Preventing the fecal contamination of soil around houses or where
vegetables are grown
Thoroughly cooking or otherwise disinfecting all vegetables before
eating them, especially in areas of the world where "night soil" is used as fertilizer
b. Tapeworms (Taeniasis)
(1) Identification. There are several tapeworms (Cestoda) that affect man.
The two most common of these parasites are the beef tapeworm, Taenia saginata,
which is widely distributed in the United States; and the pork tapeworm, Taenia solium,
which is rare in the United States. However, they are common in Mexico, Peru, East
Africa, and Eastern Europe. The disease caused by these helminths may occur in two
forms: one is taeniasis, a harmless intestinal infestation that is nonfatal and often
asymptomatic; the other is a severe disease of high fatality, known as cysticercosis.
(2) Life cycle. The life cycles of both T. saginata and T. solium require an
intermediate host, except that eggs of T. solium may be passed from man to man.
The adult worm lives in the intestine of man, and eggs are passed
with the feces.
When cattle, in the case of T. saginata, or hogs, in the case of T.
solium, eat grass or other foodstuffs contaminated with the feces of infected humans,
the eggs are ingested and hatch in the intestines of the animal.
The larvae, upon emerging from the eggs, migrate to the striated
muscles, where they encyst.
When man eats infected beef or pork, which has been improperly
cooked, the encysted larvae develop into adult worms.
Normally, only one worm reaches maturity, but it may remain in the
intestine for 30 to 40 years if untreated, reaching a length of up to 10 meters (T.
saginata) and producing eggs as long as it lives.
(3) Clinical symptoms. The clinical symptoms of infestation by the adult
worm may be absent but, when present, include:
Loss of weight
(4) Incubation period. The incubation time is from 8 to 10 weeks.