Parasitic Infections: Schistosomiasis & Taeniasis/Cysticercosis
Lesson Objectives
By the end of this module, the learner should be able to:
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Describe the epidemiology and pathophysiology of schistosomiasis and taeniasis/cysticercosis in children.
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Differentiate intestinal vs urogenital schistosomiasis.
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Recognize acute and chronic manifestations of both conditions.
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Interpret appropriate paediatric investigations.
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Outline treatment according to Zambia Standard Treatment Protocols.
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Identify when referral to higher-level facilities is required.
SCHISTOSOMIASIS
Description
Schistosomiasis is an acute or chronic parasitic disease caused by blood flukes of the genus Schistosoma.
Infection occurs when larval forms released by freshwater snails penetrate the skin during contact with contaminated water.
Major Forms and Species
| Type | Species |
|---|---|
| Intestinal Schistosomiasis | S. mansoni, S. japonicum, S. mekongi, S. intercalatum |
| Urogenital Schistosomiasis | S. haematobium |
Clinical Features
Acute Infection
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Mild maculopapular skin lesions within hours of exposure.
Intestinal Schistosomiasis
| Stage | Symptoms |
|---|---|
| Acute | Abdominal pain, diarrhoea, blood in stool, fatigue |
| Chronic | Hepatomegaly, splenomegaly, ascites, portal hypertension, pulmonary hypertension |
Urogenital Schistosomiasis
| Group | Symptoms |
|---|---|
| Acute | Haematuria, dysuria, urinary frequency |
| Chronic | Bladder & ureter fibrosis, kidney dysfunction, late bladder cancer |
| Adolescent Girls | Genital lesions, vaginal bleeding, dyspareunia, vulval nodules |
| Adolescent Boys | Seminal vesicle, prostate, and other reproductive organ pathology |
Investigations
| Investigation | Purpose |
|---|---|
| Stool/Urine M/C/S | Detect blood and Schistosoma ova |
| FBC, DC | Look for eosinophilia |
| Urea, Electrolytes, LFTs | Assess organ involvement |
| Chest X-ray | Evaluate pulmonary complications |
| Plain abdominal X-ray | Detect calcifications or fibrosis |
| Abdominal ultrasound | Assess hepatosplenic disease |
| Blood culture | Rule out secondary infection |
| Rectal snip | Identify ova (specialized) |
Treatment
| Treatment | Details |
|---|---|
| Praziquantel | 40 mg/kg single dose for children >2 years and adults |
| Steroids | Consider in very severe disease |
Adverse Effects
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Dizziness
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Headache
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Nausea/vomiting
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Diarrhoea
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Abdominal discomfort
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Bloody stool
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Urticaria
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Fever after dosing (usually mild, lasting ~24 hours)
Prevention
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Praziquantel 40 mg/kg single dose
TAENIASIS / CYSTICERCOSIS
Description
Taeniasis is an intestinal tapeworm infection acquired from eating raw or undercooked infected meat or fish.
Causative Agents
| Organism | Source |
|---|---|
| Taenia saginata | Beef tapeworm |
| Taenia solium | Pork tapeworm |
| Diphyllobothrium latum | Fish tapeworm |
| Hymenolepis nana | Faecal-oral contamination (humans/dogs) |
Cysticercosis occurs when larval forms infect tissues such as:
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Subcutaneous tissue
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Intramuscular tissue
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Eye
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Brain (neurocysticercosis: 60–90% of cases)
Clinical Features
Taeniasis
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Colicky abdominal pain
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Body weakness
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Loss or increased appetite
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Constipation or diarrhoea
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Pruritus ani
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Hyperexcitability
Neurocysticercosis
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Seizures
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Intracranial hypertension: headache, nausea, vomiting, vertigo, papilloedema
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Behavioural changes
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Learning disabilities
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Personality and mental status changes
Investigations
| Investigation | Purpose |
|---|---|
| Stool M/C/S | Identify ova, proglottids, scolex |
| Brain CT or MRI | Confirm neurocysticercosis |
Note:
Refer patients to higher centers when neurocysticercosis is suspected.
Treatment
Taeniasis
| Drug | Dose |
|---|---|
| Praziquantel | 5–10 mg/kg single dose |
Neurocysticercosis
| Treatment | Dose |
|---|---|
| Albendazole | 15 mg/kg/day in 2 divided doses × 15 days |
| Corticosteroids | Prednisolone 1–2 mg/kg/day or dexamethasone |
| Praziquantel | 50 mg/kg/day × 15 days |
| Surgery | For eye, spine, or subcutaneous cysts |
Important caution:
Albendazole and praziquantel should NOT be used for ocular or spine cysts due to risk of inflammatory permanent damage.
Further Treatment
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Anti-epileptic drugs: carbamazepine, phenobarbitone, sodium valproate
→ Continue until seizure-free for 2 years -
Osmotic diuretics for raised intracranial pressure
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Ventriculoperitoneal shunt for hydrocephalus