3. Taeniasis and Cysticercosis
• Taeniasis refers to intestinal infection by the adult
tapeworm, and cysticercosis results from larval lodging in
various sites.
4. • Two species of tapeworms infest humans, Taenia
solium or the pork tapeworm and T. saginata or beef
tapeworm.
• Man is the only definitive host for both the parasites.
• While the pork tapeworm has a scolex with suckers
and hooks that aid its attachment to the intestinal
wall, hooks are absent in T. saginata.
5. Epidemiology
• Cysticercosis is the most common parasitic disease
worldwide, with an estimated prevalence of more than 50
million persons.
• Neurocysticercosis, the neurologic manifestation of
cysticercosis, is the most prevalent infection of the brain
worldwide.
7. CLINICAL FEATURES
• Infection with adult worm is mostly symptomatic, but some children may have non-specific
symptoms like nausea, abdominal pain and diarrhea. These patients may also develop
cysticercosis through auto-infection.
• Cysts can lodge in the brain, skeletal muscle, subcutaneous tissues, spinal column and
eyes. The two sites associated with high morbidity are the brain, the most common (60-
90%) location for cysts, and the eye, the least common site (1-3%).
• Cysts in the brain parenchyma (parenchymal neurocysticercosis) ause focal or generalized
seizures and, less commonly, headache, focal neurologic deficits, or behavioral abnormality.
Heavy cyst burden can cause encephalopathy with fever, headache, nausea, vomiting,
altered mental status and seizures.
8. • Cysts in the subarachnoid or ventricular spaces may cause
meningeal signs and symptoms, obstructive hydro cephalus
or cranial nerve palsies (by nerve entrapment), those
located in the spinal column can cause radicular pain or
paresthesias.
• Ocular cysts in the subretinal space or vitreous humor can
impair vision by inflammation or It through retinal
detachment, while those in the extraocular is muscles may
limit the range of eye movements and those in the
subconjunctival tissue present as a nodular swelling.
• Skeletal muscle or subcutaneous cysticercosis may be either
asymptomatic or cause localized pain and nodules.
9. Diagnosis
• The diagnosis of teniasis is established by the demonstration of eggs or
proglottids in the stools. Patients may pass motile segments of worms
through anus.
• Diagnosis of neurocysticercosis is based on contrast CT or contrast MRI of
brain; MRI is superior to CT (Fig. 11.27). Demonstration of a solitary
contrast-enhancing lesion less than 20 mm in diameter and producing no
midline shift is highly sensitive for neurocysticercosis; if the scolex is visible,
it is pathognomonic.
10. • Cystic, nonenhancing lesions suggest viable, non-degenerating cysts;
cystic, enhancing lesions indicate degenerating cysts with some
surrounding inflammation; and calcified cysts suggest old cysts that
have already died.
• Ocular or extraocular muscle cysticercosis can be picked up on CT or
ultrasound, or by detailed eye examination.
• Detection of antibodies by enzyme-linked immunoblot assay or enzyme-
linked immunosorbent assay of the serum or cerebrospinal fluid has a
sensitivity of 65-98% and a specificity of 67-100%, varying with the cyst
burden, location, and phase of the infection; the immunoblot assay is the
preferred test.
• Biopsy of the skin or muscle provides a definitive diagnosis in
ambiguous situations, and may be the diagnostic method of choice for
ocular, extraocular muscle. or painful muscular or subcutaneous cysts.
11.
12. TREATMENT
• Infestation with the adult tapeworm (teniasis) is treated with
praziquantel (5-10 mg/kg once) or niclosamide (50 mg/kg once).
Single active parenchymal lesions usually resolve spontaneously and
may not require anticysticercal drugs.
• Watchful waiting is also indicated for calcified cysts because they are
already dead, hence children with seizures and calcified inactive
lesions on CT do not require specific therapy apart from
anticonvulsants.
• The commonly used antiepileptics are phenytoin and
carbamazepine, which should be continued for at least one year and
then tapered or continued based on radiologic resolution.
13. • A meta-analysis demonstrated that cysticidal drug therapy in patients with multiple and live
cysticerci is associated with reduced seizures and increased resolution of lesions in the brain
parenchyma. Two effective anticysticercal drugs are available: Albendazole (15 mg/ Sug kg/day
bid, max dose of 800 mg/day for 7-30 days) or praziquantel (50 mg/kg/day tid for 15-29 days).
