Cysticercosis and echinococcosis Paul R' Earl Facultad de Ciencias Biolgicas Universidad Autnoma de

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Cysticercosis and echinococcosisPaul R.
EarlFacultad de Ciencias BiológicasUniversidad
Autónoma de Nuevo LeónSan Nicolás, NL 66451,
Mexico
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Tapeworms (cestodes) are parasites of the
intestinal tract whose simple life cycle requires
at least one intermediate host. They are long,
flat worms that have a scolex or sucker located
on the head, armed with hooks or not. The
cestodes that cause significant human disease
include Taenia saginata of cattle, Taenia solium
of pigs, Hymenolepsis nana of mice and others,
and Diphyllobothrium latum of fishes. The latter
2 members of the Cestoda are not considered
further here.
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T. saginata, the most common tapeworm in humans,
is found wherever raw or undercooked beef is
eaten, especially in Africa and the Arab world In
certain cultures where raw beef is considered a
delicacy, the number of tapeworms harbored may be
considered a status symbol. Cattle become
infected in areas where raw sewage (aguas negras)
drains into pastures. Chemical treatment of the
soil does not kill the ova, which may live in the
soil for up to 6 months.
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Life cycle. Humans are the definitive host of T.
saginata, and infection occurs after ingestion of
beef containing viable larvas. The larvas are
released with digestion and mature in the upper
small intestine. Adult worms may inhabit the
intestinal tract for as long as 25 years. The
adult worms release eggs that are passed through
the feces onto soil and vegetation. Herbivorous
animals ingest the eggs, which penetrate the
intestinal tract and migrate to the skeletal
muscle.
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Clinical manifestations. The majority of T.
saginata infections are asymptomatic. The most
common symptoms are epigastric pain, nausea,
vomiting, increased appetite, weight loss, and a
spontaneous emerging of proglottid on the anus.
Intestinal obstruction is a rare complication.
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Diagnosis, treatment, and prevention. The
diagnosis is made by finding typical eggs in the
host stool. The eggs of T. saginata and T. solium
are indistinguishable however, the two may be
differentiated through examination of gravid
proglottids pressed between two glass slides. If
more than 13 uterine branches are present on each
side of the proglottid, the infection is
consistent with T. saginata.
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T. solium infection occurs in all areas where raw
or partially cooked pork is eaten. Usually,
clinical cysticercosis refers to disease caused
by T. solium. It is common throughout Mexico,
South America and southern Europe. T. solium
infection is uncommon in the United States, but
of course does occur.
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Life cycle. The life cycle of T. solium is
remarkably similar to that of T. saginata with
the primary difference being the intermediate
host, the pig. Adult worms may inhabit the human
upper intestinal tract for as long as 25 years.
Clinical manifestations. T. solium infection is
usually asymptomatic. The most common intestinal
symptoms include abdominal pain, nausea, vomiting
and diarrhea. One of the most serious
complications is cysticercosis, an infection of
the larval forms of T. solium, which invade the
brain and other organs.
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Diagnosis, treatment, and prevention. The
diagnosis of T. solium infection is made by the
identification of typical eggs in the hosts
stool or by the use of adhesive tape placed on
the anus. The treatment of T. solium infection is
the same as that for T. saginata. Prevention of
T. solium infection can be achieved with adequate
cooking of all pork and pork products. Cysticerci
develop in the brain, very rarely in other organs

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The eggs of Taenia solium and T. sagiata look the
same.Armed scolex of Taenia solium with
rostrellum and hooklets.
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Proglottid of Taenia solium

• Taenia saginata without rostellum, unarmed.

