(tapeworm) Taenia solium (pork tapeworm) is the main cause of
human cysticercosis. In addition, the larval stage of other Taenia
species (e.g., multiceps, serialis, brauni,
taeniaeformis, crassiceps) can infect humans in various sites
of localization including the brain, subcutaneous tissue, eye, or liver.
an infection of both humans and pigs with the larval stages of the
parasitic cestode, Taenia solium. This infection is caused by
ingestion of eggs shed in the feces of a human tapeworm carrier .
Pigs and humans become infected by ingesting eggs or gravid proglottids .
Humans are infected either by ingestion of food contaminated with feces,
or by autoinfection. In the latter case, a human infected with adult
T. solium can ingest eggs produced by that tapeworm, either through
fecal contamination or, possibly, from proglottids carried into the
stomach by reverse peristalsis. Once eggs are ingested, oncospheres
hatch in the intestine ,
invade the intestinal wall, and migrate to striated muscles, as well as
the brain, liver, and other tissues, where they develop into cysticerci.
In humans, cysts can cause serious sequellae if they localize in the
brain, resulting in neurocysticercosis. The parasite life cycle is
completed, resulting in human tapeworm infection, when humans ingest
undercooked pork containing cysticerci .
Cysts evaginate and attach to the small intestine by their scolex .
Adult tapeworms develop, (up to
m in length and produce less than 1000 proglottids, each with
approximately 50,000 eggs) and reside in the small intestine for years .
Distribution: Taenia solium
is found worldwide. Because pigs are intermediate hosts of the
parasite, completion of the life cycle occurs in regions where humans
live in close contact with pigs and eat undercooked pork. Taeniasis and
cysticercosis are very rare in Muslim countries. It is important to
note that human cysticercosis is acquired by ingesting T. solium
eggs shed in the feces of a human T. solium tapeworm carrier, and
thus can occur in populations that neither eat pork nor share
environments with pigs.
Features: The symptoms of
cysticercosis are caused by the development of cysticerci in various
sites. Of greatest concern is cerebral cysticercosis (or
neurocysticercosis), which can cause diverse manifestations including
seizures, mental disturbances, focal neurologic deficits, and signs of
space-occupying intracerebral lesions. Death can occur suddenly.
Extracerebral cysticercosis can cause ocular, cardiac, or spinal lesions
with associated symptoms. Asymptomatic subcutaneous nodules and
calcified intramuscular nodules can be encountered.
Diagnosis: The definitive
diagnosis consists of demonstrating the cysticercus in the tissue
involved. Demonstration of Taenia solium eggs and proglottids in
the feces diagnoses taeniasis and not cysticercosis. While suggestive,
it does not necessarily prove that cysticercosis is present. Persons
who are found to have eggs or proglottids in their feces should be
evaluated serologically since autoinfection, resulting in cysticercosis,
detection provides a useful adjunct in specific diagnosis.
Treatment: Infections are
generally treated with antiparasitic drugs in combination with
antiinflammatory drugs. Surgery is sometimes necessary to treat
infection in the eyes, cases that are not responsive to drug treatment,
or to reduce brain edema. Not all cases of cysticercosis are treated
and the use of albendazole and praziquantel is controversial.