Tapeworm

Tapeworm Infection (Taeniasis and Cysticercosis)

Introduction

Tapeworm infections are caused by intestinal parasites of the class Cestoda, most commonly species of the genus Taenia. Humans become infected by ingesting larvae or eggs from undercooked meat or contaminated food and water.

• Taeniasis refers to intestinal infection with adult tapeworms.

• Cysticercosis occurs when larvae (cysticerci) invade tissues such as muscles, skin, eyes, or the central nervous system (neurocysticercosis).

Tapeworm infections can range from asymptomatic to life-threatening depending on the species and organ involvement.

---

Causative Species

1. Taenia saginata (beef tapeworm)

   • Transmission: undercooked beef.

   • Humans: definitive host.

2. Taenia solium (pork tapeworm)

   • Transmission: undercooked pork (taeniasis) or ingestion of eggs (cysticercosis).

   • Can cause neurocysticercosis, a leading cause of seizures in endemic regions.

3. Diphyllobothrium latum (fish tapeworm)

   • Transmission: undercooked freshwater fish.

   • Can cause vitamin B12 deficiency and megaloblastic anemia.

4. Echinococcus species (E. granulosus, E. multilocularis)

   • Transmission: ingestion of eggs from dog feces.

   • Causes hydatid disease (cystic echinococcosis) with cysts in liver, lungs, other organs.

---

Life Cycle Overview

1. Eggs or larvae are ingested via contaminated food or undercooked meat.

2. In the intestine, larvae develop into adult tapeworms (several meters long).

3. Segments (proglottids) containing eggs are passed in stool.

4. Intermediate hosts (cattle, pigs, fish, dogs) ingest eggs and develop larval cysts in tissues.

5. Humans consuming infected meat perpetuate the cycle.

---

Clinical Features

Taeniasis (intestinal tapeworm)

• Often asymptomatic.

• Abdominal pain, nausea, diarrhea, or constipation.

• Weight loss or malnutrition (rare).

• Passage of tapeworm segments in stool or underwear (common complaint).

Cysticercosis (larval infection by T. solium)

• Subcutaneous nodules (painless lumps).

• Neurocysticercosis:

  • Seizures (most common symptom).

  • Headaches.

  • Hydrocephalus, focal neurological deficits.

Fish Tapeworm (D. latum)

• May be asymptomatic or cause abdominal pain.

• Vitamin B12 deficiency → megaloblastic anemia.

Hydatid Disease (Echinococcus)

• Liver cysts: abdominal pain, hepatomegaly.

• Lung cysts: cough, chest pain, hemoptysis.

• Cyst rupture → anaphylaxis.

---

Diagnostic Evaluation

• Stool examination: eggs or proglottids (for Taenia, Diphyllobothrium).

• Serology (ELISA, immunoblot): helpful for cysticercosis and echinococcosis.

• Imaging:

  • Ultrasound, CT, MRI for cysts in tissues/organs.

  • Neuroimaging crucial in neurocysticercosis.

• Blood tests: eosinophilia may be present; B12 deficiency in D. latum infection.

---

Treatment

1. Intestinal Tapeworms (Taeniasis, Diphyllobothriasis)

• Praziquantel:

  • 5–10 mg/kg orally once (Taenia saginata, T. solium).

  • 25 mg/kg orally three times in one day (Diphyllobothrium latum).

• Niclosamide (alternative):

  • 2 g orally single dose (adults).

  • 1 g for children 11–34 kg.

  • Must chew thoroughly before swallowing.

---

2. Cysticercosis (T. solium larvae)

• Albendazole: 15 mg/kg/day orally in two divided doses (max 800 mg/day) for 8–28 days.

• Praziquantel: 50–100 mg/kg/day orally in three divided doses for 15–30 days.

Adjunctive therapy:

• Corticosteroids (to reduce inflammation):

  • Prednisone 1 mg/kg/day or

  • Dexamethasone 4–16 mg/day.

• Antiepileptic drugs: for seizure control (e.g., carbamazepine, phenytoin, levetiracetam).

---

3. Hydatid Disease (Echinococcus)

• Albendazole: 10–15 mg/kg/day orally in two divided doses (max 800 mg/day) for several months.

• Mebendazole (alternative): 40–50 mg/kg/day orally in three divided doses.

• Surgery or PAIR procedure (puncture, aspiration, injection, re-aspiration) for large cysts.

• Pre- and post-surgical antihelminthic therapy reduces recurrence risk.

---

4. Supportive and Symptomatic Treatment

• Analgesics for abdominal discomfort.

• Iron and vitamin B12 supplementation (for D. latum anemia).

• Antihistamines and epinephrine for anaphylaxis (ruptured hydatid cysts).

---

Prevention

• Proper cooking of beef, pork, and freshwater fish.

• Regular deworming of dogs in endemic areas (echinococcosis prevention).

• Improved sanitation and hygiene.

• Handwashing after handling raw meat or animals.

• Meat inspection and freezing before consumption.

---

Red Flags (Urgent Medical Attention Needed)

• Sudden severe abdominal pain (possible bowel obstruction or perforation).

• Seizures or neurological deficits (neurocysticercosis).

• Cyst rupture with allergic reaction or anaphylaxis.

• Persistent unexplained weight loss and passage of worm segments.

---

Summary of Key Treatments with Doses

• Praziquantel: 5–10 mg/kg PO single dose (intestinal Taenia); 25 mg/kg TID × 1 day (D. latum).

• Niclosamide: 2 g PO single dose (adults).

• Albendazole: 15 mg/kg/day PO divided BID (max 800 mg/day) × 8–28 days (cysticercosis); 10–15 mg/kg/day for hydatid disease.

• Praziquantel (cysticercosis): 50–100 mg/kg/day PO TID × 15–30 days.

• Prednisone: 1 mg/kg/day PO (for inflammation in cysticercosis).

• Dexamethasone: 4–16 mg/day PO/IV (neurocysticercosis).

• Mebendazole: 40–50 mg/kg/day PO TID (hydatid disease).