Proglottid of Taenia saginata
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Cystycercosis. The World Health Organization
(WHO) estimates that 50 million people are
infected by the cestode teniasis/cysticercosis
complex, and that 50,000 of them die each year
(0.1 ). Rustic techniques for raising pigs are
one of many factors in disease transmission. Many
human populations show infection rates of
5-15 serologically. Often symptomless,
cysticercosis is always underreported and thus
the prevalence is rarely known. The occurrence of
cysts in the brain is the dramatic feature.
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In a Mexican study of 10,000 cases of
cysticerosis, men were 59.30 and women 40.70
of the population having 9,996 Mexicans, the rest
foreigners. Sixty percent of cases were in the
middle class, 10 in the upper class and 30
among the poor. About 60 of cysts were alive
and 40 calcified. Importantly, 13 were
previously treated with praziquantal with many
complications and required a second treatment
with radioimmune methods.
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The symptoms of the anterior cases were a) 62
headache, b) 25
seizures,
c) 12 endocranial hypertension,
d) 1 pseudotumor,
e) 1 medullar shock
and f) 1
miscellaney. Organs with cysts were a) 97.82
brain, b) 1.00 muscle, c) 0.90 subcutaneus
tissue, d) 0.02 kidney, e) 0.01 heart,
f) 0.03 submaxillary salivary glands,
g) 0.008 eye and h) 0.001 liver.
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Section of brain by Ana Flisser, Universidad
Nacional Autónoma de México, Mexico
X-ray plate showing cyst
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Echinococcosis. Regarding echinococcosis,
Central Europe as western France and eastern
Austria with 210 patients, 61.4 worked as
farmers, gardeners, foresters or hunters, 78
having symptoms. Alveolar echinococcosis was
primarily manifested as a liver disease. Of the
559 patients, 190 (34) were already affected by
spread of the parasitic larval tissue. Of 408
(73) patients alive in 2000, 4.9 were cured.
The increasing prevalence of E. multilocularis
corresponds with the increase in foxes.
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Echinococcosis in humans is a complex of
parasitic diseases caused by the larval stages of
4 species of the cestode genus Echinococcus,
which are perpetuated in life-cycles, involving
domestic and wild carnivores like foxes as
definitive hosts and a wide range of mammals
(livestock animals, rodents, etc.) as
intermediate hosts. Echinococcosis is not only
one of the most devastating parasitic diseases of
humans, but it is also very difficult and costly
to treat, control and prevent.
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Cystic echinococcosis, caused by Echinococcus
granulosus and E. multilocurlaris, remains a
considerable public health (PH) problem in many
countries. These respective diseases are alveolar
and cystic hydatidosis. In the countries of
Central and South America, human polycystic
echinococcosis occurs caused by Echinococcus
vogeli and E. oligarthrus.
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Juvenile proglottids of Echinococcus granulosus
Echinococcus granulosus
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Echinococcosis is mainly caused by larvas of 2
species of small tapeworms, Echinococcus
granulosus (cystic echinococcosis) and E.
multilocularis (alveolar echinococcosis).
E. granulosus occurs worldwide, and
E. multilocularis is found in the Northern
Hemisphere. Humans can develop the diseases when
they ingest eggs excreted with the feces of the
final hosts (dogs and foxes). E. granulosus
larvae then grow as large cysts with internal
budding of brood capsules.
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Detection, serology and related. Eggs and
proglottids in feces are commonly used for
detection. The Echinococcus Western Blot IgG
using a whole larval antigen from E.
multilocularis was evaluated for serodiagnosis
and differentiation between 2 human parasitic
infections of worldwide importance a) cystic
echinococcosis due to E. granulosus and b)
alveolar echinococcosis, due to
E. multilocularis. The assay allowed the
detection of serum immunoglobulin G (IgG)
antibodies in 97 of Echinococcus-infected
patients. E. granulosus was correctly
distinguished from E. multilocularis-infected
patients in 76 of cases.
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Education.A propoganda campaign as a warning on
handling swine and cattle, and of course raw and
undercooked meats can reduce cases, especially if
accompanied by a deparasitizing campaign for
pigs, and even for school children. For
instance, posters of the life cycle on country
fence posts might be appliciple. Control just by
deparasitizing pigs might be sufficient to truely
sanitize the environment. Ignorance of the danger
of cysts in the brain is the main problem. Can PH
education and deparasitizations reduce the number
of operated cases of neurocysticercosis so that
they actually pay for themselves?