminated with tapeworm eggs from human faeces. The eggs hatch and the embryos work their way into the cattlebeast’s muscle tissue, where they develop into larvae and form cysticerci, or "cysts". These cysts can remain viable and infective for several months to 2 years, perhaps longer.

Humans can become infected with the tapeworm stage by ingesting raw or inadequately cooked beef containing cysticerci. The tapeworm eggs, which are the infective stage for cattle, are vulnerable to hot, dry conditions but can survive months under wet, cool conditions. They are also resistant to a number of common disinfectants.

What are the clinical signs?

Cattle with Cystericercus bovis are unlikely to present any clinical signs. Diagnosis relies on detection of lesions or cysts during carcass inspection.

What controls are in place to control C.bovis?

The Animal Products Act 1999 requires inspection of all beef for any sign of disease after slaughter.

It is unusual for tapeworm cysts to be discovered during meat inspection in New Zealand. If any sign of disease is found, the carcass is removed and the suspect lesions or cysts are sent to the laboratory for confirmatory diagnosis. If a carcass tests positive for C.bovis the meat is frozen on-site for at least 20 days to kill the parasite before being declared safe for human consumption. This process meets accepted international standards. In the rare cases where there is extensive infection the entire carcass is removed and destroyed.

What happens if a number of carcasses from the one farm are infected?

When inspection indicates a number of animals from one farm are involved, an investigation will be initiated. This may include controls on the movement of animals from the farm. Cattle from the same farm may be subject to intensified inspection when slaughtered and meat may be condemned if an excessive number of cysts are detected. Meat from a farm suspected to be infected will also be frozen as an added precaution.

How common is C.bovis in New Zealand?

New Zealand has a very low prevalence of C.bovis which is endemic to most countries. We have agreements with the EU, Canada and the US to modify (increase) inspection where the disease is found.

How can I protect my cattle from C.bovis?

Avoiding human faecal contamination of cattle feed and water is the best preventative measure. In New Zealand, human sewage is not permitted to contaminate any pasture for any animal. Farmers should check they have adequate and well maintained sewage disposal facilities.

Farmers should ensure farm workers are aware of disease threats and encourage them to exercise good on-farm hygiene practices. If a farm worker or family member is suspected of being infected with human tapeworms, advise them to seek medical treatment.

Related Links

• Taenia saginata – beef tapeworm in humans

Disclaimer:

This publication is not a legal interpretation of the Animal Products Act or the Animal Products (Ancillary and Transitional Provisions) Act and is intended only as a guide.

[Updated June 2009]