CYSTICERCOSIS : BACK TO BASICS

According to the World Health Organization, taeniosis occurs in some 50 million people and kills roughly 50 000 humans per year, almost exclusively due to Taenia solium of pigs. Besides this, many more patients survive but are disabled by various forms of cysticercosis.

The South African Beef Industry alone suffers a huge R20 million loss per year for condemned and retained beef carcasses. It should also be kept in mind that many of the animals slaughtered for human consumption are not inspected, so the true prevalence of the disease is not known. Particularly in the case of pork this is very dangerous, since few if any of the bush butchers will condemn even a heavily infected carcass.

In man, the adult beef tapeworm causes diarrhoea, hunger pains, loss of weight, abdominal pain and dizziness. There is also an uncomfortable itchy sensation as the ripe segments crawl out of the anus. The pig tapeworm is a much greater threat for humans, because the measles commonly develop in the nervous system, causing neurocysticercosis

Although drugs are available to effectively treat humans, it is too expensive to treat cattle and pigs because very high doses of praziquantel are needed.

Serological tests have been investigated at the Onderstepoort Veterinary Institute to detect measles in the live animal. Subject to satisfactory results and the necessary findings, it is envisaged to implement a diagnostic kit as a pre-slaughter screening technique for detecting measles in cattle and pigs as well as to implement this kit as a management tool to control/prevent cysticercosis in cattle and pigs.

Rapid diagnostic test: Many cyst-like objects are, for various reasons, being incorrectly identified as "probable" cysticerci at slaughter, causing carcasses to be retained or condemned, thus leading to grave financial losses to feedlot owners and farmers alike. Even a single cyst or suspected calcified cyst must lead to detention of the carcass, as there may be viable cysts elsewhere in the muscles. A possible solution to these problems is to develop a rapid, sensitive and specific diagnostic test to determine more or less immediately whether the suspicious structures encountered at inspection are in fact cysticerci.

Vaccine: Non-living antigens have been found to be effective in preventing infection with this group of tapeworms. Dr Lightowlers from Australia has produced a vaccine that induces up to 99.8% protection against experimental challenge infection with Taenia saginata eggs. This vaccine can be obtained from Dr Lightowlers for evaluation in South Africa and there are currently negotiations underway to determine the feasibility of such a research project. 

The way forward: The control measures are not only basic but also inexpensive with the exception of anthelmintics for animals. So why then do we still have a problem with cysticercosis? Basic control measures include providing toilets for the staff, educating staff and their families on the transmission of measles, deworming workers and their families on a regular basis, cooking meat well and buying meat from registered butchers.

Research into serodiagnostic tests and vaccines will continue and will assist in the eradication of these diseases, but without the basics acting as a strong foundation, controlling these parasites will not be an easy task.