Albendazole is more effective than praziquantel.
• A 7-day course of albendazole is perhaps as effective as a 28-day imaging course for single
lesions, though longer courses of 30 days are preferred for giant or subarachnoid cysts. Use of
antihelminthic medications is associated with the risk of an overwhelming inflammatory
response from degenerating cysts. This can be prevented by giving oral corticosteroids
(prednisolone or dexamethasone) for 2-3 days before and during treatment. Intraocular
cysticercosis should be ruled out before using antihelminthic medications as therapy may
cause inflammation and threaten vision.
14. • Treatment of subarachnoid and intraventricular neurocysticercosis is complicated and
risky. Cysts in these locations are usually managed surgically because medical treatment is
associated with the risk of inflammation; however, recent suggest that high-dose
albendazole (30 mg/kg/day) is associated with clearance of these cysts.
• A ventriculoperitoneal shunt should be placed in all patients with evidence of significant
obstructive hydro cephalus. Surgical removal of the cyst is considered the treatment of
choice for intraocular cysts; antihelminthic medication should be avoided as discussed
earlier.
• Cysts in the extraocular muscle may be treated with albendazole and steroids, or
surgically excised. Isolated skeletal muscle or subcutaneous cysticercosis requires no
specific treatment unless, it is painful, and then simple excision may suffice.
15. HYMENOLEPIASIS
• Hymenolepis nana, also known as the dwarf tapeworm.
• Man acts as both definitive and intermediate host
because the entire life cycle may be completed in human
host; however, rodents, ticks and fleas may serve as the
intermediate host. The infestation usually results from
poor hygiene.
16. • The adult worm lives in the jejunum.
• Transmission is mainly feco-oral, but autoinfection may also
occur, such that one host may harbor upto thousands of adult
worms.
• Symptoms are usually non-specific, including mild abdominal
discomfort, poor appetite and cosmophilia, some show growth
retardation.
17. • The infection is a major cause of eosinophilia.
The diagnosis is based on the demonstration of
characteristic eggs in stools. Treatment is with
praziquantel (25mg/kg once) or
niclosamide(50mg/kg once,max 2g)
18. Echinococcosis (HYDATID CYST)
• Caused by members of genus Echinococcus
• Characterized by production of unilocular or multilocular
cyst in the lung and liver
• It is a zoonotic disease.
20. CLINICAL FEATURES
• Symptoms depend on the target organ involved.
• Very often, liver cysts may regress spontaneously without
becoming symptomatic.
• Otherwise, cysts may become symptomatic after several
years when significant mass effect results in abdominal
pain vomiting, increase in abdominal girth and a
palpable mass; jaundice is rare.
21. • Alveolar cysts have a more malignant course. Direct
spread of infected tissue may result in cysts in the
peritoneal cavity, kidneys, adrenal gland or bones.
• Lung cyst may present with chest pain, cough,
hemoptysis and breathlessness.
• Involvement of the genitourinary tract may manifest as
passage of cysts in the urine (hydatiduria) and
hematuria.
• Rupture or leakage from a hydatid cyst may cause
anaphylaxis, manifest as fever, itching and rash, and
results in dissemination of infectious scolices.
22. • Rare but potentially serious complications include
compression of important structures in the central
nervous system, bone, heart, eyes or genitourinary tract.
23. DIAGNOSIS
• Physical examination may reveal a palpable mass, hepatomegaly or
subcutaneous nodules.
• Ultrasonography is the most valuable tool in diagnosing echinococcal
cysts. Lung hydatids may be visible on plain X ray. MRI and CT may
be used for further delineation.
• Diagnostic aspiration is generally contraindicated because of risk of
infection and anaphylaxis.
• Antibody detection by ELISA is more sensitive but less specific.
24. TREATMENT
• Treatment depends on the stage and location of
the lesion, and importantly the experience of the
treating center and includes albendazole,
surgical excision or PAIR (percutaneous
aspiration, instillation of hypertonic saline or
another scolicidal agent; and reaspiration after
15 minutes).
