Neurocysticercosis
In April, a woman from Arizona underwent 6 hours of surgery to remove a parasite lodged in her brain. Her doctors believe that Taenia solium (pork tapeworm) entered her body 3 years previously, when she ate a pork taco while visiting Mexico. After eating, she fell ill for 3 weeks. Soon after, she began to experience violent seizures. Doctors determined that she had neurocysticercosis.
"Neurocysticercosis (NCC) occurs when humans inadvertently become the intermediate host for the pork tapeworm, Taenia solium. Under normal circumstances, the adult T. solium organism lives in the human intestine, and gravid proglottids [segments comprising the body of a tapeworm] and ova [eggs] are passed in the stool. Ingestion of these ova by pigs results in the development of larvae, which invade body tissues such as muscle. There, the larvae encyst and mature into a scolex, which represents the head of an adult worm. Eating undercooked pork by humans releases the scolex, which attaches to the intestinal wall, thus competing the life cycle by producing a new tape worm infestation. If humans inadvertently ingest ova [due to poor sanitation — the ova are present in the feces of infected humans], larvae may encyst in the central nervous system (CNS), producing NCC."
"In developing countries, where NCC is the most common parasitic disease of the CNS, it accounts for 10% of all acute neurologic cases. Epilepsy is the most common manifestation of NCC, occurring in 2/3 of affected patients. In Mexico City, NCC is the cause of seizures in 50% of adult-onset epilepsy."
[Labar DR and Harden C. Epilepsy - A Comprehensive Textbook. Chapter 248. p2591.]
In 1993, the World Health Organization's International Task Force for Disease Eradication declared Taenia solium (the pork tapeworm) a potentially eradicable parasite, for the following reasons: 1. the life cycle requires humans as definitive hosts;
2. tapeworm infections in humans are the only source of infection for pigs, the natural intermediate host;
3. the transmission of infection from pigs to human beings can be controlled;
4. no reservoir for infection exists in wildlife.
It is therefore expected that the strategic use of anthelmintics against the adult parasite in people and the larval parasite in swine, combined with health education and regulation of pig slaughter, is sufficient to interrupt transmission, but this approach has yet to be proven in practice.
Taeniasis (infestation by the tapework) and cysticercosis (encysted larvae in muscle) do not lead to sudden large-scale international outbreaks of disease and therefore would not seem to constitute an appropriate subject for international notification. Nevertheless, health ministries should be strongly encouraged to set up national surveillance and reporting systems, and adopt a more active approach towards prevention and control of these diseases.
Sources
The EYiE Daily News
http://www.eyie.org
(http://w1.461.telia.com/~u46118963/news/newsframe.html)
"Control of Neurocysticercosis — Report by the Secretariat"
World Health Organization Document A55/23 ea5523.pdf
April 2002
http://www.who.int
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